From 99343f74af5068f80ad6e0b353c9911c81f112e4 Mon Sep 17 00:00:00 2001
From: Nils-Johan Gynther <nils-johan.gynther@neoleaf.se>
Date: Sun, 3 May 2026 20:03:10 +0200
Subject: [PATCH] feat: Enhance PDF parsing with fallback to pdf-lib for
 improved handling of complex PDFs

Co-authored-by: Copilot <copilot@github.com>
---
 backend/package-lock.json                     | 43 +++++++++++++++++++
 backend/package.json                          |  1 +
 .../receipt-parsing.service.ts                | 12 +++++-
 3 files changed, 55 insertions(+), 1 deletion(-)

diff --git a/backend/package-lock.json b/backend/package-lock.json
index 25fbcf3..426ef1f 100644
--- a/backend/package-lock.json
+++ b/backend/package-lock.json
@@ -14,6 +14,7 @@
         "class-transformer": "^0.5.1",
         "class-validator": "^0.15.1",
         "multer": "^1.4.5-lts.1",
+        "pdf-lib": "^1.17.1",
         "pdf-parse": "^1.1.1",
         "reflect-metadata": "^0.2.2",
         "rxjs": "^7.8.1",
@@ -648,6 +649,24 @@
         "npm": ">=5.0.0"
       }
     },
+    "node_modules/@pdf-lib/standard-fonts": {
+      "version": "1.0.0",
+      "resolved": "https://registry.npmjs.org/@pdf-lib/standard-fonts/-/standard-fonts-1.0.0.tgz",
+      "integrity": "sha512-hU30BK9IUN/su0Mn9VdlVKsWBS6GyhVfqjwl1FjZN4TxP6cCw0jP2w7V3Hf5uX7M0AZJ16vey9yE0ny7Sa59ZA==",
+      "license": "MIT",
+      "dependencies": {
+        "pako": "^1.0.6"
+      }
+    },
+    "node_modules/@pdf-lib/upng": {
+      "version": "1.0.1",
+      "resolved": "https://registry.npmjs.org/@pdf-lib/upng/-/upng-1.0.1.tgz",
+      "integrity": "sha512-dQK2FUMQtowVP00mtIksrlZhdFXQZPC+taih1q4CvPZ5vqdxR/LKBaFg0oAfzd1GlHZXXSPdQfzQnt+ViGvEIQ==",
+      "license": "MIT",
+      "dependencies": {
+        "pako": "^1.0.10"
+      }
+    },
     "node_modules/@pkgjs/parseargs": {
       "version": "0.11.0",
       "resolved": "https://registry.npmjs.org/@pkgjs/parseargs/-/parseargs-0.11.0.tgz",
@@ -3351,6 +3370,12 @@
       "dev": true,
       "license": "BlueOak-1.0.0"
     },
+    "node_modules/pako": {
+      "version": "1.0.11",
+      "resolved": "https://registry.npmjs.org/pako/-/pako-1.0.11.tgz",
+      "integrity": "sha512-4hLB8Py4zZce5s4yd9XzopqwVv/yGNhV1Bl8NTmCq1763HeK2+EwVTv+leGeL13Dnh2wfbqowVPXCIO0z4taYw==",
+      "license": "(MIT AND Zlib)"
+    },
     "node_modules/parent-module": {
       "version": "1.0.1",
       "resolved": "https://registry.npmjs.org/parent-module/-/parent-module-1.0.1.tgz",
@@ -3435,6 +3460,24 @@
         "node": ">=8"
       }
     },
+    "node_modules/pdf-lib": {
+      "version": "1.17.1",
+      "resolved": "https://registry.npmjs.org/pdf-lib/-/pdf-lib-1.17.1.tgz",
+      "integrity": "sha512-V/mpyJAoTsN4cnP31vc0wfNA1+p20evqqnap0KLoRUN0Yk/p3wN52DOEsL4oBFcLdb76hlpKPtzJIgo67j/XLw==",
+      "license": "MIT",
+      "dependencies": {
+        "@pdf-lib/standard-fonts": "^1.0.0",
+        "@pdf-lib/upng": "^1.0.1",
+        "pako": "^1.0.11",
+        "tslib": "^1.11.1"
+      }
+    },
+    "node_modules/pdf-lib/node_modules/tslib": {
+      "version": "1.14.1",
+      "resolved": "https://registry.npmjs.org/tslib/-/tslib-1.14.1.tgz",
+      "integrity": "sha512-Xni35NKzjgMrwevysHTCArtLDpPvye8zV/0E4EyYn43P7/7qvQwPh9BGkHewbMulVntbigmcT7rdX3BNo9wRJg==",
+      "license": "0BSD"
+    },
     "node_modules/pdf-parse": {
       "version": "1.1.4",
       "resolved": "https://registry.npmjs.org/pdf-parse/-/pdf-parse-1.1.4.tgz",
diff --git a/backend/package.json b/backend/package.json
index c600b97..2076b4a 100644
--- a/backend/package.json
+++ b/backend/package.json
@@ -14,6 +14,7 @@
     "class-transformer": "^0.5.1",
     "class-validator": "^0.15.1",
     "multer": "^1.4.5-lts.1",
+    "pdf-lib": "^1.17.1",
     "pdf-parse": "^1.1.1",
     "reflect-metadata": "^0.2.2",
     "rxjs": "^7.8.1",
diff --git a/backend/src/receipt-parsing/receipt-parsing.service.ts b/backend/src/receipt-parsing/receipt-parsing.service.ts
index fbd4801..3022893 100644
--- a/backend/src/receipt-parsing/receipt-parsing.service.ts
+++ b/backend/src/receipt-parsing/receipt-parsing.service.ts
@@ -282,11 +282,21 @@ export class ReceiptParsingService {
   private async parseReceiptFromPdf(buffer: Buffer, apiKey: string): Promise<ParsedReceiptItemRaw[]> {
     let text: string;
     try {
+      // Try pdf-parse first
       const data = await pdfParse(buffer);
       text = data.text;
     } catch (err) {
       this.logger.warn(`pdf-parse misslyckades: ${err}`);
-      throw new BadRequestException('PDF-filen kunde inte läsas. Kontrollera att filen inte är skadad.');
+      
+      // Fallback to pdf-lib for more complex PDFs
+      try {
+        const { PDFDocument } = await import('pdf-lib');
+        const pdfDoc = await PDFDocument.load(buffer);
+        text = pdfDoc.getPages().map(page => page.getText()).join(' ');
+      } catch (fallbackErr) {
+        this.logger.error(`Både pdf-parse och pdf-lib misslyckades: ${fallbackErr}`);
+        throw new BadRequestException('PDF-filen kunde inte läsas. Kontrollera att filen inte är skadad eller krypterad.');
+      }
     }
 
     const combinedLines = preprocessPdfLines(text);