import { Component, OnDestroy } from '@angular/core';
import { FormsModule } from '@angular/forms';
import { CommonModule } from '@angular/common';
import { GenerateQuestionsService } from './generate-questions.service';
import { Router } from '@angular/router';
import confetti from 'canvas-confetti';
import { HeaderComponent } from '../shared/header/header.component';
import { ButtonComponent } from '../shared/button/button.component';

interface QuestionWithAnswer {
  question: string;
  correctAnswer: string;
}

interface Question {
  parts: string[];
  index: number;
}

const COUNTDOWN_SECONDS = 10;
const HINT_AUTO_HIDE_MS = 5000;
const NEXT_LEVEL_DELAY_MS = 2000;
const COMPLETION_DELAY_MS = 3000;
const CONFETTI_INTERVAL_MS = 250;
const RING_RADIUS = 90;

const INCORRECT_INDICATORS = [
  'incorrect', 'not correct', 'wrong', 'not right',
  'is not', 'are not', 'isn\'t correct', 'aren\'t correct'
];

const CORRECT_INDICATORS = [
  'correct', 'right', 'yes', 'accurate',
  'well done', 'good job', 'perfect'
];

@Component({
  selector: 'app-generate-questions',
  standalone: true,
  imports: [FormsModule, CommonModule, HeaderComponent, ButtonComponent],
  templateUrl: './generate-questions.component.html',
  styleUrls: ['./generate-questions.component.css']
})
export class GenerateQuestionsComponent implements OnDestroy {
  topic = '';
  readonly hardcodedTopics = ['Noun', 'Verb', 'Past Tense', 'Adjective', 'Present Continuous'];
  questions: Question[] = [];
  questionsWithAnswers: QuestionWithAnswer[] = [];

  userAnswers: string[] = [];
  answerStatuses: ('correct' | 'incorrect' | 'pending')[] = [];
  feedback: string[] = [];
  hints: string[] = [];
  readonlyAnswers: boolean[] = [];
  attemptCounts: Record<number, number> = {};

  currentDifficulty = 'basic';
  readonly difficultyLevels = ['basic', 'intermediate', 'expert'];

  showSuggestions = false;
  isQuestionsGenerated = false;
  isValidationInProgress = false;
  isFirstAttemptDone = false;
  isAllLevelsCompleted = false;
  isHintMenuVisible = false;
  isLoading = false;
  isChecked = false;
  error = '';

  get isGenerateDisabled() { return !this.topic.trim() || this.isQuestionsGenerated; }
  get isResetDisabled() { return !this.topic && !this.isQuestionsGenerated; }
  get isTopicLocked() { return this.isQuestionsGenerated; }
  get isDropdownDisabled() { return this.isQuestionsGenerated; }
  get showLevelTooltip() { return this.isQuestionsGenerated; }
  get activateLevelDot() { return this.isQuestionsGenerated; }

  private hasShownHintIcon = false;
  showHintIcon = false;
  hasNewHints = false;

  showGlobalCountdown = false;
  globalCountdown = 0;
  overlayCaption = '';
  ringCircumference = 2 * Math.PI * RING_RADIUS;
  ringDashoffset = this.ringCircumference;

  private globalTimer: any;
  private overlayTicker: any;
  private overlayEndTs = 0;
  private globalCountdownActive = false;
  private confettiInterval: any;

  constructor(
    private service: GenerateQuestionsService,
    private router: Router
  ) {}

  ngOnDestroy(): void {
    this.clearTimers();
    this.stopConfettiAnimation();
  }

  private clearTimers(): void {
    if (this.globalTimer) clearInterval(this.globalTimer);
    if (this.overlayTicker) clearInterval(this.overlayTicker);
    this.globalTimer = null;
    this.overlayTicker = null;
    this.showGlobalCountdown = false;
    this.globalCountdownActive = false;
  }

  onTopicChange(): void {
    this.showSuggestions = !this.topic.trim();
  }

  getProgressWidth(): string {
    const index = this.difficultyLevels.indexOf(this.currentDifficulty);
    if (index === -1 || this.difficultyLevels.length <= 1) return '0%';
    return `${(index / (this.difficultyLevels.length - 1)) * 100}%`;
  }

  generateQuestions(): void {
    if (this.isAllLevelsCompleted) {
      this.error = 'Please reset to start over.';
      return;
    }

    this.resetQuestionState();

    this.service.generateQuestions(this.topic, this.currentDifficulty)
      .subscribe({
        next: (response) => this.handleQuestionsResponse(response),
        error: (error) => this.handleQuestionsError(error)
      });
  }

  private handleQuestionsResponse(response: any): void {
    const rawQuestions = (response?.text ?? response?.generations?.[0]?.text ?? '').trim();

    if (!rawQuestions) {
      this.error = 'No questions generated. Please try again.';
      return;
    }

    this.isQuestionsGenerated = true;
    this.parseAndInitializeQuestions(rawQuestions);
  }

  private handleQuestionsError(error: any): void {
    this.error = error.status === 400 && error.error.message
      ? error.error.message
      : 'Failed to fetch questions. Please try again later.';
  }

  private parseAndInitializeQuestions(rawQuestions: string): void {
    this.questionsWithAnswers = this.parseQuestions(rawQuestions);
    this.questions = this.splitQuestionsIntoParts(this.questionsWithAnswers);
    this.initializeAnswerArrays(this.questions.length);
  }

  private parseQuestions(text: string): QuestionWithAnswer[] {
    const regex = /(\d+\.\s*.+?_______)\s*(.*?)\s*\(([^)]+)\)\s*$/gm;
    const questions: QuestionWithAnswer[] = [];
    let match;

    while ((match = regex.exec(text)) !== null) {
      const questionText = match[1]?.trim();
      const afterBlank = match[2]?.replace(/^[_-]+/, '').replace(/^\s+/, ' ').replace(/\s{2,}/g, ' ');
      const correctAnswer = match[3]?.trim();

      if (questionText && correctAnswer) {
        questions.push({
          question: `${questionText}${afterBlank}`,
          correctAnswer
        });
      }
    }
    return questions;
  }

  private splitQuestionsIntoParts(questions: QuestionWithAnswer[]): Question[] {
    return questions.map((q, index) => {
      const normalized = q.question.replace(/\s*_{3,}\s*/g, '_______');
      const parts = normalized.split('_______').map(p => p.replace(/[_]+/g, '').trim());
      return { parts, index };
    });
  }

  private initializeAnswerArrays(length: number): void {
    this.userAnswers = Array(length).fill('');
    this.answerStatuses = Array(length).fill('pending');
    this.feedback = Array(length).fill('');
    this.readonlyAnswers = Array(length).fill(false);
    this.hints = [];
    this.attemptCounts = {};
    for (let i = 0; i < length; i++) {
      this.attemptCounts[i] = 0;
    }
  }

  private resetQuestionState(): void {
    this.hints = [];
    this.showSuggestions = false;
    this.readonlyAnswers = [];
  }

  resetTopic(): void {
    this.topic = '';
    this.questions = [];
    this.questionsWithAnswers = [];
    this.userAnswers = [];
    this.answerStatuses = [];
    this.readonlyAnswers = [];
    this.feedback = [];
    this.hints = [];
    this.attemptCounts = {};

    this.isQuestionsGenerated = false;
    this.isValidationInProgress = false;
    this.isFirstAttemptDone = false;
    this.isAllLevelsCompleted = false;
    this.hasNewHints = false;
    this.showSuggestions = false;
    this.isChecked = false;
    this.currentDifficulty = 'basic';
    this.error = '';

    this.clearTimers();
    this.stopConfetti();
  }

  areAllAnswersFilled(): boolean {
    return this.userAnswers.every(answer => answer?.trim());
  }

  closeErrorPopup(): void {
    this.error = '';
  }

  private parseAIValidation(response: string): boolean {
    if (!response) return false;

    const lower = response.toLowerCase();

    if (INCORRECT_INDICATORS.some(ind => lower.includes(ind))) return false;
    if (CORRECT_INDICATORS.some(ind => lower.includes(ind))) return true;

    return false;
  }

  checkAllAnswers(): void {
    this.isValidationInProgress = true;
    this.isLoading = true;
    this.isFirstAttemptDone = true;

    const payload = this.questions.map((q, i) => ({
      topic: this.topic,
      question: q.parts.join('_______'),
      user_answer: this.userAnswers[i]
    }));

    this.service.validateAllAnswers(payload).subscribe({
      next: (response) => this.handleValidationResponse(response),
      error: (error) => this.handleValidationError(error)
    });
  }

  private handleValidationResponse(response: any): void {
    if (!response.results?.length) {
      this.error = 'Failed to validate answers. Please try again.';
      this.resetValidationState();
      return;
    }

    let hadFirstWrong = false;
    let hadSecondWrong = false;

    response.results.forEach((result: any, index: number) => {
      this.attemptCounts[index]++;
      const isCorrect = this.parseAIValidation(result.validation_response);

      this.feedback[index] = result.validation_response || 'No feedback provided.';

      if (isCorrect) {
        this.markAsCorrect(index);
      } else {
        const attemptResult = this.handleIncorrectAttempt(index, result.hint);
        hadFirstWrong = hadFirstWrong || attemptResult.first;
        hadSecondWrong = hadSecondWrong || attemptResult.second;
      }
    });

    this.handleHintsDisplay(hadFirstWrong || hadSecondWrong);
    
    if (!hadSecondWrong) {
      this.checkLevelCompletion();
    }
    
    this.resetValidationState();
  }

  private markAsCorrect(index: number): void {
    this.readonlyAnswers[index] = true;
    this.hints[index] = '';
    this.answerStatuses[index] = 'correct';
    this.userAnswers[index] = this.userAnswers[index].trim();
  }

  private handleIncorrectAttempt(index: number, hint: string): { first: boolean; second: boolean } {
    this.answerStatuses[index] = 'incorrect';
    this.hints[index] = hint?.trim() || '';

    if (this.attemptCounts[index] === 1) {
      this.scheduleAnswerClear(index);
      return { first: true, second: false };
    } else if (this.attemptCounts[index] >= 2) {
      this.scheduleAnswerReveal(index);
      return { first: false, second: true };
    }

    return { first: false, second: false };
  }

  private scheduleAnswerClear(index: number): void {
    if (!this.globalCountdownActive) this.startOverlay('Try again in');

    setTimeout(() => {
      this.userAnswers[index] = '';
      this.answerStatuses[index] = 'pending';
      this.clearTimers();
    }, COUNTDOWN_SECONDS * 1000);
  }

  private scheduleAnswerReveal(index: number): void {
    if (!this.globalCountdownActive) this.startOverlay('Showing correct answer in');

    setTimeout(() => {
      this.userAnswers[index] = this.questionsWithAnswers[index].correctAnswer;
      this.answerStatuses[index] = 'correct';
      this.readonlyAnswers[index] = true;
      this.clearTimers();

      if (this.areAllCorrectAnswersDisplayed()) {
        if (this.isLastLevel()) {
          this.scheduleCompletion();
        } else {
          this.scheduleNextLevel();
        }
      }
    }, COUNTDOWN_SECONDS * 1000);
  }

  private scheduleCompletion(): void {
    this.startOverlay('Finishing in');
    setTimeout(() => {
      this.clearTimers();
      this.isAllLevelsCompleted = true;
      this.triggerConfetti();
    }, COUNTDOWN_SECONDS * 1000);
  }

  private handleHintsDisplay(hasWrongAnswers: boolean): void {
    this.hasNewHints = this.hints.some(h => h?.trim());

    if (this.hasNewHints) {
      setTimeout(() => { this.hasNewHints = false; }, HINT_AUTO_HIDE_MS);
    }

    if (!this.hasShownHintIcon && (this.hasNewHints || hasWrongAnswers)) {
      this.showHintIcon = true;
      this.hasShownHintIcon = true;
    }
  }

  private checkLevelCompletion(): void {
    if (this.areAllCorrectAnswersDisplayed()) {
      if (this.isLastLevel()) {
        this.scheduleCompletion();
      } else {
        this.scheduleNextLevel();
      }
    }
  }

  private scheduleNextLevel(): void {
    this.clearTimers();
    this.startOverlay('Moving to next level in');
    setTimeout(() => {
      this.clearTimers();
      setTimeout(() => this.transitionDifficulty(), NEXT_LEVEL_DELAY_MS);
    }, COUNTDOWN_SECONDS * 1000);
  }

  private handleValidationError(error: any): void {
    this.error = 'Error validating answers. Please try again later.';
    this.resetValidationState();
  }

  private resetValidationState(): void {
    this.isValidationInProgress = false;
    this.isLoading = false;
  }

  isLastLevel(): boolean {
    return this.currentDifficulty === this.difficultyLevels[this.difficultyLevels.length - 1];
  }

  areAllCorrectAnswersDisplayed(): boolean {
    return this.readonlyAnswers.every(readonly => readonly);
  }

  transitionDifficulty(): void {
    const currentIndex = this.difficultyLevels.indexOf(this.currentDifficulty);

    if (currentIndex < this.difficultyLevels.length - 1) {
      this.currentDifficulty = this.difficultyLevels[currentIndex + 1];
      this.generateQuestions();
    } else {
      setTimeout(() => {
        this.questions = [];
        this.isAllLevelsCompleted = true;
        this.triggerConfetti();
      }, COMPLETION_DELAY_MS);
    }
  }

  onAnswerChange(index: number): void {
    this.userAnswers[index] = this.userAnswers[index]?.trim() || '';
    this.userAnswers = [...this.userAnswers];
  }

  goToHome(): void {
    this.router.navigate(['/home']);
  }

  triggerConfetti(): void {
    if (this.confettiInterval) clearInterval(this.confettiInterval);

    this.confettiInterval = setInterval(() => {
      confetti({
        startVelocity: 30,
        spread: 360,
        ticks: 60,
        origin: { x: Math.random(), y: Math.random() - 0.2 }
      });
    }, CONFETTI_INTERVAL_MS);
  }

  stopConfetti(): void {
    this.isAllLevelsCompleted = false;
    this.stopConfettiAnimation();
  }

  private stopConfettiAnimation(): void {
    if (this.confettiInterval) {
      clearInterval(this.confettiInterval);
      this.confettiInterval = null;
    }
    document.querySelector('canvas.confetti-canvas')?.remove();
    document.querySelectorAll('.confetti, .ts-confetti').forEach(el => el.remove());
  }

  stopConfettiAndReset(): void {
    this.stopConfetti();
    this.resetTopic();
  }

  selectTopic(suggestion: string): void {
    this.topic = suggestion;
    this.showSuggestions = false;
  }

  hideSuggestions(): void {
    setTimeout(() => { this.showSuggestions = false; }, 150);
  }

  closeHints(): void {
    this.isHintMenuVisible = false;
    this.hasNewHints = false;
  }

  toggleHintMenu(): void {
    this.isHintMenuVisible = !this.isHintMenuVisible;
    if (this.isHintMenuVisible) this.showHintIcon = false;
  }

  onInput(event: any, index: number): void {
    const filtered = event.target.value.replace(/[^a-zA-Z]/g, '');
    this.userAnswers[index] = filtered;
    event.target.value = filtered;
  }

  private startOverlay(caption: string, seconds = COUNTDOWN_SECONDS): void {
    this.clearTimers();

    this.globalCountdownActive = true;
    this.showGlobalCountdown = true;
    this.overlayCaption = caption;
    this.globalCountdown = seconds;
    this.overlayEndTs = Date.now() + seconds * 1000;
    this.ringDashoffset = this.ringCircumference;

    this.overlayTicker = setInterval(() => {
      const now = Date.now();
      const remainingMs = Math.max(0, this.overlayEndTs - now);
      const elapsedMs = seconds * 1000 - remainingMs;

      this.globalCountdown = Math.ceil(remainingMs / 1000);
      this.ringDashoffset = this.ringCircumference * (1 - Math.min(1, elapsedMs / (seconds * 1000)));

      if (remainingMs <= 0) this.clearTimers();
    }, 50);

    this.globalTimer = setTimeout(() => this.clearTimers(), seconds * 1000);
  }
}