#Merge PDF files using pyPDF2
'''
Usage:
python3 pdfMergeFiles.py -h
  or
python3 pdfMergeFiles.py files -f file_1.pdf file_2.pdf ...
  or
python3 pdfMergeFiles.py folder -d .
  or
python3 pdfMergeFiles.py folder -d folder_with_PDF
'''
from PyPDF2 import PdfFileReader, PdfFileWriter, PdfFileMerger
import sys, os, argparse
def mergePDF(all_in_folder, file_names, folderPath='.'):
  # all_in_folder = 0, specify file names on the command line
  # all_in_folder = 1, specify folder path containing PDF file
  
  inpdf = []
  if all_in_folder == 0:
    for pdf in file_names:
      inpdf.append(PdfFileReader(pdf))

  else:
    if folderPath == '.':
      folder_with_PDF = os.getcwd()
    else:
      folder_with_PDF = os.getcwd()+"/"+folderPath
    
    files_in_folder = [f for f in os.listdir(folder_with_PDF)]
    if(len(files_in_folder) <= 1):
      print("\nEither single PDF or no PDF file found, exiting!\n")
      sys.exit()

    for f in files_in_folder:
      full_path = os.path.join(folder_with_PDF, f)
      if os.path.isfile(full_path):
        extn = f.split('.')[-1]
        if (extn.upper() == "PDF"):
          inpdf.append(PdfFileReader(full_path))
          
  new_file =  os.getcwd() + "/" + "Merged_File.pdf"
  out_pdf = PdfFileWriter()
  for pdf_file in inpdf:
    for k in range(pdf_file.getNumPages()):
      p = pdf_file.getPage(k)
      out_pdf.addPage(p)
  
  with open(new_file, 'wb') as merged_pdf_file:
    out_pdf.write(merged_pdf_file)
# -----------------------------------------------------------------------------
# Create the top-level parser
parser = argparse.ArgumentParser()
subparsers = parser.add_subparsers(dest="command")

# Create the (sub) parser for the 'files' command
parser_files = subparsers.add_parser('files', 
                                 help="Merge files specified on command line")
parser_files.add_argument('-f', nargs='*')

# Create the (sub) parser for the 'folder' command
parser_folder = subparsers.add_parser('folder', 
                                 help="Merge PDF files in specified directory")
parser_folder.add_argument('-d', nargs=1)

# Parse the arguments and call whatever function was specified on command line
args = parser.parse_args()
if args.command == 'files':
  if args.f:
    mergePDF(0, args.f)
elif args.command == 'folder':
  if args.d:
      mergePDF(1, args.d[0])
else:
  print("\n  ---No sub-command name provided. \n")