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 { 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 { 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 { UNIQUE_SUBMISSION_QUESTION_IDX } from '../../constants';

@Injectable()
export class AnswerAuthenticatedProvider {
  constructor(
    /**
     * Inject Submission Repository
     */
    @InjectRepository(Submission)
    private readonly submissionRepository: Repository<Submission>,

    /**
     * Inject SubmisionAnswer Repository
     */
    @InjectRepository(SubmissionAnswer)
    private readonly submissionAnswerRepository: Repository<SubmissionAnswer>,

    /**
     * Inject SubmissionResult Repository
     */
    @InjectRepository(SubmissionResult)
    private readonly submissionResultRepository: Repository<SubmissionResult>,

    /**
     * Inject DataSource
     */
    private readonly dataSource: DataSource,

    /**
     * Inject CalculateResult Provider
     */
    private readonly calculateResultProvider: CalculateResultProvider,
  ) {}

  public async answer(
    id: string,
    answerSubmissionDto: AnswerSubmissionDTO,
    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,
            outgoingTransitions: {
              toQuestion: {
                choices: true,
              },
            },
          },
        },
      });
    } catch (err) {
      throw new AppTimeoutException(err);
    }

    if (!submission) {
      throw new AppException(
        'common.errors.entityNotFound',
        HttpStatus.NOT_FOUND,
        { entity: '$t(submissions.fields.submission)' },
      );
    }

    const currentQuestion = submission.currentQuestion;

    if (!currentQuestion) {
      let result: SubmissionResult | null;

      try {
        result = await this.submissionResultRepository.findOne({
          where: { submission: { id: submission.id } },
          relations: {
            resultRange: true,
          },
        });
      } catch (err) {
        throw new AppTimeoutException(err);
      }

      return new AppResponse({
        isCompleted: true,
        currentQuestion: null,
        result: result
          ? {
              score: result.score,
              probability: result.probability,
              title: result.resultRange?.title,
              description: result.resultRange?.description,
            }
          : null,
      });
    }

    checkAnswerCorrectness(currentQuestion, answerSubmissionDto);

    const submissionAnswer = this.submissionAnswerRepository.create({
      submission,
      question: currentQuestion,
    });

    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)' },
        );
      }

      submissionAnswer.choice = choice;
    } else if (
      currentQuestion.type === QuestionType.NUMERIC &&
      answerSubmissionDto.numericValue !== undefined
    ) {
      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 (
          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,
            );

          return {
            isCompleted: true,
            currentQuestion: null,
            result,
          };
        }

        await manager.update(
          Submission,
          { id: submission.id },
          { 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);
    }

    if (completedResponse) {
      return new AppResponse(completedResponse);
    }

    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,
        })),
      },
    });
  }
}