Fix PDF processing: add poppler dev package and better error handling

apt.txt

@@ -1,3 +1,4 @@
 poppler-utils
 tesseract-ocr
 libzbar0
+libpoppler-cpp-dev

pdf_comparator.py

@@ -49,10 +49,21 @@ def _is_pdf(path: str) -> bool:
 
 def load_first_page(path: str, dpi: int = 300) -> Image.Image:
     if _is_pdf(path):
-        imgs = convert_from_path(path, dpi=dpi, first_page=1, last_page=1)
-        if not imgs:
-            raise ValueError(f"No pages in PDF: {path}")
-        return imgs[0].convert("RGB")
+        try:
+            # Try with poppler_path explicitly set
+            imgs = convert_from_path(path, dpi=dpi, first_page=1, last_page=1, poppler_path="/usr/bin")
+            if not imgs:
+                raise ValueError(f"No pages in PDF: {path}")
+            return imgs[0].convert("RGB")
+        except Exception as e1:
+            try:
+                # Fallback: try without explicit poppler_path
+                imgs = convert_from_path(path, dpi=dpi, first_page=1, last_page=1)
+                if not imgs:
+                    raise ValueError(f"No pages in PDF: {path}")
+                return imgs[0].convert("RGB")
+            except Exception as e2:
+                raise ValueError(f"Failed to convert PDF to image. Error 1: {str(e1)}. Error 2: {str(e2)}. Make sure poppler-utils is installed.")
     return Image.open(path).convert("RGB")
 
 def match_sizes(a: Image.Image, b: Image.Image) -> Tuple[Image.Image, Image.Image]:
@@ -73,7 +84,7 @@ def find_diff_boxes(diff_img: Image.Image, threshold: int = 12, min_area: int =
     out: List[Box] = []
     for p in regionprops(labeled):
         if p.area < min_area:
-            continue
+                            continue
         minr, minc, maxr, maxc = p.bbox
         out.append(Box(minr, minc, maxr, maxc, int(p.area)))
     return out
@@ -120,25 +131,25 @@ def find_misspell_boxes(img: Image.Image) -> List[Box]:
     try:
         spell = SpellChecker()
         data = pytesseract.image_to_data(img, output_type=pytesseract.Output.DICT)
-    except Exception:
-        return []
-    n = len(data.get("text", []))
+            except Exception:
+            return []
+        n = len(data.get("text", []))
     boxes: List[Box] = []
-    for i in range(n):
+        for i in range(n):
         text = data["text"][i]
         if not text:
-            continue
+                continue
         token = normalize_token(text)
         if len(token) < 2:
-            continue
+                    continue
         if token in spell:
-            continue
+                    continue
         left  = data.get("left",  [0])[i]
         top   = data.get("top",   [0])[i]
         width = data.get("width", [0])[i]
         height= data.get("height",[0])[i]
         if width <= 0 or height <= 0:
-            continue
+                    continue
         boxes.append(Box(top, left, top+height, left+width, width*height))
     return boxes
 
@@ -182,7 +193,7 @@ def boxes_from_rect(x: int, y: int, w: int, h: int) -> Box:
 def decode_with_variants(img: Image.Image):
     if not HAS_BARCODE:
         return []
-    results = []
+        results = []
     def do_decode(pil_img):
         try:
             dec = zbar_decode(pil_img)
@@ -194,8 +205,8 @@ def decode_with_variants(img: Image.Image):
     if not results:      do_decode(img.resize((img.width*2, img.height*2), Image.BICUBIC))
     if not results and img.mode != 'RGB':
         do_decode(img.convert('RGB'))
-    return results
-
+        return results
+    
 def find_barcode_boxes_and_info(img: Image.Image):
     decodes = decode_with_variants(img)
     boxes: List[Box] = []
@@ -281,7 +292,7 @@ def compare_pdfs(file_a, file_b):
         if HAS_BARCODE:
             bar_a, info_a = find_barcode_boxes_and_info(a)
             bar_b, info_b = find_barcode_boxes_and_info(b)
-        else:
+                    else:
             bar_a, info_a = [], []
             bar_b, info_b = [], []
 
@@ -322,7 +333,7 @@ def compare_pdfs(file_a, file_b):
 
         return overlay, a_disp, b_disp, status, codes_a, codes_b
 
-    except Exception as e:
+        except Exception as e:
         error_msg = f"❌ **Error:** {str(e)}"
         return None, None, None, error_msg, [], []