إنشاء PDF من LaTeX على Vercel

// app/api/pdf/route.ts
import type { NextRequest } from "next/server"

// Use the Node.js runtime — the Edge runtime does not support
// the full fetch API response streaming needed for binary files.
export const runtime = "nodejs"

// Vercel Hobby: 10 s max. Pro / Enterprise: up to 300 s.
// Set this to at least 30 s to handle complex documents.
export const maxDuration = 30

export async function POST(request: NextRequest) {
  const body = await request.json()
  const source: string = body.source ?? ""
  const engine: string = body.engine ?? "pdflatex"

  if (!source) {
    return Response.json({ error: "source is required" }, { status: 400 })
  }

  const apiKey = process.env.FORMATEX_API_KEY
  if (!apiKey) {
    return Response.json({ error: "FORMATEX_API_KEY is not configured" }, { status: 500 })
  }

  const upstream = await fetch("https://api.formatex.io/api/v1/compile", {
    method: "POST",
    headers: {
      "X-API-Key": apiKey,
      "Content-Type": "application/json",
    },
    body: JSON.stringify({ latex: source, engine }),
  })

  if (!upstream.ok) {
    const err = await upstream.json().catch(() => ({ error: "compilation failed" }))
    return Response.json(err, { status: upstream.status })
  }

  // Stream the PDF bytes directly to the client — no buffering in memory.
  return new Response(upstream.body, {
    headers: {
      "Content-Type": "application/pdf",
      "Content-Disposition": 'attachment; filename="document.pdf"',
    },
  })
}