(function() {
    'use strict';
    class UserDataSync {
        constructor() {
            this.username = null;
            this.data = {
                favorite_channels: [],
                download_concurrency: 16,
                batch_download_concurrency: 3,
                fab_position: { bottom: 30, right: 30 },
                playback_history: [],
                program_reminders: []
            };
            this.isInitialized = false;
            this.pendingUpdates = {};
            this.saveTimer = null;
        }

        /**
         * 初始化用户数据
         */
        init(username) {
            if (!username) {
                console.warn('⚠️ UserDataSync: 未提供用户名');
                return false;
            }

            this.username = username;
            
            // ✅ 从 sessionStorage 加载（登录时后端已写入）
            const userDataKey = `user_data_${username}`;
            const savedData = sessionStorage.getItem(userDataKey);
            
            if (savedData) {
                try {
                    const parsed = JSON.parse(savedData);
                    this.data = { ...this.data, ...parsed };
                    console.log('✅ 用户数据已加载:', Object.keys(this.data));
                } catch (e) {
                    console.error('❌ 解析用户数据失败:', e);
                }
            }
            
            this.isInitialized = true;
            return true;
        }

        /**
         * 标记数据已修改（防抖保存）
         */
        markChanged(key) {
            if (!this.isInitialized) return;
            
            this.pendingUpdates[key] = this.data[key];
            
            // 防抖：1秒后保存
            if (this.saveTimer) {
                clearTimeout(this.saveTimer);
            }
            
            this.saveTimer = setTimeout(() => {
                this.save();
            }, 1000);
        }

        /**
         * 立即保存到后端
         */
        async save(force = false) {
            if (!this.isInitialized || !this.username) return false;
            if (!force && Object.keys(this.pendingUpdates).length === 0) return true;

            const updates = force ? this.data : this.pendingUpdates;

            try {
                // ✅ 保存到 sessionStorage（同步）
                const userDataKey = `user_data_${this.username}`;
                sessionStorage.setItem(userDataKey, JSON.stringify(this.data));

                // ✅ 通过后端保存到 Redis
                const response = await fetch('/api/user/data/sync', {
                    method: 'POST',
                    headers: {
                        'Content-Type': 'application/json'
                    },
                    body: JSON.stringify({
                        username: this.username,
                        data: updates
                    })
                });

                if (response.ok) {
                    console.log('✅ 用户数据已同步到 Redis:', Object.keys(updates));
                    this.pendingUpdates = {};
                    return true;
                } else {
                    console.warn('⚠️ 同步失败，数据已保存到本地');
                    return false;
                }
            } catch (error) {
                console.error('❌ 同步失败:', error);
                return false;
            }
        }

        // ==================== 便捷方法 ====================

        getFavorites() {
            return this.data.favorite_channels || [];
        }

        setFavorites(favorites) {
            this.data.favorite_channels = Array.isArray(favorites) ? favorites : [];
            this.markChanged('favorite_channels');
        }

        getDownloadConcurrency() {
            return this.data.download_concurrency || 16;
        }

        setDownloadConcurrency(concurrency) {
            const value = parseInt(concurrency);
            if (value >= 1 && value <= 32) {
                this.data.download_concurrency = value;
                this.markChanged('download_concurrency');
            }
        }

        getBatchConcurrency() {
            return this.data.batch_download_concurrency || 3;
        }

        setBatchConcurrency(concurrency) {
            const value = parseInt(concurrency);
            if (value >= 1 && value <= 10) {
                this.data.batch_download_concurrency = value;
                this.markChanged('batch_download_concurrency');
            }
        }

        getFabPosition() {
            return this.data.fab_position || { bottom: 30, right: 30 };
        }

        setFabPosition(position) {
            if (position && typeof position === 'object') {
                this.data.fab_position = position;
                this.markChanged('fab_position');
            }
        }

        getPlaybackHistory() {
            return this.data.playback_history || [];
        }

        addPlaybackHistory(item) {
            if (!Array.isArray(this.data.playback_history)) {
                this.data.playback_history = [];
            }
            
            // 去重
            this.data.playback_history = this.data.playback_history.filter(
                h => h.path !== item.path
            );
            
            // 添加到开头
            this.data.playback_history.unshift(item);
            
            // 最多保留 50 条
            if (this.data.playback_history.length > 50) {
                this.data.playback_history = this.data.playback_history.slice(0, 50);
            }
            
            this.markChanged('playback_history');
        }

        getProgramReminders() {
            return this.data.program_reminders || [];
        }

        addProgramReminder(reminder) {
            if (!Array.isArray(this.data.program_reminders)) {
                this.data.program_reminders = [];
            }
            
            const exists = this.data.program_reminders.some(
                r => r.title === reminder.title && r.startTime === reminder.startTime
            );
            
            if (!exists) {
                this.data.program_reminders.push(reminder);
                this.markChanged('program_reminders');
            }
        }

        removeProgramReminder(reminderId) {
            if (Array.isArray(this.data.program_reminders)) {
                this.data.program_reminders = this.data.program_reminders.filter(
                    r => r.id !== reminderId
                );
                this.markChanged('program_reminders');
            }
        }
    }

    // 创建全局单例
    window.userDataSync = new UserDataSync();

    // 页面卸载时保存
    window.addEventListener('beforeunload', () => {
        if (window.userDataSync && window.userDataSync.isInitialized) {
            window.userDataSync.save(true);
        }
    });

    console.log('✅ UserDataSync 已加载（无需 API）');

})();