import posthog from 'posthog-js'

class PostHogTracker {
  constructor(config) {
    // US Cloud 或 EU Cloud 或自托管地址
    this.apiHost = config.apiHost || 'https://us.i.posthog.com';
    this.apiKey = config.apiKey; // 项目 API Key
    this.distinctId = null;
  }

  // 初始化并获取用户唯一标识
  init() {
    // 优先使用 openid，如果没有则生成随机 ID
    const storedId = uni.getStorageSync('posthog_distinct_id');
    if (storedId) {
      this.distinctId = storedId;
    } else {
      this.distinctId = this._generateUUID();
      uni.setStorageSync('posthog_distinct_id', this.distinctId);
    }
    return this;
  }

  // 设置用户 ID（登录后调用）
  identify(userId, userProperties = {}) {
    this.distinctId = userId;
    uni.setStorageSync('posthog_distinct_id', userId);
    
    // 发送 $identify 事件
    this._capture('$identify', {
      $set: userProperties
    });
  }

  // 捕获事件
  capture(eventName, properties = {}) {
    this._capture(eventName, properties);
  }

  // 页面浏览事件
  pageView(pagePath, pageTitle) {
    this._capture('$pageview', {
      $current_url: pagePath,
      $title: pageTitle
    });
  }

  // 内部发送方法
  _capture(event, properties = {}) {
    const payload = {
      api_key: this.apiKey,
      event: event,
      distinct_id: this.distinctId,
      timestamp: new Date().toISOString(),
      properties: {
        ...properties,
        $lib: 'uniapp-miniprogram',
        $lib_version: '1.0.0',
        ...this._getDefaultProperties()
      }
    };

    uni.request({
      url: `${this.apiHost}/i/v0/e/`,
      method: 'POST',
      header: {
        'Content-Type': 'application/json'
      },
      data: payload,
      success: (res) => {
        console.log('PostHog event captured:', event);
      },
      fail: (err) => {
        console.error('PostHog capture failed:', err);
        // 可以考虑将失败的事件存储到本地，稍后重试
        this._saveFailedEvent(payload);
      }
    });
  }

  // 批量发送事件（性能优化）
  captureBatch(events) {
    const payload = events.map(e => ({
      api_key: this.apiKey,
      event: e.event,
      distinct_id: this.distinctId,
      timestamp: e.timestamp || new Date().toISOString(),
      properties: {
        ...e.properties,
        ...this._getDefaultProperties()
      }
    }));

    uni.request({
      url: `${this.apiHost}/batch/`,
      method: 'POST',
      header: {
        'Content-Type': 'application/json'
      },
      data: payload,
      success: (res) => {
        console.log('PostHog batch captured:', events.length, 'events');
      }
    });
  }

  // 获取默认属性
  _getDefaultProperties() {
    const systemInfo = uni.getSystemInfoSync();
    return {
      $os: systemInfo.platform,
      $os_version: systemInfo.system,
      $device: systemInfo.model,
      $screen_height: systemInfo.screenHeight,
      $screen_width: systemInfo.screenWidth,
      mp_platform: 'uniapp'
    };
  }

  // 生成 UUID
  _generateUUID() {
    return 'xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx'.replace(/[xy]/g, (c) => {
      const r = Math.random() * 16 | 0;
      const v = c === 'x' ? r : (r & 0x3 | 0x8);
      return v.toString(16);
    });
  }

  // 保存失败事件（离线支持）
  _saveFailedEvent(payload) {
    const failedEvents = uni.getStorageSync('posthog_failed_events') || [];
    failedEvents.push(payload);
    uni.setStorageSync('posthog_failed_events', failedEvents);
  }

  // 重试发送失败的事件
  retryFailedEvents() {
    const failedEvents = uni.getStorageSync('posthog_failed_events') || [];
    if (failedEvents.length > 0) {
      this.captureBatch(failedEvents);
      uni.removeStorageSync('posthog_failed_events');
    }
  }
}

// 导出单例
export default new PostHogTracker({
  apiHost: 'https://us.i.posthog.com', // 或 eu.i.posthog.com
  apiKey: 'YOUR_PROJECT_API_KEY'  // 在 PostHog 项目设置中获取
}).init();