import { NextResponse } from "next/server";
import { requireUser } from "@/lib/auth/requireUser";
import { db } from "@/lib/prisma";
import { buildCertificatePdf } from "@/lib/certificates";

function getText(value: unknown): string {
  if (!value) return "";
  if (typeof value === "string") return value;
  if (typeof value === "object") {
    const record = value as Record<string, unknown>;
    if (typeof record.en === "string") return record.en;
    if (typeof record.es === "string") return record.es;
  }
  return "";
}

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

export async function GET(_: Request, { params }: Params) {
  try {
    const user = await requireUser();
    if (!user?.id) {
      return NextResponse.json({ error: "Unauthorized" }, { status: 401 });
    }

    const { id } = await params;
    const certificate = await db.certificate.findUnique({
      where: { id },
      include: {
        course: {
          select: {
            title: true,
          },
        },
      },
    });

    if (!certificate || certificate.userId !== user.id) {
      return NextResponse.json({ error: "Not found" }, { status: 404 });
    }
    const certificateNumber =
      (certificate as Record<string, unknown>).certificateNumber ??
      (certificate.metadataSnapshot as Record<string, unknown> | null)?.certificateNumber ??
      `ACVE-${certificate.id.slice(0, 8)}`;

    const pdf = buildCertificatePdf({
      certificateNumber: String(certificateNumber),
      learnerName: user.fullName || user.email || "Learner",
      learnerEmail: user.email,
      courseTitle: getText(certificate.course.title) || "Untitled course",
      issuedAt: certificate.issuedAt,
    });

    return new Response(Buffer.from(pdf), {
      headers: {
        "Content-Type": "application/pdf",
        "Content-Disposition": `attachment; filename="certificate-${String(certificateNumber)}.pdf"`,
        "Cache-Control": "private, no-store",
      },
    });
  } catch {
    return NextResponse.json(
      { error: "Certificate service is not available until latest migrations are applied." },
      { status: 503 },
    );
  }
}