feat: add submission history

src/common/modules/redis/providers/redis.service.ts

@@ -1,6 +1,7 @@
 import { Inject, Injectable } from '@nestjs/common';
 import { REDIS } from '../constants/redis.constants';
 import Redis from 'ioredis';
+import { randomUUID } from 'crypto';
 
 @Injectable()
 export class RedisService {
@@ -38,6 +39,22 @@ export class RedisService {
     return await this.redis.del(key);
   }
 
+  async acquireLock(key: string, ttlSeconds = 5): Promise<string | null> {
+    const token = randomUUID();
+
+    const result = await this.redis.set(key, token, 'EX', ttlSeconds, 'NX');
+
+    return result === 'OK' ? token : null;
+  }
+
+  async releaseLock(key: string, token: string): Promise<void> {
+    const value = await this.redis.get(key);
+
+    if (value === token) {
+      await this.redis.del(key);
+    }
+  }
+
   async onModuleDestroy() {
     await this.redis.quit();
   }

src/i18n/en/common.json

@@ -3,7 +3,8 @@
     "internalServerError": "Internal Server Error",
     "tooManyRequests": "Too many requests! Try again after {minutes} min.",
     "requestTimeout": "Unable to process your request at the moment.",
-    "entityNotFound": "{entity} not found."
+    "entityNotFound": "{entity} not found.",
+    "sameProcessInProgress": "Same process is in progress."
   },
   "messages": {
     "createSuccess": "{entity} created successfully.",

src/i18n/en/questions.json

@@ -31,8 +31,12 @@
       "endMustNotHaveCondition": "End must not have condition.",
       "invalidTransition": "Invalid Transition!",
       "defaultMustNotHaveCondition": "Default must not have condition.",
+      "fromQuestionMustBeSingleChoice": "fromQuestion must be single choice.",
       "fromQuestionMustBeMultiChoice": "fromQuestion must be multi choice.",
       "invalidChoiceCondition": "Invalid choice condition!",
+      "invalidMultiChoiceCondition": "Invalid multi choice condition!",
+      "invalidMultiChoiceOperator": "Invalid multi choice operator!",
+      "duplicateChoiceIds": "Duplicate choice Ids!",
       "choiceNotBelongToQuestion": "Choice does not belong to the question.",
       "fromQuestionMustBeNumeric": "fromQuestion must be numeric.",
       "invalidNumberRange": "Invalid number range!",

src/i18n/en/submissions.json

@@ -4,13 +4,17 @@
     "questionId": "Question's Id",
     "submission": "Submission",
     "submissionId": "Submission's Id",
-    "choiceId": "Choice's Id"
+    "choiceId": "Choice's Id",
+    "choiceIds": "Choice Ids list"
   },
   "errors": {
     "alreadyTookTest": "You already took this test.",
     "choiceNumericConstraint": "You must send either choiceId or numericValue.",
     "emptyNumericValue": "A numeric value should be provided as answer.",
     "numericValueRange": "Numeric value is out of specified range.",
-    "emptyChoiceId": "Choice Id should be provided as answer."
+    "emptyChoiceId": "Choice Id should be provided as answer.",
+    "emptyChoiceIds": "Choice Ids should be provided as answer.",
+    "transitionNotFound": "No transition found for the test",
+    "uniqueSubmissionQuestion": "Question's Answer already exists."
   }
 }

src/i18n/en/tests.json

@@ -9,7 +9,14 @@
   },
   "errors": {
     "intPrice": "Price should be an integer.",
-    "priceAccessConstraint": "Test's price depends on access type of 'Paid'."
+    "priceAccessConstraint": "Test's price depends on access type of 'Paid'.",
+    "mustHaveSingleStart": "Test must have single start.",
+    "hasOrphanQuestions": "Test has some orphan questions.",
+    "hasCycle": "Test has cycle.",
+    "notEndingFlow": "Test include some flows which never end.",
+    "notActiveTest": "Test is not active.",
+    "multiChoiceMustHaveFallback": "Multi choice must have fallback.",
+    "questionHasMultipleFallbacks": "Question has multiple fallbacks."
   },
   "messages": {
     "createSuccess": "Test Created Successfully."

src/i18n/fa/common.json

@@ -3,7 +3,8 @@
     "internalServerError": "خطایی رخ داد",
     "tooManyRequests": "تعداد درخواست ها بیشتر از حد مجاز است! لطفا بعد از {minutes} دقیقه دوباره امتحان کنید.",
     "requestTimeout": "امکان پردازش درخواست شما در این لحظه وجود ندارد.",
-    "entityNotFound": "{entity} مورد نظر یافت نشد."
+    "entityNotFound": "{entity} مورد نظر یافت نشد.",
+    "sameProcessInProgress": "فرایند مشابهی در حال اجراست."
   },
   "messages": {
     "createSuccess": "{entity} با موفقیت ایجاد شد.",

src/i18n/fa/questions.json

@@ -31,8 +31,12 @@
       "endMustNotHaveCondition": "حالت پایان نباید شرط داشته باشد.",
       "invalidTransition": "مسیر اشتباه است!",
       "defaultMustNotHaveCondition": "حالت پیشفرض نباید شرط داشته باشد.",
-      "fromQuestionMustBeMultiChoice": "سوال مبدا باید چند گزینه ای باشد.",
+      "fromQuestionMustBeSingleChoice": "سوال مبدا باید تک انتخابی باشد.",
+      "fromQuestionMustBeMultiChoice": "سوال مبدا باید چند انتخابی باشد.",
       "invalidChoiceCondition": "شرط گزینه اشتباه است!",
+      "invalidMultiChoiceCondition": "شرط گزینه ها اشتباه است!",
+      "invalidMultiChoiceOperator": "عملگر شرط اشتباه است!",
+      "duplicateChoiceIds": "شناسه گزینه ها تکراری است!",
       "choiceNotBelongToQuestion": "گزینه متعلق به سوال نیست.",
       "fromQuestionMustBeNumeric": "سوال مبدا باید از نوع عددی باشد.",
       "invalidNumberRange": "بازه عددی اشتباه است!",

src/i18n/fa/submissions.json

@@ -4,13 +4,17 @@
     "questionId": "شناسه سوال",
     "submission": "Submission",
     "submissionId": "شناسه Submission",
-    "choiceId": "شناسه گزینه"
+    "choiceId": "شناسه گزینه",
+    "choiceIds": "لیست شناسه گزینه ها"
   },
   "errors": {
     "alreadyTookTest": "قبلا این آزمون را انجام داده اید.",
     "choiceNumericConstraint": "حتما باید یکی از فیلد های شناسه انتخاب و یا مقدار عددی فرستاده شود.",
     "emptyNumericValue": "یک مقدار عددی باید به عنوان پاسخ سوال مشخص شود.",
     "numericValueRange": "مقدار عددی خارج از بازه مشخص شده است.",
-    "emptyChoiceId": "شناسه گزینه باید به عنوان پاسخ مشخص شود."
+    "emptyChoiceId": "شناسه گزینه باید به عنوان پاسخ مشخص شود.",
+    "emptyChoiceIds": "لیستی از شناسه گزینه ها باید به عنوان پاسخ مشخص شود.",
+    "transitionNotFound": "مسیری برای تست پیدا نشد.",
+    "uniqueSubmissionQuestion": "این سوال قبلا پاسخ داده شده است."
   }
 }

src/i18n/fa/tests.json

@@ -9,7 +9,14 @@
   },
   "errors": {
     "intPrice": "قیمت باید عدد صحیح باشد.",
-    "priceAccessConstraint": "قیمت تست به نوع دسترسی 'پرداخت' وابسته است."
+    "priceAccessConstraint": "قیمت تست به نوع دسترسی 'پرداخت' وابسته است.",
+    "mustHaveSingleStart": "تست باید یک سوال شروع داشته باشد.",
+    "hasOrphanQuestions": "تست شامل تعدادی سوال یتیم است.",
+    "hasCycle": "تست شامل حلقه است.",
+    "notEndingFlow": "تست شامل جریان بی پایان است.",
+    "notActiveTest": "تست مورد نظر فعال نیست.",
+    "multiChoiceMustHaveFallback": "سوال چند انتخابی باید یک مسیر جایگزین داشته باشد.",
+    "questionHasMultipleFallbacks": "سوال چند جایگزین دارد!"
   },
   "messages": {
     "createSuccess": "تست با موفقیت ایجاد شد."

src/migrations/1786282238898-SubmissionCurrentQuestion.ts

@@ -0,0 +1,67 @@
+import { MigrationInterface, QueryRunner } from 'typeorm';
+
+export class SubmissionCurrentQuestion1786282238898 implements MigrationInterface {
+  name = 'SubmissionCurrentQuestion1786282238898';
+
+  public async up(queryRunner: QueryRunner): Promise<void> {
+    await queryRunner.query(`DROP INDEX IF EXISTS "public"."unq_test_start"`);
+    await queryRunner.query(`DROP INDEX IF EXISTS "public"."unq_question_end"`);
+    await queryRunner.query(
+      `DROP INDEX IF EXISTS "public"."unq_question_default"`,
+    );
+    await queryRunner.query(
+      `DROP INDEX IF EXISTS "public"."unq_question_choice"`,
+    );
+    await queryRunner.query(
+      `DROP INDEX IF EXISTS "public"."unq_question_number_range"`,
+    );
+    await queryRunner.query(
+      `ALTER TABLE "question_transition" DROP CONSTRAINT "ex_question_number_range_overlap"`,
+    );
+    await queryRunner.query(
+      `ALTER TABLE "submission" RENAME COLUMN "currentQuestionOrder" TO "currentQuestionId"`,
+    );
+    await queryRunner.query(
+      `ALTER TABLE "submission" ALTER COLUMN "currentQuestionId" DROP NOT NULL`,
+    );
+    await queryRunner.query(
+      `ALTER TABLE "submission" ALTER COLUMN "currentQuestionId" DROP DEFAULT`,
+    );
+    await queryRunner.query(
+      `ALTER TABLE "submission" ADD CONSTRAINT "FK_71b22c49b79a4eb32e9b1f05c76" FOREIGN KEY ("currentQuestionId") REFERENCES "question"("id") ON DELETE SET NULL ON UPDATE NO ACTION`,
+    );
+  }
+
+  public async down(queryRunner: QueryRunner): Promise<void> {
+    await queryRunner.query(
+      `ALTER TABLE "submission" DROP CONSTRAINT "FK_71b22c49b79a4eb32e9b1f05c76"`,
+    );
+    await queryRunner.query(
+      `ALTER TABLE "submission" ALTER COLUMN "currentQuestionId" SET DEFAULT '1'`,
+    );
+    await queryRunner.query(
+      `ALTER TABLE "submission" ALTER COLUMN "currentQuestionId" SET NOT NULL`,
+    );
+    await queryRunner.query(
+      `ALTER TABLE "submission" RENAME COLUMN "currentQuestionId" TO "currentQuestionOrder"`,
+    );
+    await queryRunner.query(
+      `ALTER TABLE "question_transition" ADD CONSTRAINT "ex_question_number_range_overlap" EXCLUDE USING gist ("fromQuestionId" WITH =, int4range(((condition ->> 'min'::text))::integer, ((condition ->> 'max'::text))::integer, '[]'::text) WITH &&) WHERE ((type = 'number-range'::question_transition_type_enum))`,
+    );
+    await queryRunner.query(
+      `CREATE UNIQUE INDEX "unq_question_number_range" ON "question_transition" ("fromQuestionId") WHERE (type = 'number-range'::question_transition_type_enum)`,
+    );
+    await queryRunner.query(
+      `CREATE UNIQUE INDEX "unq_question_choice" ON "question_transition" ("fromQuestionId") WHERE (type = 'choice'::question_transition_type_enum)`,
+    );
+    await queryRunner.query(
+      `CREATE UNIQUE INDEX "unq_question_default" ON "question_transition" ("fromQuestionId") WHERE (type = 'default'::question_transition_type_enum)`,
+    );
+    await queryRunner.query(
+      `CREATE UNIQUE INDEX "unq_question_end" ON "question_transition" ("fromQuestionId") WHERE (type = 'end'::question_transition_type_enum)`,
+    );
+    await queryRunner.query(
+      `CREATE UNIQUE INDEX "unq_test_start" ON "question_transition" ("testId") WHERE (type = 'start'::question_transition_type_enum)`,
+    );
+  }
+}

src/migrations/1787294625853-MultiChoiceSubmission.ts

@@ -0,0 +1,107 @@
+import { MigrationInterface, QueryRunner } from 'typeorm';
+
+export class MultiChoiceSubmission1787294625853 implements MigrationInterface {
+  name = 'MultiChoiceSubmission1787294625853';
+
+  public async up(queryRunner: QueryRunner): Promise<void> {
+    await queryRunner.query(
+      `DROP INDEX "public"."IDX_ea78aac2e76e03f1c2fc720f1d"`,
+    );
+    await queryRunner.query(
+      `CREATE TABLE "submission_answer_choices_choice" ("submissionAnswerId" integer NOT NULL, "choiceId" integer NOT NULL, CONSTRAINT "PK_d3154f459415dc8f97a4bb10a1e" PRIMARY KEY ("submissionAnswerId", "choiceId"))`,
+    );
+    await queryRunner.query(
+      `CREATE INDEX "IDX_6f1902623cd8b3b52a5688a949" ON "submission_answer_choices_choice" ("submissionAnswerId") `,
+    );
+    await queryRunner.query(
+      `CREATE INDEX "IDX_2e699b5f339fb37917549c2fbf" ON "submission_answer_choices_choice" ("choiceId") `,
+    );
+    await queryRunner.query(
+      `ALTER TYPE "public"."question_transition_type_enum" RENAME TO "question_transition_type_enum_old"`,
+    );
+    await queryRunner.query(
+      `CREATE TYPE "public"."question_transition_type_enum" AS ENUM('start', 'default', 'choice', 'multi-choice', 'number-range', 'end')`,
+    );
+    await queryRunner.query(
+      `ALTER TABLE "question_transition" ALTER COLUMN "type" TYPE "public"."question_transition_type_enum" USING "type"::"text"::"public"."question_transition_type_enum"`,
+    );
+    await queryRunner.query(
+      `DROP TYPE "public"."question_transition_type_enum_old"`,
+    );
+    await queryRunner.query(
+      `ALTER TYPE "public"."question_type_enum" RENAME TO "question_type_enum_old"`,
+    );
+    await queryRunner.query(
+      `CREATE TYPE "public"."question_type_enum" AS ENUM('single-choice', 'multi-choice', 'numeric', 'text')`,
+    );
+    await queryRunner.query(
+      `ALTER TABLE "question" ALTER COLUMN "type" DROP DEFAULT`,
+    );
+    await queryRunner.query(
+      `ALTER TABLE "question" ALTER COLUMN "type" TYPE "public"."question_type_enum" USING "type"::"text"::"public"."question_type_enum"`,
+    );
+    await queryRunner.query(
+      `ALTER TABLE "question" ALTER COLUMN "type" SET DEFAULT 'single-choice'`,
+    );
+    await queryRunner.query(`DROP TYPE "public"."question_type_enum_old"`);
+    await queryRunner.query(
+      `CREATE UNIQUE INDEX "UNQ_SUBMISSION_QUESTION_IDX" ON "submission_answer" ("submissionId", "questionId") `,
+    );
+    await queryRunner.query(
+      `ALTER TABLE "submission_answer_choices_choice" ADD CONSTRAINT "FK_6f1902623cd8b3b52a5688a949b" FOREIGN KEY ("submissionAnswerId") REFERENCES "submission_answer"("id") ON DELETE CASCADE ON UPDATE CASCADE`,
+    );
+    await queryRunner.query(
+      `ALTER TABLE "submission_answer_choices_choice" ADD CONSTRAINT "FK_2e699b5f339fb37917549c2fbfc" FOREIGN KEY ("choiceId") REFERENCES "choice"("id") ON DELETE CASCADE ON UPDATE CASCADE`,
+    );
+  }
+
+  public async down(queryRunner: QueryRunner): Promise<void> {
+    await queryRunner.query(
+      `ALTER TABLE "submission_answer_choices_choice" DROP CONSTRAINT "FK_2e699b5f339fb37917549c2fbfc"`,
+    );
+    await queryRunner.query(
+      `ALTER TABLE "submission_answer_choices_choice" DROP CONSTRAINT "FK_6f1902623cd8b3b52a5688a949b"`,
+    );
+    await queryRunner.query(
+      `DROP INDEX "public"."UNQ_SUBMISSION_QUESTION_IDX"`,
+    );
+    await queryRunner.query(
+      `CREATE TYPE "public"."question_type_enum_old" AS ENUM('multi-choice', 'numeric', 'text')`,
+    );
+    await queryRunner.query(
+      `ALTER TABLE "question" ALTER COLUMN "type" DROP DEFAULT`,
+    );
+    await queryRunner.query(
+      `ALTER TABLE "question" ALTER COLUMN "type" TYPE "public"."question_type_enum_old" USING "type"::"text"::"public"."question_type_enum_old"`,
+    );
+    await queryRunner.query(
+      `ALTER TABLE "question" ALTER COLUMN "type" SET DEFAULT 'multi-choice'`,
+    );
+    await queryRunner.query(`DROP TYPE "public"."question_type_enum"`);
+    await queryRunner.query(
+      `ALTER TYPE "public"."question_type_enum_old" RENAME TO "question_type_enum"`,
+    );
+    await queryRunner.query(
+      `CREATE TYPE "public"."question_transition_type_enum_old" AS ENUM('start', 'default', 'choice', 'number-range', 'end')`,
+    );
+    await queryRunner.query(
+      `ALTER TABLE "question_transition" ALTER COLUMN "type" TYPE "public"."question_transition_type_enum_old" USING "type"::"text"::"public"."question_transition_type_enum_old"`,
+    );
+    await queryRunner.query(
+      `DROP TYPE "public"."question_transition_type_enum"`,
+    );
+    await queryRunner.query(
+      `ALTER TYPE "public"."question_transition_type_enum_old" RENAME TO "question_transition_type_enum"`,
+    );
+    await queryRunner.query(
+      `DROP INDEX "public"."IDX_2e699b5f339fb37917549c2fbf"`,
+    );
+    await queryRunner.query(
+      `DROP INDEX "public"."IDX_6f1902623cd8b3b52a5688a949"`,
+    );
+    await queryRunner.query(`DROP TABLE "submission_answer_choices_choice"`);
+    await queryRunner.query(
+      `CREATE UNIQUE INDEX "IDX_ea78aac2e76e03f1c2fc720f1d" ON "submission_answer" ("questionId", "submissionId") `,
+    );
+  }
+}

src/migrations/1787294625900-MultiChoiceTransitionUnqIndex.ts

@@ -0,0 +1,26 @@
+import { UNIQUE_QUESTION_MULTI_CHOICE } from '@/modules/questions/constants';
+import { QuestionTransitionType } from '@/modules/questions/enums/question-transition-type.enum';
+import { MigrationInterface, QueryRunner } from 'typeorm';
+
+export class MultiChoiceTransitionUniqueIndex1786856474000 implements MigrationInterface {
+  name = 'AddMultiChoiceTransitionUniqueIndex1750000000000';
+
+  public async up(queryRunner: QueryRunner): Promise<void> {
+    await queryRunner.query(`
+      CREATE UNIQUE INDEX ${UNIQUE_QUESTION_MULTI_CHOICE}
+      ON "question_transition" (
+        "fromQuestionId",
+        "type",
+        (("condition" ->> 'operator')),
+        (("condition" -> 'choiceIds'))
+      )
+      WHERE "type" = '${QuestionTransitionType.MULTI_CHOICE}'
+    `);
+  }
+
+  public async down(queryRunner: QueryRunner): Promise<void> {
+    await queryRunner.query(`
+      DROP INDEX ${UNIQUE_QUESTION_MULTI_CHOICE}
+    `);
+  }
+}

src/modules/questions/constants/index.ts

@@ -8,3 +8,4 @@ export const UNIQUE_QUESTION_END = 'UNQ_QUESTION_END';
 export const UNIQUE_TEST_START = 'UNQ_TEST_START';
 export const EX_QUESTION_NUMBER_RANGE_OVERLAP =
   'EX_QUESTION_NUMBER_RANGE_OVERLAP';
+export const UNIQUE_QUESTION_MULTI_CHOICE = 'UNQ_QUESTION_MULTI_CHOICE';

src/modules/questions/dtos/create-question.dto.ts

@@ -8,7 +8,7 @@ import {
   Validate,
 } from 'class-validator';
 import { QuestionType } from '../enums/question-type.enum';
-import { MultiChoiceMetadataDTO } from './multi-choice-metadata.dto';
+import { SingleChoiceMetadataDTO } from './single-choice-metadata.dto';
 import { NumericMetadataDTO } from './numeric-metadata.dto';
 import { QuestionMetadataValidator } from '../validators/question-metadata.validator';
 import { i18nValidationMessage as t } from 'nestjs-i18n';
@@ -60,5 +60,5 @@ export class CreateQuestionDTO {
 
   @Validate(QuestionMetadataValidator)
   @IsOptional()
-  metadata?: MultiChoiceMetadataDTO | NumericMetadataDTO;
+  metadata?: SingleChoiceMetadataDTO | NumericMetadataDTO;
 }

src/modules/questions/dtos/single-choice-metadata.dto.ts

@@ -1,6 +1,6 @@
 import { IsBoolean, IsOptional } from 'class-validator';
 
-export class MultiChoiceMetadataDTO {
+export class SingleChoiceMetadataDTO {
   @IsBoolean()
   @IsOptional()
   allowOther?: boolean;

src/modules/questions/dtos/update-question.dto.ts

@@ -7,7 +7,7 @@ import {
 } from 'class-validator';
 import { i18nValidationMessage as t } from 'nestjs-i18n';
 import { QuestionType } from '../enums/question-type.enum';
-import { MultiChoiceMetadataDTO } from './multi-choice-metadata.dto';
+import { SingleChoiceMetadataDTO } from './single-choice-metadata.dto';
 import { NumericMetadataDTO } from './numeric-metadata.dto';
 
 export class UpdateQuestionDTO {
@@ -48,5 +48,5 @@ export class UpdateQuestionDTO {
   required?: boolean;
 
   @IsOptional()
-  metadata?: MultiChoiceMetadataDTO | NumericMetadataDTO;
+  metadata?: SingleChoiceMetadataDTO | NumericMetadataDTO;
 }

src/modules/questions/entities/question-transition.entity.ts

@@ -9,7 +9,7 @@ export class QuestionTransition {
   @PrimaryGeneratedColumn()
   id!: number;
 
-  @ManyToOne(() => Test, { onDelete: 'CASCADE' })
+  @ManyToOne(() => Test, (test) => test.transitions, { onDelete: 'CASCADE' })
   test!: Test;
 
   @ManyToOne(() => Question, { nullable: true, onDelete: 'CASCADE' })

src/modules/questions/entities/question.entity.ts

@@ -29,7 +29,7 @@ export class Question {
   @Column({
     type: 'enum',
     enum: QuestionType,
-    default: QuestionType.MULTI_CHOICE,
+    default: QuestionType.SINGLE_CHOICE,
   })
   type!: QuestionType;
 
@@ -59,7 +59,7 @@ export class Question {
   outgoingTransitions!: Array<QuestionTransition>;
 
   @OneToMany(() => QuestionTransition, (transition) => transition.toQuestion)
-  incomingTransition!: Array<QuestionTransition>;
+  incomingTransitions!: Array<QuestionTransition>;
 
   @CreateDateColumn()
   createdAt!: Date;

src/modules/questions/enums/multi-choice-tcondition-operator.enum.ts

@@ -0,0 +1,5 @@
+export enum MultiChoiceTConditionOperator {
+  ANY = 'any',
+  ALL = 'all',
+  EXACT = 'exact',
+}

src/modules/questions/enums/question-transition-type.enum.ts

@@ -2,6 +2,7 @@ export enum QuestionTransitionType {
   START = 'start',
   DEFAULT = 'default',
   CHOICE = 'choice',
+  MULTI_CHOICE = 'multi-choice',
   NUMBER_RANGE = 'number-range',
   END = 'end',
 }

src/modules/questions/enums/question-type.enum.ts

@@ -1,4 +1,5 @@
 export enum QuestionType {
+  SINGLE_CHOICE = 'single-choice',
   MULTI_CHOICE = 'multi-choice',
   NUMERIC = 'numeric',
   TEXT = 'text',

src/modules/questions/helpers/validate-metadata.helper.ts

@@ -2,7 +2,7 @@ import { plainToInstance } from 'class-transformer';
 import { QuestionType } from '../enums/question-type.enum';
 import { QuestionMetadata } from '../types/question-metadata.type';
 import { NumericMetadataDTO } from '../dtos/numeric-metadata.dto';
-import { MultiChoiceMetadataDTO } from '../dtos/multi-choice-metadata.dto';
+import { SingleChoiceMetadataDTO } from '../dtos/single-choice-metadata.dto';
 import { validate } from 'class-validator';
 import { ValidationError } from '@nestjs/common';
 
@@ -22,8 +22,8 @@ export const validateMetadata = async (
       break;
 
     default:
-    case QuestionType.MULTI_CHOICE:
-      validateDto = plainToInstance(MultiChoiceMetadataDTO, metadata);
+    case QuestionType.SINGLE_CHOICE:
+      validateDto = plainToInstance(SingleChoiceMetadataDTO, metadata);
       break;
   }
 

src/modules/questions/interfaces/multi-choice-condition.interface.ts

@@ -0,0 +1,6 @@
+import { MultiChoiceTConditionOperator } from '../enums/multi-choice-tcondition-operator.enum';
+
+export interface MultiChoiceCondition {
+  choiceIds: number[];
+  operator: MultiChoiceTConditionOperator;
+}

src/modules/questions/interfaces/multi-choice-metadata.interface.ts

@@ -1,3 +0,0 @@
-export interface MultiChoiceMetadata {
-  allowOther?: boolean;
-}

src/modules/questions/interfaces/single-choice-metadata.interface.ts

@@ -0,0 +1,3 @@
+export interface SingleChoiceMetadata {
+  allowOther?: boolean;
+}

src/modules/questions/providers/transition/question-transition-command.provider.ts

@@ -15,6 +15,8 @@ import {
 import { UpdateQuestionTransitionDTO } from '../../dtos/update-question-transition.dto';
 import { AppTimeoutException } from '@/common/exceptions/app-timeout.exception';
 import { AppException } from '@/common/exceptions/app.exception';
+import { QuestionTransitionType } from '../../enums/question-transition-type.enum';
+import { MultiChoiceCondition } from '../../interfaces/multi-choice-condition.interface';
 
 @Injectable()
 export class QuestionTransitionCommandProvider {
@@ -44,7 +46,15 @@ export class QuestionTransitionCommandProvider {
       fromQuestion,
       toQuestion,
       type,
-      condition: conditionValue,
+      condition:
+        type !== QuestionTransitionType.MULTI_CHOICE
+          ? conditionValue
+          : {
+              ...conditionValue,
+              choiceIds: [
+                ...(conditionValue as MultiChoiceCondition).choiceIds,
+              ].sort((a, b) => a - b),
+            },
     });
 
     try {

src/modules/questions/providers/transition/validations/check-transition-db.provider.ts

@@ -1,6 +1,7 @@
 import { AppException } from '@/common/exceptions/app.exception';
 import { QuestionTransition } from '@/modules/questions/entities/question-transition.entity';
 import { QuestionTransitionType } from '@/modules/questions/enums/question-transition-type.enum';
+import { MultiChoiceCondition } from '@/modules/questions/interfaces/multi-choice-condition.interface';
 import { NumericCondition } from '@/modules/questions/interfaces/numeric-condition.interface';
 import { SingleChoiceCondition } from '@/modules/questions/interfaces/single-choice-condition.interface';
 import { TransitionValidateOptions } from '@/modules/questions/interfaces/transition-validate-options.interface';
@@ -147,6 +148,20 @@ export class CheckTransitionDBProvider {
       });
     }
 
+    if (options.type === QuestionTransitionType.MULTI_CHOICE) {
+      const condition = options.conditionValue as MultiChoiceCondition;
+
+      qb.andWhere(`t.condition ->> 'operator' = :operator`, {
+        operator: condition.operator,
+      });
+
+      qb.andWhere(`t.condition -> 'choiceIds' = :choiceIds::jsonb`, {
+        choiceIds: JSON.stringify(
+          [...condition.choiceIds].sort((a, b) => a - b),
+        ),
+      });
+    }
+
     if (options.type === QuestionTransitionType.NUMBER_RANGE) {
       qb.andWhere(`t.condition ->> 'min' = :min`, {
         min: String((options.conditionValue as NumericCondition).min),

src/modules/questions/questions.module.ts

@@ -60,6 +60,7 @@ import { QuestionTransitionService } from './providers/transition/question-trans
     ChoicesService,
     QuestionRangeRuleService,
     QuestionTransitionService,
+    TypeOrmModule,
   ],
 })
 export class QuestionsModule {}

src/modules/questions/types/question-metadata.type.ts

@@ -1,4 +1,4 @@
-import { MultiChoiceMetadata } from '../interfaces/multi-choice-metadata.interface';
+import { SingleChoiceMetadata } from '../interfaces/single-choice-metadata.interface';
 import { NumericMetadata } from '../interfaces/numeric-metadata.interface';
 
-export type QuestionMetadata = NumericMetadata | MultiChoiceMetadata;
+export type QuestionMetadata = NumericMetadata | SingleChoiceMetadata;

src/modules/questions/types/transition-condition.type.ts

@@ -1,7 +1,6 @@
+import { MultiChoiceCondition } from '../interfaces/multi-choice-condition.interface';
 import { NumericCondition } from '../interfaces/numeric-condition.interface';
 import { SingleChoiceCondition } from '../interfaces/single-choice-condition.interface';
 
 export type TransitionConditionType =
-  | SingleChoiceCondition
-  | NumericCondition
-  | null;
+  SingleChoiceCondition | MultiChoiceCondition | NumericCondition | null;

src/modules/questions/validators/question-transition-type.validator.ts

@@ -6,6 +6,8 @@ import { SingleChoiceCondition } from '@/modules/questions/interfaces/single-cho
 import { TransitionValidateOptions } from '@/modules/questions/interfaces/transition-validate-options.interface';
 import { HttpStatus } from '@nestjs/common';
 import { NumericMetadata } from '../interfaces/numeric-metadata.interface';
+import { MultiChoiceCondition } from '../interfaces/multi-choice-condition.interface';
+import { MultiChoiceTConditionOperator } from '../enums/multi-choice-tcondition-operator.enum';
 
 export class QuestionTransitionTypeValidator {
   public static validateTransitionType(options: TransitionValidateOptions) {
@@ -26,6 +28,10 @@ export class QuestionTransitionTypeValidator {
         this.validateChoiceTransition(options);
         return;
 
+      case QuestionTransitionType.MULTI_CHOICE:
+        this.validateMultiChoiceTransition(options);
+        return;
+
       case QuestionTransitionType.NUMBER_RANGE:
         this.validateNumberBetweenTransition(options);
         return;
@@ -104,9 +110,9 @@ export class QuestionTransitionTypeValidator {
       );
     }
 
-    if (fromQuestion.type !== QuestionType.MULTI_CHOICE) {
+    if (fromQuestion.type !== QuestionType.SINGLE_CHOICE) {
       throw new AppException(
-        'questions.errors.questionTransition.fromQuestionMustBeMultiChoice',
+        'questions.errors.questionTransition.fromQuestionMustBeSingleChoice',
         HttpStatus.BAD_REQUEST,
       );
     }
@@ -132,6 +138,83 @@ export class QuestionTransitionTypeValidator {
     }
   }
 
+  private static validateMultiChoiceTransition(
+    options: TransitionValidateOptions,
+  ) {
+    const { fromQuestion, toQuestion, conditionValue } = options;
+
+    if (!fromQuestion || !toQuestion) {
+      throw new AppException(
+        'questions.errors.questionTransition.invalidTransition',
+        HttpStatus.BAD_REQUEST,
+      );
+    }
+
+    if (fromQuestion.type !== QuestionType.MULTI_CHOICE) {
+      throw new AppException(
+        'questions.errors.questionTransition.fromQuestionMustBeMultiChoice',
+        HttpStatus.BAD_REQUEST,
+      );
+    }
+
+    const condition = conditionValue as MultiChoiceCondition;
+
+    if (
+      !condition ||
+      !Array.isArray(condition.choiceIds) ||
+      condition.choiceIds.length === 0
+    ) {
+      throw new AppException(
+        'questions.errors.questionTransition.invalidMultiChoiceCondition',
+        HttpStatus.BAD_REQUEST,
+      );
+    }
+
+    if (
+      !Object.values(MultiChoiceTConditionOperator).includes(condition.operator)
+    ) {
+      throw new AppException(
+        'questions.errors.questionTransition.invalidMultiChoiceOperator',
+        HttpStatus.BAD_REQUEST,
+      );
+    }
+
+    const choiceIdsAreValid = condition.choiceIds.every(
+      (choiceId) => typeof choiceId === 'number' && Number.isInteger(choiceId),
+    );
+
+    if (!choiceIdsAreValid) {
+      throw new AppException(
+        'questions.errors.questionTransition.invalidMultiChoiceCondition',
+        HttpStatus.BAD_REQUEST,
+      );
+    }
+
+    const uniqueChoiceIds = new Set(condition.choiceIds);
+
+    if (uniqueChoiceIds.size !== condition.choiceIds.length) {
+      throw new AppException(
+        'questions.errors.questionTransition.duplicateChoiceIds',
+        HttpStatus.BAD_REQUEST,
+      );
+    }
+
+    const questionChoiceIds = new Set(
+      fromQuestion.choices?.map((choice) => choice.id) ?? [],
+    );
+
+    const allChoicesBelongToQuestion = condition.choiceIds.every((choiceId) =>
+      questionChoiceIds.has(choiceId),
+    );
+
+    if (!allChoicesBelongToQuestion) {
+      throw new AppException(
+        'questions.errors.questionTransition.choiceNotBelongToQuestion',
+        HttpStatus.BAD_REQUEST,
+      );
+    }
+  }
+
   private static validateNumberBetweenTransition(
     options: TransitionValidateOptions,
   ) {

src/modules/scoring/scoring.module.ts

@@ -13,6 +13,6 @@ import { ResultRangeQueryProvider } from './providers/result-range-query.provide
     ResultRangeQueryProvider,
     ResultRangeService,
   ],
-  exports: [ResultRangeService],
+  exports: [ResultRangeService, TypeOrmModule],
 })
 export class ScoringModule {}

src/modules/submissions/constants/index.ts

@@ -0,0 +1 @@
+export const UNIQUE_SUBMISSION_QUESTION_IDX = 'UNQ_SUBMISSION_QUESTION_IDX';

src/modules/submissions/dtos/answer-submission.dto.ts

@@ -1,4 +1,4 @@
-import { IsNumber, IsOptional } from 'class-validator';
+import { IsArray, IsInt, IsNumber, IsOptional } from 'class-validator';
 import { SubmissionAnswer } from '../decorators/submission-answer.decorator';
 
 export class AnswerSubmissionDTO {
@@ -6,6 +6,11 @@ export class AnswerSubmissionDTO {
   @IsOptional()
   choiceId?: number;
 
+  @IsArray()
+  @IsOptional()
+  @IsInt({ each: true })
+  choiceIds?: number[];
+
   @IsNumber()
   @IsOptional()
   numericValue?: number;

src/modules/submissions/entities/submission-answer.entity.ts

@@ -2,15 +2,20 @@ import {
   Column,
   Entity,
   Index,
+  JoinTable,
+  ManyToMany,
   ManyToOne,
   PrimaryGeneratedColumn,
 } from 'typeorm';
 import { Submission } from './submission.entity';
 import { Question } from '@/modules/questions/entities/question.entity';
 import { Choice } from '@/modules/questions/entities/choice.entity';
+import { UNIQUE_SUBMISSION_QUESTION_IDX } from '../constants';
 
 @Entity()
-@Index(['submission', 'question'], { unique: true })
+@Index(UNIQUE_SUBMISSION_QUESTION_IDX, ['submission', 'question'], {
+  unique: true,
+})
 export class SubmissionAnswer {
   @PrimaryGeneratedColumn()
   id!: number;
@@ -26,6 +31,10 @@ export class SubmissionAnswer {
   @ManyToOne(() => Choice, { nullable: true, onDelete: 'CASCADE' })
   choice?: Choice;
 
+  @ManyToMany(() => Choice)
+  @JoinTable()
+  choices?: Array<Choice>;
+
   @Column({ type: 'int', nullable: true })
   numericValue?: number;
 

src/modules/submissions/entities/submission.entity.ts

@@ -12,6 +12,7 @@ import {
 import { SubmissionStatus } from '../enums/submission-status.enum';
 import { SubmissionAnswer } from './submission-answer.entity';
 import { SubmissionResult } from './submission-result.entity';
+import { Question } from '@/modules/questions/entities/question.entity';
 
 @Entity()
 export class Submission {
@@ -31,8 +32,8 @@ export class Submission {
   })
   status!: SubmissionStatus;
 
-  @Column({ type: 'int', nullable: false, default: 1 })
-  currentQuestionOrder!: number;
+  @ManyToOne(() => Question, { onDelete: 'SET NULL', nullable: true })
+  currentQuestion!: Question | null;
 
   @OneToMany(() => SubmissionAnswer, (answer) => answer.submission)
   answers!: Array<SubmissionAnswer>;

src/modules/submissions/helpers/check-answer-correctness.helper.ts

@@ -0,0 +1,59 @@
+import { Question } from '@/modules/questions/entities/question.entity';
+import { AnswerSubmissionDTO } from '../dtos/answer-submission.dto';
+import { BadRequestException, HttpStatus } from '@nestjs/common';
+import { QuestionType } from '@/modules/questions/enums/question-type.enum';
+import { NumericMetadata } from '@/modules/questions/interfaces/numeric-metadata.interface';
+import { AppException } from '@/common/exceptions/app.exception';
+
+export const checkAnswerCorrectness = (
+  question: Question,
+  answerSubmissionDto: AnswerSubmissionDTO,
+) => {
+  if (!answerSubmissionDto) throw new BadRequestException();
+
+  const { choiceId, choiceIds, numericValue } = answerSubmissionDto;
+
+  if (question.type === QuestionType.NUMERIC) {
+    if (numericValue === undefined) {
+      throw new BadRequestException('submissions.errors.emptyNumericValue');
+    }
+
+    const metadata = question.metadata as NumericMetadata;
+
+    if (
+      metadata &&
+      (numericValue < metadata.min || numericValue > metadata.max)
+    ) {
+      throw new BadRequestException('submissions.errors.numericValueRange');
+    }
+  }
+
+  const questionChoiceIds = question.choices.map((el) => el.id);
+
+  if (question.type === QuestionType.SINGLE_CHOICE) {
+    if (choiceId === undefined || choiceId === null) {
+      throw new BadRequestException('submissions.errors.emptyChoiceId');
+    }
+
+    if (!questionChoiceIds.some((c) => c === choiceId)) {
+      throw new AppException('validation.wrongField', HttpStatus.BAD_REQUEST, {
+        field: '$t(submissions.fields.choiceId)',
+      });
+    }
+  }
+
+  if (question.type === QuestionType.MULTI_CHOICE) {
+    if (choiceIds === undefined || choiceIds === null) {
+      throw new BadRequestException('submissions.errors.emptyChoiceId');
+    }
+
+    if (
+      choiceIds.length > 0 &&
+      !choiceIds.every((el) => questionChoiceIds.includes(el))
+    ) {
+      throw new AppException('validation.wrongField', HttpStatus.BAD_REQUEST, {
+        field: '$t(submissions.fields.choiceIds)',
+      });
+    }
+  }
+};

src/modules/submissions/helpers/get-next-transition.helper.ts

@@ -0,0 +1,116 @@
+import { Question } from '@/modules/questions/entities/question.entity';
+import { AnswerSubmissionDTO } from '../dtos/answer-submission.dto';
+import { QuestionTransitionType } from '@/modules/questions/enums/question-transition-type.enum';
+import { QuestionType } from '@/modules/questions/enums/question-type.enum';
+import { SingleChoiceCondition } from '@/modules/questions/interfaces/single-choice-condition.interface';
+import { NumericCondition } from '@/modules/questions/interfaces/numeric-condition.interface';
+import { AppException } from '@/common/exceptions/app.exception';
+import { HttpStatus } from '@nestjs/common';
+import { MultiChoiceCondition } from '@/modules/questions/interfaces/multi-choice-condition.interface';
+import { MultiChoiceTConditionOperator } from '@/modules/questions/enums/multi-choice-tcondition-operator.enum';
+
+export const getNextTransition = (
+  question: Question,
+  answerSubmissionDto: AnswerSubmissionDTO,
+) => {
+  const transitions = question.outgoingTransitions ?? [];
+
+  const endTransition = transitions.find(
+    (t) => t.type === QuestionTransitionType.END,
+  );
+
+  if (
+    question.type === QuestionType.SINGLE_CHOICE &&
+    answerSubmissionDto.choiceId !== undefined
+  ) {
+    const transition = transitions.find(
+      (t) =>
+        t.type === QuestionTransitionType.CHOICE &&
+        (t.condition as SingleChoiceCondition).choiceId ===
+          answerSubmissionDto.choiceId,
+    );
+
+    if (transition) return transition;
+  }
+
+  if (
+    question.type === QuestionType.MULTI_CHOICE &&
+    answerSubmissionDto.choiceIds !== undefined
+  ) {
+    const selectedChoiceIds = new Set(answerSubmissionDto.choiceIds);
+
+    const transition = transitions.find((t) => {
+      if (t.type !== QuestionTransitionType.MULTI_CHOICE) {
+        return false;
+      }
+
+      const condition = t.condition as MultiChoiceCondition;
+
+      if (
+        !condition ||
+        !Array.isArray(condition.choiceIds) ||
+        !condition.operator
+      ) {
+        return false;
+      }
+
+      const conditionChoiceIds = new Set(condition.choiceIds);
+
+      switch (condition.operator) {
+        case MultiChoiceTConditionOperator.ANY:
+          return [...conditionChoiceIds].some((id) =>
+            selectedChoiceIds.has(id),
+          );
+
+        case MultiChoiceTConditionOperator.ALL:
+          return [...conditionChoiceIds].every((id) =>
+            selectedChoiceIds.has(id),
+          );
+
+        case MultiChoiceTConditionOperator.EXACT:
+          if (selectedChoiceIds.size !== conditionChoiceIds.size) {
+            return false;
+          }
+
+          return [...conditionChoiceIds].every((id) =>
+            selectedChoiceIds.has(id),
+          );
+
+        default:
+          return false;
+      }
+    });
+
+    if (transition) return transition;
+  }
+
+  if (
+    question.type === QuestionType.NUMERIC &&
+    answerSubmissionDto.numericValue !== undefined
+  ) {
+    const value = answerSubmissionDto.numericValue;
+
+    const transition = transitions.find((t) => {
+      if (t.type !== QuestionTransitionType.NUMBER_RANGE) return false;
+
+      const condition = t.condition as NumericCondition;
+
+      return value >= condition.min && value <= condition.max;
+    });
+
+    if (transition) return transition;
+  }
+
+  const defaultTransition = transitions.find(
+    (t) => t.type === QuestionTransitionType.DEFAULT,
+  );
+
+  if (defaultTransition) return defaultTransition;
+
+  if (endTransition) return endTransition;
+
+  throw new AppException(
+    'submissions.errors.nextQuestionNotFound',
+    HttpStatus.BAD_REQUEST,
+  );
+};

src/modules/submissions/interfaces/guest-submission-answer.interface.ts

@@ -0,0 +1,6 @@
+export interface GuestSubmissionAnswer {
+  questionId: number;
+  choiceId?: number;
+  choiceIds?: Array<number>;
+  numericValue?: number;
+}

src/modules/submissions/interfaces/guest-submission-result.interface.ts

@@ -0,0 +1,6 @@
+export interface GuestSubmissionResult {
+  score: number;
+  probability: number;
+  title: string;
+  description: string;
+}

src/modules/submissions/interfaces/guest-submission-session.interface.ts

@@ -0,0 +1,9 @@
+import { GuestSubmissionAnswer } from './guest-submission-answer.interface';
+import { GuestSubmissionResult } from './guest-submission-result.interface';
+
+export interface GuestSubmissionSession {
+  testId: number;
+  currentQuestionId: number | null;
+  answers: Array<GuestSubmissionAnswer>;
+  result?: GuestSubmissionResult;
+}

src/modules/submissions/interfaces/guest-submission-session.interfaces.ts

@@ -1,9 +0,0 @@
-export interface GuestSubmissionSession {
-  testId: number;
-  currentQuestion: number;
-  answers: Array<{
-    questionId: number;
-    choiceId: number;
-    numericValue: number;
-  }>;
-}

src/modules/submissions/providers/answer/answer-authenticated.provider.ts

@@ -1,25 +1,24 @@
-import { BadRequestException, HttpStatus, Injectable } from '@nestjs/common';
-import { DataSource, In, Repository } from 'typeorm';
-import { Submission } from '../entities/submission.entity';
-import { InjectRepository } from '@nestjs/typeorm';
-import { AnswerSubmissionDTO } from '../dtos/answer-submission.dto';
-import { AppTimeoutException } from '@/common/exceptions/app-timeout.exception';
+import { ConflictException, HttpStatus, Injectable } from '@nestjs/common';
+import { AnswerSubmissionDTO } from '../../dtos/answer-submission.dto';
 import { User } from '@/modules/users/entities/user.entity';
+import { Submission } from '../../entities/submission.entity';
 import { AppException } from '@/common/exceptions/app.exception';
-import { RedisService } from '@/common/modules/redis/providers/redis.service';
-import { isUUID } from 'class-validator';
-import { GuestSubmissionSession } from '../interfaces/guest-submission-session.interfaces';
-import { Question } from '@/modules/questions/entities/question.entity';
+import { AppTimeoutException } from '@/common/exceptions/app-timeout.exception';
+import { SubmissionResult } from '../../entities/submission-result.entity';
 import { AppResponse } from '@/common/responses';
+import { checkAnswerCorrectness } from '../../helpers/check-answer-correctness.helper';
 import { QuestionType } from '@/modules/questions/enums/question-type.enum';
-import { NumericMetadata } from '@/modules/questions/interfaces/numeric-metadata.interface';
-import { SubmissionAnswer } from '../entities/submission-answer.entity';
+import { getNextTransition } from '../../helpers/get-next-transition.helper';
+import { DataSource, QueryFailedError, Repository } from 'typeorm';
+import { InjectRepository } from '@nestjs/typeorm';
+import { SubmissionAnswer } from '../../entities/submission-answer.entity';
+import { QuestionTransitionType } from '@/modules/questions/enums/question-transition-type.enum';
+import { SubmissionStatus } from '../../enums/submission-status.enum';
 import { CalculateResultProvider } from './calculate-result.provider';
-import { QuestionsService } from '@/modules/questions/providers/questions.service';
-import { SubmissionResult } from '../entities/submission-result.entity';
+import { UNIQUE_SUBMISSION_QUESTION_IDX } from '../../constants';
 
 @Injectable()
-export class AnswerSubmissionProvider {
+export class AnswerAuthenticatedProvider {
   constructor(
     /**
      * Inject Submission Repository
@@ -27,11 +26,6 @@ export class AnswerSubmissionProvider {
     @InjectRepository(Submission)
     private readonly submissionRepository: Repository<Submission>,
 
-    /**
-     * Inject Redis Service
-     */
-    private readonly redisService: RedisService,
-
     /**
      * Inject SubmisionAnswer Repository
      */
@@ -45,34 +39,17 @@ export class AnswerSubmissionProvider {
     private readonly submissionResultRepository: Repository<SubmissionResult>,
 
     /**
-     * Inject Questions Service
+     * Inject DataSource
      */
-    private readonly questionsService: QuestionsService,
+    private readonly dataSource: DataSource,
 
     /**
      * Inject CalculateResult Provider
      */
     private readonly calculateResultProvider: CalculateResultProvider,
-
-    /**
-     * Inject DataSource
-     */
-    private readonly dataSource: DataSource,
   ) {}
 
   public async answer(
-    id: string,
-    answerSubmissionDto: AnswerSubmissionDTO,
-    user?: User,
-  ) {
-    if (user) {
-      return await this.answerAuthenticated(id, answerSubmissionDto, user);
-    } else {
-      return await this.answerGuest(id, answerSubmissionDto);
-    }
-  }
-
-  private async answerAuthenticated(
     id: string,
     answerSubmissionDto: AnswerSubmissionDTO,
     user: User,
@@ -94,6 +71,14 @@ export class AnswerSubmissionProvider {
         where: { id: submissionId, user: { id: user.id } },
         relations: {
           test: true,
+          currentQuestion: {
+            choices: true,
+            outgoingTransitions: {
+              toQuestion: {
+                choices: true,
+              },
+            },
+          },
         },
       });
     } catch (err) {
@@ -108,23 +93,7 @@ export class AnswerSubmissionProvider {
       );
     }
 
-    const [currentQuestion, nextQuestion]: Array<Question | null> =
-      await this.questionsService.findByOptionsForAdmin({
-        where: {
-          test: { id: submission.test.id },
-          order: In([
-            submission.currentQuestionOrder,
-            submission.currentQuestionOrder + 1,
-          ]),
-        },
-        relations: {
-          choices: true,
-          rangeRules: true,
-        },
-        order: {
-          order: 'ASC',
-        },
-      });
+    const currentQuestion = submission.currentQuestion;
 
     if (!currentQuestion) {
       let result: SubmissionResult | null;
@@ -154,7 +123,7 @@ export class AnswerSubmissionProvider {
       });
     }
 
-    this.checkAnswerCorrectness(currentQuestion, answerSubmissionDto);
+    checkAnswerCorrectness(currentQuestion, answerSubmissionDto);
 
     const submissionAnswer = this.submissionAnswerRepository.create({
       submission,
@@ -162,8 +131,8 @@ export class AnswerSubmissionProvider {
     });
 
     if (
-      currentQuestion.type === QuestionType.MULTI_CHOICE &&
-      answerSubmissionDto.choiceId
+      currentQuestion.type === QuestionType.SINGLE_CHOICE &&
+      answerSubmissionDto.choiceId !== undefined
     ) {
       const choice = currentQuestion.choices.find(
         (el) => el.id === answerSubmissionDto.choiceId,
@@ -178,6 +147,15 @@ export class AnswerSubmissionProvider {
       }
 
       submissionAnswer.choice = choice;
+    } else if (
+      currentQuestion.type === QuestionType.MULTI_CHOICE &&
+      answerSubmissionDto.choiceIds !== undefined
+    ) {
+      const choices = currentQuestion.choices.filter((el) =>
+        answerSubmissionDto.choiceIds?.includes(el.id),
+      );
+
+      submissionAnswer.choices = choices;
     } else if (
       currentQuestion.type === QuestionType.NUMERIC &&
       answerSubmissionDto.numericValue !== undefined
@@ -185,14 +163,31 @@ export class AnswerSubmissionProvider {
       submissionAnswer.numericValue = answerSubmissionDto.numericValue;
     }
 
+    const nextTransition = getNextTransition(
+      currentQuestion,
+      answerSubmissionDto,
+    );
+
+    const nextQuestion = nextTransition.toQuestion ?? null;
+
     let completedResponse: object | null = null;
 
     try {
       completedResponse = await this.dataSource.transaction(async (manager) => {
         await manager.save(submissionAnswer);
 
-        if (!nextQuestion) {
-          const result = await this.calculateResultProvider.calculate(
+        if (
+          nextTransition.type === QuestionTransitionType.END ||
+          !nextQuestion
+        ) {
+          await manager.update(
+            Submission,
+            { id: submission.id },
+            { currentQuestion: null, status: SubmissionStatus.COMPLETED },
+          );
+
+          const result =
+            await this.calculateResultProvider.calculateAuthenticated(
               submission,
               manager,
             );
@@ -204,16 +199,25 @@ export class AnswerSubmissionProvider {
           };
         }
 
-        await manager.increment(
+        await manager.update(
           Submission,
           { id: submission.id },
-          'currentQuestionOrder',
-          1,
+          { currentQuestion: nextQuestion },
         );
 
         return null;
       });
     } catch (err) {
+      if (
+        err instanceof QueryFailedError &&
+        // eslint-disable-next-line @typescript-eslint/no-unsafe-member-access
+        (err as any).constraint === UNIQUE_SUBMISSION_QUESTION_IDX
+      ) {
+        throw new ConflictException(
+          'submissions.errors.uniqueSubmissionQuestion',
+        );
+      }
+
       throw new AppTimeoutException(err);
     }
 
@@ -225,11 +229,11 @@ export class AnswerSubmissionProvider {
       isCompleted: false,
       // isFinal: ,
       currentQuestion: {
-        type: nextQuestion.type,
-        content: nextQuestion.content,
-        required: nextQuestion.required,
-        metadata: nextQuestion.metadata,
-        choices: nextQuestion.choices.map((el) => ({
+        type: nextQuestion?.type,
+        content: nextQuestion?.content,
+        required: nextQuestion?.required,
+        metadata: nextQuestion?.metadata,
+        choices: nextQuestion?.choices.map((el) => ({
           id: el.id,
           text: el.text,
           order: el.order,
@@ -237,63 +241,4 @@ export class AnswerSubmissionProvider {
       },
     });
   }
-
-  private async answerGuest(
-    id: string,
-    answerSubmissionDto: AnswerSubmissionDTO,
-  ) {
-    console.log(id, answerSubmissionDto);
-
-    if (!isUUID(id)) {
-      throw new AppException(
-        'validation.wrongFieldFormat',
-        HttpStatus.BAD_REQUEST,
-        { field: '$t(submissions.fields.submissionId)' },
-      );
-    }
-
-    const submission = await this.redisService.get<GuestSubmissionSession>(
-      `guest_submission:${id}`,
-    );
-
-    return submission;
-  }
-
-  private checkAnswerCorrectness(
-    question: Question,
-    answerSubmissionDto: AnswerSubmissionDTO,
-  ) {
-    if (!answerSubmissionDto) throw new BadRequestException();
-
-    const { choiceId, numericValue } = answerSubmissionDto;
-
-    if (question.type === QuestionType.NUMERIC) {
-      if (numericValue === undefined) {
-        throw new BadRequestException('submissions.errors.emptyNumericValue');
-      }
-
-      const metadata = question.metadata as NumericMetadata;
-
-      if (
-        metadata &&
-        (numericValue < metadata.min || numericValue > metadata.max)
-      ) {
-        throw new BadRequestException('submissions.errors.numericValueRange');
-      }
-    }
-
-    if (question.type === QuestionType.MULTI_CHOICE) {
-      if (!choiceId) {
-        throw new BadRequestException('submissions.errors.emptyChoiceId');
-      }
-
-      if (!question.choices.some((c) => c.id === choiceId)) {
-        throw new AppException(
-          'validation.wrongField',
-          HttpStatus.BAD_REQUEST,
-          { field: '$t(submissions.fields.choiceId)' },
-        );
-      }
-    }
-  }
 }

src/modules/submissions/providers/answer/answer-guest.provider.ts

@@ -0,0 +1,215 @@
+import { HttpStatus, Injectable } from '@nestjs/common';
+import { AnswerSubmissionDTO } from '../../dtos/answer-submission.dto';
+import { isUUID } from 'class-validator';
+import { AppException } from '@/common/exceptions/app.exception';
+import { GuestSubmissionSession } from '../../interfaces/guest-submission-session.interface';
+import { AppTimeoutException } from '@/common/exceptions/app-timeout.exception';
+import { Question } from '@/modules/questions/entities/question.entity';
+import { AppResponse } from '@/common/responses';
+import { checkAnswerCorrectness } from '../../helpers/check-answer-correctness.helper';
+import { GuestSubmissionAnswer } from '../../interfaces/guest-submission-answer.interface';
+import { QuestionType } from '@/modules/questions/enums/question-type.enum';
+import { getNextTransition } from '../../helpers/get-next-transition.helper';
+import { QuestionTransitionType } from '@/modules/questions/enums/question-transition-type.enum';
+import { InjectRepository } from '@nestjs/typeorm';
+import { RedisService } from '@/common/modules/redis/providers/redis.service';
+import { Repository } from 'typeorm';
+import { CalculateResultProvider } from './calculate-result.provider';
+
+@Injectable()
+export class AnswerGuestProvider {
+  constructor(
+    /**
+     * Inject Redis Service
+     */
+    private readonly redisService: RedisService,
+
+    /**
+     * Inject Questions Repository
+     */
+    @InjectRepository(Question)
+    private readonly questionsRepository: Repository<Question>,
+
+    /**
+     * Inject CalculateResult Provider
+     */
+    private readonly calculateResultProvider: CalculateResultProvider,
+  ) {}
+
+  public async answer(id: string, answerSubmissionDto: AnswerSubmissionDTO) {
+    if (!isUUID(id)) {
+      throw new AppException(
+        'validation.wrongFieldFormat',
+        HttpStatus.BAD_REQUEST,
+        { field: '$t(submissions.fields.submissionId)' },
+      );
+    }
+
+    const lockKey = `lock:guest_submission:${id}`;
+    const lockToken = await this.redisService.acquireLock(lockKey, 5);
+
+    if (!lockToken) {
+      throw new AppException(
+        'common.errors.processingInProgress',
+        HttpStatus.CONFLICT,
+      );
+    }
+
+    try {
+      return await this.answerGuest(id, answerSubmissionDto);
+    } finally {
+      await this.redisService.releaseLock(lockKey, lockToken);
+    }
+  }
+
+  private async answerGuest(
+    id: string,
+    answerSubmissionDto: AnswerSubmissionDTO,
+  ) {
+    let submission: GuestSubmissionSession | null = null;
+
+    try {
+      submission = await this.redisService.get<GuestSubmissionSession>(
+        `guest_submission:${id}`,
+      );
+    } catch (err) {
+      throw new AppTimeoutException(err);
+    }
+
+    if (!submission) {
+      throw new AppException(
+        'common.errors.entityNotFound',
+        HttpStatus.NOT_FOUND,
+        { entity: '$t(submissions.fields.submission)' },
+      );
+    }
+
+    let currentQuestion: Question | null = null;
+
+    if (submission.currentQuestionId !== null) {
+      try {
+        currentQuestion = await this.questionsRepository.findOne({
+          where: { id: submission.currentQuestionId },
+          relations: {
+            choices: true,
+            outgoingTransitions: {
+              toQuestion: {
+                choices: true,
+              },
+            },
+          },
+        });
+      } catch (err) {
+        throw new AppTimeoutException(err);
+      }
+    }
+
+    if (!currentQuestion) {
+      return new AppResponse({
+        isCompleted: true,
+        currentQuestion: null,
+        result: submission.result
+          ? {
+              score: submission.result.score,
+              probability: submission.result.probability,
+              title: submission.result.title,
+              description: submission.result.description,
+            }
+          : null,
+      });
+    }
+
+    checkAnswerCorrectness(currentQuestion, answerSubmissionDto);
+
+    const newAnswer: GuestSubmissionAnswer = {
+      questionId: currentQuestion.id,
+    };
+
+    if (
+      currentQuestion.type === QuestionType.SINGLE_CHOICE &&
+      answerSubmissionDto.choiceId !== undefined
+    ) {
+      const choice = currentQuestion.choices.find(
+        (el) => el.id === answerSubmissionDto.choiceId,
+      );
+
+      if (!choice) {
+        throw new AppException(
+          'validation.wrongField',
+          HttpStatus.BAD_REQUEST,
+          { field: '$t(submissions.fields.choiceId)' },
+        );
+      }
+
+      newAnswer.choiceId = choice.id;
+    } else if (
+      currentQuestion.type === QuestionType.MULTI_CHOICE &&
+      answerSubmissionDto.choiceIds !== undefined
+    ) {
+      const choiceIds = currentQuestion.choices
+        .filter((el) => answerSubmissionDto.choiceIds?.includes(el.id))
+        .map((el) => el.id);
+
+      newAnswer.choiceIds = [...new Set(choiceIds)].sort((a, b) => a - b);
+    } else if (
+      currentQuestion.type === QuestionType.NUMERIC &&
+      answerSubmissionDto.numericValue !== undefined
+    ) {
+      newAnswer.numericValue = answerSubmissionDto.numericValue;
+    }
+
+    const nextTransition = getNextTransition(
+      currentQuestion,
+      answerSubmissionDto,
+    );
+
+    const nextQuestion = nextTransition.toQuestion ?? null;
+
+    submission.answers = [...submission.answers, newAnswer];
+
+    try {
+      if (nextTransition.type === QuestionTransitionType.END || !nextQuestion) {
+        submission.currentQuestionId = null;
+
+        const result =
+          await this.calculateResultProvider.calculateGuest(submission);
+
+        await this.redisService.set<GuestSubmissionSession>(
+          `guest_submission:${id}`,
+          submission,
+          3600,
+        );
+
+        return new AppResponse({
+          isCompleted: true,
+          currentQuestion: null,
+          result,
+        });
+      }
+
+      await this.redisService.set<GuestSubmissionSession>(
+        `guest_submission:${id}`,
+        { ...submission, currentQuestionId: nextQuestion.id },
+        3600,
+      );
+    } catch (err) {
+      throw new AppTimeoutException(err);
+    }
+
+    return new AppResponse({
+      isCompleted: false,
+      // isFinal: ,
+      currentQuestion: {
+        type: nextQuestion?.type,
+        content: nextQuestion?.content,
+        required: nextQuestion?.required,
+        metadata: nextQuestion?.metadata,
+        choices: nextQuestion?.choices.map((el) => ({
+          id: el.id,
+          text: el.text,
+          order: el.order,
+        })),
+      },
+    });
+  }
+}

src/modules/submissions/providers/answer/answer-submission.provider.ts

@@ -0,0 +1,36 @@
+import { Injectable } from '@nestjs/common';
+import { AnswerSubmissionDTO } from '../../dtos/answer-submission.dto';
+import { User } from '@/modules/users/entities/user.entity';
+import { AnswerAuthenticatedProvider } from './answer-authenticated.provider';
+import { AnswerGuestProvider } from './answer-guest.provider';
+
+@Injectable()
+export class AnswerSubmissionProvider {
+  constructor(
+    /**
+     * Inject Answer Autenticated Provider
+     */
+    private readonly answerAuthenticatedProvider: AnswerAuthenticatedProvider,
+
+    /**
+     * Inject Answer Guest Provider
+     */
+    private readonly answerGuestProvider: AnswerGuestProvider,
+  ) {}
+
+  public async answer(
+    id: string,
+    answerSubmissionDto: AnswerSubmissionDTO,
+    user?: User,
+  ) {
+    if (user) {
+      return await this.answerAuthenticatedProvider.answer(
+        id,
+        answerSubmissionDto,
+        user,
+      );
+    } else {
+      return await this.answerGuestProvider.answer(id, answerSubmissionDto);
+    }
+  }
+}

src/modules/submissions/providers/answer/calculate-result.provider.ts

@@ -0,0 +1,250 @@
+import { Injectable } from '@nestjs/common';
+import {
+  EntityManager,
+  In,
+  LessThanOrEqual,
+  MoreThanOrEqual,
+  Repository,
+} from 'typeorm';
+import { InjectRepository } from '@nestjs/typeorm';
+
+import { SubmissionResult } from '../../entities/submission-result.entity';
+import { Submission } from '../../entities/submission.entity';
+import { QuestionType } from '@/modules/questions/enums/question-type.enum';
+import { AppTimeoutException } from '@/common/exceptions/app-timeout.exception';
+import { SubmissionAnswer } from '../../entities/submission-answer.entity';
+import { Question } from '@/modules/questions/entities/question.entity';
+import { ResultRange } from '@/modules/scoring/entities/result-range.entity';
+import { GuestSubmissionSession } from '../../interfaces/guest-submission-session.interface';
+
+@Injectable()
+export class CalculateResultProvider {
+  constructor(
+    /**
+     * Inject Question Repository
+     */
+    @InjectRepository(Question)
+    private readonly questionRepository: Repository<Question>,
+
+    /**
+     * Inject Result Range Repository
+     */
+    @InjectRepository(ResultRange)
+    private readonly resultRangeRepository: Repository<ResultRange>,
+  ) {}
+
+  public async calculateAuthenticated(
+    submission: Submission,
+    manager: EntityManager,
+  ) {
+    let submissionAnswers: SubmissionAnswer[] = [];
+
+    try {
+      submissionAnswers = await manager.find(SubmissionAnswer, {
+        where: { submission: { id: submission.id } },
+        relations: {
+          question: {
+            rangeRules: true,
+          },
+          choice: true,
+          choices: true,
+        },
+      });
+    } catch (err) {
+      throw new AppTimeoutException(err);
+    }
+
+    const result = await this.calculateFromAnswers(
+      submissionAnswers.map((answer) => ({
+        questionId: answer.question.id,
+        question: answer.question,
+        choiceId: answer.choice?.id,
+        choice: answer.choice,
+        choiceIds: answer.choices?.map((choice) => choice.id),
+        choices: answer.choices,
+        numericValue: answer.numericValue,
+      })),
+      async (questionIds) =>
+        manager.find(Question, {
+          where: { id: In(questionIds) },
+          relations: {
+            choices: true,
+            rangeRules: true,
+          },
+        }),
+      async (score) =>
+        manager.find(ResultRange, {
+          where: {
+            test: { id: submission.test.id },
+            minScore: LessThanOrEqual(score),
+            maxScore: MoreThanOrEqual(score),
+          },
+        }),
+    );
+
+    const submissionResult = manager.create(SubmissionResult, {
+      submission,
+      score: result.score,
+      probability: result.probability,
+      resultRange: result.resultRange,
+    });
+
+    try {
+      await manager.save(submissionResult);
+    } catch (err) {
+      throw new AppTimeoutException(err);
+    }
+
+    return {
+      score: result.score,
+      probability: result.probability,
+      title: result.resultRange?.title,
+      description: result.resultRange?.description,
+    };
+  }
+
+  public async calculateGuest(submission: GuestSubmissionSession) {
+    const result = await this.calculateFromAnswers(
+      submission.answers.map((answer) => ({
+        questionId: answer.questionId,
+        choiceId: answer.choiceId,
+        choiceIds: answer.choiceIds,
+        numericValue: answer.numericValue,
+      })),
+      async (questionIds) =>
+        this.questionRepository.find({
+          where: { id: In(questionIds) },
+          relations: {
+            choices: true,
+            rangeRules: true,
+          },
+        }),
+      async (score) =>
+        this.resultRangeRepository.find({
+          where: {
+            test: { id: submission.testId },
+            minScore: LessThanOrEqual(score),
+            maxScore: MoreThanOrEqual(score),
+          },
+        }),
+    );
+
+    submission.result = {
+      score: result.score,
+      probability: result.probability,
+      title: result.resultRange?.title || '',
+      description: result.resultRange?.description || '',
+    };
+
+    return submission.result;
+  }
+
+  private async calculateFromAnswers(
+    answers: Array<{
+      questionId: number;
+      question?: Question;
+      choiceId?: number;
+      choice?: { id: number; score: number };
+      choiceIds?: Array<number>;
+      choices?: Array<{ id: number; score: number }>;
+      numericValue?: number;
+    }>,
+    loadQuestions: (questionIds: number[]) => Promise<Question[]>,
+    loadResultRanges: (score: number) => Promise<ResultRange[]>,
+  ) {
+    let score = 0;
+
+    const questionIds = answers.map((a) => a.questionId);
+
+    const questions = await loadQuestions(questionIds);
+
+    const questionsMap = new Map<number, Question>();
+
+    questions.forEach((q) => questionsMap.set(q.id, q));
+
+    for (const answer of answers) {
+      const question = answer.question ?? questionsMap.get(answer.questionId);
+
+      if (!question) continue;
+
+      if (
+        question.type === QuestionType.SINGLE_CHOICE &&
+        answer.choiceId !== undefined
+      ) {
+        const choice =
+          answer.choice ??
+          question.choices.find((c) => c.id === answer.choiceId);
+
+        if (choice) {
+          score += question.weight * choice.score;
+        }
+      } else if (
+        question.type === QuestionType.MULTI_CHOICE &&
+        answer.choiceIds !== undefined
+      ) {
+        const selectedChoiceIds = new Set(answer.choiceIds);
+
+        const selectedChoices =
+          answer.choices ??
+          question.choices.filter((choice) => selectedChoiceIds.has(choice.id));
+
+        const multiChoiceScore = selectedChoices.reduce(
+          (sum, choice) => sum + choice.score,
+          0,
+        );
+
+        score += question.weight * multiChoiceScore;
+      } else if (
+        question.type === QuestionType.NUMERIC &&
+        answer.numericValue !== undefined
+      ) {
+        question.rangeRules?.forEach((rule) => {
+          if (
+            answer.numericValue! >= rule.min &&
+            answer.numericValue! <= rule.max
+          ) {
+            score += question.weight * rule.score;
+          }
+        });
+      }
+    }
+
+    let totalScores = 0;
+
+    questions.forEach((question) => {
+      if (question.type === QuestionType.SINGLE_CHOICE) {
+        const maxScore =
+          question.choices.length > 0
+            ? Math.max(...question.choices.map((choice) => choice.score))
+            : 0;
+
+        totalScores += question.weight * maxScore;
+      } else if (question.type === QuestionType.MULTI_CHOICE) {
+        const maxScore = question.choices.reduce(
+          (sum, choice) => sum + choice.score,
+          0,
+        );
+
+        totalScores += question.weight * maxScore;
+      } else if (
+        question.type === QuestionType.NUMERIC &&
+        question.rangeRules &&
+        question.rangeRules.length > 0
+      ) {
+        const maxScore = Math.max(
+          ...question.rangeRules.map((rule) => rule.score),
+        );
+
+        totalScores += question.weight * maxScore;
+      }
+    });
+
+    const resultRanges = await loadResultRanges(score);
+
+    return {
+      score,
+      probability: totalScores > 0 ? Math.ceil((score / totalScores) * 100) : 0,
+      resultRange: resultRanges.length > 0 ? resultRanges[0] : undefined,
+    };
+  }
+}

src/modules/submissions/providers/calculate-result.provider.ts

@@ -1,115 +0,0 @@
-import { Injectable } from '@nestjs/common';
-import { EntityManager, LessThanOrEqual, MoreThanOrEqual } from 'typeorm';
-import { SubmissionResult } from '../entities/submission-result.entity';
-import { Submission } from '../entities/submission.entity';
-import { QuestionType } from '@/modules/questions/enums/question-type.enum';
-import { AppTimeoutException } from '@/common/exceptions/app-timeout.exception';
-import { SubmissionAnswer } from '../entities/submission-answer.entity';
-import { Question } from '@/modules/questions/entities/question.entity';
-import { ResultRange } from '@/modules/scoring/entities/result-range.entity';
-
-@Injectable()
-export class CalculateResultProvider {
-  public async calculate(submission: Submission, manager: EntityManager) {
-    let score = 0;
-
-    let submissionAnswers: Array<SubmissionAnswer> = [];
-
-    try {
-      submissionAnswers = await manager.find(SubmissionAnswer, {
-        where: { submission: { id: submission.id } },
-        relations: {
-          question: {
-            rangeRules: true,
-          },
-          choice: true,
-        },
-      });
-    } catch (err) {
-      throw new AppTimeoutException(err);
-    }
-
-    for (const answer of submissionAnswers) {
-      if (answer.question.type === QuestionType.MULTI_CHOICE && answer.choice) {
-        score += answer.question.weight * answer.choice.score;
-      } else if (
-        answer.question.type === QuestionType.NUMERIC &&
-        answer.numericValue !== undefined
-      ) {
-        if (
-          answer.question.rangeRules &&
-          answer.question.rangeRules.length > 0
-        ) {
-          answer.question.rangeRules.forEach((rule) => {
-            if (
-              answer.numericValue !== undefined &&
-              answer.numericValue >= rule.min &&
-              answer.numericValue <= rule.max
-            ) {
-              score += answer.question.weight * rule.score;
-            }
-          });
-        }
-      }
-    }
-
-    let totalScores = 0;
-
-    const testQuestions = await manager.find(Question, {
-      where: { test: { id: submission.test.id } },
-      relations: {
-        choices: true,
-        rangeRules: true,
-      },
-    });
-
-    testQuestions.forEach((question) => {
-      const answerScores: Array<number> = [];
-      if (question.type === QuestionType.MULTI_CHOICE) {
-        question.choices.forEach((choice) => {
-          answerScores.push(choice.score);
-        });
-      } else if (
-        question.type === QuestionType.NUMERIC &&
-        question.rangeRules &&
-        question.rangeRules.length > 0
-      ) {
-        question.rangeRules.forEach((rule) => {
-          answerScores.push(rule.score);
-        });
-      }
-
-      const maxScore = answerScores.length > 0 ? Math.max(...answerScores) : 0;
-
-      totalScores += question.weight * maxScore;
-    });
-
-    const resultRanges = await manager.find(ResultRange, {
-      where: {
-        test: { id: submission.test.id },
-        minScore: LessThanOrEqual(score),
-        maxScore: MoreThanOrEqual(score),
-      },
-    });
-
-    const submissionResult = manager.create(SubmissionResult, {
-      submission,
-      score,
-      probability: Math.ceil((score / totalScores) * 100),
-      resultRange: resultRanges.length > 0 ? resultRanges[0] : undefined,
-    });
-
-    try {
-      await manager.save(submissionResult);
-    } catch (err) {
-      throw new AppTimeoutException(err);
-    }
-
-    return {
-      score,
-      probability: submissionResult.probability,
-      title: submissionResult.resultRange?.title,
-      description: submissionResult.resultRange?.description,
-    };
-  }
-}

src/modules/submissions/providers/history/history-authenticated.provider.ts

@@ -0,0 +1,144 @@
+import { HttpStatus, Injectable } from '@nestjs/common';
+import { InjectRepository } from '@nestjs/typeorm';
+import { Repository } from 'typeorm';
+import { Submission } from '../../entities/submission.entity';
+import { SubmissionAnswer } from '../../entities/submission-answer.entity';
+import { AppException } from '@/common/exceptions/app.exception';
+import { AppTimeoutException } from '@/common/exceptions/app-timeout.exception';
+import { User } from '@/modules/users/entities/user.entity';
+import { AppResponse } from '@/common/responses';
+
+@Injectable()
+export class HistoryAuthenticatedProvider {
+  constructor(
+    /**
+     * Inject Submission Repository
+     */
+    @InjectRepository(Submission)
+    private readonly submissionRepository: Repository<Submission>,
+
+    /**
+     * Inject Submission Answer Repository
+     */
+    @InjectRepository(SubmissionAnswer)
+    private readonly submissionAnswerRepository: Repository<SubmissionAnswer>,
+  ) {}
+
+  public async getHistory(id: string, user: User) {
+    let submission: Submission | null = null;
+
+    const submissionId = Number(id);
+
+    if (Number.isNaN(submissionId)) {
+      throw new AppException(
+        'validation.wrongFieldFormat',
+        HttpStatus.BAD_REQUEST,
+        { field: '$t(submissions.fields.submissionId)' },
+      );
+    }
+
+    try {
+      submission = await this.submissionRepository.findOne({
+        where: {
+          id: submissionId,
+          user: {
+            id: user.id,
+          },
+        },
+        relations: {
+          test: true,
+          currentQuestion: {
+            choices: true,
+          },
+        },
+      });
+    } catch (err) {
+      throw new AppTimeoutException(err);
+    }
+
+    if (!submission) {
+      throw new AppException(
+        'common.errors.entityNotFound',
+        HttpStatus.NOT_FOUND,
+        {
+          entity: '$t(submissions.fields.submission)',
+        },
+      );
+    }
+
+    let answers: SubmissionAnswer[] = [];
+
+    try {
+      answers = await this.submissionAnswerRepository.find({
+        where: {
+          submission: {
+            id: submission.id,
+          },
+        },
+        relations: {
+          question: {
+            choices: true,
+          },
+          choice: true,
+          choices: true,
+        },
+        order: {
+          id: 'ASC',
+        },
+      });
+    } catch (err) {
+      throw new AppTimeoutException(err);
+    }
+
+    const messages = answers.map((answer) => ({
+      question: {
+        id: answer.question.id,
+        type: answer.question.type,
+        content: answer.question.content,
+        required: answer.question.required,
+        metadata: answer.question.metadata,
+      },
+      answer: {
+        choiceId: answer.choice?.id,
+        choice: answer.choice
+          ? {
+              id: answer.choice.id,
+              text: answer.choice.text,
+              order: answer.choice.order,
+            }
+          : undefined,
+
+        choiceIds: answer.choices?.map((choice) => choice.id),
+
+        choices: answer.choices?.map((choice) => ({
+          id: choice.id,
+          text: choice.text,
+          order: choice.order,
+        })),
+
+        numericValue: answer.numericValue,
+      },
+    }));
+
+    return new AppResponse({
+      messages,
+
+      currentQuestion: submission.currentQuestion
+        ? {
+            id: submission.currentQuestion.id,
+            type: submission.currentQuestion.type,
+            content: submission.currentQuestion.content,
+            required: submission.currentQuestion.required,
+            metadata: submission.currentQuestion.metadata,
+            choices: submission.currentQuestion.choices?.map((choice) => ({
+              id: choice.id,
+              text: choice.text,
+              order: choice.order,
+            })),
+          }
+        : null,
+
+      isCompleted: submission.currentQuestion === null,
+    });
+  }
+}

src/modules/submissions/providers/history/history-guest.provider.ts

@@ -0,0 +1,192 @@
+import { HttpStatus, Injectable } from '@nestjs/common';
+import { InjectRepository } from '@nestjs/typeorm';
+import { In, Repository } from 'typeorm';
+
+import { RedisService } from '@/common/modules/redis/providers/redis.service';
+import { AppException } from '@/common/exceptions/app.exception';
+import { AppTimeoutException } from '@/common/exceptions/app-timeout.exception';
+import { AppResponse } from '@/common/responses';
+
+import { Question } from '@/modules/questions/entities/question.entity';
+import { GuestSubmissionSession } from '../../interfaces/guest-submission-session.interface';
+import { isUUID } from 'class-validator';
+
+@Injectable()
+export class HistoryGuestProvider {
+  constructor(
+    /**
+     * Inject Redis Service
+     */
+    private readonly redisService: RedisService,
+
+    /**
+     * Inject Questions Repository
+     */
+    @InjectRepository(Question)
+    private readonly questionsRepository: Repository<Question>,
+  ) {}
+
+  public async getHistory(id: string) {
+    if (!isUUID(id)) {
+      throw new AppException(
+        'validation.wrongFieldFormat',
+        HttpStatus.BAD_REQUEST,
+        { field: '$t(submissions.fields.submissionId)' },
+      );
+    }
+
+    const key = `guest_submission:${id}`;
+
+    let submission: GuestSubmissionSession | null = null;
+
+    try {
+      submission = await this.redisService.get<GuestSubmissionSession>(key);
+    } catch (err) {
+      throw new AppTimeoutException(err);
+    }
+
+    if (!submission) {
+      throw new AppException(
+        'common.errors.entityNotFound',
+        HttpStatus.NOT_FOUND,
+        {
+          entity: '$t(submissions.fields.submission)',
+        },
+      );
+    }
+
+    /**
+     * Get all question IDs that we need.
+     */
+    const questionIds = new Set<number>();
+
+    for (const answer of submission.answers) {
+      questionIds.add(answer.questionId);
+    }
+
+    if (submission.currentQuestionId !== null) {
+      questionIds.add(submission.currentQuestionId);
+    }
+
+    /**
+     * Load questions from DB.
+     */
+    let questions: Question[] = [];
+
+    if (questionIds.size > 0) {
+      try {
+        questions = await this.questionsRepository.find({
+          where: {
+            id: In([...questionIds]),
+          },
+          relations: {
+            choices: true,
+          },
+        });
+      } catch (err) {
+        throw new AppTimeoutException(err);
+      }
+    }
+
+    const questionsMap = new Map<number, Question>();
+
+    for (const question of questions) {
+      questionsMap.set(question.id, question);
+    }
+
+    /**
+     * Build messages.
+     */
+    const messages = submission.answers
+      .map((answer) => {
+        const question = questionsMap.get(answer.questionId);
+
+        if (!question) {
+          return null;
+        }
+
+        const selectedChoices = answer.choiceIds
+          ? question.choices.filter((choice) =>
+              answer.choiceIds!.includes(choice.id),
+            )
+          : [];
+
+        const selectedChoice =
+          answer.choiceId !== undefined
+            ? question.choices.find((choice) => choice.id === answer.choiceId)
+            : undefined;
+
+        return {
+          question: {
+            id: question.id,
+            type: question.type,
+            content: question.content,
+            required: question.required,
+            metadata: question.metadata,
+          },
+
+          answer: {
+            choiceId: answer.choiceId,
+
+            choice: selectedChoice
+              ? {
+                  id: selectedChoice.id,
+                  text: selectedChoice.text,
+                  order: selectedChoice.order,
+                }
+              : undefined,
+
+            choiceIds: answer.choiceIds,
+
+            choices: selectedChoices.map((choice) => ({
+              id: choice.id,
+              text: choice.text,
+              order: choice.order,
+            })),
+
+            numericValue: answer.numericValue,
+          },
+        };
+      })
+      .filter((message) => message !== null);
+
+    /**
+     * Current question.
+     */
+    const currentQuestion =
+      submission.currentQuestionId !== null
+        ? questionsMap.get(submission.currentQuestionId)
+        : null;
+
+    return new AppResponse({
+      messages,
+
+      currentQuestion: currentQuestion
+        ? {
+            id: currentQuestion.id,
+            type: currentQuestion.type,
+            content: currentQuestion.content,
+            required: currentQuestion.required,
+            metadata: currentQuestion.metadata,
+
+            choices: currentQuestion.choices?.map((choice) => ({
+              id: choice.id,
+              text: choice.text,
+              order: choice.order,
+            })),
+          }
+        : null,
+
+      isCompleted: submission.currentQuestionId === null,
+
+      result: submission.result
+        ? {
+            score: submission.result.score,
+            probability: submission.result.probability,
+            title: submission.result.title,
+            description: submission.result.description,
+          }
+        : null,
+    });
+  }
+}

src/modules/submissions/providers/history/submission-history.provider.ts

@@ -0,0 +1,27 @@
+import { Injectable } from '@nestjs/common';
+import { HistoryGuestProvider } from './history-guest.provider';
+import { HistoryAuthenticatedProvider } from './history-authenticated.provider';
+import { User } from '@/modules/users/entities/user.entity';
+
+@Injectable()
+export class SubmissionHistoryProvider {
+  constructor(
+    /**
+     * Inject History Guest Provider
+     */
+    private readonly historyGuestProvider: HistoryGuestProvider,
+
+    /**
+     * Inject History Authenticated Provider
+     */
+    private readonly historyAuthenticatedProvider: HistoryAuthenticatedProvider,
+  ) {}
+
+  public async getHistory(id: string, user?: User) {
+    if (user) {
+      return await this.historyAuthenticatedProvider.getHistory(id, user);
+    } else {
+      return await this.historyGuestProvider.getHistory(id);
+    }
+  }
+}

src/modules/submissions/providers/start/start-submission.provider.ts

@@ -5,17 +5,21 @@ import {
   BadRequestException,
   ForbiddenException,
   Injectable,
+  NotFoundException,
 } from '@nestjs/common';
 import { Repository } from 'typeorm';
-import { Submission } from '../entities/submission.entity';
+import { Submission } from '../../entities/submission.entity';
 import { InjectRepository } from '@nestjs/typeorm';
 import { AppTimeoutException } from '@/common/exceptions/app-timeout.exception';
 import { AppResponse } from '@/common/responses';
-import { SubmissionStatus } from '../enums/submission-status.enum';
+import { SubmissionStatus } from '../../enums/submission-status.enum';
 import { Test } from '@/modules/tests/entities/test.entity';
 import { randomUUID } from 'crypto';
 import { RedisService } from '@/common/modules/redis/providers/redis.service';
-import { GuestSubmissionSession } from '../interfaces/guest-submission-session.interfaces';
+import { GuestSubmissionSession } from '../../interfaces/guest-submission-session.interface';
+import { TestStatus } from '@/modules/tests/enums/test-status.enum';
+import { QuestionTransition } from '@/modules/questions/entities/question-transition.entity';
+import { QuestionTransitionType } from '@/modules/questions/enums/question-transition-type.enum';
 
 @Injectable()
 export class StartSubmissionProvider {
@@ -35,27 +39,57 @@ export class StartSubmissionProvider {
      * Inject Redis Service
      */
     private readonly redisService: RedisService,
+
+    /**
+     * Inject QuestionTransition Repository
+     */
+    @InjectRepository(QuestionTransition)
+    private readonly transitionsRepository: Repository<QuestionTransition>,
   ) {}
 
   public async start(testId: number, user?: User) {
-    const test = await this.testsService.adminGetOne(testId, {
+    const test = await this.testsService.adminGetOne(testId);
+
+    if (!test.isActive || test.status !== TestStatus.PUBLISHED) {
+      throw new ForbiddenException('tests.errors.notActiveTest');
+    }
+
+    if (test.accessType !== AccessType.FREE && !user) {
+      throw new ForbiddenException('auth.errors.accessDenied');
+    }
+
+    if (user) {
+      return await this.startAuthenticated(test, user);
+    }
+
+    return await this.startGuest(test);
+  }
+
+  private async getFirstQuestion(testId: number) {
+    let transition: QuestionTransition | null = null;
+
+    try {
+      transition = await this.transitionsRepository.findOne({
+        where: {
+          test: { id: testId },
+          type: QuestionTransitionType.START,
+        },
         relations: {
-        questions: {
+          toQuestion: {
             choices: true,
+            rangeRules: true,
           },
         },
         order: {
-        questions: {
-          order: 'ASC',
+          toQuestion: {
             choices: {
               order: 'ASC',
             },
           },
         },
         select: {
-        questions: {
+          toQuestion: {
             id: true,
-          order: true,
             type: true,
             content: true,
             required: true,
@@ -68,16 +102,15 @@ export class StartSubmissionProvider {
           },
         },
       });
-
-    if (test.accessType !== AccessType.FREE && !user) {
-      throw new ForbiddenException('auth.errors.accessDenied');
+    } catch (err) {
+      throw new AppTimeoutException(err);
     }
 
-    if (user) {
-      return await this.startAuthenticated(test, user);
+    if (!transition || !transition.toQuestion) {
+      throw new NotFoundException('submissions.errors.transitionNotFound');
     }
 
-    return await this.startGuest(test);
+    return transition.toQuestion;
   }
 
   private async startAuthenticated(test: Test, user: User) {
@@ -102,10 +135,13 @@ export class StartSubmissionProvider {
       throw new BadRequestException('submissions.errors.alreadyTookTest');
     }
 
+    const firstQuestion = await this.getFirstQuestion(test.id);
+
     if (!submission) {
       submission = this.submissionsRepository.create({
         test,
         user: user || undefined,
+        currentQuestion: firstQuestion,
       });
 
       try {
@@ -117,26 +153,32 @@ export class StartSubmissionProvider {
 
     return new AppResponse({
       submissionId: submission.id,
-      question: test.questions.length > 0 ? test.questions[0] : null,
+      question: firstQuestion,
     });
   }
 
   private async startGuest(test: Test) {
+    const firstQuestion = await this.getFirstQuestion(test.id);
+
     const guestSubmissionId = randomUUID();
 
+    try {
       await this.redisService.set<GuestSubmissionSession>(
         `guest_submission:${guestSubmissionId}`,
         {
           testId: test.id,
-        currentQuestion: 0,
+          currentQuestionId: firstQuestion.id,
           answers: [],
         },
         3600,
       );
+    } catch (err) {
+      throw new AppTimeoutException(err);
+    }
 
     return new AppResponse({
       guestSubmissionId,
-      question: test.questions[0],
+      question: firstQuestion,
     });
   }
 }

src/modules/submissions/providers/submissions.service.ts

@@ -1,8 +1,9 @@
 import { Injectable } from '@nestjs/common';
-import { StartSubmissionProvider } from './start-submission.provider';
+import { StartSubmissionProvider } from './start/start-submission.provider';
 import { User } from '@/modules/users/entities/user.entity';
-import { AnswerSubmissionProvider } from './answer-submission.provider';
+import { AnswerSubmissionProvider } from './answer/answer-submission.provider';
 import { AnswerSubmissionDTO } from '../dtos/answer-submission.dto';
+import { SubmissionHistoryProvider } from './history/submission-history.provider';
 
 @Injectable()
 export class SubmissionsService {
@@ -16,6 +17,11 @@ export class SubmissionsService {
      * Inject Answer Submission Provider
      */
     private readonly answerSubmissionProvider: AnswerSubmissionProvider,
+
+    /**
+     * Inject Submission History Provider
+     */
+    private readonly submissionHistoryProvider: SubmissionHistoryProvider,
   ) {}
 
   public async startSubmission(testId: number, user?: User) {
@@ -33,4 +39,8 @@ export class SubmissionsService {
       user,
     );
   }
+
+  public async getSubmissionHistory(id: string, user?: User) {
+    return await this.submissionHistoryProvider.getHistory(id, user);
+  }
 }

src/modules/submissions/submissions.controller.ts

@@ -1,6 +1,7 @@
 import {
   Body,
   Controller,
+  Get,
   HttpCode,
   HttpStatus,
   Param,
@@ -53,4 +54,11 @@ export class SubmissionsController {
       user,
     );
   }
+
+  @Public()
+  @Get(':id/history')
+  @UseGuards(OptionalJwtGuard)
+  public async getHistory(@Param('id') id: string, @ActiveUser() user?: User) {
+    return await this.submissionsService.getSubmissionHistory(id, user);
+  }
 }

src/modules/submissions/submissions.module.ts

@@ -4,14 +4,19 @@ import { Submission } from './entities/submission.entity';
 import { SubmissionAnswer } from './entities/submission-answer.entity';
 import { SubmissionResult } from './entities/submission-result.entity';
 import { SubmissionsController } from './submissions.controller';
-import { StartSubmissionProvider } from './providers/start-submission.provider';
+import { StartSubmissionProvider } from './providers/start/start-submission.provider';
 import { SubmissionsService } from './providers/submissions.service';
 import { TestsModule } from '../tests/tests.module';
-import { AnswerSubmissionProvider } from './providers/answer-submission.provider';
+import { AnswerSubmissionProvider } from './providers/answer/answer-submission.provider';
 import { RedisModule } from '@/common/modules/redis/redis.module';
 import { QuestionsModule } from '../questions/questions.module';
-import { CalculateResultProvider } from './providers/calculate-result.provider';
+import { CalculateResultProvider } from './providers/answer/calculate-result.provider';
 import { ScoringModule } from '../scoring/scoring.module';
+import { AnswerGuestProvider } from './providers/answer/answer-guest.provider';
+import { AnswerAuthenticatedProvider } from './providers/answer/answer-authenticated.provider';
+import { HistoryAuthenticatedProvider } from './providers/history/history-authenticated.provider';
+import { HistoryGuestProvider } from './providers/history/history-guest.provider';
+import { SubmissionHistoryProvider } from './providers/history/submission-history.provider';
 
 @Module({
   imports: [
@@ -24,8 +29,13 @@ import { ScoringModule } from '../scoring/scoring.module';
   controllers: [SubmissionsController],
   providers: [
     StartSubmissionProvider,
-    AnswerSubmissionProvider,
     CalculateResultProvider,
+    AnswerAuthenticatedProvider,
+    AnswerGuestProvider,
+    AnswerSubmissionProvider,
+    HistoryAuthenticatedProvider,
+    HistoryGuestProvider,
+    SubmissionHistoryProvider,
     SubmissionsService,
   ],
 })

src/modules/tests/entities/test.entity.ts

@@ -10,6 +10,7 @@ import { AccessType } from '../enums/access-types.enum';
 import { Question } from '@/modules/questions/entities/question.entity';
 import { ResultRange } from '@/modules/scoring/entities/result-range.entity';
 import { TestStatus } from '../enums/test-status.enum';
+import { QuestionTransition } from '@/modules/questions/entities/question-transition.entity';
 
 @Entity()
 @Check(`
@@ -70,6 +71,9 @@ export class Test {
   @OneToMany(() => ResultRange, (range) => range.test)
   resultRanges!: Array<ResultRange>;
 
+  @OneToMany(() => QuestionTransition, (transition) => transition.test)
+  transitions!: Array<QuestionTransition>;
+
   @CreateDateColumn()
   createdAt!: Date;
 }

src/modules/tests/providers/publish-test-validator.provider.ts

@@ -0,0 +1,233 @@
+import { HttpStatus, Injectable } from '@nestjs/common';
+import { Repository } from 'typeorm';
+import { Test } from '../entities/test.entity';
+import { InjectRepository } from '@nestjs/typeorm';
+import { AppException } from '@/common/exceptions/app.exception';
+import { QuestionTransitionType } from '@/modules/questions/enums/question-transition-type.enum';
+import { AppTimeoutException } from '@/common/exceptions/app-timeout.exception';
+import { QuestionTransition } from '@/modules/questions/entities/question-transition.entity';
+import { Question } from '@/modules/questions/entities/question.entity';
+import { MultiChoiceTransitionValidator } from '../validators/multi-choice-transition.validator';
+
+@Injectable()
+export class PublishTestValidatorProvider {
+  constructor(
+    /**
+     * Inject Tests Repository
+     */
+    @InjectRepository(Test)
+    private readonly testsRepository: Repository<Test>,
+  ) {}
+
+  public async validate(testId: number) {
+    let test: Test | null = null;
+
+    try {
+      test = await this.testsRepository.findOne({
+        where: {
+          id: testId,
+        },
+        relations: {
+          questions: true,
+          transitions: {
+            fromQuestion: true,
+            toQuestion: true,
+          },
+        },
+      });
+    } catch (err) {
+      throw new AppTimeoutException(err);
+    }
+
+    if (!test) {
+      throw new AppException(
+        'common.errors.entityNotFound',
+        HttpStatus.NOT_FOUND,
+        { entity: '$t(tests.fields.test)' },
+      );
+    }
+
+    const transitions = test.transitions;
+
+    const startTransitions = transitions.filter(
+      (t) => t.type === QuestionTransitionType.START,
+    );
+
+    if (startTransitions.length !== 1) {
+      throw new AppException(
+        'tests.errors.mustHaveSingleStart',
+        HttpStatus.BAD_REQUEST,
+      );
+    }
+
+    const startQuestionId = startTransitions[0].toQuestion!.id;
+
+    MultiChoiceTransitionValidator.validate(test.questions, transitions);
+
+    const transitionsGraph = new Map<number, QuestionTransition[]>();
+
+    this.createTransitionsGraph(transitions, transitionsGraph);
+
+    if (
+      this.hasOrphanQuestions(startQuestionId, transitionsGraph, test.questions)
+    ) {
+      throw new AppException(
+        'tests.errors.hasOrphanQuestions',
+        HttpStatus.BAD_REQUEST,
+      );
+    }
+
+    const visiting = new Set<number>();
+    const visitedCycle = new Set<number>();
+
+    if (
+      this.graphHasCycle(
+        startQuestionId,
+        visiting,
+        visitedCycle,
+        transitionsGraph,
+      )
+    ) {
+      throw new AppException('tests.errors.hasCycle', HttpStatus.BAD_REQUEST);
+    }
+
+    const endingQuestionsMemo = new Map<number, boolean>();
+
+    if (
+      !this.allPathsReachEnd(
+        startQuestionId,
+        endingQuestionsMemo,
+        transitionsGraph,
+      )
+    ) {
+      throw new AppException(
+        'tests.errors.notEndingFlow',
+        HttpStatus.BAD_REQUEST,
+      );
+    }
+  }
+
+  private createTransitionsGraph(
+    transitions: QuestionTransition[],
+    graph: Map<number, QuestionTransition[]>,
+  ) {
+    for (const transition of transitions) {
+      if (!transition.fromQuestion) continue;
+
+      const list = graph.get(transition.fromQuestion.id) ?? [];
+
+      list.push(transition);
+
+      graph.set(transition.fromQuestion.id, list);
+    }
+  }
+
+  private hasOrphanQuestions(
+    startQuestionId: number,
+    graph: Map<number, QuestionTransition[]>,
+    allQuestions: Array<Question>,
+  ) {
+    const visited = new Set<number>();
+    const stack = [startQuestionId];
+
+    while (stack.length) {
+      const id = stack.pop();
+      if (!id) break;
+
+      if (visited.has(id)) continue;
+
+      visited.add(id);
+
+      const nextTransitions = graph.get(id) ?? [];
+
+      for (const transition of nextTransitions) {
+        const toQuestion = transition.toQuestion;
+
+        if (toQuestion) {
+          stack.push(toQuestion.id);
+        }
+      }
+    }
+
+    const orphanQuestions = allQuestions.filter((q) => !visited.has(q.id));
+
+    return orphanQuestions.length > 0;
+  }
+
+  private graphHasCycle(
+    id: number,
+    visiting: Set<number>,
+    visitedCycle: Set<number>,
+    graph: Map<number, QuestionTransition[]>,
+  ): boolean {
+    if (visiting.has(id)) return true;
+    if (visitedCycle.has(id)) return false;
+
+    visiting.add(id);
+
+    for (const transition of graph.get(id) ?? []) {
+      if (transition.toQuestion) {
+        if (
+          this.graphHasCycle(
+            transition.toQuestion.id,
+            visiting,
+            visitedCycle,
+            graph,
+          )
+        )
+          return true;
+      }
+    }
+
+    visiting.delete(id);
+    visitedCycle.add(id);
+
+    return false;
+  }
+
+  private allPathsReachEnd(
+    questionId: number,
+    memo: Map<number, boolean>,
+    graph: Map<number, QuestionTransition[]>,
+  ): boolean {
+    if (memo.has(questionId)) {
+      return memo.get(questionId)!;
+    }
+
+    const outgoing = graph.get(questionId) ?? [];
+
+    if (outgoing.length === 0) {
+      memo.set(questionId, false);
+      return false;
+    }
+
+    let hasEndTransition = false;
+
+    for (const transition of outgoing) {
+      if (transition.type === QuestionTransitionType.END) {
+        hasEndTransition = true;
+        continue;
+      }
+
+      if (
+        !transition.toQuestion ||
+        !this.allPathsReachEnd(transition.toQuestion.id, memo, graph)
+      ) {
+        memo.set(questionId, false);
+        return false;
+      }
+    }
+
+    const result =
+      hasEndTransition ||
+      outgoing.every(
+        (t) =>
+          t.type === QuestionTransitionType.END ||
+          (t.toQuestion && memo.get(t.toQuestion.id) === true),
+      );
+
+    memo.set(questionId, result);
+
+    return result;
+  }
+}

src/modules/tests/providers/tests-command.provider.ts

@@ -9,6 +9,8 @@ import { AppResponse } from '@/common/responses';
 import { AppTimeoutException } from '@/common/exceptions/app-timeout.exception';
 import { UpdateTestDTO } from '../dtos/update-test.dto';
 import { AccessType } from '../enums/access-types.enum';
+import { PublishTestValidatorProvider } from './publish-test-validator.provider';
+import { TestStatus } from '../enums/test-status.enum';
 
 @Injectable()
 export class TestsCommandProvider {
@@ -23,6 +25,11 @@ export class TestsCommandProvider {
      * Inject I18n Service
      */
     private readonly i18nService: I18nService,
+
+    /**
+     * Inject Publish Test Validator Provider
+     */
+    private readonly publishTestValidatorProvider: PublishTestValidatorProvider,
   ) {}
 
   public async createOne(createTestDto: CreateTestDTO) {
@@ -76,6 +83,10 @@ export class TestsCommandProvider {
 
     Object.assign(test, updateTestDto);
 
+    if (updateTestDto.status === TestStatus.PUBLISHED) {
+      await this.publishTestValidatorProvider.validate(test.id);
+    }
+
     try {
       return await this.testRepository.save(test);
     } catch (err) {

src/modules/tests/providers/tests-query.provider.ts

@@ -8,6 +8,7 @@ import { filterTests } from '../helpers/filter-tests.helper';
 import Utils from '@/common/utils';
 import { Test } from '../entities/test.entity';
 import { AppException } from '@/common/exceptions/app.exception';
+import { TestStatus } from '../enums/test-status.enum';
 
 @Injectable()
 export class TestsQueryProvider {
@@ -49,7 +50,7 @@ export class TestsQueryProvider {
   public async findAllForUser() {
     try {
       return await this.testRepository.find({
-        where: { isActive: true },
+        where: { isActive: true, status: TestStatus.PUBLISHED },
         select: {
           id: true,
           accessType: true,

src/modules/tests/tests.module.ts

@@ -5,11 +5,17 @@ import { TestsService } from './providers/tests.service';
 import { TestsController } from './tests.controller';
 import { TestsQueryProvider } from './providers/tests-query.provider';
 import { TestsCommandProvider } from './providers/tests-command.provider';
+import { PublishTestValidatorProvider } from './providers/publish-test-validator.provider';
 
 @Module({
   imports: [TypeOrmModule.forFeature([Test])],
   controllers: [TestsController],
-  providers: [TestsService, TestsQueryProvider, TestsCommandProvider],
+  providers: [
+    TestsService,
+    TestsQueryProvider,
+    PublishTestValidatorProvider,
+    TestsCommandProvider,
+  ],
   exports: [TestsService],
 })
 export class TestsModule {}

src/modules/tests/validators/multi-choice-transition.validator.ts

@@ -0,0 +1,158 @@
+import { AppException } from '@/common/exceptions/app.exception';
+import { QuestionTransition } from '@/modules/questions/entities/question-transition.entity';
+import { Question } from '@/modules/questions/entities/question.entity';
+import { MultiChoiceTConditionOperator } from '@/modules/questions/enums/multi-choice-tcondition-operator.enum';
+import { QuestionTransitionType } from '@/modules/questions/enums/question-transition-type.enum';
+import { QuestionType } from '@/modules/questions/enums/question-type.enum';
+import { MultiChoiceCondition } from '@/modules/questions/interfaces/multi-choice-condition.interface';
+import { HttpStatus } from '@nestjs/common';
+
+export class MultiChoiceTransitionValidator {
+  public static validate(
+    questions: Question[],
+    transitions: QuestionTransition[],
+  ) {
+    for (const question of questions) {
+      if (question.type !== QuestionType.MULTI_CHOICE) {
+        continue;
+      }
+
+      const outgoing = transitions.filter(
+        (t) => t.fromQuestion?.id === question.id,
+      );
+
+      const conditional = outgoing.filter(
+        (t) => t.type === QuestionTransitionType.MULTI_CHOICE,
+      );
+
+      if (conditional.length === 0) {
+        continue;
+      }
+
+      const hasDefault = outgoing.some(
+        (t) => t.type === QuestionTransitionType.DEFAULT,
+      );
+
+      const hasEnd = outgoing.some(
+        (t) => t.type === QuestionTransitionType.END,
+      );
+
+      if (!hasDefault && !hasEnd) {
+        throw new AppException(
+          'tests.errors.multiChoiceMustHaveFallback',
+          HttpStatus.BAD_REQUEST,
+        );
+      }
+
+      if (hasDefault && hasEnd) {
+        throw new AppException(
+          'tests.errors.questionHasMultipleFallbacks',
+          HttpStatus.BAD_REQUEST,
+        );
+      }
+
+      for (let i = 0; i < conditional.length; i++) {
+        for (let j = i + 1; j < conditional.length; j++) {
+          if (
+            this.multiChoiceConditionsOverlap(
+              conditional[i].condition as MultiChoiceCondition,
+              conditional[j].condition as MultiChoiceCondition,
+            )
+          ) {
+            throw new AppException(
+              'tests.errors.multiChoiceTransitionsOverlap',
+              HttpStatus.BAD_REQUEST,
+            );
+          }
+        }
+      }
+    }
+  }
+
+  public static multiChoiceConditionsOverlap(
+    a: MultiChoiceCondition,
+    b: MultiChoiceCondition,
+  ): boolean {
+    const aIds = new Set(a.choiceIds);
+    const bIds = new Set(b.choiceIds);
+
+    if (
+      a.operator === MultiChoiceTConditionOperator.EXACT &&
+      b.operator === MultiChoiceTConditionOperator.EXACT
+    ) {
+      return this.sameSet(aIds, bIds);
+    }
+
+    if (
+      a.operator === MultiChoiceTConditionOperator.EXACT &&
+      b.operator === MultiChoiceTConditionOperator.ALL
+    ) {
+      return this.isSubset(bIds, aIds);
+    }
+
+    if (
+      a.operator === MultiChoiceTConditionOperator.ALL &&
+      b.operator === MultiChoiceTConditionOperator.EXACT
+    ) {
+      return this.isSubset(aIds, bIds);
+    }
+
+    if (
+      a.operator === MultiChoiceTConditionOperator.EXACT &&
+      b.operator === MultiChoiceTConditionOperator.ANY
+    ) {
+      return this.hasIntersection(aIds, bIds);
+    }
+
+    if (
+      a.operator === MultiChoiceTConditionOperator.ANY &&
+      b.operator === MultiChoiceTConditionOperator.EXACT
+    ) {
+      return this.hasIntersection(aIds, bIds);
+    }
+
+    if (
+      a.operator === MultiChoiceTConditionOperator.ANY &&
+      b.operator === MultiChoiceTConditionOperator.ANY
+    ) {
+      return this.hasIntersection(aIds, bIds);
+    }
+
+    // ALL + ALL
+    if (
+      a.operator === MultiChoiceTConditionOperator.ALL &&
+      b.operator === MultiChoiceTConditionOperator.ALL
+    ) {
+      return true;
+    }
+
+    // ANY + ALL
+    return true;
+  }
+
+  public static sameSet(a: Set<number>, b: Set<number>): boolean {
+    if (a.size !== b.size) return false;
+
+    for (const id of a) {
+      if (!b.has(id)) return false;
+    }
+
+    return true;
+  }
+
+  public static isSubset(subset: Set<number>, superset: Set<number>): boolean {
+    for (const id of subset) {
+      if (!superset.has(id)) return false;
+    }
+
+    return true;
+  }
+
+  public static hasIntersection(a: Set<number>, b: Set<number>): boolean {
+    for (const id of a) {
+      if (b.has(id)) return true;
+    }
+
+    return false;
+  }
+}