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 (probability) =>
        manager.find(ResultRange, {
          where: {
            test: { id: submission.test.id },
            minProbability: LessThanOrEqual(probability),
            maxProbability: MoreThanOrEqual(probability),
          },
        }),
    );

    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 (probability) =>
        this.resultRangeRepository.find({
          where: {
            test: { id: submission.testId },
            minProbability: LessThanOrEqual(probability),
            maxProbability: MoreThanOrEqual(probability),
          },
        }),
    );

    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: (probability: 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 probability =
      totalScores > 0 ? Math.ceil((score / totalScores) * 100) : 0;

    const resultRanges = await loadResultRanges(probability);

    return {
      score,
      probability,
      resultRange: resultRanges.length > 0 ? resultRanges[0] : undefined,
    };
  }
}