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

import { getCharacterMaxHp, getCharacterMaxMana } from '../data/characterPresets';
import { normalizeRoster } from '../data/companionRoster';
import { getInitialPlayerCurrency } from '../data/economy';
import {
  applyEquipmentLoadoutToState,
  buildInitialEquipmentLoadout,
  createEmptyEquipmentLoadout,
} from '../data/equipmentEffects';
import { normalizeNpcPersistentState } from '../data/npcInteractions';
import { normalizeQuestLogEntries } from '../data/questFlow';
import { normalizeGameRuntimeStats } from '../data/runtimeStats';
import { ensureSceneEncounterPreview, TREASURE_ENCOUNTERS_ENABLED } from '../data/sceneEncounterPreviews';
import type { SavedGameSnapshot } from '../persistence/gameSaveStorage';
import {
  deleteSaveSnapshot,
  getSaveSnapshot,
  putSaveSnapshot,
} from '../services/storageService';
import {
  applyStoryEngineMigration,
  buildSaveMigrationManifest,
} from '../services/storyEngine/saveMigrationManifest';
import { createEmptyStoryEngineMemoryState } from '../services/storyEngine/visibilityEngine';
import { GameState, StoryMoment } from '../types';
import { BottomTab } from './useGameFlow';

const AUTO_SAVE_DELAY_MS = 400;

function normalizeSavedStory(story: StoryMoment | null) {
  if (!story) return null;
  return {
    ...story,
    streaming: false,
  } satisfies StoryMoment;
}

function normalizeCharacterChats(gameState: GameState) {
  const entries = Object.entries(gameState.characterChats ?? {}).map(([characterId, record]) => [
    characterId,
    {
      history: Array.isArray(record?.history)
        ? record.history
          .filter(turn => turn && typeof turn.text === 'string' && (turn.speaker === 'player' || turn.speaker === 'character'))
          .map(turn => ({
            speaker: turn.speaker,
            text: turn.text,
          }))
        : [],
      summary: typeof record?.summary === 'string' ? record.summary : '',
      updatedAt: typeof record?.updatedAt === 'string' ? record.updatedAt : null,
    },
  ] as const);

  return Object.fromEntries(entries);
}

function normalizeSavedGameState(gameState: GameState) {
  const migrationManifest = buildSaveMigrationManifest({
    version: 'story-engine-v5',
  });
  const migratedState = applyStoryEngineMigration({
    state: gameState,
    manifest: migrationManifest,
  });
  const normalizedRoster = normalizeRoster(gameState.roster ?? [], gameState.companions ?? []);
  const normalizedEncounterState = !TREASURE_ENCOUNTERS_ENABLED && migratedState.currentEncounter?.kind === 'treasure'
    ? ensureSceneEncounterPreview({
        ...migratedState,
        currentEncounter: null,
        sceneHostileNpcs: [],
        inBattle: false,
      } as GameState)
    : migratedState;
  const normalizedRuntimeStats = normalizeGameRuntimeStats(normalizedEncounterState.runtimeStats, {
    isActiveRun: Boolean(
      normalizedEncounterState.playerCharacter &&
      normalizedEncounterState.currentScene === 'Story'
    ),
  });
  const normalizedCommonState = {
    ...normalizedEncounterState,
    customWorldProfile: normalizedEncounterState.customWorldProfile ?? null,
    runtimeStats: normalizedRuntimeStats,
    storyEngineMemory:
      normalizedEncounterState.storyEngineMemory ??
      createEmptyStoryEngineMemoryState(),
    chapterState:
      normalizedEncounterState.chapterState
      ?? normalizedEncounterState.storyEngineMemory?.currentChapter
      ?? null,
    campaignState:
      normalizedEncounterState.campaignState
      ?? normalizedEncounterState.storyEngineMemory?.campaignState
      ?? null,
    activeScenarioPackId:
      normalizedEncounterState.activeScenarioPackId
      ?? normalizedEncounterState.customWorldProfile?.scenarioPackId
      ?? null,
    activeCampaignPackId:
      normalizedEncounterState.activeCampaignPackId
      ?? normalizedEncounterState.customWorldProfile?.campaignPackId
      ?? null,
    npcInteractionActive: normalizedEncounterState.npcInteractionActive ?? false,
    playerCurrency: typeof gameState.playerCurrency === 'number'
      ? gameState.playerCurrency
      : getInitialPlayerCurrency(gameState.worldType),
    quests: normalizeQuestLogEntries(normalizedEncounterState.quests ?? []),
    roster: normalizedRoster,
    npcStates: Object.fromEntries(
      Object.entries(normalizedEncounterState.npcStates ?? {}).map(([npcId, npcState]) => [
        npcId,
        normalizeNpcPersistentState(npcState),
      ]),
    ),
    characterChats: normalizeCharacterChats(normalizedEncounterState),
    activeBuildBuffs: normalizedEncounterState.activeBuildBuffs ?? [],
  } satisfies GameState;

  if (!normalizedEncounterState.playerCharacter) {
    return {
      ...normalizedCommonState,
      playerEquipment: createEmptyEquipmentLoadout(),
    } satisfies GameState;
  }

  const resolvedEquipment = normalizedEncounterState.playerEquipment
    ? normalizedEncounterState.playerEquipment
    : buildInitialEquipmentLoadout(normalizedEncounterState.playerCharacter);

  const playerMaxHp = getCharacterMaxHp(
    normalizedEncounterState.playerCharacter,
    normalizedEncounterState.worldType,
    normalizedEncounterState.customWorldProfile,
  );

  return applyEquipmentLoadoutToState({
    ...normalizedCommonState,
    playerMaxHp,
    playerHp: Math.min(normalizedEncounterState.playerHp, playerMaxHp),
    playerMaxMana: getCharacterMaxMana(normalizedEncounterState.playerCharacter),
    playerMana: getCharacterMaxMana(normalizedEncounterState.playerCharacter),
    playerEquipment: createEmptyEquipmentLoadout(),
  } as GameState, resolvedEquipment);
}

function canPersistSnapshot(gameState: GameState, story: StoryMoment | null) {
  return (
    gameState.currentScene === 'Story' &&
    Boolean(gameState.worldType) &&
    Boolean(gameState.playerCharacter) &&
    story?.streaming !== true
  );
}

export function useGamePersistence({
  gameState,
  bottomTab,
  currentStory,
  isLoading,
  setGameState,
  setBottomTab,
  hydrateStoryState,
  resetStoryState,
}: {
  gameState: GameState;
  bottomTab: BottomTab;
  currentStory: StoryMoment | null;
  isLoading: boolean;
  setGameState: (state: GameState) => void;
  setBottomTab: (tab: BottomTab) => void;
  hydrateStoryState: (story: StoryMoment | null) => void;
  resetStoryState: () => void;
}) {
  const [hasSavedGame, setHasSavedGame] = useState(false);
  const [savedSnapshot, setSavedSnapshot] = useState<SavedGameSnapshot | null>(null);

  useEffect(() => {
    let isActive = true;

    void getSaveSnapshot()
      .then((snapshot) => {
        if (!isActive) return;
        setSavedSnapshot(snapshot);
        setHasSavedGame(Boolean(snapshot));
      })
      .catch((error) => {
        console.warn('[useGamePersistence] failed to load remote snapshot', error);
      });

    return () => {
      isActive = false;
    };
  }, []);

  useEffect(() => {
    const canPersist = !isLoading && canPersistSnapshot(gameState, currentStory);

    if (!canPersist) return;

    const timeoutId = window.setTimeout(() => {
      void putSaveSnapshot({
        gameState,
        bottomTab,
        currentStory,
      })
        .then((snapshot) => {
          setSavedSnapshot(snapshot);
          setHasSavedGame(true);
        })
        .catch((error) => {
          console.warn('[useGamePersistence] failed to autosave remote snapshot', error);
        });
    }, AUTO_SAVE_DELAY_MS);

    return () => window.clearTimeout(timeoutId);
  }, [bottomTab, currentStory, gameState, isLoading]);

  const saveCurrentGame = useCallback(async (override?: {
    gameState?: GameState;
    bottomTab?: BottomTab;
    currentStory?: StoryMoment | null;
  }) => {
    const nextGameState = override?.gameState ?? gameState;
    const nextBottomTab = override?.bottomTab ?? bottomTab;
    const nextStory = override?.currentStory ?? currentStory;

    if (!canPersistSnapshot(nextGameState, nextStory)) {
      return false;
    }

    try {
      const snapshot = await putSaveSnapshot({
        gameState: nextGameState,
        bottomTab: nextBottomTab,
        currentStory: nextStory,
      });
      setSavedSnapshot(snapshot);
      setHasSavedGame(true);
      return true;
    } catch (error) {
      console.warn('[useGamePersistence] failed to save remote snapshot', error);
      return false;
    }
  }, [bottomTab, currentStory, gameState]);

  const clearSavedGame = useCallback(async () => {
    try {
      await deleteSaveSnapshot();
    } catch (error) {
      console.warn('[useGamePersistence] failed to delete remote snapshot', error);
    }

    setSavedSnapshot(null);
    setHasSavedGame(false);
  }, []);

  const continueSavedGame = useCallback(async () => {
    const snapshot = savedSnapshot ?? await getSaveSnapshot().catch((error) => {
      console.warn('[useGamePersistence] failed to refetch remote snapshot', error);
      return null;
    });
    if (!snapshot) {
      setSavedSnapshot(null);
      setHasSavedGame(false);
      return false;
    }

    resetStoryState();
    setGameState(normalizeSavedGameState(snapshot.gameState));
    setBottomTab(snapshot.bottomTab ?? 'adventure');
    hydrateStoryState(normalizeSavedStory(snapshot.currentStory));
    setSavedSnapshot(snapshot);
    setHasSavedGame(true);
    return true;
  }, [hydrateStoryState, resetStoryState, savedSnapshot, setBottomTab, setGameState]);

  return {
    hasSavedGame,
    saveCurrentGame,
    continueSavedGame,
    clearSavedGame,
  };
}