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

export async function GET(req: Request) {
  const { searchParams } = new URL(req.url);
  const q = (searchParams.get("q") || "").trim();
  const page = Math.max(1, parseInt(searchParams.get("page") || "1", 10));
  const pageSize = Math.min(50, parseInt(searchParams.get("pageSize") || "15", 10));
  const sort = searchParams.get("sort") || "latest";

  if (!q) {
    return NextResponse.json({ topics: [], totalCount: 0, page, pageSize, q: "" });
  }

  const where: any = {
    isHidden: false,
  };

  // 优先使用全文索引，回退到 LIKE
  const useFullText = q.length >= 2;
  if (useFullText) {
    // MySQL FULLTEXT 的 boolean mode 搜索
    // 把关键词拆词，规避 FULLTEXT 最小长度限制
    const tokens = q
      .split(/\s+/)
      .filter((t) => t.length >= 1)
      .slice(0, 10)
      .map((t) => `+${t.replace(/[+\-><()~*"@]/g, "")}*`);
    if (tokens.length > 0) {
      // Prisma 的 where.fulltext 字段是 reserved，使用原始查询更稳
      // 这里先尝试简单的 contains 组合
      const ors: any[] = [];
      for (const t of q.split(/\s+/).filter((x) => x.length >= 1)) {
        ors.push({ title: { contains: t } });
        ors.push({ content: { contains: t } });
      }
      where.OR = ors;
    } else {
      where.OR = [{ title: { contains: q } }, { content: { contains: q } }];
    }
  } else {
    where.OR = [{ title: { contains: q } }, { content: { contains: q } }];
  }

  const orderBy: any = {};
  if (sort === "relevance" && useFullText) {
    // 简化：标题命中权重更高 → 让标题命中靠前
    orderBy.isPinned = "desc";
  } else if (sort === "hot") {
    orderBy.viewCount = "desc";
  } else if (sort === "active") {
    orderBy.lastReplyAt = "desc";
  } else {
    orderBy.createdAt = "desc";
  }

  const [topics, totalCount] = await Promise.all([
    prisma.forumTopic.findMany({
      where,
      include: {
        category: { select: { name: true, slug: true, icon: true } },
        user: { select: { id: true, name: true, email: true, avatarUrl: true, level: true, points: true, isBot: true } },
        _count: { select: { posts: true } },
        tags: { include: { tag: true } },
      },
      orderBy: [{ isPinned: "desc" }, orderBy],
      skip: (page - 1) * pageSize,
      take: pageSize,
    }),
    prisma.forumTopic.count({ where }),
  ]);

  // 生成高亮摘要
  const snippets = topics.map((t) => {
    const titleHit = q && t.title.toLowerCase().includes(q.toLowerCase());
    let snippet = "";
    if (q) {
      const idx = t.content.toLowerCase().indexOf(q.toLowerCase());
      if (idx >= 0) {
        const start = Math.max(0, idx - 50);
        const end = Math.min(t.content.length, idx + q.length + 100);
        snippet =
          (start > 0 ? "..." : "") +
          t.content.slice(start, end).replace(/\s+/g, " ").trim() +
          (end < t.content.length ? "..." : "");
      } else {
        snippet = t.content.slice(0, 150).replace(/\s+/g, " ").trim() + (t.content.length > 150 ? "..." : "");
      }
    } else {
      snippet = t.content.slice(0, 150).replace(/\s+/g, " ").trim();
    }
    return { topicId: t.id, titleHit, snippet };
  });

  return NextResponse.json({ topics, totalCount, page, pageSize, q, snippets });
}