fix(merge): page labels, retain-labels option, and workflow alignment with cpdf

src/js/utils/merge-cpdf.ts

@@ -0,0 +1,61 @@
+import { WasmProvider } from './wasm-provider';
+import { wfError } from '../workflow/errors';
+
+export interface MergeFile {
+  name: string;
+  data: ArrayBuffer;
+}
+
+export async function mergePdfsCpdf(
+  files: MergeFile[],
+  options?: { retainPageLabels?: boolean }
+): Promise<Uint8Array> {
+  if (files.length === 0) {
+    throw new Error(wfError('noPdfsConnected', { node: 'Merge' }));
+  }
+
+  const cpdfBaseUrl = WasmProvider.getUrl('cpdf');
+  if (!cpdfBaseUrl) {
+    throw new Error(wfError('cpdfNotConfigured'));
+  }
+
+  const jobs = files.map((f) => ({
+    fileName: f.name,
+    rangeType: 'all' as const,
+  }));
+
+  return new Promise<Uint8Array>((resolve, reject) => {
+    const worker = new Worker(
+      import.meta.env.BASE_URL + 'workers/merge.worker.js'
+    );
+
+    worker.onmessage = (e: MessageEvent) => {
+      worker.terminate();
+      if (e.data.status === 'success') {
+        resolve(new Uint8Array(e.data.pdfBytes));
+      } else {
+        reject(
+          new Error(
+            e.data.message || wfError('workerError', { message: 'unknown' })
+          )
+        );
+      }
+    };
+
+    worker.onerror = (err) => {
+      worker.terminate();
+      reject(new Error(wfError('workerError', { message: err.message })));
+    };
+
+    worker.postMessage(
+      {
+        command: 'merge',
+        files,
+        jobs,
+        cpdfUrl: cpdfBaseUrl + 'coherentpdf.browser.min.js',
+        retainPageLabels: options?.retainPageLabels === true,
+      },
+      files.map((f) => f.data)
+    );
+  });
+}