import { NextRequest, NextResponse } from 'next/server';
import clickhouse from '@/lib/clickhouse';
import type { ApiResponse } from '@/lib/types';

interface UtmData {
  utm_value: string;
  clicks: number;
  visitors: number;
  avg_time_spent: number;
  bounces: number;
  conversions: number;
}

// 格式化日期时间字符串为ClickHouse支持的格式
const formatDateTime = (dateStr: string): string => {
  return dateStr.replace('T', ' ').replace('Z', '');
};

export async function GET(request: NextRequest) {
  try {
    const searchParams = request.nextUrl.searchParams;
    
    // 获取过滤参数
    const startTime = searchParams.get('startTime');
    const endTime = searchParams.get('endTime');
    const linkId = searchParams.get('linkId');
    
    // 获取UTM类型参数
    const utmType = searchParams.get('utmType') || 'source';
    
    // 构建WHERE子句
    let whereClause = '';
    const conditions = [];
    
    if (startTime) {
      conditions.push(`event_time >= toDateTime('${formatDateTime(startTime)}')`);
    }
    
    if (endTime) {
      conditions.push(`event_time <= toDateTime('${formatDateTime(endTime)}')`);
    }
    
    if (linkId) {
      conditions.push(`link_id = '${linkId}'`);
    }
    
    if (conditions.length > 0) {
      whereClause = `WHERE ${conditions.join(' AND ')}`;
    }
    
    // 确定要分组的UTM字段
    let utmField;
    switch (utmType) {
      case 'source':
        utmField = 'utm_source';
        break;
      case 'medium':
        utmField = 'utm_medium';
        break;
      case 'campaign':
        utmField = 'utm_campaign';
        break;
      case 'term':
        utmField = 'utm_term';
        break;
      case 'content':
        utmField = 'utm_content';
        break;
      default:
        utmField = 'utm_source';
    }
    
    // 构建SQL查询
    const query = `
      SELECT 
        ${utmField} AS utm_value,
        COUNT(*) AS clicks,
        uniqExact(visitor_id) AS visitors,
        round(AVG(time_spent_sec), 2) AS avg_time_spent,
        countIf(is_bounce = 1) AS bounces,
        countIf(conversion_type IN ('visit', 'stay', 'interact', 'signup', 'subscription', 'purchase')) AS conversions
      FROM shorturl_analytics.events
      ${whereClause}
      ${whereClause ? 'AND' : 'WHERE'} ${utmField} != ''
      GROUP BY utm_value
      ORDER BY clicks DESC
      LIMIT 100
    `;
    
    // 执行查询
    const result = await clickhouse.query({
      query,
      format: 'JSONEachRow',
    });
    
    // 获取查询结果
    const rows = await result.json();
    const data = rows as UtmData[];
    
    // 返回数据
    const response: ApiResponse<UtmData[]> = {
      success: true,
      data
    };
    
    return NextResponse.json(response);
  } catch (error) {
    console.error('Error fetching UTM data:', error);
    
    const response: ApiResponse<null> = {
      success: false,
      error: error instanceof Error ? error.message : 'Unknown error occurred'
    };
    
    return NextResponse.json(response, { status: 500 });
  }
}