import sys
import os.path
import argparse

class Settings():
    pass

def get_path(path):
    return

def check_path(path, force=False):
    return

def is_valid_file(parser, arg):
    """Helper function for argparse to check if a file exists"""
    if not os.path.isfile(arg):
        parser.error('The file %s does not exist!' % arg)
    else:
        #return open(arg, 'r')
        return arg

def is_valid_dir(parser, arg):
    """Helper function for argparse to check if a directory exists"""
    if not os.path.isdir(os.path.expanduser(arg)):
        parser.error('The directory %s does not exist!' % arg)
    else:
        return os.path.expanduser(arg)

def main():
    """Main function, argparse demonstration"""
    parser = argparse.ArgumentParser(description='Example method to demonstrate some '
                                     'some of the capabilities of argsparse')
    parser.add_argument('-c', '--config', nargs=1, metavar='config_file',
                        dest='config', required=True,
                        type=lambda x: is_valid_file(parser, x),
                        help='Required: Specify a config file')
    parser.add_argument('-o', '--output', nargs=1, metavar='output_directory',
                        type=lambda x: is_valid_dir(parser, x),
                        help='Optional: Custom output directory')
    parser.add_argument('-l', '--list', nargs='?', const=True,
                        help='List the amount of existing entries in files'
                        'in the output directory and exit; if "all" is specified'
                        'as an optional argument, the amount of entries will be listed')
    parser.add_argument('-e', '--example-config', nargs='?', const='example.config',
                        help='Export an example config file and exit. '
                        'If no file is specified, the output will be written to "example.config"')
    parser.add_argument('-n', '--number', type=int, nargs=1, metavar='integer',
                        help='Number of entries')
    parser.add_argument('-q', '--queue', type=str, nargs=1, metavar='queue',
                        help='The used queue system')
    parser.add_argument('-f', '--force', action='store_true',
                        help='Force creation of directories if they do not exist'
                        'or overwrite existing files')
    parser.add_argument('-v', '--verbose', action='store_true',
                        help='Print additional output')

    args = parser.parse_args()
    verbose = args.verbose
    force = args.force

    if args.example_config:
        print('[INFO] Write example config to file "%s"' % args.example_config)
        sys.exit(0)

    config = args.config
    settings = None
    if verbose:
        print('Use config file %s' % config)
    with open(config, 'r') as conf:
        settings = settings.read_config(conf)

    if args.list:
        if verbose and args.list == 'all':
            print('Trying to determine the total amount file entries')
        if args.output:
            settings.set('OUTPUT_PATH', get_path(args.output[0]))
        list_file_amount(settings, args.list == 'all')
        sys.exit(0)

    if args.queue:
        if verbose:
            print('Use the queue', args.queue[0])
        settings.set('QUEUE', args.queue[0])

    if args.number:
        if verbose:
            print('%d entries specified', args.number[0])
        settings.set('NUMBER', args.number[0])

    if verbose:
        print('The following settings will be used:')
        settings.print()

    if args.output:
        if not check_path(args.output[0], force):
            sys.exit('The output directory %s cannot be used' % args.output[0])
        output = get_path(args.output[0])
        print('Setting custom output directory: %s' % output)