import axios from 'axios';
import AsyncStorage from '@react-native-async-storage/async-storage';
import { Track } from './types';

const API_BASE_URL = 'https://traesite.umersoft.com:8975';
const PLAYLIST_LIST_PATH = '/api/zen_box/playlists';
const DEFAULT_PLAYLIST_FILE = 'playlist.json';
const PLAYLIST_SNAPSHOT_KEY_PREFIX = '@zen_box_playlist_snapshot:';
const SELECTED_PLAYLIST_KEY = '@zen_box_selected_playlist';
const RESUME_ENABLED_KEY = '@zen_box_resume_enabled';
const PLAYBACK_POSITION_KEY_PREFIX = '@zen_box_playback_position:';

const api = axios.create({
  baseURL: API_BASE_URL,
  timeout: 10000,
  headers: {
    'Content-Type': 'application/json',
  },
});

export const formatError = (error: any): string => {
  if (error.response) {
    return `服务器响应 ${error.response.status}: ${error.response.statusText}`;
  } else if (error.request) {
    return `服务器无响应: 无法连接到 ${API_BASE_URL}`;
  } else if (error.message) {
    return `请求错误: ${error.message}`;
  } else {
    return `未知错误`;
  }
};

const normalizePlaylistFile = (fileName?: string): string => {
  return String(fileName || DEFAULT_PLAYLIST_FILE).trim() || DEFAULT_PLAYLIST_FILE;
};

const buildPlaylistPath = (fileName?: string): string => {
  return `/tools/zen_box/${encodeURIComponent(normalizePlaylistFile(fileName))}`;
};

const getPlaylistSnapshotKey = (fileName?: string): string => {
  return `${PLAYLIST_SNAPSHOT_KEY_PREFIX}${normalizePlaylistFile(fileName)}`;
};

const getPlaybackPositionKey = (playlistFile?: string, trackSrc?: string): string => {
  return `${PLAYBACK_POSITION_KEY_PREFIX}${normalizePlaylistFile(playlistFile)}::${String(trackSrc || '').trim()}`;
};

export const getPlaylistFiles = async (): Promise<string[]> => {
  try {
    const response = await api.get<{ ok?: boolean; playlists?: string[] }>(PLAYLIST_LIST_PATH);
    const raw = Array.isArray(response.data?.playlists) ? response.data.playlists : [];
    const files = raw.map(item => String(item || '')).filter(Boolean);
    if (!files.includes(DEFAULT_PLAYLIST_FILE)) {
      files.unshift(DEFAULT_PLAYLIST_FILE);
    }
    return files;
  } catch (error) {
    console.error('读取歌单列表失败:', error);
    return [DEFAULT_PLAYLIST_FILE];
  }
};

export const getSavedSelectedPlaylist = async (): Promise<string> => {
  try {
    const value = await AsyncStorage.getItem(SELECTED_PLAYLIST_KEY);
    return normalizePlaylistFile(value || DEFAULT_PLAYLIST_FILE);
  } catch (error) {
    console.error('读取当前歌单失败:', error);
    return DEFAULT_PLAYLIST_FILE;
  }
};

export const saveSelectedPlaylist = async (fileName: string): Promise<void> => {
  try {
    await AsyncStorage.setItem(SELECTED_PLAYLIST_KEY, normalizePlaylistFile(fileName));
  } catch (error) {
    console.error('保存当前歌单失败:', error);
  }
};

export const getResumePlaybackEnabled = async (): Promise<boolean> => {
  try {
    const value = await AsyncStorage.getItem(RESUME_ENABLED_KEY);
    if (value === null) {
      return true;
    }
    return value === '1';
  } catch (error) {
    console.error('读取断点续播设置失败:', error);
    return true;
  }
};

export const saveResumePlaybackEnabled = async (enabled: boolean): Promise<void> => {
  try {
    await AsyncStorage.setItem(RESUME_ENABLED_KEY, enabled ? '1' : '0');
  } catch (error) {
    console.error('保存断点续播设置失败:', error);
  }
};

export const getSavedPlaybackPosition = async (playlistFile?: string, trackSrc?: string): Promise<number> => {
  try {
    const key = getPlaybackPositionKey(playlistFile, trackSrc);
    const value = await AsyncStorage.getItem(key);
    const seconds = Number(value || 0);
    return Number.isFinite(seconds) && seconds > 0 ? seconds : 0;
  } catch (error) {
    console.error('读取播放进度失败:', error);
    return 0;
  }
};

export const savePlaybackPosition = async (
  playlistFile: string,
  trackSrc: string,
  positionSeconds: number
): Promise<void> => {
  try {
    const key = getPlaybackPositionKey(playlistFile, trackSrc);
    const safeSeconds = Math.max(0, Math.floor(positionSeconds || 0));
    await AsyncStorage.setItem(key, String(safeSeconds));
  } catch (error) {
    console.error('保存播放进度失败:', error);
  }
};

export const clearPlaybackPosition = async (playlistFile: string, trackSrc: string): Promise<void> => {
  try {
    const key = getPlaybackPositionKey(playlistFile, trackSrc);
    await AsyncStorage.removeItem(key);
  } catch (error) {
    console.error('清除播放进度失败:', error);
  }
};

export const getPlaylist = async (fileName?: string): Promise<Track[]> => {
  try {
    const response = await api.get<Track[]>(buildPlaylistPath(fileName));
    return response.data;
  } catch (error) {
    throw new Error(formatError(error));
  }
};

const isValidPlaylist = (data: unknown): data is Track[] => {
  return Array.isArray(data) && data.every((item) => {
    if (!item || typeof item !== 'object') {
      return false;
    }
    const track = item as Track;
    return typeof track.title === 'string'
      && typeof track.artist === 'string'
      && typeof track.src === 'string';
  });
};

export const savePlaylistSnapshot = async (tracks: Track[], fileName?: string): Promise<void> => {
  try {
    await AsyncStorage.setItem(getPlaylistSnapshotKey(fileName), JSON.stringify(tracks));
  } catch (error) {
    console.error('保存歌单快照失败:', error);
  }
};

export const getPlaylistSnapshot = async (fileName?: string): Promise<Track[]> => {
  try {
    const raw = await AsyncStorage.getItem(getPlaylistSnapshotKey(fileName));
    if (!raw) {
      return [];
    }

    const parsed: unknown = JSON.parse(raw);
    return isValidPlaylist(parsed) ? parsed : [];
  } catch (error) {
    console.error('读取歌单快照失败:', error);
    return [];
  }
};

export const getPlaylistWithFallback = async (fileName?: string): Promise<{
  tracks: Track[];
  source: 'remote' | 'snapshot';
  fallbackReason?: string;
  playlistFile: string;
}> => {
  const normalizedFile = normalizePlaylistFile(fileName);
  try {
    const tracks = await getPlaylist(normalizedFile);
    await savePlaylistSnapshot(tracks, normalizedFile);
    return { tracks, source: 'remote', playlistFile: normalizedFile };
  } catch (error) {
    const fallbackTracks = await getPlaylistSnapshot(normalizedFile);
    if (fallbackTracks.length > 0) {
      return {
        tracks: fallbackTracks,
        source: 'snapshot',
        fallbackReason: error instanceof Error ? error.message : '远程歌单加载失败',
        playlistFile: normalizedFile,
      };
    }
    throw error;
  }
};