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# this work for additional information regarding copyright ownership.
# The ASF licenses this file to You under the Apache License, Version 2.0
# (the "License"); you may not use this file except in compliance with
# the License.  You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
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# distributed under the License is distributed on an "AS IS" BASIS,
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from ..validation import Issue
from .utils import (parse_types_dict_names, report_issue_for_unknown_type,
                    report_issue_for_parent_is_self, report_issue_for_unknown_parent_type,
                    report_issue_for_circular_type_hierarchy)


def type_validator(type_name, *types_dict_names):
    """
    Makes sure that the field refers to an existing type defined in the root presenter.

    The arguments from the second onwards are used to locate a nested field under
    :code:`service_template` under the root presenter. The first of these can optionally
    be a function, in which case it will be called to convert type names. This can be used
    to support shorthand type names, aliases, etc.

    Can be used with the :func:`field_validator` decorator.
    """

    types_dict_names, convert = parse_types_dict_names(types_dict_names)

    def validator_fn(field, presentation, context):
        field.default_validate(presentation, context)

        # Make sure type exists
        value = getattr(presentation, field.name)
        if value is not None:
            types_dict = context.presentation.get('service_template', *types_dict_names) or {}

            if convert:
                value = convert(context, value, types_dict)

            if value not in types_dict:
                report_issue_for_unknown_type(context, presentation, type_name, field.name)

    return validator_fn


def list_type_validator(type_name, *types_dict_names):
    """
    Makes sure that the field's elements refer to existing types defined in the root presenter.

    Assumes that the field is a list.

    The arguments from the second onwards are used to locate a nested field under
    :code:`service_template` under the root presenter. The first of these can optionally
    be a function, in which case it will be called to convert type names. This can be used
    to support shorthand type names, aliases, etc.

    Can be used with the :func:`field_validator` decorator.
    """

    types_dict_names, convert = parse_types_dict_names(types_dict_names)

    def validator_fn(field, presentation, context):
        field.default_validate(presentation, context)

        # Make sure types exist
        values = getattr(presentation, field.name)
        if values is not None:
            types_dict = context.presentation.get('service_template', *types_dict_names) or {}

            for value in values:
                if convert:
                    value = convert(context, value, types_dict)

                if value not in types_dict:
                    report_issue_for_unknown_type(context, presentation, type_name, field.name)

    return validator_fn


def list_length_validator(length):
    """
    Makes sure the field has exactly a specific number of elements.

    Assumes that the field is a list.

    Can be used with the :func:`field_validator` decorator.
    """

    def validator_fn(field, presentation, context):
        field.default_validate(presentation, context)

        # Make sure list has exactly the length
        values = getattr(presentation, field.name)
        if isinstance(values, list):
            if len(values) != length:
                context.validation.report('field "%s" does not have exactly %d elements in "%s"'
                                          % (field.name, length, presentation._fullname),
                                          locator=presentation._get_child_locator(field.name),
                                          level=Issue.FIELD)

    return validator_fn


def derived_from_validator(*types_dict_names):
    """
    Makes sure that the field refers to a valid parent type defined in the root presenter.

    Checks that we do not derive from ourselves and that we do not cause a circular hierarchy.

    The arguments are used to locate a nested field under
    :code:`service_template` under the root presenter.
    The first of these can optionally be a function, in which case it will be called to convert type
    names. This can be used to support shorthand type names, aliases, etc.

    Can be used with the :func:`field_validator` decorator.
    """

    types_dict_names, convert = parse_types_dict_names(types_dict_names)

    def validator_fn(field, presentation, context):
        field.default_validate(presentation, context)

        value = getattr(presentation, field.name)
        if value is not None:
            types_dict = context.presentation.get('service_template', *types_dict_names) or {}

            if convert:
                value = convert(context, value, types_dict)

            # Make sure not derived from self
            if value == presentation._name:
                report_issue_for_parent_is_self(context, presentation, field.name)
            # Make sure derived from type exists
            elif value not in types_dict:
                report_issue_for_unknown_parent_type(context, presentation, field.name)
            else:
                # Make sure derivation hierarchy is not circular
                hierarchy = [presentation._name]
                presentation_tmp = presentation
                while presentation_tmp.derived_from is not None:
                    derived_from = presentation_tmp.derived_from
                    if convert:
                        derived_from = convert(context, derived_from, types_dict)

                    if derived_from == presentation_tmp._name:
                        # This should cause a validation issue at that type
                        break
                    elif derived_from not in types_dict:
                        # This should cause a validation issue at that type
                        break
                    presentation_tmp = types_dict[derived_from]
                    if presentation_tmp._name in hierarchy:
                        report_issue_for_circular_type_hierarchy(context, presentation, field.name)
                        break
                    hierarchy.append(presentation_tmp._name)

    return validator_fn