import { serverAuth } from "@/lib/pb";
import { revalidateInvoicePages } from "@/lib/invoice-revalidate";

export const dynamic = "force-dynamic";

// POST /api/invoices/upload
// Body: multipart/form-data with `file` and `invoiceNo`.
//
// Stores the original document against the invoice's `source_pdf` file field so the
// source of every extracted figure stays attached to the row it came from.
//
// Accepts PDF only — an invoice in any other format cannot have its line items verified
// against the PDF totals, and accepting it silently would break that guarantee.

const MAX_BYTES = 20 * 1024 * 1024; // matches the PocketBase field's maxSize

export async function POST(req: Request) {
  let form: FormData;
  try {
    form = await req.formData();
  } catch {
    return Response.json({ ok: false, error: "Expected multipart/form-data" }, { status: 400 });
  }

  const file = form.get("file");
  const invoiceNo = String(form.get("invoiceNo") ?? "").trim();

  if (!(file instanceof File) || file.size === 0) {
    return Response.json({ ok: false, error: "No file received" }, { status: 400 });
  }
  if (file.type !== "application/pdf" && !file.name.toLowerCase().endsWith(".pdf")) {
    return Response.json(
      { ok: false, error: "Only PDF invoices are accepted" },
      { status: 400 },
    );
  }
  if (file.size > MAX_BYTES) {
    return Response.json(
      { ok: false, error: `File is ${(file.size / 1048576).toFixed(1)} MB — limit is 20 MB` },
      { status: 400 },
    );
  }

  const pb = await serverAuth();

  try {
    // Resolve the invoice by number; fall back to the only one present.
    let target = null;
    if (invoiceNo) {
      const found = await pb.collection("invoices").getFullList({
        filter: `invoice_no = "${invoiceNo.replace(/"/g, "")}"`,
        perPage: 1,
      });
      target = found[0] ?? null;
      if (!target) {
        return Response.json(
          { ok: false, error: `No invoice found with number "${invoiceNo}"` },
          { status: 404 },
        );
      }
    } else {
      const all = await pb.collection("invoices").getFullList({ perPage: 2 });
      if (all.length === 0) {
        return Response.json({ ok: false, error: "No invoices exist yet" }, { status: 404 });
      }
      if (all.length > 1) {
        return Response.json(
          { ok: false, error: "More than one invoice — specify which by number" },
          { status: 400 },
        );
      }
      target = all[0];
    }

    const safeName = file.name.replace(/[^\w.\- ]+/g, "_").slice(-120);
    const form2 = new FormData();
    form2.append("source_pdf", new File([await file.arrayBuffer()], safeName, { type: "application/pdf" }));

    const updated = await pb.collection("invoices").update(target.id, form2);

    revalidateInvoicePages();

    const stored = updated.source_pdf as string | undefined;
    return Response.json({
      ok: true,
      invoice_no: target.invoice_no,
      file: safeName,
      size: file.size,
      // PocketBase returns "filename" or "filename_abcd1234"; the base name is the file.
      path: stored?.split("/").pop() ?? null,
    });
  } catch (e: any) {
    return Response.json(
      { ok: false, error: e?.message || "Upload failed" },
      { status: 500 },
    );
  }
}