// app/api/admin/stats/route.ts
import { NextResponse } from 'next/server';
import { getServerSession } from 'next-auth';
import { authOptions } from '@/lib/auth-options';
import { prisma } from '@/lib/prisma';
import { Prisma } from '@prisma/client';

export async function GET(req: Request) {
  try {
    const session = await getServerSession(authOptions);
    if (!session?.user?.email)
      return NextResponse.json({ error: 'Unauthorized' }, { status: 401 });

    const role = (session as any)?.user?.role ?? null;
    if (!(role === 'admin' || role === 'superadmin')) {
      return NextResponse.json({ error: 'Forbidden' }, { status: 403 });
    }

    // Fetch all videos with aggregated stats using raw queries for better performance
    const videos = await prisma.video.findMany({
      include: {
        playlist: {
          select: {
            title: true,
          },
        },
        uploader: {
          select: {
            id: true,
            name: true,
          },
        },
        _count: {
          select: {
            likes: true,
            comments: true,
            unlocks: true,
          },
        },
      },
      orderBy: { createdAt: 'desc' },
    });

    // Fetch detailed stats for each video using raw queries for better performance
    const statsData = await prisma.$queryRaw<
      Array<{
        videoId: string;
        totalViewers: number;
        totalSecondsWatched: bigint;
        avgPercentWatched: number | null;
        totalSegments: number;
        completionCount: number;
      }>
    >`
      SELECT 
        p."videoId",
        COUNT(DISTINCT p."userId") as "totalViewers",
        CAST(COALESCE(SUM(p."watchedSec"), 0) AS BIGINT) as "totalSecondsWatched",
        ROUND(CAST(AVG(p."percent") AS NUMERIC), 2) as "avgPercentWatched",
        (SELECT COUNT(*) FROM "VideoWatchSegment" ws WHERE ws."videoId" = p."videoId") as "totalSegments",
        COUNT(CASE WHEN p."completed" = true THEN 1 END) as "completionCount"
      FROM "VideoProgress" p
      GROUP BY p."videoId"
    `;

    // Create a map for quick lookup
    const statsMap = new Map(statsData.map(item => [item.videoId, item]));

    // Combine video data with stats
    const videosWithStats = videos.map(video => {
      const stats = statsMap.get(video.id);
      const views = video._count.unlocks || 0;
      const totalViewers = stats ? Number(stats.totalViewers) : 0;
      const completions = stats ? Number(stats.completionCount) : 0;
      const engagement = (video._count.likes || 0) + (video._count.comments || 0);
      const avgWatched = stats?.avgPercentWatched ? Number(stats.avgPercentWatched) : 0;

      return {
        id: video.id,
        title: video.title,
        playlistTitle: video.playlist.title,
        uploaderName: video.uploader?.name || 'Unknown',
        views,
        totalViewers,
        completions,
        completionRate: totalViewers > 0 ? ((completions / totalViewers) * 100).toFixed(2) : '0.00',
        likes: video._count.likes,
        comments: video._count.comments,
        engagement,
        avgPercentWatched: avgWatched,
        totalSecondsWatched: stats ? Number(stats.totalSecondsWatched) : 0,
        totalSegments: stats ? Number(stats.totalSegments) : 0,
        durationSec: video.durationSec,
        createdAt: video.createdAt,
      };
    });

    return NextResponse.json(videosWithStats);
  } catch (err: any) {
    console.error('get stats error', err);
    return NextResponse.json(
      { error: err?.message ?? 'server error' },
      { status: 500 }
    );
  }
}