import { useCallback, useEffect, useRef, useState } from 'react';

import type { GameState, StoryMoment, StoryOption } from '../../types';

export type SceneTransitionPhase = 'idle' | 'exiting' | 'entering';
export type SceneTransitionTriggerMode = 'scene-change' | 'content-change';

type SceneTransitionRequest = {
  mode: SceneTransitionTriggerMode;
  baselineSceneId: string | null;
  baselineContentKey: string;
  exitComplete: boolean;
};

const DEFAULT_SCENE_SWITCH_EXIT_MS = 5000;
const DEFAULT_SCENE_SWITCH_ENTRY_MS = 5930;

export const SCENE_TRANSITION_FUNCTION_MODES: Partial<
  Record<string, SceneTransitionTriggerMode>
> = {
  story_continue_adventure: 'content-change',
  idle_travel_next_scene: 'scene-change',
  camp_travel_home_scene: 'scene-change',
  idle_explore_forward: 'content-change',
  idle_follow_clue: 'content-change',
};

function buildSceneTransitionContentKey(
  gameState: GameState,
  currentStory: StoryMoment | null,
) {
  const sceneId = gameState.currentScenePreset?.id ?? 'scene:none';
  const sceneActId =
    gameState.storyEngineMemory?.currentSceneActState?.currentActId ??
    'act:none';
  const encounterKey = gameState.currentEncounter
    ? `${gameState.currentEncounter.kind}:${gameState.currentEncounter.id ?? gameState.currentEncounter.npcName ?? 'unknown'}`
    : 'encounter:none';
  const monsterKey = gameState.sceneHostileNpcs
    .map(
      (monster) =>
        `${monster.id}:${monster.renderKind}:${monster.xMeters}:${monster.animation}`,
    )
    .join('|');
  const storyKey = currentStory
    ? `${currentStory.displayMode ?? 'story'}:${currentStory.text ?? ''}:${currentStory.dialogue?.length ?? 0}:${currentStory.options.map((option) => option.functionId).join('|')}:${currentStory.deferredAutoChoice?.functionId ?? 'auto:none'}`
    : 'story:none';
  return [sceneId, sceneActId, encounterKey, monsterKey, storyKey].join('::');
}

/**
 * RPG 运行态场景过场模型真实入口。
 * 第三批收口后，`rpg-runtime-shell` 直接承载场景过场状态。
 */
export function useRpgSceneTransitionModel(params: {
  gameState: GameState;
  currentStory: StoryMoment | null;
  openingCampSceneId: string | null;
  onDeferredAutoChoice?: ((option: StoryOption) => void) | null;
}) {
  const {
    gameState,
    currentStory,
    openingCampSceneId,
    onDeferredAutoChoice = null,
  } = params;
  const [renderGameState, setRenderGameState] = useState(gameState);
  const [renderCurrentStory, setRenderCurrentStory] = useState(currentStory);
  const [sceneTransitionPhase, setSceneTransitionPhase] =
    useState<SceneTransitionPhase>('idle');
  const [sceneTransitionToken, setSceneTransitionToken] = useState(0);
  const [sceneTransitionDurations, setSceneTransitionDurations] = useState({
    exitMs: DEFAULT_SCENE_SWITCH_EXIT_MS,
    entryMs: DEFAULT_SCENE_SWITCH_ENTRY_MS,
  });

  const pendingScenePayloadRef = useRef<{
    gameState: GameState;
    currentStory: StoryMoment | null;
  }>({
    gameState,
    currentStory,
  });
  const sceneTransitionTimerIdsRef = useRef<number[]>([]);
  const sceneTransitionRequestRef = useRef<SceneTransitionRequest | null>(null);
  const pendingDeferredAutoChoiceRef =
    useRef<StoryOption | null>(null);
  const onDeferredAutoChoiceRef = useRef(onDeferredAutoChoice);

  useEffect(() => {
    onDeferredAutoChoiceRef.current = onDeferredAutoChoice;
  }, [onDeferredAutoChoice]);

  useEffect(() => {
    return () => {
      sceneTransitionTimerIdsRef.current.forEach((timerId) =>
        window.clearTimeout(timerId),
      );
      sceneTransitionTimerIdsRef.current = [];
      sceneTransitionRequestRef.current = null;
      pendingDeferredAutoChoiceRef.current = null;
    };
  }, []);

  const startSceneEntering = useCallback(
    (payload: { gameState: GameState; currentStory: StoryMoment | null }) => {
      sceneTransitionTimerIdsRef.current.forEach((timerId) =>
        window.clearTimeout(timerId),
      );
      sceneTransitionTimerIdsRef.current = [];
      sceneTransitionRequestRef.current = null;
      setRenderGameState(payload.gameState);
      setRenderCurrentStory(payload.currentStory);
      setSceneTransitionToken((current) => current + 1);
      setSceneTransitionPhase('entering');

      const entryTimerId = window.setTimeout(() => {
        setSceneTransitionPhase('idle');
        const autoChoice =
          payload.currentStory?.deferredAutoChoice ??
          pendingDeferredAutoChoiceRef.current;
        if (autoChoice) {
          pendingDeferredAutoChoiceRef.current = null;
          // 中文注释：入场计时器可能跨过一次 currentStory/gameState 更新，
          // 必须读取最新回调，避免用点击“继续冒险”前的旧状态自动开聊。
          onDeferredAutoChoiceRef.current?.(autoChoice);
        }
      }, sceneTransitionDurations.entryMs);
      sceneTransitionTimerIdsRef.current.push(entryTimerId);
    },
    [sceneTransitionDurations.entryMs],
  );

  const beginSceneTransition = useCallback(
    (mode: SceneTransitionTriggerMode) => {
      if (sceneTransitionPhase !== 'idle') return;

      pendingScenePayloadRef.current = { gameState, currentStory };
      pendingDeferredAutoChoiceRef.current = null;
      sceneTransitionTimerIdsRef.current.forEach((timerId) =>
        window.clearTimeout(timerId),
      );
      sceneTransitionTimerIdsRef.current = [];
      sceneTransitionRequestRef.current = {
        mode,
        baselineSceneId:
          renderGameState.currentScenePreset?.id ??
          gameState.currentScenePreset?.id ??
          null,
        baselineContentKey: buildSceneTransitionContentKey(
          renderGameState,
          renderCurrentStory,
        ),
        exitComplete: false,
      };
      setSceneTransitionPhase('exiting');

      const exitTimerId = window.setTimeout(() => {
        const request = sceneTransitionRequestRef.current;
        if (!request) return;
        request.exitComplete = true;

        const pendingPayload = pendingScenePayloadRef.current;
        const isReady =
          request.mode === 'scene-change'
            ? (pendingPayload.gameState.currentScenePreset?.id ?? null) !==
              request.baselineSceneId
            : buildSceneTransitionContentKey(
                pendingPayload.gameState,
                pendingPayload.currentStory,
              ) !== request.baselineContentKey;

        if (isReady) {
          startSceneEntering(pendingPayload);
        }
      }, sceneTransitionDurations.exitMs);
      sceneTransitionTimerIdsRef.current.push(exitTimerId);
    },
    [
      currentStory,
      gameState,
      renderCurrentStory,
      renderGameState,
      sceneTransitionDurations.exitMs,
      sceneTransitionPhase,
      startSceneEntering,
    ],
  );

  useEffect(() => {
    pendingScenePayloadRef.current = { gameState, currentStory };

    const request = sceneTransitionRequestRef.current;
    if (sceneTransitionPhase === 'exiting' && request?.exitComplete) {
      const isReady =
        request.mode === 'scene-change'
          ? (gameState.currentScenePreset?.id ?? null) !== request.baselineSceneId
          : buildSceneTransitionContentKey(gameState, currentStory) !==
            request.baselineContentKey;
      if (isReady) {
        pendingDeferredAutoChoiceRef.current =
          currentStory?.deferredAutoChoice ?? null;
        startSceneEntering({ gameState, currentStory });
      }
      return;
    }

    if (sceneTransitionPhase !== 'exiting') {
      setRenderGameState(gameState);
      setRenderCurrentStory(currentStory);
    }
  }, [currentStory, gameState, sceneTransitionPhase, startSceneEntering]);

  useEffect(() => {
    if (sceneTransitionPhase !== 'idle') {
      return;
    }
    if (renderGameState.playerCharacter) {
      return;
    }
    if (!gameState.playerCharacter || gameState.currentScene !== 'Story') {
      return;
    }
    if (gameState.storyHistory.length > 0) {
      return;
    }
    if (
      !openingCampSceneId ||
      gameState.currentScenePreset?.id !== openingCampSceneId
    ) {
      return;
    }

    startSceneEntering({ gameState, currentStory });
  }, [
    currentStory,
    gameState,
    openingCampSceneId,
    renderGameState.playerCharacter,
    sceneTransitionPhase,
    startSceneEntering,
  ]);

  return {
    visibleGameState:
      sceneTransitionPhase === 'idle' ? gameState : renderGameState,
    visibleCurrentStory:
      sceneTransitionPhase === 'idle' ? currentStory : renderCurrentStory,
    sceneTransitionPhase,
    sceneTransitionToken,
    setSceneTransitionDurations,
    beginSceneTransition,
  };
}