cheat/cheat

#!/usr/bin/env python
import os
import sys

DEFAULT_CHEAT_DIR = os.path.join(os.path.expanduser('~'), '.cheats')

# assembles a list of directories containing cheatsheets
def cheat_directories():
    default_directories = [DEFAULT_CHEAT_DIR]
    try:
        import cheatsheets
        default_directories.append(cheatsheets.cheat_dir)
    except ImportError:
        pass

    default = [ default_dir for default_dir in default_directories if os.path.isdir(default_dir) ]
    if 'CHEATPATH' in os.environ and os.environ['CHEATPATH']:
        return [ path for path in os.environ['CHEATPATH'].split(os.pathsep)\
                if os.path.isdir(path) ] + default
    else:
        return default

# assembles a dictionary of cheatsheets found in the above directories
def cheat_files(cheat_directories):
    cheats = {}
    for cheat_dir in reversed(cheat_directories):
        cheats.update(dict([ (cheat, cheat_dir)\
                for cheat in os.listdir(cheat_dir) if '.' not in cheat ]))
    return cheats

def main():
    """MAIN"""

    # assemble a keyphrase out of all params passed to the script
    keyphrase  = ' '.join(sys.argv[1:])
    cheat_dirs = cheat_directories()

    # verify that we have at least one cheat directory
    if not cheat_dirs:
        error_msg = 'The {default} dir does not exist or the CHEATPATH var is not set.'
        print >> sys.stderr, error_msg.format(default=DEFAULT_CHEAT_DIR)
        exit()

    # list the files in the ~/.cheat directory
    cheatsheets = cheat_files(cheat_dirs)

    # print help if requested
    if keyphrase.lower() in ['', 'cheat', 'help', '-h', '-help', '--help']:
        print "Usage: cheat [keyphrase]\n"
        print "Available keyphrases:"
        max_command = max([ len(x) for x in cheatsheets.keys() ]) + 3
        print '\n'.join(sorted([ '%s [%s]' % (key.ljust(max_command), value)\
                for key, value in cheatsheets.items() ]))
        exit()

    # print the cheatsheet if it exists
    if keyphrase in cheatsheets:
        with open (os.path.join(cheatsheets[keyphrase], keyphrase), 'r')\
                as cheatsheet:
            print cheatsheet.read()

    # if it does not, say so
    else:
        print 'No cheatsheet found for %s.' % keyphrase

if __name__ == '__main__':
    main()