import { useEffect, useRef, useCallback, useState } from 'react';
import { useSharedValue, withTiming, Easing, runOnJS } from 'react-native-reanimated';
import { MathQuestion } from '../types';
import { generateQuestions } from '../constants/gameData';

interface GameEngineConfig {
  totalQuestions?: number;
  timePerQuestion?: number; // seconds
  basePoints?: number;
  comboMultiplier?: number;
}

interface GameEngineReturn {
  questions: MathQuestion[];
  currentQuestionIndex: number;
  score: number;
  combo: number;
  maxCombo: number;
  correctAnswers: number;
  isGameOver: boolean;
  timerProgress: ReturnType<typeof useSharedValue>;
  answerFeedback: (boolean | null)[];
  handleAnswer: (selectedAnswer: number) => void;
  totalQuestions: number;
  avgTime: number;
}

export const useGameEngine = (
  config: GameEngineConfig = {},
  onGameOver?: (results: {
    score: number;
    combo: number;
    correctAnswers: number;
    totalQuestions: number;
    accuracy: number;
    avgTime: number;
  }) => void
): GameEngineReturn => {
  const {
    totalQuestions = 10,
    timePerQuestion = 15,
    basePoints = 100,
    comboMultiplier = 0.5,
  } = config;

  const [questions] = useState(() => generateQuestions(totalQuestions));
  const [currentQuestionIndex, setCurrentQuestionIndex] = useState(0);
  const [score, setScore] = useState(0);
  const [combo, setCombo] = useState(0);
  const [maxCombo, setMaxCombo] = useState(0);
  const [correctAnswers, setCorrectAnswers] = useState(0);
  const [isGameOver, setIsGameOver] = useState(false);
  const [answerFeedback, setAnswerFeedback] = useState<(boolean | null)[]>(
    Array(4).fill(null)
  );
  const [answerDisabled, setAnswerDisabled] = useState(false);

  const timerProgress = useSharedValue(1);
  const questionStartTime = useRef(Date.now());
  const totalTimeSpent = useRef(0);
  const timerRef = useRef<ReturnType<typeof setTimeout> | null>(null);

  // Start timer for current question
  const startTimer = useCallback(() => {
    timerProgress.value = 1;
    timerProgress.value = withTiming(0, {
      duration: timePerQuestion * 1000,
      easing: Easing.linear,
    });
    questionStartTime.current = Date.now();

    // Auto timeout
    if (timerRef.current) clearTimeout(timerRef.current);
    timerRef.current = setTimeout(() => {
      handleTimeout();
    }, timePerQuestion * 1000);
  }, [timePerQuestion]);

  useEffect(() => {
    if (!isGameOver) {
      startTimer();
    }
    return () => {
      if (timerRef.current) clearTimeout(timerRef.current);
    };
  }, [currentQuestionIndex, isGameOver]);

  const handleTimeout = () => {
    if (isGameOver) return;
    setCombo(0);
    moveToNextQuestion();
  };

  const moveToNextQuestion = () => {
    if (timerRef.current) clearTimeout(timerRef.current);

    const timeSpent = (Date.now() - questionStartTime.current) / 1000;
    totalTimeSpent.current += timeSpent;

    if (currentQuestionIndex >= totalQuestions - 1) {
      // Game over
      setIsGameOver(true);
      const accuracy = Math.round((correctAnswers / totalQuestions) * 100);
      const avgTime = Math.round((totalTimeSpent.current / totalQuestions) * 10) / 10;
      if (onGameOver) {
        setTimeout(() => {
          onGameOver({
            score,
            combo: maxCombo,
            correctAnswers,
            totalQuestions,
            accuracy,
            avgTime,
          });
        }, 800);
      }
    } else {
      setTimeout(() => {
        setCurrentQuestionIndex((prev) => prev + 1);
        setAnswerFeedback(Array(4).fill(null));
        setAnswerDisabled(false);
      }, 600);
    }
  };

  const handleAnswer = (selectedAnswer: number) => {
    if (answerDisabled || isGameOver) return;
    setAnswerDisabled(true);

    if (timerRef.current) clearTimeout(timerRef.current);

    const question = questions[currentQuestionIndex];
    const isCorrect = selectedAnswer === question.correctAnswer;

    // Set feedback for each option
    const feedback = question.options.map((opt) => {
      if (opt === question.correctAnswer) return true;
      if (opt === selectedAnswer && !isCorrect) return false;
      return null;
    });
    setAnswerFeedback(feedback);

    const timeSpent = (Date.now() - questionStartTime.current) / 1000;
    totalTimeSpent.current += timeSpent;

    if (isCorrect) {
      const newCombo = combo + 1;
      const comboBonus = Math.floor(basePoints * comboMultiplier * (newCombo - 1));
      const timeBonus = Math.floor(Math.max(0, (timePerQuestion - timeSpent) * 10));
      const points = basePoints + comboBonus + timeBonus;

      setScore((prev) => prev + points);
      setCombo(newCombo);
      setMaxCombo((prev) => Math.max(prev, newCombo));
      setCorrectAnswers((prev) => prev + 1);
    } else {
      setCombo(0);
    }

    // Move to next question after short delay
    if (currentQuestionIndex >= totalQuestions - 1) {
      // Last question - game over
      setTimeout(() => {
        setIsGameOver(true);
        const finalCorrect = isCorrect ? correctAnswers + 1 : correctAnswers;
        const accuracy = Math.round((finalCorrect / totalQuestions) * 100);
        const avgTime = Math.round((totalTimeSpent.current / totalQuestions) * 10) / 10;
        if (onGameOver) {
          onGameOver({
            score: isCorrect ? score + basePoints + Math.floor(basePoints * comboMultiplier * combo) : score,
            combo: Math.max(maxCombo, isCorrect ? combo + 1 : combo),
            correctAnswers: finalCorrect,
            totalQuestions,
            accuracy,
            avgTime,
          });
        }
      }, 800);
    } else {
      setTimeout(() => {
        setCurrentQuestionIndex((prev) => prev + 1);
        setAnswerFeedback(Array(4).fill(null));
        setAnswerDisabled(false);
      }, 600);
    }
  };

  return {
    questions,
    currentQuestionIndex,
    score,
    combo,
    maxCombo,
    correctAnswers,
    isGameOver,
    timerProgress,
    answerFeedback,
    handleAnswer,
    totalQuestions,
    avgTime: totalTimeSpent.current > 0
      ? Math.round((totalTimeSpent.current / Math.max(currentQuestionIndex, 1)) * 10) / 10
      : 0,
  };
};