#!/usr/bin/env python3

import os, sys, json, traceback

# Definitions
def stdout(string, end='\n', flush=False):
    print(string, end=end, file=sys.stdout, flush=flush)

def stderr(string, end='\n', flush=False):
    print(string, end=end, file=sys.stderr, flush=flush)

stderr("Variable Grabbler - version 5.0_pre1\n--------------------------------------------------------------------------------")
################################################################################
# Chnages in this version:
# - port to Python 3
# - output to stdout instead of rewriting the file
#===============================================================================
# Full documentation: tbd
#===============================================================================
# Exit codes:
# 0: normal exit
# 1: wrong usage
# 2: error while processing

# Command line input handling
usage = "Usage: python3 "+sys.argv[0]+" <macro config file> <file to be processed>"
if not len(sys.argv)==3:
    stderr("E: Wrong amount of arguments.")
    stderr(usage)
    sys.exit(1)
if sys.argv[1] == sys.argv[2]:
    stderr("E: Both input files are the same.")
    stderr(usage)
    sys.exit(1)

stderr("I: Reading macro definitions... ", end="")
macros = {}
try:
    if os.path.isfile(sys.argv[1]):
        macro_file = open(sys.argv[1], "r")
        macros = json.loads(macro_file.read())
        macro_file.close()
    elif sys.argv[1] == '-':
        macros = json.loads(sys.stdin.read())
    else:
        stderr("E: Not a valid file: "+sys.argv[1])
        sys.exit(2)
except:
    stderr("E: An exception occurred while trying to read macro definitions:")
    traceback.print_exc()
    sys.exit(2)
stderr("Done.")

try:
    input_file = sys.stdin
    if os.path.isfile(sys.argv[2]):
        input_file = open(sys.argv[2], "r")
    elif sys.argv[2] == '-':
        # nothing to do here bc input_file is already set to sys.stdin
        pass
    else:
        stderr("E: Not a valid file: "+sys.argv[2])
        sys.exit(2)
    for line in input_file:
        stdout(line, end="")
    # close input file if it's not sys.stdin, assume sys.stdin is being handled for us
    if not input_file==sys.stdin:
        input_file.close()
except:
    stderr("E: An exception occured while processing " + input_file.name + ":")
    traceback.print_exc()
    sys.exit(2)