AlexMathew/scrapple

"""
scrapple.utils.exceptions
~~~~~~~~~~~~~~~~~~~~~~~~~

Functions related to handling exceptions in the input arguments
"""

import re


class InvalidType(ValueError):
    """Exception class for invalid type in arguments."""
    pass


class InvalidSelector(ValueError):
    """Exception class for invalid in arguments."""
    pass


class InvalidOutputType(ValueError):
    """Exception class for invalid output_type in arguments."""
    pass


class InvalidProjectName(ValueError):
    """Exception class for invalid <projectname> in arguments."""
    pass


class InvalidLevels(ValueError):
    """Exception class for invalid levels in arguments."""
    pass


def check_arguments(args):
    """
    Validates the arguments passed through the CLI commands.

    :param args: The arguments passed in the CLI, parsed by the docopt module
    :return: None

    """
    projectname_re = re.compile(r'[^a-zA-Z0-9_]')
    if args['genconfig']:
        if args['--type'] not in ['scraper', 'crawler']:
            raise InvalidType("--type has to be 'scraper' or 'crawler'")
        if args['--selector'] not in ['xpath', 'css']:
            raise InvalidSelector("--selector has to be 'xpath' or 'css'")
    if args['generate'] or args['run']:
        if args['--output_type'] not in ['json', 'csv']:
            raise InvalidOutputType("--output_type has to be 'json' or 'csv'")
    if args['genconfig'] or args['generate'] or args['run']:
        if projectname_re.search(args['<projectname>']) is not None:
            message = "<projectname> should consist of letters, digits or _"
            raise InvalidProjectName(message)
    try:
        if int(args['--levels']) < 1:
            message = "--levels should be greater than, or equal to 1"
            raise InvalidLevels(message)
    except (TypeError, ValueError):
        message = " ".join([
            "--levels should be an integer and not of type",
            "{}".format(type(args['--levels']))
        ])
        raise InvalidLevels(message)