import React, { useState, useEffect } from 'react';
import { View, Text, StyleSheet, TouchableOpacity, Alert, Switch, ActivityIndicator, ScrollView } from 'react-native';
import { SafeAreaView } from 'react-native-safe-area-context';
import Svg, { Path } from 'react-native-svg';
import { theme } from '../theme';
import * as Cache from '../utils/cache';

const TrashIcon = () => (
  <Svg width={20} height={20} viewBox="0 0 24 24" fill="none" stroke={theme.colors.error} strokeWidth={2} strokeLinecap="round" strokeLinejoin="round">
    <Path d="M3 6h18M19 6v14a2 2 0 0 1-2 2H7a2 2 0 0 1-2-2V6m3 0V4a2 2 0 0 1 2-2h4a2 2 0 0 1 2 2v2" />
  </Svg>
);

const InfoIcon = () => (
  <Svg width={20} height={20} viewBox="0 0 24 24" fill="none" stroke={theme.colors.textSecondary} strokeWidth={2} strokeLinecap="round" strokeLinejoin="round">
    <Path d="M12 22s8-4 8-10V5l-8-3-8 3v7c0 6 8 10 8 10z" />
    <Path d="M12 12h.01M12 16h.01" />
  </Svg>
);

const ChevronRight = () => (
  <Svg width={16} height={16} viewBox="0 0 24 24" fill="none" stroke={theme.colors.textSecondary} strokeWidth={2} strokeLinecap="round" strokeLinejoin="round">
    <Path d="M9 18l6-6-6-6" />
  </Svg>
);

interface SettingItemProps {
  title: string;
  subtitle?: string;
  rightElement?: React.ReactNode;
  onPress?: () => void;
  showChevron?: boolean;
  isDanger?: boolean;
}

const SettingItem: React.FC<SettingItemProps> = ({
  title,
  subtitle,
  rightElement,
  onPress,
  showChevron = false,
  isDanger = false,
}) => (
  <TouchableOpacity
    style={styles.settingItem}
    onPress={onPress}
    disabled={!onPress}
  >
    <View style={styles.settingItemLeft}>
      <Text style={[styles.settingTitle, isDanger && styles.settingTitleDanger]}>
        {title}
      </Text>
      {subtitle && (
        <Text style={styles.settingSubtitle}>{subtitle}</Text>
      )}
    </View>
    {rightElement}
    {showChevron && <ChevronRight />}
  </TouchableOpacity>
);

interface SettingsScreenProps {
  cacheOnly: boolean;
  resumePlaybackEnabled: boolean;
  playlistFiles: string[];
  currentPlaylistFile: string;
  cachedTrackCount: number;
  trackCount: number;
  loggedInUser: string | null;
  onCacheOnlyChange: (value: boolean) => Promise<void>;
  onResumePlaybackChange: (value: boolean) => Promise<void>;
  onCacheChanged: () => Promise<void> | void;
  onPlaylistChange: (fileName: string) => Promise<void>;
  onLoginPress: () => void;
  onLogout: () => void;
}

export const SettingsScreen: React.FC<SettingsScreenProps> = ({
  cacheOnly,
  resumePlaybackEnabled,
  playlistFiles,
  currentPlaylistFile,
  cachedTrackCount,
  trackCount,
  loggedInUser,
  onCacheOnlyChange,
  onResumePlaybackChange,
  onCacheChanged,
  onPlaylistChange,
  onLoginPress,
  onLogout,
}) => {
  const [cacheSize, setCacheSize] = useState<string>('0 B');
  const [isLoading, setIsLoading] = useState(false);
  const [playlistExpanded, setPlaylistExpanded] = useState(false);
  const [isSwitchingPlaylist, setIsSwitchingPlaylist] = useState(false);

  const loadCacheSize = async () => {
    try {
      const size = await Cache.getCacheSize();
      setCacheSize(Cache.formatSize(size));
    } catch (error) {
      console.error('Failed to get cache size:', error);
    }
  };

  const toggleCacheOnly = async (value: boolean) => {
    try {
      await onCacheOnlyChange(value);
    } catch (error) {
      console.error('Failed to save setting:', error);
      Alert.alert('错误', '保存设置失败');
    }
  };

  const toggleResumePlayback = async (value: boolean) => {
    try {
      await onResumePlaybackChange(value);
    } catch (error) {
      console.error('Failed to save resume playback setting:', error);
      Alert.alert('错误', '保存设置失败');
    }
  };

  useEffect(() => {
    loadCacheSize();
  }, []);

  const handlePlaylistPress = async (fileName: string) => {
    if (fileName === currentPlaylistFile || isSwitchingPlaylist) {
      setPlaylistExpanded(false);
      return;
    }
    setIsSwitchingPlaylist(true);
    try {
      await onPlaylistChange(fileName);
      setPlaylistExpanded(false);
    } catch (error) {
      console.error('切换歌单失败:', error);
    } finally {
      setIsSwitchingPlaylist(false);
    }
  };

  const handleClearCache = () => {
    Alert.alert(
      '清除缓存',
      '确定要清除所有缓存的音频文件吗？这不会删除歌曲列表。',
      [
        { text: '取消', style: 'cancel' },
        {
          text: '清除',
          style: 'destructive',
          onPress: async () => {
            setIsLoading(true);
            try {
              await Cache.clearAllCache();
              await onCacheChanged();
              await loadCacheSize();
              Alert.alert('完成', '缓存已清除');
            } catch (error) {
              Alert.alert('错误', '清除缓存失败');
            } finally {
              setIsLoading(false);
            }
          },
        },
      ]
    );
  };

  const handleLogout = () => {
    Alert.alert(
      '退出登录',
      '确定要退出登录吗？退出后云端配置将不再同步。',
      [
        { text: '取消', style: 'cancel' },
        {
          text: '退出',
          style: 'destructive',
          onPress: () => {
            onLogout();
            Alert.alert('已退出', '已退出登录');
          },
        },
      ]
    );
  };

  return (
    <SafeAreaView style={styles.container} edges={['top', 'bottom']}>
      <View style={styles.header}>
        <Text style={styles.headerTitle}>设置</Text>
      </View>

      <ScrollView style={styles.scrollContent} contentContainerStyle={styles.scrollContentInner}>

      <View style={styles.section}>
        <Text style={styles.sectionTitle}>播放设置</Text>
        <SettingItem
          title="当前歌单"
          subtitle={currentPlaylistFile}
          onPress={() => setPlaylistExpanded((prev) => !prev)}
          rightElement={
            isSwitchingPlaylist
              ? <ActivityIndicator size="small" color={theme.colors.primary} />
              : <Text style={styles.settingMeta}>{cachedTrackCount}/{trackCount} 已缓存</Text>
          }
          showChevron={!isSwitchingPlaylist}
        />
        {playlistExpanded && (
          <View style={styles.playlistOptions}>
            {playlistFiles.map((fileName) => {
              const isActive = fileName === currentPlaylistFile;
              return (
                <TouchableOpacity
                  key={fileName}
                  style={[styles.playlistOption, isActive && styles.playlistOptionActive]}
                  onPress={() => { void handlePlaylistPress(fileName); }}
                  disabled={isSwitchingPlaylist}
                >
                  <Text
                    style={[styles.playlistOptionText, isActive && styles.playlistOptionTextActive]}
                    numberOfLines={2}
                  >
                    {fileName}
                  </Text>
                  {isActive && <Text style={styles.playlistOptionBadge}>当前</Text>}
                </TouchableOpacity>
              );
            })}
            <Text style={styles.playlistHint}>
              自动读取所有以 playlist.json 结尾的歌单，并记住你上次选择。
            </Text>
          </View>
        )}
        <View style={styles.settingItem}>
          <View style={styles.settingItemLeft}>
            <Text style={styles.settingTitle}>记住上次位置继续听</Text>
            <Text style={styles.settingSubtitle}>默认开启，下次打开时从上次暂停的位置继续播放</Text>
          </View>
          <Switch
            value={resumePlaybackEnabled}
            onValueChange={toggleResumePlayback}
            trackColor={{ false: theme.colors.surface2, true: theme.colors.primarySoft }}
            thumbColor={resumePlaybackEnabled ? theme.colors.primary : theme.colors.textSecondary}
          />
        </View>
        <View style={styles.settingItem}>
          <View style={styles.settingItemLeft}>
            <Text style={styles.settingTitle}>只用缓存听歌曲</Text>
            <Text style={styles.settingSubtitle}>节约流量，只播放已缓存的歌曲</Text>
          </View>
          <Switch
            value={cacheOnly}
            onValueChange={toggleCacheOnly}
            trackColor={{ false: theme.colors.surface2, true: theme.colors.primarySoft }}
            thumbColor={cacheOnly ? theme.colors.primary : theme.colors.textSecondary}
          />
        </View>
      </View>

      <View style={styles.section}>
        <Text style={styles.sectionTitle}>缓存管理</Text>
        <SettingItem
          title="已缓存大小"
          subtitle={cacheSize}
          rightElement={<InfoIcon />}
        />
        <SettingItem
          title="清除所有缓存"
          onPress={handleClearCache}
          isDanger={true}
          rightElement={<TrashIcon />}
        />
      </View>

      <View style={styles.section}>
        <Text style={styles.sectionTitle}>账号</Text>
        {loggedInUser ? (
          <>
            <SettingItem
              title="已登录"
              subtitle={`当前账号：${loggedInUser}`}
              rightElement={
                <TouchableOpacity onPress={handleLogout} style={styles.logoutBtn}>
                  <Text style={styles.logoutText}>退出</Text>
                </TouchableOpacity>
              }
            />
            <Text style={styles.syncHint}>
              歌单选择、播放进度等配置已同步到云端，跨设备可用。
            </Text>
          </>
        ) : (
          <SettingItem
            title="登录以同步配置"
            subtitle="跨设备同步歌单选择、播放进度等"
            onPress={onLoginPress}
            showChevron={true}
          />
        )}
      </View>

      <View style={styles.section}>
        <Text style={styles.sectionTitle}>关于</Text>
        <View style={styles.aboutCard}>
          <Text style={styles.aboutTitle}>观空禅音</Text>
          <Text style={styles.aboutEnglish}>ZenVoid</Text>
          <Text style={styles.aboutBody}>
            这不是一款为了喧闹和效率而设计的播放器。它更像一处留白，让人愿意慢下来，听见一点安静。
          </Text>
          <Text style={styles.aboutBody}>
            “ZenVoid”和“观空”都不是标准答案，只是我们尽力靠近这种感受的一种表达。希望它陪你在日常里，留一点空，听一点静。
          </Text>
        </View>
        <SettingItem
          title="版本"
          subtitle="1.0.0 (2)"
        />
      </View>
      </ScrollView>
    </SafeAreaView>
  );
};

const styles = StyleSheet.create({
  container: {
    flex: 1,
    backgroundColor: theme.colors.background,
  },
  scrollContent: {
    flex: 1,
  },
  scrollContentInner: {
    paddingBottom: theme.spacing.xl,
  },
  header: {
    paddingHorizontal: theme.spacing.md,
    paddingVertical: theme.spacing.sm,
  },
  headerTitle: {
    fontSize: 18,
    fontWeight: '600',
    color: theme.colors.text,
  },
  section: {
    marginTop: theme.spacing.md,
  },
  sectionTitle: {
    fontSize: 13,
    fontWeight: '600',
    color: theme.colors.textSecondary,
    textTransform: 'uppercase',
    letterSpacing: 0.5,
    paddingHorizontal: theme.spacing.md,
    marginBottom: theme.spacing.xs,
  },
  settingItem: {
    flexDirection: 'row',
    alignItems: 'center',
    justifyContent: 'space-between',
    paddingVertical: theme.spacing.md,
    paddingHorizontal: theme.spacing.md,
    backgroundColor: theme.colors.surface,
    borderTopWidth: 1,
    borderBottomWidth: 1,
    borderColor: theme.colors.border,
  },
  settingItemLeft: {
    flex: 1,
  },
  settingTitle: {
    fontSize: 16,
    color: theme.colors.text,
  },
  settingTitleDanger: {
    color: theme.colors.error,
  },
  settingSubtitle: {
    fontSize: 14,
    color: theme.colors.textSecondary,
    marginTop: 2,
  },
  settingMeta: {
    fontSize: 12,
    color: theme.colors.primary,
    marginRight: theme.spacing.xs,
  },
  playlistOptions: {
    marginTop: 1,
    paddingHorizontal: theme.spacing.md,
    paddingTop: theme.spacing.sm,
    paddingBottom: theme.spacing.md,
    backgroundColor: theme.colors.surface,
    borderTopWidth: 1,
    borderBottomWidth: 1,
    borderColor: theme.colors.border,
    gap: theme.spacing.xs,
  },
  playlistOption: {
    flexDirection: 'row',
    alignItems: 'center',
    justifyContent: 'space-between',
    gap: theme.spacing.sm,
    paddingHorizontal: theme.spacing.sm,
    paddingVertical: theme.spacing.sm,
    borderRadius: theme.borderRadius.md,
    backgroundColor: 'rgba(255,255,255,0.03)',
  },
  playlistOptionActive: {
    borderWidth: 1,
    borderColor: theme.colors.primary,
    backgroundColor: theme.colors.primarySoft,
  },
  playlistOptionText: {
    flex: 1,
    fontSize: 14,
    color: theme.colors.text,
  },
  playlistOptionTextActive: {
    color: theme.colors.primary,
    fontWeight: '600',
  },
  playlistOptionBadge: {
    fontSize: 12,
    color: theme.colors.primary,
  },
  playlistHint: {
    marginTop: theme.spacing.xs,
    fontSize: 12,
    lineHeight: 18,
    color: theme.colors.textSecondary,
  },
  aboutCard: {
    marginHorizontal: theme.spacing.md,
    marginBottom: theme.spacing.xs,
    paddingHorizontal: theme.spacing.md,
    paddingVertical: theme.spacing.md,
    backgroundColor: theme.colors.surface,
    borderWidth: 1,
    borderColor: theme.colors.border,
    borderRadius: theme.borderRadius.lg,
  },
  aboutTitle: {
    fontSize: 18,
    fontWeight: '600',
    color: theme.colors.text,
  },
  aboutEnglish: {
    marginTop: 4,
    fontSize: 13,
    letterSpacing: 0.8,
    color: theme.colors.primary,
  },
  aboutBody: {
    marginTop: theme.spacing.sm,
    fontSize: 14,
    lineHeight: 22,
    color: theme.colors.textSecondary,
  },
  logoutBtn: {
    paddingHorizontal: theme.spacing.sm,
    paddingVertical: theme.spacing.xs,
    borderRadius: theme.borderRadius.sm,
    borderWidth: 1,
    borderColor: theme.colors.error,
  },
  logoutText: {
    fontSize: 13,
    color: theme.colors.error,
  },
  syncHint: {
    fontSize: 12,
    lineHeight: 18,
    color: theme.colors.textSecondary,
    paddingHorizontal: theme.spacing.md,
    paddingVertical: theme.spacing.xs,
  },
});