#!/usr/bin/env python
import sys,os,shutil,argparse
#-----------------------------------------------------------------------
def replace_string(file,oldstr,newstr):
#
# Replace all occurrences of "oldstr" in oldfile to "newstr" in newfile.
# Note oldfile and newfile may be the same, i.e., overwrite oldfile. 
#
# Read contents first, then close input file.
#
  file_read = open(file,'r')
  contents = file_read.read()
  file_read.close()
# print contents
#
# Open output file and change chars per line.
#
  fw = open(file,'w')
  for line in contents:
    newline = line.replace(oldstr,newstr)
    fw.write(newline)
  fw.close()
#-----------------------------------------------------------------------
#
description='''\
Change namelist comment character from ";" to "!" in input file(s).

If the -overwrite option is NOT set, user is prompted for whether or 
  not to overwrite the input files.
If the -overwrite option IS set (yes or no), then the option will be
  honored, and the user will NOT be prompted.
If input files are not overwritten, files with a '.new' suffix 
  added to the original file name will be written with the comment 
  character changed.
'''

epilog='''\
Example 1:
  change_nlcomment tiegcm.inp mynamelist.inp
  (User will be prompted whether or not to overwrite each input file)
Example 2:
  change_nlcomment -overwrite=no *.inp  
  (Files will be NOT be overwritten without prompting the user)
Example 3:
  change_nlcomment -overwrite=yes *.inp 
  (Files WILL be overwritten without prompting the user)
Example 4:
  change_nlcomment -overwrite=yes `find . -name \*.inp`
  (Files found by the "find" command will be overwritten without prompting the user)
'''

parser = argparse.ArgumentParser(description=description, \
  formatter_class=argparse.RawTextHelpFormatter,epilog=epilog)

help_overwrite = 'Overwrite input files (yes/no)? (If set, user will not be prompted for overwrite)'
help_nlfiles = 'One or more input namelist files in which to change the comment character.'

parser.add_argument('nlfiles', nargs='+', help=help_nlfiles)
parser.add_argument('-overwrite', help=help_overwrite)

args = parser.parse_args()

overwrite = ''
if args.overwrite: overwrite = args.overwrite
if overwrite != '':
  if overwrite == 'yes' or overwrite == 'y':
    print 'Will overwrite input files.'
  else:
    print 'Will NOT overwrite input files.'

nlfiles = args.nlfiles
print 'There are ',len(nlfiles),' input files.'

oldstr = ';'
newstr = '!'

for file in nlfiles:
  if os.path.isfile(file):
#
# Use command line argument, if provided:
#
    if overwrite != '':
      if overwrite == 'yes' or overwrite == 'y':
        replace_string(file,oldstr,newstr)
        print 'Overwrote file ',file
      else:
        newfile = file+'.new'
        shutil.copyfile(file,newfile)
        replace_string(newfile,oldstr,newstr)
        print 'Wrote file ',newfile
      continue
#
# Prompt user for each file (command line arg not provided):
#
    answer = raw_input('Overwrite file '+file+' (y/n/q, default=n)? ')
    if answer == 'q': sys.exit()
    if answer == 'y':
      replace_string(file,oldstr,newstr)
      print 'Overwrote file ',file
    elif answer == 'n' or answer == '':
      newfile = file+'.new'
      shutil.copyfile(file,newfile)
      replace_string(newfile,oldstr,newstr)
      print 'Wrote file ',newfile
    else:
      print 'File ',file,' is unchanged.'
#
# File not found:
#
  else:
    print '>>> Cannot find file ',file
    continue