showaliases

#!/usr/bin/env python3
# -*- coding: utf-8 -*-
##############################################################################
#
# NAME:         showaliases
#
# DESCRIPTION:  Print a two column list of all shell aliases that exist in 
#               all the files that are passed as parameters or from stdin
#               if no file is specified.
#
#               The alias name is coloured so that it stands out.
#
#               Note that for an alias to be list, the word alias must be the
#               first in the line. If an alias is defined inside a conditional
#               block, it will listed regardless of the value of the
#               condition.
#
# USAGE:        showaliases [FILE [FILE ...] |  - ]
#               
#               Since it can also read its input from stdin, it can be run as
#               filter for the output of the alias command (at least in bash):
#               $ alias | showaliases
#
#
# DEPENDENCIES: None  
#
##############################################################################
#


__description__ = ''

# ---------------------------------------------------------------------------
# Standard imports:
import argparse
import fileinput
import os
import re
import sys
from functools import reduce

# Third party imports

# Local imports

# ---------------------------------------------------------------------------


ANSI_BLUE  = "\x1b[0;36m"
ANSI_RESET = "\x1b[0m"

def ansify(string, colour):
    """
    Paints a string usgint eh given ANSI colour code.
    """
    return "%s%s%s" % (colour, string, ANSI_RESET)

def printalias(alist):
    """
    Print a list of alias tuples in two left aligned columns.
    The first column contains the alias name in blue colour and the second
    column has the definition.
    """

    # Find the largest alias name length to align all definitions
    colsize = reduce(max, [len(x[0]) for x in alist])

    for alias in alist:
        fmt = "%%%ds = %%s" % (colsize+12)
        print(fmt % (ansify(alias[0], ANSI_BLUE), alias[1]))

def get_aliases(files, args):
    """
    For each line of all the input files, find those that define aliases and
    return a list where each element is a tuple with the alias name and its
    value.
    """

    if args.without_alias:
        regex = r'^\s*(\S+?)\s*=\s*(.*)$'
    else:
        regex = r'^\s*alias\s+(\S+)\s*=\s*(.*)$'

    line_matcher = re.compile(regex)
    aliases = []
    for line in fileinput.input(files):
        m = line_matcher.search(line)
        if m:
            aliases.append((m.group(1), m.group(2)))
    return aliases


def parse_args(argv):
    """ Parse and validate command line arguments """
    parser = argparse.ArgumentParser(description=__description__)
    # TODO: Add arguments here
    parser.add_argument('file', nargs='+', help='Files to look for aliases in. Use - for STDIN')
    parser.add_argument('--without-alias', '-a', action='store_true', help='Do not expect aliases to have the word alias')

    args = parser.parse_args(argv[1:])
    # TODO: Add validation here
    # if args.blah: parser.error("error")

    return args

def main(argv=[__name__]):
    """ Run this program """
    args = parse_args(argv)
    try:

        files = [x for x in args.file if os.path.isfile(x) or x=='-']
        if len(files) == 0 and args != sys.argv[1:]:
            print("Some files could not be found", file=sys.stderr)
            return 1

        alist = get_aliases(files, args)
        printalias(alist)

    except KeyboardInterrupt:
        return -1

if __name__ == '__main__':
    sys.exit(main(sys.argv) or 0)