Use pypdf to detect the number of pages in a pdf, if available

1 files changed, 26 insertions, 12 deletions

diff --git a/page_manipulation/a5_book.py b/page_manipulation/a5_book.py
index 846ca86..1e004e0 100755
--- a/page_manipulation/a5_book.py
+++ b/page_manipulation/a5_book.py
@@ -4,6 +4,11 @@ import argparse
 import os.path
 import subprocess
 
+try:
+        import pypdf
+except ImportError:
+        pypdf = None
+
 
 SIGNATURE = (
     15, 0,
@@ -20,12 +25,12 @@ SIGNATURE = (
 def get_parser():
     parser = argparse.ArgumentParser()
     parser.add_argument(
-        "--file", '-f',
-        help="Name of the PDF file",
+        "--pagespec",
+        help="Page selection. At the moment only '<start>-<end>' is supported"
     )
     parser.add_argument(
-        "pagespec",
-        help="Page selection. At the moment only '<start>-<end>' is supported"
+        "file",
+        help="Name of the PDF file",
     )
     return parser
 
@@ -33,14 +38,23 @@ def get_parser():
 def main():
     parser = get_parser()
     args = parser.parse_args()
-    pspec = args.pagespec.split('-')
-    try:
-        start = int(pspec[0])
-        end = int(pspec[1])
-    except ValueError:
-        parser.print_usage()
-    except IndexError:
-        parser.print_usage()
+
+    if not args.pagespec:
+        if not pypdf:
+            print("Detecting the number of pages in the pdf requires pypdf")
+            sys.exit(1)
+        reader = pypdf.PdfReader(args.file)
+        start = 1
+        end = end = len(reader.pages)
+    else:
+        pspec = args.pagespec.split('-')
+        try:
+            start = int(pspec[0])
+            end = int(pspec[1])
+        except ValueError:
+            parser.print_usage()
+        except IndexError:
+            parser.print_usage()
 
     pages = [str(i) for i in range(start, end+1)]
     if len(pages) % 16 != 0: