From ef96f523e316ee0cbf6c0f8093aff79530b6bcea Mon Sep 17 00:00:00 2001
From: rehlert <post@rehlert.de>
Date: Sat, 13 Jun 2026 13:32:55 +0200
Subject: [PATCH] The git changes introduce functionality to merge attachments
 from a processed ZIP archive into a single PDF file. Here is a summary of the
 changes:           ### New Features                         - PDF Merging:
 Added the ability to merge multiple attachments (PDFs and images) from a
 processed ZIP archive into a single PDF document.                    - Image
 Conversion: Implemented automatic conversion of non-PNG images (like JPGs) to
 PNG format before embedding them into the merged PDF.               ### File
 Changes                         - Dependencies: Added pdf-lib to the
 project's dependencies.                 - src/lib/zip-processing.ts:  - Added
 mergeProcessedZipArchive to handle the core logic of creating a merged PDF.  
                       - Implemented helpers to embed PDF pages and
 convert/embed images.     - Added toArrayBuffer and convertImageBytesToPng
 utilities for handling binary data and canvas-based image processing.      -
 src/lib/components/ProcessedZipArchiveEditor.svelte:  - Added a "PDF
 herunterladen" (Download PDF) button.              - Added UI states to
 handle the merging process (loading state, error messages).      - Integrated
 the mergeProcessedZipArchive function with the UI.       -
 src/lib/components/AttachmentPreview.svelte:  - Added a fix to ensure
 attachment.data is treated as a Uint8Array when loading PDF documents.

---
 .idea/workspace.xml                           |  32 ++++-
 package.json                                  |   1 +
 pnpm-lock.yaml                                |  37 ++++++
 src/lib/components/AttachmentPreview.svelte   |   4 +-
 .../ProcessedZipArchiveEditor.svelte          |  56 ++++++++-
 src/lib/zip-processing.ts                     | 119 ++++++++++++++++++
 6 files changed, 243 insertions(+), 6 deletions(-)

diff --git a/.idea/workspace.xml b/.idea/workspace.xml
index 9444ab9..e595adb 100644
--- a/.idea/workspace.xml
+++ b/.idea/workspace.xml
@@ -3,7 +3,11 @@
   <component name="ChangeListManager">
     <list default="true" id="89f9fc3a-63ad-41cb-8d25-f07df352eb98" name="Changes" comment="">
       <change beforePath="$PROJECT_DIR$/.idea/workspace.xml" beforeDir="false" afterPath="$PROJECT_DIR$/.idea/workspace.xml" afterDir="false" />
-      <change beforePath="$PROJECT_DIR$/src/routes/+page.svelte" beforeDir="false" afterPath="$PROJECT_DIR$/src/routes/+page.svelte" afterDir="false" />
+      <change beforePath="$PROJECT_DIR$/package.json" beforeDir="false" afterPath="$PROJECT_DIR$/package.json" afterDir="false" />
+      <change beforePath="$PROJECT_DIR$/pnpm-lock.yaml" beforeDir="false" afterPath="$PROJECT_DIR$/pnpm-lock.yaml" afterDir="false" />
+      <change beforePath="$PROJECT_DIR$/src/lib/components/AttachmentPreview.svelte" beforeDir="false" afterPath="$PROJECT_DIR$/src/lib/components/AttachmentPreview.svelte" afterDir="false" />
+      <change beforePath="$PROJECT_DIR$/src/lib/components/ProcessedZipArchiveEditor.svelte" beforeDir="false" afterPath="$PROJECT_DIR$/src/lib/components/ProcessedZipArchiveEditor.svelte" afterDir="false" />
+      <change beforePath="$PROJECT_DIR$/src/lib/zip-processing.ts" beforeDir="false" afterPath="$PROJECT_DIR$/src/lib/zip-processing.ts" afterDir="false" />
     </list>
     <option name="SHOW_DIALOG" value="false" />
     <option name="HIGHLIGHT_CONFLICTS" value="true" />
@@ -29,6 +33,7 @@
     "RunOnceActivity.ShowReadmeOnStart": "true",
     "RunOnceActivity.TerminalTabsStorage.copyFrom.TerminalArrangementManager.252": "true",
     "RunOnceActivity.cidr.known.project.marker": "true",
+    "RunOnceActivity.git.unshallow": "true",
     "RunOnceActivity.readMode.enableVisualFormatting": "true",
     "RunOnceActivity.typescript.service.memoryLimit.init": "true",
     "cidr.known.project.marker": "true",
@@ -49,7 +54,8 @@
       <option name="presentableId" value="Default" />
       <updated>1781169139290</updated>
       <workItem from="1781169141138" duration="309000" />
-      <workItem from="1781251694220" duration="14041000" />
+      <workItem from="1781251694220" duration="22281000" />
+      <workItem from="1781349431536" duration="774000" />
     </task>
     <task id="LOCAL-00001" summary="adapts styling of rvg.legal">
       <option name="closed" value="true" />
@@ -123,7 +129,23 @@
       <option name="project" value="LOCAL" />
       <updated>1781264568851</updated>
     </task>
-    <option name="localTasksCounter" value="10" />
+    <task id="LOCAL-00010" summary="range settings">
+      <option name="closed" value="true" />
+      <created>1781267754325</created>
+      <option name="number" value="00010" />
+      <option name="presentableId" value="LOCAL-00010" />
+      <option name="project" value="LOCAL" />
+      <updated>1781267754325</updated>
+    </task>
+    <task id="LOCAL-00011" summary="name generation improvement">
+      <option name="closed" value="true" />
+      <created>1781268046478</created>
+      <option name="number" value="00011" />
+      <option name="presentableId" value="LOCAL-00011" />
+      <option name="project" value="LOCAL" />
+      <updated>1781268046478</updated>
+    </task>
+    <option name="localTasksCounter" value="12" />
     <servers />
   </component>
   <component name="TypeScriptGeneratedFilesManager">
@@ -142,7 +164,9 @@
     <MESSAGE value="renders thumbnails" />
     <MESSAGE value="ignores mac special folders" />
     <MESSAGE value="handles zips in zip correctly" />
-    <option name="LAST_COMMIT_MESSAGE" value="handles zips in zip correctly" />
+    <MESSAGE value="range settings" />
+    <MESSAGE value="name generation improvement" />
+    <option name="LAST_COMMIT_MESSAGE" value="name generation improvement" />
   </component>
   <component name="XDebuggerManager">
     <breakpoint-manager>
diff --git a/package.json b/package.json
index 58a5eec..d40f0a7 100644
--- a/package.json
+++ b/package.json
@@ -33,6 +33,7 @@
 		"@skeletonlabs/skeleton": "^4.15.2",
 		"@skeletonlabs/skeleton-svelte": "^4.15.2",
 		"fflate": "^0.8.3",
+		"pdf-lib": "^1.17.1",
 		"pdfjs-dist": "^6.0.227"
 	}
 }
diff --git a/pnpm-lock.yaml b/pnpm-lock.yaml
index f9df5cc..dcafeaa 100644
--- a/pnpm-lock.yaml
+++ b/pnpm-lock.yaml
@@ -17,6 +17,9 @@ importers:
       fflate:
         specifier: ^0.8.3
         version: 0.8.3
+      pdf-lib:
+        specifier: ^1.17.1
+        version: 1.17.1
       pdfjs-dist:
         specifier: ^6.0.227
         version: 6.0.227
@@ -187,6 +190,12 @@ packages:
   '@oxc-project/types@0.133.0':
     resolution: {integrity: sha512-KzkdCd6Uxqnf6l3HOw1xfatAlUURA0g14cvBYFyJ5SaNOQbOUvBr9PKArcPcrNIeRsBdgcUzOGrhKveVpvOIGA==}
 
+  '@pdf-lib/standard-fonts@1.0.0':
+    resolution: {integrity: sha512-hU30BK9IUN/su0Mn9VdlVKsWBS6GyhVfqjwl1FjZN4TxP6cCw0jP2w7V3Hf5uX7M0AZJ16vey9yE0ny7Sa59ZA==}
+
+  '@pdf-lib/upng@1.0.1':
+    resolution: {integrity: sha512-dQK2FUMQtowVP00mtIksrlZhdFXQZPC+taih1q4CvPZ5vqdxR/LKBaFg0oAfzd1GlHZXXSPdQfzQnt+ViGvEIQ==}
+
   '@polka/url@1.0.0-next.29':
     resolution: {integrity: sha512-wwQAWhWSuHaag8c4q/KN/vCoeOJYshAIvMQwD4GpSb3OiZklFfvAgmj0VCBBImRpuF/aFgIRzllXlVX93Jevww==}
 
@@ -798,6 +807,12 @@ packages:
     resolution: {integrity: sha512-AWGB9WFcRXOQs48Z/udjI5ZcZMHXwX8XPByNpOydgcGsDLIzjGizhoMWJyKAWze7AVW/2W1i+/gPX4YtKe5cyg==}
     engines: {node: '>=12.20.0'}
 
+  pako@1.0.11:
+    resolution: {integrity: sha512-4hLB8Py4zZce5s4yd9XzopqwVv/yGNhV1Bl8NTmCq1763HeK2+EwVTv+leGeL13Dnh2wfbqowVPXCIO0z4taYw==}
+
+  pdf-lib@1.17.1:
+    resolution: {integrity: sha512-V/mpyJAoTsN4cnP31vc0wfNA1+p20evqqnap0KLoRUN0Yk/p3wN52DOEsL4oBFcLdb76hlpKPtzJIgo67j/XLw==}
+
   pdfjs-dist@6.0.227:
     resolution: {integrity: sha512-/P6M4SXw+70waMVLUM7rdRtvo+dEzqE1t6W/zQNvBETo2MaRa5rrvCcAYdfWGiUzadTgM0lJmRApUrW0d9zgKg==}
     engines: {node: '>=22.13.0 || >=24'}
@@ -938,6 +953,9 @@ packages:
     resolution: {integrity: sha512-sf4i37nQ2LBx4m3wB74y+ubopq6W/dIzXg0FDGjsYnZHVa1Da8FH853wlL2gtUhg+xJXjfk3kUZS3BRoQeoQBQ==}
     engines: {node: '>=6'}
 
+  tslib@1.14.1:
+    resolution: {integrity: sha512-Xni35NKzjgMrwevysHTCArtLDpPvye8zV/0E4EyYn43P7/7qvQwPh9BGkHewbMulVntbigmcT7rdX3BNo9wRJg==}
+
   tslib@2.8.1:
     resolution: {integrity: sha512-oJFu94HQb+KVduSUQL7wnpmqnfmLsOA/nAh6b6EH0wCEoK0/mPeXU6c3wKDV83MkOuHPRHtSXKKU99IBazS/2w==}
 
@@ -1112,6 +1130,14 @@ snapshots:
 
   '@oxc-project/types@0.133.0': {}
 
+  '@pdf-lib/standard-fonts@1.0.0':
+    dependencies:
+      pako: 1.0.11
+
+  '@pdf-lib/upng@1.0.1':
+    dependencies:
+      pako: 1.0.11
+
   '@polka/url@1.0.0-next.29': {}
 
   '@rolldown/binding-android-arm64@1.0.3':
@@ -1786,6 +1812,15 @@ snapshots:
 
   obug@2.1.2: {}
 
+  pako@1.0.11: {}
+
+  pdf-lib@1.17.1:
+    dependencies:
+      '@pdf-lib/standard-fonts': 1.0.0
+      '@pdf-lib/upng': 1.0.1
+      pako: 1.0.11
+      tslib: 1.14.1
+
   pdfjs-dist@6.0.227:
     optionalDependencies:
       '@napi-rs/canvas': 1.0.0
@@ -1902,6 +1937,8 @@ snapshots:
 
   totalist@3.0.1: {}
 
+  tslib@1.14.1: {}
+
   tslib@2.8.1: {}
 
   typescript@6.0.3: {}
diff --git a/src/lib/components/AttachmentPreview.svelte b/src/lib/components/AttachmentPreview.svelte
index a198a16..eadfa78 100644
--- a/src/lib/components/AttachmentPreview.svelte
+++ b/src/lib/components/AttachmentPreview.svelte
@@ -50,7 +50,9 @@
                 }
 
                 try {
-                    const loadingTask = getDocument({ data: attachment.data });
+                    // create a copy, getDocument seems to manipulate the data -> creating pdfs fails
+                    const buffer = new Uint8Array(attachment.data);
+                    const loadingTask = getDocument({ data: buffer });
                     const pdfDocument = await loadingTask.promise;
                     const page = await pdfDocument.getPage(1);
 
diff --git a/src/lib/components/ProcessedZipArchiveEditor.svelte b/src/lib/components/ProcessedZipArchiveEditor.svelte
index f7fe174..bd55993 100644
--- a/src/lib/components/ProcessedZipArchiveEditor.svelte
+++ b/src/lib/components/ProcessedZipArchiveEditor.svelte
@@ -1,6 +1,6 @@
 <script lang="ts">
     import AttachmentPreview from "$lib/components/AttachmentPreview.svelte";
-    import type {ProcessedZipArchive, ZipAttachment} from "$lib/zip-processing";
+    import { mergeProcessedZipArchive, type ProcessedZipArchive, type ZipAttachment } from "$lib/zip-processing";
 
     type Props = {
         archive: ProcessedZipArchive;
@@ -19,6 +19,14 @@
     let archiveName = $state("");
     let dragIndex = $state<number | null>(null);
     let dropIndex = $state<number | null>(null);
+    let isMerging = $state(false);
+    let mergeError = $state<string | null>(null);
+
+    const toArrayBuffer = (bytes: Uint8Array) => {
+        const copy = new Uint8Array(bytes.byteLength);
+        copy.set(bytes);
+        return copy.buffer;
+    };
 
     $effect(() => {
         archiveName = archive.name;
@@ -33,6 +41,37 @@
         });
     };
 
+    const downloadMergedPdf = async () => {
+        if (attachments.length === 0 || isMerging) {
+            return;
+        }
+
+        isMerging = true;
+        mergeError = null;
+
+        try {
+            const mergedBytes = await mergeProcessedZipArchive({
+                ...archive,
+                name: archiveName,
+                attachments: attachments.map((attachment) => ({...attachment}))
+            });
+
+            const pdfBlob = new Blob([toArrayBuffer(mergedBytes)], {type: "application/pdf"});
+            const objectUrl = URL.createObjectURL(pdfBlob);
+            const downloadLink = document.createElement("a");
+            downloadLink.href = objectUrl;
+            downloadLink.download = archiveName.toLowerCase().endsWith(".pdf") ? archiveName : `${archiveName}.pdf`;
+            downloadLink.rel = "noopener";
+            downloadLink.click();
+            window.setTimeout(() => URL.revokeObjectURL(objectUrl), 1000);
+        } catch (error) {
+            console.error(`Failed to merge archive ${archive.name}`, error);
+            mergeError = "PDF konnte nicht erstellt werden.";
+        } finally {
+            isMerging = false;
+        }
+    };
+
     const moveAttachment = (fromIndex: number, toIndex: number) => {
         if (
             fromIndex === toIndex ||
@@ -107,8 +146,23 @@
                 {attachments.length} relevante Datei{attachments.length === 1 ? "" : "en"}
             </p>
         </div>
+
+        <button
+                class="rounded-container whitespace-nowrap bg-primary-900 px-4 py-2 text-[14px] font-bold leading-6 text-white shadow-sm transition hover:bg-primary-800 disabled:cursor-not-allowed disabled:bg-primary-300"
+                type="button"
+                disabled={attachments.length === 0 || isMerging}
+                onclick={downloadMergedPdf}
+        >
+            {isMerging ? "PDF wird erstellt" : "PDF herunterladen"}
+        </button>
     </header>
 
+    {#if mergeError}
+        <div class="rounded-container bg-red-50 px-4 py-3 text-[14px] font-medium text-red-900">
+            {mergeError}
+        </div>
+    {/if}
+
     <ul class="flex gap-3 overflow-x-auto pb-1">
         {#each attachments as attachment, index (attachment.path)}
             <li
diff --git a/src/lib/zip-processing.ts b/src/lib/zip-processing.ts
index b412d4c..829d740 100644
--- a/src/lib/zip-processing.ts
+++ b/src/lib/zip-processing.ts
@@ -1,4 +1,5 @@
 import { unzip } from 'fflate';
+import { PDFDocument } from 'pdf-lib';
 
 export type ZipAttachmentKind = 'pdf' | 'image';
 
@@ -287,3 +288,121 @@ export const extractZipArchives = async (file: File): Promise<ProcessedZipArchiv
 
 	return extractZipEntries(archiveBytes, file.name);
 };
+
+const loadImageElement = (src: string) =>
+	new Promise<HTMLImageElement>((resolve, reject) => {
+		const image = new Image();
+		image.decoding = 'async';
+		image.onload = () => resolve(image);
+		image.onerror = () => reject(new Error(`Unable to decode image asset: ${src}`));
+		image.src = src;
+	});
+
+const toArrayBuffer = (bytes: Uint8Array) =>
+	(() => {
+		const copy = new Uint8Array(bytes.byteLength);
+		copy.set(bytes);
+		return copy.buffer;
+	})();
+
+const convertImageBytesToPng = async (imageBytes: Uint8Array) => {
+	if (typeof document === 'undefined') {
+		throw new Error('Image conversion requires a browser environment.');
+	}
+
+	const objectUrl = URL.createObjectURL(new Blob([toArrayBuffer(imageBytes)]));
+
+	try {
+		const image = await loadImageElement(objectUrl);
+		const canvas = document.createElement('canvas');
+		canvas.width = image.naturalWidth || image.width;
+		canvas.height = image.naturalHeight || image.height;
+
+		const context = canvas.getContext('2d');
+
+		if (!context) {
+			throw new Error('Could not create a canvas context for image conversion.');
+		}
+
+		context.drawImage(image, 0, 0);
+
+		const pngBlob = await new Promise<Blob>((resolve, reject) => {
+			canvas.toBlob((blob) => {
+				if (blob) {
+					resolve(blob);
+					return;
+				}
+
+				reject(new Error('Could not encode image asset as PNG.'));
+			}, 'image/png');
+		});
+
+		return new Uint8Array(await pngBlob.arrayBuffer());
+	} finally {
+		URL.revokeObjectURL(objectUrl);
+	}
+};
+
+const embedAttachmentImage = async (pdfDocument: PDFDocument, attachment: ZipAttachment) => {
+	const extension = getExtension(attachment.path);
+	const imageData = attachment.data;
+
+	if (extension === '.jpg' || extension === '.jpeg') {
+		return pdfDocument.embedJpg(imageData);
+	}
+
+	if (extension === '.png') {
+		return pdfDocument.embedPng(imageData);
+	}
+
+	const pngBytes = await convertImageBytesToPng(imageData);
+
+	return pdfDocument.embedPng(pngBytes);
+};
+
+const mergeAttachmentIntoPdf = async (mergedPdf: PDFDocument, attachment: ZipAttachment) => {
+	const canLoadAsPdf = attachment.kind === 'pdf'
+
+	if (canLoadAsPdf) {
+		const sourcePdf = await PDFDocument.load(attachment.data, { ignoreEncryption: true });
+		const copiedPages = await mergedPdf.copyPages(sourcePdf, sourcePdf.getPageIndices());
+
+		for (const page of copiedPages) {
+			mergedPdf.addPage(page);
+		}
+
+		return;
+	}
+
+	try {
+		const embeddedImage = await embedAttachmentImage(mergedPdf, attachment);
+		const page = mergedPdf.addPage([embeddedImage.width, embeddedImage.height]);
+
+		page.drawImage(embeddedImage, {
+			x: 0,
+			y: 0,
+			width: page.getWidth(),
+			height: page.getHeight()
+		});
+	} catch (error) {
+		if (attachment.kind === 'pdf') {
+			throw new Error(`Attachment "${attachment.name}" is not a valid PDF and could not be rendered as an image.`);
+		}
+
+		throw error;
+	}
+};
+
+export const mergeProcessedZipArchive = async (archive: ProcessedZipArchive) => {
+	if (archive.attachments.length === 0) {
+		throw new Error('Cannot create a PDF from an empty archive.');
+	}
+
+	const mergedPdf = await PDFDocument.create();
+
+	for (const attachment of archive.attachments) {
+		await mergeAttachmentIntoPdf(mergedPdf, attachment);
+	}
+
+	return mergedPdf.save();
+};