#!/usr/bin/python

#

# Simple utility script to manipulate

# certain types of strings in a file

# This can be used in various projects where

# there is the need to replace strings in files,

# and is copied from GLib's $(srcroot)/build/win32

# Author: Fan, Chun-wei

# Date: September 03, 2014

import os

import sys

import re

import string

import argparse

valid_actions = ['remove-prefix',

                 'replace-var',

                 'replace-str',

                 'remove-str']

def open_file(filename, mode):

    if sys.version_info[0] < 3:

        return open(filename, mode=mode)

    else:

        return open(filename, mode=mode, encoding='utf-8')

def replace_multi(src, dest, replace_items):

    with open_file(src, 'r') as s:

        with open_file(dest, 'w') as d:

            for line in s:

                replace_dict = dict((re.escape(key), value) \

                               for key, value in replace_items.items())

                replace_pattern = re.compile("|".join(replace_dict.keys()))

                d.write(replace_pattern.sub(lambda m: \

                        replace_dict[re.escape(m.group(0))], line))

def replace(src, dest, instring, outstring):

    replace_item = {instring: outstring}

    replace_multi(src, dest, replace_item)

def check_required_args(args, params):

    for param in params:

        if getattr(args, param, None) is None:

            raise SystemExit('%s: error: --%s argument is required' % (__file__, param))

def warn_ignored_args(args, params):

    for param in params:

        if getattr(args, param, None) is not None:

            print('%s: warning: --%s argument is ignored' % (__file__, param))

def main(argv):

    parser = argparse.ArgumentParser(description='Process strings in a file.')

    parser.add_argument('-a',

                        '--action',

                        help='Action to carry out.  Can be one of:\n'

                             'remove-prefix\n'

                             'replace-var\n'

                             'replace-str\n'

                             'remove-str',

                        choices=valid_actions)

    parser.add_argument('-i', '--input', help='Input file')

    parser.add_argument('-o', '--output', help='Output file')

    parser.add_argument('--instring', help='String to replace or remove')

    parser.add_argument('--var', help='Autotools variable name to replace')

    parser.add_argument('--outstring',

                        help='New String to replace specified string or variable')

    parser.add_argument('--removeprefix', help='Prefix of string to remove')

    args = parser.parse_args()

    input_string = ''

    output_string = ''

    # We must have action, input, output for all operations

    check_required_args(args, ['action','input','output'])

    # Build the arguments by the operation that is to be done,

    # to be fed into replace()

    # Get rid of prefixes from a string

    if args.action == 'remove-prefix':

        check_required_args(args, ['instring','removeprefix'])

        warn_ignored_args(args, ['outstring','var'])

        input_string = args.removeprefix + args.instring

        output_string = args.instring

    # Replace an m4-style variable (those surrounded by @...@)

    if args.action == 'replace-var':

        check_required_args(args, ['var','outstring'])

        warn_ignored_args(args, ['instring','removeprefix'])

        input_string = '@' + args.var + '@'

        output_string = args.outstring

    # Replace a string

    if args.action == 'replace-str':

        check_required_args(args, ['instring','outstring'])

        warn_ignored_args(args, ['var','removeprefix'])

        input_string = args.instring

        output_string = args.outstring

    # Remove a string

    if args.action == 'remove-str':

        check_required_args(args, ['instring'])

        warn_ignored_args(args, ['var','outstring','removeprefix'])

        input_string = args.instring

        output_string = ''

    replace(args.input, args.output, input_string, output_string)

if __name__ == '__main__':

    sys.exit(main(sys.argv))