Gooey/gooey/python_bindings/argparse_to_json.py

"""
Converts argparse parser actions into json "Build Specs"
"""
import argparse
import os
import sys
from argparse import (
    _CountAction,
    _HelpAction,
    _StoreConstAction,
    _StoreFalseAction,
    _StoreTrueAction,
    _SubParsersAction)
from collections import OrderedDict
from functools import partial
from uuid import uuid4

from gooey.python_bindings.gooey_parser import GooeyParser
from gooey.util.functional import merge, getin, identity, assoc


VALID_WIDGETS = (
    'FileChooser',
    'MultiFileChooser',
    'FileSaver',
    'DirChooser',
    'DateChooser',
    'TextField',
    'Dropdown',
    'Counter',
    'RadioGroup',
    'CheckBox',
    'BlockCheckbox',
    'MultiDirChooser',
    'Textarea',
    'PasswordField',
    'Listbox'
)


class UnknownWidgetType(Exception):
    pass


class UnsupportedConfiguration(Exception):
    pass



# TODO: merge the default foreground and bg colors from the
# baseline build_spec
item_default = {
    'error_color': '#ea7878',
    'label_color': '#000000',
    'help_color': '#363636',
    'full_width': False,
    'validator': {
        'type': 'local',
        'test': 'lambda x: True',
        'message': ''
    },
    'external_validator': {
        'cmd': '',
    }
}


def convert(parser, **kwargs):
    """
    Converts a parser into a JSON representation

    This is in desperate need of refactor. It wasn't build with supporting
    all (or any) of this configuration in mind. The use of global defaults
    are actively getting in the way of easily adding more configuration options.
    """

    group_defaults = {
        'legacy': {
            'required_cols': kwargs['num_required_cols'],
            'optional_cols': kwargs['num_optional_cols']
        },
        'columns': 2,
        'padding': 10,
        'show_border': False
    }

    assert_subparser_constraints(parser)
    x = {
        'layout': 'standard',
        'widgets': OrderedDict(
            (choose_name(name, sub_parser), {
                'command': name,
                'name': choose_name(name, sub_parser),
                'help': get_subparser_help(sub_parser),
                'description': '',
                'contents': process(sub_parser,
                                    getattr(sub_parser, 'widgets', {}),
                                    getattr(sub_parser, 'options', {}),
                                    group_defaults)
            }) for name, sub_parser in iter_parsers(parser))
    }

    if kwargs.get('use_legacy_titles'):
        return apply_default_rewrites(x)
    return x


def process(parser, widget_dict, options, group_defaults):
    mutex_groups = parser._mutually_exclusive_groups
    raw_action_groups = [extract_groups(group, group_defaults) for group in parser._action_groups
                         if group._group_actions]
    corrected_action_groups = reapply_mutex_groups(mutex_groups, raw_action_groups)

    return categorize2(strip_empty(corrected_action_groups), widget_dict, options)


def strip_empty(groups):
    return [group for group in groups if group['items']]


def assert_subparser_constraints(parser):
    if has_subparsers(parser._actions):
        if has_required(parser._actions):
            raise UnsupportedConfiguration(
                "Gooey doesn't currently support top level required arguments "
                "when subparsers are present.")


def iter_parsers(parser):
    ''' Iterate over name, parser pairs '''
    try:
        return get_subparser(parser._actions).choices.items()
    except:
        return iter([('::gooey/default', parser)])


def get_subparser_help(parser):
    if isinstance(parser, GooeyParser):
        return getattr(parser.parser, 'usage', '')
    else:
        return getattr(parser, 'usage', '')


def extract_groups(action_group, group_defaults):
    '''
    Recursively extract argument groups and associated actions
    from ParserGroup objects
    '''
    return {
        'name': action_group.title,
        'description': action_group.description,
        'items': [action for action in action_group._group_actions
                  if not is_help_message(action)],
        'groups': [extract_groups(group, group_defaults)
                   for group in action_group._action_groups],
        'options': handle_option_merge(
            group_defaults,
            getattr(action_group, 'gooey_options', {}),
            action_group.title)
    }


def handle_option_merge(group_defaults, incoming_options, title):
    """
    Merges a set of group defaults with incoming options.

    A bunch of ceremony here is to ensure backwards compatibility with the old
    num_required_cols and num_optional_cols decorator args. They are used as
    the seed values for the new group defaults which keeps the old behavior
    _mostly_ in tact.

    Known failure points:
        * Using custom groups / names. No 'positional arguments' group
          means no required_cols arg being honored
        * Non-positional args marked as required. It would take group
          shuffling along the lines of that required to make
          mutually exclusive groups show in the correct place. In short, not
          worth the complexity for a legacy feature that's been succeeded by
          a much more powerful alternative.
    """
    if title == 'positional arguments':
        # the argparse default 'required' bucket
        req_cols = getin(group_defaults, ['legacy', 'required_cols'], 2)
        new_defaults = assoc(group_defaults, 'columns', req_cols)
        return merge(new_defaults, incoming_options)
    else:
        opt_cols = getin(group_defaults, ['legacy', 'optional_cols'], 2)
        new_defaults = assoc(group_defaults, 'columns', opt_cols)
        return merge(new_defaults, incoming_options)



def apply_default_rewrites(spec):
    top_level_subgroups = list(spec['widgets'].keys())

    for subgroup in top_level_subgroups:
        path = ['widgets', subgroup, 'contents']
        contents = getin(spec, path)
        for group in contents:
            if group['name'] == 'positional arguments':
                group['name'] = 'Required Arguments'
            if group['name'] == 'optional arguments':
                group['name'] = 'Optional Arguments'
    return spec


def contains_actions(a, b):
    ''' check if any actions(a) are present in actions(b) '''
    return set(a).intersection(set(b))


def reapply_mutex_groups(mutex_groups, action_groups):
    # argparse stores mutually exclusive groups independently
    # of all other groups. So, they must be manually re-combined
    # with the groups/subgroups to which they were originally declared
    # in order to have them appear in the correct location in the UI.
    #
    # Order is attempted to be preserved by inserting the MutexGroup
    # into the _actions list at the first occurrence of any item
    # where the two groups intersect
    def swap_actions(actions):
        for mutexgroup in mutex_groups:
            mutex_actions = mutexgroup._group_actions
            if contains_actions(mutex_actions, actions):
                # make a best guess as to where we should store the group
                targetindex = actions.index(mutexgroup._group_actions[0])
                # insert the _ArgumentGroup container
                actions[targetindex] = mutexgroup
                # remove the duplicated individual actions
                return [action for action in actions
                        if action not in mutex_actions]
        return actions

    return [group.update({'items': swap_actions(group['items'])}) or group
            for group in action_groups]


def categorize2(groups, widget_dict, options):
    defaults = {'label_color': '#000000', 'description_color': '#363636'}
    return [{
        'name': group['name'],
        'items': list(categorize(group['items'], widget_dict, options)),
        'groups': categorize2(group['groups'], widget_dict, options),
        'description': group['description'],
        'options': merge(defaults ,group['options'])
    } for group in groups]


def categorize(actions, widget_dict, options):
    _get_widget = partial(get_widget, widget_dict)
    for action in actions:

        if is_mutex(action):
            yield build_radio_group(action, widget_dict, options)

        elif is_standard(action):
            yield action_to_json(action, _get_widget(action, 'TextField'), options)

        elif is_choice(action):
            yield action_to_json(action, _get_widget(action, 'Dropdown'), options)

        elif is_flag(action):
            yield action_to_json(action, _get_widget(action, 'CheckBox'), options)

        elif is_counter(action):
            _json = action_to_json(action, _get_widget(action, 'Counter'), options)
            # pre-fill the 'counter' dropdown
            _json['data']['choices'] = list(map(str, range(1, 11)))
            yield _json
        else:
            raise UnknownWidgetType(action)


def get_widget(widgets, action, default):
    supplied_widget = widgets.get(action.dest, None)
    type_arg_widget = 'FileChooser' if action.type == argparse.FileType else None
    return supplied_widget or type_arg_widget or default


def is_required(action):
    '''
    _actions possessing the `required` flag and not implicitly optional
    through `nargs` being '*' or '?'
    '''
    return not isinstance(action, _SubParsersAction) and (
    action.required == True and action.nargs not in ['*', '?'])


def is_mutex(action):
    return isinstance(action, argparse._MutuallyExclusiveGroup)


def has_required(actions):
    return list(filter(None, list(filter(is_required, actions))))


def is_subparser(action):
    return isinstance(action, _SubParsersAction)


def has_subparsers(actions):
    return list(filter(is_subparser, actions))


def get_subparser(actions):
    return list(filter(is_subparser, actions))[0]


def is_optional(action):
    '''
    _actions either not possessing the `required` flag or implicitly optional
    through `nargs` being '*' or '?'
    '''
    return (not action.required) or action.nargs in ['*', '?']


def is_choice(action):
    ''' action with choices supplied '''
    return action.choices


def is_standard(action):
    """ actions which are general "store" instructions.
    e.g. anything which has an argument style like:
       $ script.py -f myfilename.txt
    """
    boolean_actions = (
        _StoreConstAction, _StoreFalseAction,
        _StoreTrueAction
    )
    return (not action.choices
            and not isinstance(action, _CountAction)
            and not isinstance(action, _HelpAction)
            and type(action) not in boolean_actions)


def is_flag(action):
    """ _actions which are either storeconst, store_bool, etc.. """
    action_types = [_StoreTrueAction, _StoreFalseAction, _StoreConstAction]
    return any(list(map(lambda Action: isinstance(action, Action), action_types)))


def is_counter(action):
    """ _actions which are of type _CountAction """
    return isinstance(action, _CountAction)


def is_default_progname(name, subparser):
    return subparser.prog == '{} {}'.format(os.path.split(sys.argv[0])[-1], name)


def is_help_message(action):
    return isinstance(action, _HelpAction)


def choose_name(name, subparser):
    return name if is_default_progname(name, subparser) else subparser.prog


def build_radio_group(mutex_group, widget_group, options):
  return {
    'id': str(uuid4()),
    'type': 'RadioGroup',
    'cli_type': 'optional',
    'group_name': 'Choose Option',
    'required': mutex_group.required,
    'options': merge(item_default, getattr(mutex_group, 'gooey_options', {})),
    'data': {
      'commands': [action.option_strings for action in mutex_group._group_actions],
      'widgets': list(categorize(mutex_group._group_actions, widget_group, options))
    }
  }


def action_to_json(action, widget, options):
    dropdown_types = {'Listbox', 'Dropdown', 'Counter'}
    if action.required:
        # Text fields get a default check that user input is present
        # and not just spaces, dropdown types get a simplified
        # is-it-present style check
        validator = ('user_input and not user_input.isspace()'
                     if widget not in dropdown_types
                     else 'user_input')
        error_msg = 'This field is required'
    else:
        # not required; do nothing;
        validator = 'True'
        error_msg = ''

    base = merge(item_default, {
        'validator': {
            'test': validator,
            'message': error_msg
        },
    })

    default = coerce_default(action.default, widget)

    return {
        'id': action.option_strings[0] if action.option_strings else action.dest,
        'type': widget,
        'cli_type': choose_cli_type(action),
        'required': action.required,
        'data': {
            'display_name': action.metavar or action.dest,
            'help': action.help,
            'required': action.required,
            'nargs': action.nargs or '',
            'commands': action.option_strings,
            'choices': list(map(str, action.choices)) if action.choices else [],
            'default': default,
            'dest': action.dest,
        },
        'options': merge(base, options.get(action.dest) or {})
    }





def choose_cli_type(action):
    return 'positional' \
            if action.required and not action.option_strings \
            else 'optional'


def coerce_default(default, widget):
    """coerce a default value to the best appropriate type for
    ingestion into wx"""
    dispatcher = {
        'Listbox': clean_list_defaults,
        'Dropdown': safe_string,
        'Counter': safe_string
    }

    # Issue #321:
    # Defaults for choice types must be coerced to strings
    # to be able to match the stringified `choices` used by `wx.ComboBox`
    cleaned = clean_default(default)

    # dispatch to the appropriate cleaning function, or return the value
    # as is if no special handler is present
    return dispatcher.get(widget, identity)(cleaned)



def clean_list_defaults(default_values):
    """
    Listbox's default's can be passed as a single value
    or a list of values (due to multiple selections). The list interface
    is standardized on for ease.
    """
    wrapped_values = ([default_values]
                      if isinstance(default_values, str)
                      else default_values)
    return [safe_string(value) for value in wrapped_values]


def clean_default(default):
    '''
    Attemps to safely coalesce the default value down to
    a valid JSON type.

    See: Issue #147.
    function references supplied as arguments to the
    `default` parameter in Argparse cause errors in Gooey.
    '''
    return default.__name__ if callable(default) else default


def safe_string(value):
    """
    Coerce a type to string as long as it isn't None
    """
    if value is None or isinstance(value, bool):
        return value
    else:
        return str(value)