import { NextResponse } from "next/server";
import prisma from "@/lib/prisma";

export async function GET(req: Request) {
  const { searchParams } = new URL(req.url);
  const boardId = searchParams.get("boardId");
  const period = searchParams.get("period") || "daily"; // daily | weekly

  // 날짜 범위 계산
  const now = new Date();
  const startOfToday = new Date(now.getFullYear(), now.getMonth(), now.getDate(), 0, 0, 0, 0);
  const endOfToday = new Date(now.getFullYear(), now.getMonth(), now.getDate(), 23, 59, 59, 999);
  const startOfWeek = new Date(now);
  startOfWeek.setDate(now.getDate() - 7);
  startOfWeek.setHours(0, 0, 0, 0);

  const dateFilter = period === "daily" 
    ? { 
        date: {
          gte: startOfToday,
          lte: endOfToday,
        }
      }
    : { date: { gte: startOfWeek } };

  // 일일 조회수 테이블에서 조회수 합계 계산
  const dailyViews = await prisma.dailyPostView.groupBy({
    by: ["postId"],
    where: dateFilter,
    _sum: {
      viewCount: true,
    },
    orderBy: {
      _sum: {
        viewCount: "desc",
      },
    },
    take: 20, // 조회수 상위 20개만 가져와서 게시글 정보 조회
  });

  if (dailyViews.length === 0) {
    return NextResponse.json({ items: [], period });
  }

  const postIds = dailyViews.map((dv) => dv.postId);

  // 게시글 정보 조회
  const posts = await prisma.post.findMany({
    where: {
      id: { in: postIds },
      status: "published",
      ...(boardId ? { boardId } : {}),
    },
    select: {
      id: true,
      title: true,
      createdAt: true,
      boardId: true,
      board: { select: { id: true, name: true, slug: true } },
      isPinned: true,
      status: true,
      author: { select: { userId: true, nickname: true } },
      stat: { select: { recommendCount: true, views: true, commentsCount: true } },
      postTags: { select: { tag: { select: { name: true, slug: true } } } },
    },
  });

  // 조회수와 게시글 매핑
  const viewCountMap = new Map(
    dailyViews.map((dv) => [dv.postId, dv._sum.viewCount ?? 0])
  );

  // 조회수 순으로 정렬 (조회수가 0보다 큰 것만)
  const postsWithViews = posts
    .map((post) => ({
      ...post,
      viewCount: viewCountMap.get(post.id) ?? 0,
    }))
    .filter((post) => post.viewCount > 0) // 조회수가 0보다 큰 것만
    .sort((a, b) => {
      // 고정글 우선
      if (a.isPinned && !b.isPinned) return -1;
      if (!a.isPinned && b.isPinned) return 1;
      // 조회수 순
      if (b.viewCount !== a.viewCount) return b.viewCount - a.viewCount;
      // 최신순
      return new Date(b.createdAt).getTime() - new Date(a.createdAt).getTime();
    })
    .slice(0, 5); // 상위 5개만

  return NextResponse.json({ items: postsWithViews, period });
}