import { NextRequest, NextResponse } from "next/server";
import { headers } from "next/headers";
import { auth } from "@/lib/auth";
import { uploadFile } from "@/lib/s3";
import { randomUUID } from "crypto";

// Images only: comments render them inline, and anything else would just be an
// unlabelled blob in the middle of a discussion.
const ALLOWED_TYPES = new Set(["image/jpeg", "image/png", "image/gif", "image/webp"]);
const ALLOWED_EXTS = new Set(["jpg", "jpeg", "png", "gif", "webp"]);
const MAX_BYTES = 5 * 1024 * 1024; // 5 MB — enough for a screenshot

export async function POST(req: NextRequest) {
  const session = await auth.api.getSession({ headers: await headers() });
  if (!session) return NextResponse.json({ error: "Unauthorized" }, { status: 401 });

  const form = await req.formData();
  const file = form.get("file") as File | null;
  if (!file) return NextResponse.json({ error: "Missing file" }, { status: 400 });

  if (file.size > MAX_BYTES) {
    return NextResponse.json({ error: "Изображение слишком большое (макс. 5 МБ)" }, { status: 413 });
  }

  if (!ALLOWED_TYPES.has(file.type)) {
    return NextResponse.json({ error: "Разрешены только изображения: jpg, png, gif, webp" }, { status: 415 });
  }

  const ext = file.name.split(".").pop()?.toLowerCase() ?? "bin";
  if (!ALLOWED_EXTS.has(ext)) {
    return NextResponse.json({ error: "Недопустимое расширение файла" }, { status: 415 });
  }

  const key = `comments/${session.user.id}/${randomUUID()}.${ext}`;
  const buffer = Buffer.from(await file.arrayBuffer());
  const url = await uploadFile(key, buffer, file.type);

  return NextResponse.json({ name: file.name, url, size: file.size });
}