import * as Sentry from "@sentry/nextjs";
import { NextResponse } from "next/server";
import { requireClient, unauthorizedJson, UnauthorizedError } from "@/lib/nextcloud-session";
import { normalizePath } from "@/lib/paths";
import { Readable } from "node:stream";

export const runtime = "nodejs";
export const dynamic = "force-dynamic";

function badRequest(message: string) {
  return NextResponse.json({ error: message }, { status: 400 });
}

export async function GET(req: Request) {
  try {
    const { searchParams } = new URL(req.url);
    const rawPath = searchParams.get("path");
    if (!rawPath) return badRequest("Missing path");
    const path = normalizePath(rawPath);

    let client;
    try {
      client = await requireClient(req);
    } catch (err) {
      if (err instanceof UnauthorizedError) return unauthorizedJson();
      throw err;
    }

    const result = await Sentry.startSpan(
      { op: "function", name: "api.files.download" },
      async (span) => {
        span.setAttribute("path", path);

        // Optionally stat to get metadata (mime/name). Non-fatal if it fails.
        const stat = await client.stat(path).catch(() => null);

        const nodeStream = await client.downloadStream(path);
        // Convert Node.js readable to Web ReadableStream
        const asReadable = Readable as unknown as {
          toWeb?: (s: NodeJS.ReadableStream) => ReadableStream;
        };
        const webStream =
          typeof asReadable.toWeb === "function"
            ? asReadable.toWeb(nodeStream)
            : (nodeStream as unknown as ReadableStream);

        const filename = stat?.name ?? path.split("/").pop() ?? "download";
        const contentType = stat?.contentType ?? "application/octet-stream";

        const headers = new Headers();
        headers.set("Content-Type", contentType);
        // Default to attachment; UI may change to inline for previews later
        headers.set(
          "Content-Disposition",
          `attachment; filename*=UTF-8''${encodeURIComponent(filename)}`,
        );
        if (stat?.etag) headers.set("ETag", stat.etag);

        return new Response(webStream, { headers });
      },
    );

    return result;
  } catch (error) {
    Sentry.captureException(error);
    return NextResponse.json(
      {
        error: "Failed to download file",
        message: error instanceof Error ? error.message : String(error),
      },
      { status: 500 },
    );
  }
}