import { NextRequest, NextResponse } from "next/server";
import fs from "fs";
import path from "path";

export async function GET(
  req: NextRequest,
  { params }: { params: Promise<{ key: string[] }> }
) {
  const { key } = await params;
  // key is a catch-all segment array, e.g. ["videos", "uuid-filename.mp4"]
  const relativePath = key.join("/");

  // Sanitize: prevent path traversal
  const uploadDir = path.resolve(process.env.LOCAL_UPLOAD_DIR ?? "./uploads");
  const filePath = path.resolve(path.join(uploadDir, relativePath));

  if (!filePath.startsWith(uploadDir)) {
    return new NextResponse("Forbidden", { status: 403 });
  }

  if (!fs.existsSync(filePath)) {
    return new NextResponse("Not found", { status: 404 });
  }

  const stat = fs.statSync(filePath);
  const ext = path.extname(filePath).toLowerCase();
  const mimeMap: Record<string, string> = {
    ".mp4": "video/mp4",
    ".mov": "video/quicktime",
    ".avi": "video/x-msvideo",
    ".mxf": "application/mxf",
    ".webm": "video/webm",
  };
  const contentType = mimeMap[ext] ?? "application/octet-stream";

  // Support range requests so the HTML5 video player can seek
  const rangeHeader = req.headers.get("range");

  if (rangeHeader) {
    const [startStr, endStr] = rangeHeader.replace("bytes=", "").split("-");
    const start = parseInt(startStr, 10);
    const end = endStr ? parseInt(endStr, 10) : stat.size - 1;
    const chunkSize = end - start + 1;

    const stream = fs.createReadStream(filePath, { start, end });
    const nodeStream = stream as unknown as ReadableStream;

    return new NextResponse(nodeStream, {
      status: 206,
      headers: {
        "Content-Range": `bytes ${start}-${end}/${stat.size}`,
        "Accept-Ranges": "bytes",
        "Content-Length": String(chunkSize),
        "Content-Type": contentType,
      },
    });
  }

  const stream = fs.createReadStream(filePath) as unknown as ReadableStream;
  return new NextResponse(stream, {
    headers: {
      "Content-Length": String(stat.size),
      "Content-Type": contentType,
      "Accept-Ranges": "bytes",
    },
  });
}