#!/usr/bin/python2

print """
Variable Grabbler - version 3.4
-------------------------------"""
################################################################
# Changes in this version:
#===============================================================
# * added support for command execution
# * some internal technicalities that should not impact features
# * Yes.
#

################################################################
# Exit codes:
#===============================================================
# 0 => normal exit
# 1 => argument error
# 2 => error while processing
#

# definitions
import os, json, sys, subprocess

def print_err(text):
  print >> sys.stderr, text

if not len(sys.argv)==3:
  print_err("Error: Exactly two arguments required: \"python variable_grabbler.py <file to be rewritten> <config file>\"")
  sys.exit(1)

print "Reading config file...",
config_file = open(sys.argv[2],"r")
config_values = json.loads(config_file.read().decode("utf-8"))
config_file.close()
print "Done."

print "Working on file: "+sys.argv[1]
for variable in config_values:
  print "> "+variable+" => ",
  file_in = open(sys.argv[1], "r")
  file_content = file_in.read()
  file_in.close()
  if config_values[variable][0] == "file":
    print "Found array. Adding file instead: " + config_values[variable][1]
    file_replacement = open(config_values[variable][1], "r")
    replacement = file_replacement.read()
    file_replacement.close()
  elif config_values[variable][0] == "exec":
    print "Found array. Executing command instead: " + config_values[variable][1]
    process = subprocess.Popen(config_values[variable][1], shell=True, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
    stdout, stderr = process.communicate()
    if process.returncode == 0:
      print "Process exited normally. Replacing variable with the output from STDOUT..."
      print_err("Subprocess exited normally.\nThe following error messages were produced:")
      print_err(stderr)
      replacement = stdout
    else:
      print "Process exited abnormally. Exiting. No changes will be made."
      print_err("Subprocess exited abnormally. Exiting.\nThe following output was produced:")
      print_err(stdout)
      print_err("The following error messages were produced:")
      print_err(stderr)
      print "Exiting now."
      sys.exit(2)
  else:
    replacement = config_values[variable]
    print repr(replacement)
  file_out = open(sys.argv[1], "w")
  file_out.write(file_content.decode('utf-8').replace("%" + variable.upper() + "%", replacement).encode('utf-8'))
  file_out.close()
print "Done."