import { NextResponse } from "next/server";

import { canDocumentExpense } from "@/lib/domain";
import { uploadExpenseProofToDrive } from "@/lib/google-drive";
import prisma from "@/lib/prisma";
import { getCurrentViewer } from "@/lib/session";

const ACCEPTED_MIME_TYPES = new Set(["application/pdf", "image/jpeg", "image/png", "image/webp", "image/heic", "image/heif"]);
const MAX_FILE_SIZE = 12 * 1024 * 1024;

type Context = {
  params: Promise<{
    id: string;
  }>;
};

export async function POST(request: Request, { params }: Context) {
  const { id } = await params;
  const viewer = await getCurrentViewer();

  if (!viewer) {
    return NextResponse.json({ error: "Nicht angemeldet." }, { status: 401 });
  }

  const expense = await prisma.expense.findUnique({
    where: { id }
  });

  if (!expense) {
    return NextResponse.json({ error: "Ausgabe nicht gefunden." }, { status: 404 });
  }

  if (expense.creatorId !== viewer.id && !canDocumentExpense(viewer.role)) {
    return NextResponse.json({ error: "Du darfst fuer diese Ausgabe keinen Beleg hochladen." }, { status: 403 });
  }

  const formData = await request.formData().catch(() => null);
  const file = formData?.get("file");

  if (!(file instanceof File)) {
    return NextResponse.json({ error: "Bitte einen Beleg als Bild oder PDF auswaehlen." }, { status: 400 });
  }

  if (!ACCEPTED_MIME_TYPES.has(file.type)) {
    return NextResponse.json({ error: "Nur Bilder und PDFs sind als Beleg erlaubt." }, { status: 400 });
  }

  if (file.size > MAX_FILE_SIZE) {
    return NextResponse.json({ error: "Der Beleg darf maximal 12 MB gross sein." }, { status: 400 });
  }

  const proofUrl = await uploadExpenseProofToDrive({
    title: expense.title,
    fileName: file.name,
    mimeType: file.type,
    buffer: Buffer.from(await file.arrayBuffer())
  });

  const updatedExpense = await prisma.expense.update({
    where: { id: expense.id },
    data: {
      proofUrl
    }
  });

  return NextResponse.json({ proofUrl, expense: updatedExpense });
}