import { NextRequest, NextResponse } from "next/server";
import { readFile } from "fs/promises";
import { connectDB } from "@/lib/db";
import { Expense } from "@/models/Expense";
import { hasPermission } from "@/lib/adminAuth";
import { receiptUploadPath } from "@/lib/uploads";

export async function GET(_req: NextRequest, { params }: { params: Promise<{ expenseId: string; filename: string }> }) {
  if (!(await hasPermission("expenses_view"))) return new NextResponse("Unauthorized", { status: 401 });

  const { expenseId, filename } = await params;
  await connectDB();
  const expense = await Expense.findById(expenseId).lean();
  if (!expense || expense.receiptStoredName !== filename) {
    return new NextResponse("Not found", { status: 404 });
  }

  try {
    const buffer = await readFile(receiptUploadPath(expenseId, filename));
    return new NextResponse(new Uint8Array(buffer), {
      headers: {
        "Cache-Control": "private, max-age=0, no-store",
        "Content-Disposition": `inline; filename="${encodeURIComponent(expense.receiptFilename || filename)}"`,
      },
    });
  } catch {
    return new NextResponse("Not found", { status: 404 });
  }
}