"use client";

import { useReducer, useCallback, useMemo } from "react";
import { gameReducer, createInitialState } from "@/lib/game/engine";
import { calculateScore } from "@/lib/game/scoring";
import type { ShuffledQuestion, GameMode } from "@/lib/game/types";

export function useGameState(mode: GameMode, questions: ShuffledQuestion[]) {
  const [state, dispatch] = useReducer(gameReducer, createInitialState(mode, questions));

  const currentQuestion = useMemo(
    () => state.questions[state.currentQuestionIndex] ?? null,
    [state.questions, state.currentQuestionIndex],
  );

  const start = useCallback(() => dispatch({ type: "START" }), []);
  const timeUp = useCallback(() => dispatch({ type: "TIME_UP" }), []);
  const nextPhase = useCallback(() => dispatch({ type: "NEXT_PHASE" }), []);

  const answer = useCallback(
    (selectedAnswer: string, timeRemainingS: number, totalTimeS: number) => {
      if (!currentQuestion) return;
      const isCorrect = selectedAnswer === currentQuestion.correctAnswer;
      if (isCorrect) {
        // Pass the POST-increment streak so the 3rd consecutive correct
        // answer earns the streak=3 multiplier (matches what the UI shows
        // after this answer lands). state.streak is the value BEFORE this
        // answer, so add 1.
        const points = calculateScore(currentQuestion.difficulty, state.streak + 1, timeRemainingS, totalTimeS);
        dispatch({ type: "ANSWER_CORRECT", points });
      } else {
        dispatch({ type: "ANSWER_WRONG" });
      }
      return isCorrect;
    },
    [currentQuestion, state.streak],
  );

  const addQuestions = useCallback(
    (newQuestions: ShuffledQuestion[]) => dispatch({ type: "ADD_QUESTIONS", questions: newQuestions }),
    [],
  );

  const setQuestions = useCallback(
    (newQuestions: ShuffledQuestion[]) => dispatch({ type: "SET_QUESTIONS", questions: newQuestions }),
    [],
  );

  return { state, currentQuestion, start, answer, timeUp, nextPhase, addQuestions, setQuestions };
}