"""Filters.

The filters are used in the override mechanisms. Those filters perform checks
between the values they hold and the values that are part of the context (
always ensure the context you provide is consistent.)

Example:

    overrides:
        variant_name:
            user_ids: [id1, id2]
            vendor_ids: [7123]

In this case, we will compare in the `user_ids` filter, the value in the
context to the values provided (`id1`, `id2`), and in the `vendor_ids` filter,
the value in the context to the values provided (`7123`).
"""

from features.constants import context as context_constants
from features.constants import yaml as yaml_constants


class FilterNotFoundException(Exception):
    """FilterNotFoundException."""

    pass


def get_from_context(filter_name):
    """Get a filter by its name.

    Args:
        filter_name (str): name of the filter.
    Raises:
        FilterNotFound: if the filter name does not exist.
    Return:
        callable: the filter.
    """
    yaml_filter_name = _context_to_yaml_map.get(filter_name)
    return get(yaml_filter_name)


def get(filter_name):
    """Get a filter by its name.

    Args:
        filter_name (str): name of the filter.
    Raises:
        FilterNotFound: if the filter name does not exist.
    Return:
        callable: the filter.
    """
    filter_method = _yaml_to_filter_map.get(filter_name)

    if not filter_method:
        raise FilterNotFoundException(
            'The filter {} does not exist'.format(filter_name)
        )

    return filter_method


def filter_user_id(values, context):
    """Filter for user ids.

    Args:
        values (list): the list of all the values to compare the user id
            against.
        context (dict): the context.
    Return:
        boolean: if the user id is in the values.
    """
    return context.get(context_constants.USER_ID) in values


def filter_vendor_id(values, context):
    """Filter for vendor ids.

    Args:
        values (list): the list of all the values to compare the vendor id
            against.
        context (dict): the context.
    Return:
        boolean: if the vendor id is in the values
    """
    return context.get(context_constants.VENDOR_ID) in values


def filter_profile_id(values, context):
    """Filter for profile ids - really {profile_type}:{profile_id}.

    Args:
        values (list): the list of all the values to compare
            {profile_type}:{profile_id} against.
        context (dict): the context.
    Return:
        boolean: if the profile_type:profile_id is in the values
    """
    return context.get(context_constants.PROFILE_TYPE_AND_ID) in values


def filter_identity_id(values, context):
    """Filter for identiy ids.

    Args:
        values (list): the list of all the values to compare
            identity_id against.
        context (dict): the context.
    Return:
        boolean: if the vendor id is in the values
    """
    return context.get(context_constants.IDENTITY_ID) in values


_yaml_to_filter_map = {
    yaml_constants.USER_ID: filter_user_id,
    yaml_constants.VENDOR_ID: filter_vendor_id,
    yaml_constants.PROFILE_ID: filter_profile_id,
    yaml_constants.IDENTITY_ID: filter_identity_id,
}

_context_to_yaml_map = {
    context_constants.USER_ID: yaml_constants.USER_ID,
    context_constants.VENDOR_ID: yaml_constants.VENDOR_ID,
    context_constants.PROFILE_TYPE_AND_ID: yaml_constants.PROFILE_ID,
    context_constants.IDENTITY_ID: yaml_constants.IDENTITY_ID,
}