feat: add pdf-to-image backend route with info and processing endpoints

apps/api/src/routes/tools/index.ts

@@ -23,6 +23,7 @@ import { registerGifTools } from "./gif-tools.js";
 import { registerImageToPdf } from "./image-to-pdf.js";
 import { registerInfo } from "./info.js";
 import { registerOcr } from "./ocr.js";
+import { registerPdfToImage } from "./pdf-to-image.js";
 import { registerQrGenerate } from "./qr-generate.js";
 import { registerRemoveBackground } from "./remove-background.js";
 import { registerReplaceColor } from "./replace-color.js";
@@ -111,6 +112,7 @@ export async function registerToolRoutes(app: FastifyInstance): Promise<void> {
     { id: "svg-to-raster", register: registerSvgToRaster },
     { id: "vectorize", register: registerVectorize },
     { id: "gif-tools", register: registerGifTools },
+    { id: "pdf-to-image", register: registerPdfToImage },
 
     // Optimization extras
     { id: "bulk-rename", register: registerBulkRename },

apps/api/src/routes/tools/pdf-to-image.ts

@@ -0,0 +1,285 @@
+import { randomUUID } from "node:crypto";
+import { writeFile } from "node:fs/promises";
+import { join } from "node:path";
+import archiver from "archiver";
+import type { FastifyInstance } from "fastify";
+import * as mupdf from "mupdf";
+import sharp from "sharp";
+import { z } from "zod";
+import { createWorkspace } from "../../lib/workspace.js";
+
+// ── Settings schema ──────────────────────────────────────────────
+const settingsSchema = z.object({
+  format: z.enum(["png", "jpg", "webp", "avif", "tiff"]).default("png"),
+  dpi: z.union([z.literal(72), z.literal(150), z.literal(300), z.literal(600)]).default(150),
+  pages: z.string().default("all"),
+});
+
+// ── Page range parser (exported for unit tests) ──────────────────
+export function parsePageRange(input: string, totalPages: number): number[] {
+  const trimmed = input.trim();
+  if (trimmed === "" || trimmed.toLowerCase() === "all") {
+    return Array.from({ length: totalPages }, (_, i) => i + 1);
+  }
+
+  const pages = new Set<number>();
+  const segments = trimmed.split(",");
+
+  for (const segment of segments) {
+    const seg = segment.trim();
+    if (seg === "") {
+      throw new Error("Invalid page range format");
+    }
+
+    if (seg.includes("-")) {
+      const [startStr, endStr] = seg.split("-").map((s) => s.trim());
+      const start = Number(startStr);
+      const end = Number(endStr);
+
+      if (!Number.isInteger(start) || !Number.isInteger(end)) {
+        throw new Error("Invalid page range format");
+      }
+      if (start < 1 || end < 1) {
+        throw new Error("Page numbers must be positive");
+      }
+      if (start > end) {
+        throw new Error("Invalid page range: start exceeds end");
+      }
+      if (end > totalPages) {
+        throw new Error(`Page(s) ${end} out of range (document has ${totalPages} pages)`);
+      }
+
+      for (let i = start; i <= end; i++) {
+        pages.add(i);
+      }
+    } else {
+      const page = Number(seg);
+      if (!Number.isInteger(page)) {
+        throw new Error("Invalid page range format");
+      }
+      if (page < 1) {
+        throw new Error("Page numbers must be positive");
+      }
+      if (page > totalPages) {
+        throw new Error(`Page(s) ${page} out of range (document has ${totalPages} pages)`);
+      }
+      pages.add(page);
+    }
+  }
+
+  return [...pages].sort((a, b) => a - b);
+}
+
+// ── Sharp format mapping ─────────────────────────────────────────
+const FORMAT_EXT: Record<string, string> = {
+  png: ".png",
+  jpg: ".jpg",
+  webp: ".webp",
+  avif: ".avif",
+  tiff: ".tiff",
+};
+
+function convertWithSharp(pngBuffer: Uint8Array, format: string): Promise<Buffer> {
+  const s = sharp(Buffer.from(pngBuffer));
+  switch (format) {
+    case "jpg":
+      return s.jpeg().toBuffer();
+    case "webp":
+      return s.webp().toBuffer();
+    case "avif":
+      return s.avif().toBuffer();
+    case "tiff":
+      return s.tiff().toBuffer();
+    default:
+      return s.png().toBuffer();
+  }
+}
+
+// ── Render a single page ─────────────────────────────────────────
+function renderPage(doc: mupdf.Document, pageIndex: number, dpi: number): Uint8Array {
+  const page = doc.loadPage(pageIndex);
+  try {
+    const scale = dpi / 72;
+    const pixmap = page.toPixmap(
+      mupdf.Matrix.scale(scale, scale),
+      mupdf.ColorSpace.DeviceRGB,
+      false,
+      true,
+    );
+    try {
+      return pixmap.asPNG();
+    } finally {
+      pixmap.destroy();
+    }
+  } finally {
+    page.destroy();
+  }
+}
+
+// ── Route registration ───────────────────────────────────────────
+export function registerPdfToImage(app: FastifyInstance) {
+  // ── Info endpoint ────────────────────────────────────────────
+  app.post("/api/v1/tools/pdf-to-image/info", async (request, reply) => {
+    let fileBuffer: Buffer | null = null;
+
+    try {
+      const parts = request.parts();
+      for await (const part of parts) {
+        if (part.type === "file") {
+          const chunks: Buffer[] = [];
+          for await (const chunk of part.file) {
+            chunks.push(chunk);
+          }
+          fileBuffer = Buffer.concat(chunks);
+        }
+      }
+    } catch (err) {
+      return reply.status(400).send({
+        error: "Failed to parse multipart request",
+        details: err instanceof Error ? err.message : String(err),
+      });
+    }
+
+    if (!fileBuffer || fileBuffer.length === 0) {
+      return reply.status(400).send({ error: "No PDF file provided" });
+    }
+
+    let doc: mupdf.Document | null = null;
+    try {
+      doc = mupdf.Document.openDocument(fileBuffer, "application/pdf");
+      if (doc.needsPassword()) {
+        return reply.status(400).send({ error: "Password-protected PDFs are not supported" });
+      }
+      const pageCount = doc.countPages();
+      return reply.send({ pageCount });
+    } catch (err) {
+      if (
+        err instanceof Error &&
+        (err.message.includes("password") || err.message.includes("Password"))
+      ) {
+        return reply.status(400).send({ error: "Password-protected PDFs are not supported" });
+      }
+      return reply.status(400).send({ error: "Invalid or corrupt PDF file" });
+    } finally {
+      doc?.destroy();
+    }
+  });
+
+  // ── Main processing endpoint ─────────────────────────────────
+  app.post("/api/v1/tools/pdf-to-image", async (request, reply) => {
+    let fileBuffer: Buffer | null = null;
+    let settingsRaw: string | null = null;
+
+    try {
+      const parts = request.parts();
+      for await (const part of parts) {
+        if (part.type === "file") {
+          const chunks: Buffer[] = [];
+          for await (const chunk of part.file) {
+            chunks.push(chunk);
+          }
+          fileBuffer = Buffer.concat(chunks);
+        } else if (part.fieldname === "settings") {
+          settingsRaw = part.value as string;
+        }
+      }
+    } catch (err) {
+      return reply.status(400).send({
+        error: "Failed to parse multipart request",
+        details: err instanceof Error ? err.message : String(err),
+      });
+    }
+
+    if (!fileBuffer || fileBuffer.length === 0) {
+      return reply.status(400).send({ error: "No PDF file provided" });
+    }
+
+    let settings: z.infer<typeof settingsSchema>;
+    try {
+      const parsed = settingsRaw ? JSON.parse(settingsRaw) : {};
+      const result = settingsSchema.safeParse(parsed);
+      if (!result.success) {
+        return reply.status(400).send({ error: "Invalid settings", details: result.error.issues });
+      }
+      settings = result.data;
+    } catch {
+      return reply.status(400).send({ error: "Settings must be valid JSON" });
+    }
+
+    let doc: mupdf.Document | null = null;
+    try {
+      doc = mupdf.Document.openDocument(fileBuffer, "application/pdf");
+      if (doc.needsPassword()) {
+        return reply.status(400).send({ error: "Password-protected PDFs are not supported" });
+      }
+
+      const totalPages = doc.countPages();
+
+      let selectedPages: number[];
+      try {
+        selectedPages = parsePageRange(settings.pages, totalPages);
+      } catch (err) {
+        return reply
+          .status(400)
+          .send({ error: err instanceof Error ? err.message : "Invalid page range" });
+      }
+
+      const ext = FORMAT_EXT[settings.format] ?? ".png";
+
+      // ── Single page: workspace + JSON response ─────────────
+      if (selectedPages.length === 1) {
+        const pageNum = selectedPages[0];
+        const pngBytes = renderPage(doc, pageNum - 1, settings.dpi);
+        doc.destroy();
+        doc = null;
+
+        const imageBuffer = await convertWithSharp(pngBytes, settings.format);
+
+        const jobId = randomUUID();
+        const workspacePath = await createWorkspace(jobId);
+        const filename = `page-${pageNum}${ext}`;
+        await writeFile(join(workspacePath, "output", filename), imageBuffer);
+
+        return reply.send({
+          jobId,
+          downloadUrl: `/api/v1/download/${jobId}/${encodeURIComponent(filename)}`,
+          pageCount: totalPages,
+          selectedPages,
+          format: settings.format,
+        });
+      }
+
+      // ── Multiple pages: stream ZIP ─────────────────────────
+      const jobId = randomUUID();
+
+      reply.hijack();
+      reply.raw.writeHead(200, {
+        "Content-Type": "application/zip",
+        "Content-Disposition": `attachment; filename="pdf-pages-${jobId.slice(0, 8)}.zip"`,
+        "Transfer-Encoding": "chunked",
+      });
+
+      const archive = archiver("zip", { zlib: { level: 5 } });
+      archive.pipe(reply.raw);
+
+      for (const pageNum of selectedPages) {
+        const pngBytes = renderPage(doc, pageNum - 1, settings.dpi);
+        const imageBuffer = await convertWithSharp(pngBytes, settings.format);
+        archive.append(imageBuffer, { name: `page-${pageNum}${ext}` });
+      }
+
+      doc.destroy();
+      doc = null;
+
+      await archive.finalize();
+    } catch (err) {
+      doc?.destroy();
+      if (!reply.raw.headersSent) {
+        return reply.status(422).send({
+          error: "PDF conversion failed",
+          details: err instanceof Error ? err.message : "Unknown error",
+        });
+      }
+    }
+  });
+}