import { NextRequest, NextResponse } from "next/server";
import { db } from "@/lib/db";
import { generatedImage, user } from "@/lib/db/schema";
import { eq, sql, desc, count, and, gte, lt } from "drizzle-orm";
import { auth } from "@/app/(auth)/auth";

export async function GET(request: NextRequest) {
  try {
    const session = await auth();
    
    if (!session?.user?.id) {
      return NextResponse.json({ error: "Unauthorized" }, { status: 401 });
    }

    // 检查是否为管理员
    const currentUser = await db.query.user.findFirst({
      where: eq(user.id, session.user.id),
    });

    if (currentUser?.role !== "admin") {
      return NextResponse.json({ error: "Forbidden" }, { status: 403 });
    }

    // 获取查询参数
    const searchParams = request.nextUrl.searchParams;
    const month = searchParams.get("month"); // 格式: YYYY-MM
    const selectedDate = searchParams.get("date"); // 格式: YYYY-MM-DD，用于高峰时段筛选

    // 1. 总体统计
    const totalStats = await db
      .select({
        totalImages: sql<number>`count(*)::int`,
        totalUsers: sql<number>`count(distinct ${generatedImage.userId})::int`,
      })
      .from(generatedImage);

    // 2. 按用户统计（Top 20）
    const userStats = await db
      .select({
        userId: generatedImage.userId,
        userName: user.name,
        userEmail: user.email,
        imageCount: sql<number>`count(*)::int`,
      })
      .from(generatedImage)
      .leftJoin(user, eq(generatedImage.userId, user.id))
      .groupBy(generatedImage.userId, user.name, user.email)
      .orderBy(desc(sql`count(*)`))
      .limit(20);

    // 3. 按日期统计（最近30天）
    const dailyStats = await db
      .select({
        date: sql<string>`date(${generatedImage.createdAt})::text`,
        count: sql<number>`count(*)::int`,
      })
      .from(generatedImage)
      .where(sql`${generatedImage.createdAt} >= now() - interval '30 days'`)
      .groupBy(sql`date(${generatedImage.createdAt})`)
      .orderBy(sql`date(${generatedImage.createdAt})`);

    // 4. 按图片尺寸统计
    const sizeStats = await db
      .select({
        imageSize: generatedImage.imageSize,
        count: sql<number>`count(*)::int`,
      })
      .from(generatedImage)
      .groupBy(generatedImage.imageSize)
      .orderBy(desc(sql`count(*)`));

    // 5. 按模型统计
    const modelStats = await db
      .select({
        modelId: generatedImage.modelId,
        count: sql<number>`count(*)::int`,
      })
      .from(generatedImage)
      .groupBy(generatedImage.modelId)
      .orderBy(desc(sql`count(*)`))
      .limit(10);

    // 6. 按月份统计
    const monthlyStats = await db
      .select({
        month: sql<string>`to_char(${generatedImage.createdAt}, 'YYYY-MM')`,
        count: sql<number>`count(*)::int`,
      })
      .from(generatedImage)
      .groupBy(sql`to_char(${generatedImage.createdAt}, 'YYYY-MM')`)
      .orderBy(sql`to_char(${generatedImage.createdAt}, 'YYYY-MM')`);

    // 7. 按小时统计（用于分析高峰时段，支持按日期筛选）
    let hourlyWhereClause = undefined;
    if (selectedDate) {
      const dateStart = new Date(selectedDate);
      const dateEnd = new Date(selectedDate);
      dateEnd.setDate(dateEnd.getDate() + 1);
      hourlyWhereClause = and(
        gte(generatedImage.createdAt, dateStart),
        lt(generatedImage.createdAt, dateEnd)
      );
    }

    const hourlyStats = await db
      .select({
        hour: sql<number>`extract(hour from ${generatedImage.createdAt})::int`,
        count: sql<number>`count(*)::int`,
      })
      .from(generatedImage)
      .where(hourlyWhereClause)
      .groupBy(sql`extract(hour from ${generatedImage.createdAt})`)
      .orderBy(sql`extract(hour from ${generatedImage.createdAt})`);

    // 8. 今日统计
    const todayStats = await db
      .select({
        count: sql<number>`count(*)::int`,
        users: sql<number>`count(distinct ${generatedImage.userId})::int`,
      })
      .from(generatedImage)
      .where(sql`date(${generatedImage.createdAt}) = current_date`);

    // 9. 本周统计
    const weekStats = await db
      .select({
        count: sql<number>`count(*)::int`,
        users: sql<number>`count(distinct ${generatedImage.userId})::int`,
      })
      .from(generatedImage)
      .where(sql`${generatedImage.createdAt} >= date_trunc('week', current_date)`);

    // 10. 指定月份统计（支持选择月份）
    let monthStart: Date;
    let monthEnd: Date;
    
    if (month) {
      // 解析指定月份
      const [year, mon] = month.split("-").map(Number);
      monthStart = new Date(year, mon - 1, 1);
      monthEnd = new Date(year, mon, 1); // 下个月第一天
    } else {
      // 默认当前月
      const now = new Date();
      monthStart = new Date(now.getFullYear(), now.getMonth(), 1);
      monthEnd = new Date(now.getFullYear(), now.getMonth() + 1, 1);
    }

    const monthStats = await db
      .select({
        count: sql<number>`count(*)::int`,
        users: sql<number>`count(distinct ${generatedImage.userId})::int`,
      })
      .from(generatedImage)
      .where(and(
        gte(generatedImage.createdAt, monthStart),
        lt(generatedImage.createdAt, monthEnd)
      ));

    return NextResponse.json({
      overview: {
        totalImages: totalStats[0]?.totalImages || 0,
        totalUsers: totalStats[0]?.totalUsers || 0,
        todayImages: todayStats[0]?.count || 0,
        todayUsers: todayStats[0]?.users || 0,
        weekImages: weekStats[0]?.count || 0,
        weekUsers: weekStats[0]?.users || 0,
        monthImages: monthStats[0]?.count || 0,
        monthUsers: monthStats[0]?.users || 0,
        selectedMonth: month || `${new Date().getFullYear()}-${String(new Date().getMonth() + 1).padStart(2, "0")}`,
        selectedDate: selectedDate || null,
      },
      userStats,
      dailyStats,
      sizeStats,
      modelStats,
      monthlyStats,
      hourlyStats,
    });
  } catch (error) {
    console.error("[Admin Images Analytics API] Error:", error);
    return NextResponse.json({ error: "Failed to fetch analytics" }, { status: 500 });
  }
}