"""
Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
SPDX-License-Identifier: MIT-0
"""
import hashlib
import json
from cfnlint.rules import CloudFormationLintRule
from cfnlint.rules import RuleMatch

from cfnlint.helpers import RESOURCE_SPECS


class ListDuplicates(CloudFormationLintRule):
    """Check if duplicates exist in a List"""
    id = 'E3037'
    shortdesc = 'Check if a list has duplicate values'
    description = 'Certain lists don\'t support duplicate items. ' \
                  'Check when duplicates are provided but not supported.'
    source_url = 'https://github.com/aws-cloudformation/cfn-python-lint/blob/master/docs/cfn-resource-specification.md#allowedvalue'
    tags = ['resources', 'property', 'list']

    def initialize(self, cfn):
        """Initialize the rule"""
        for resource_type_spec in RESOURCE_SPECS.get(cfn.regions[0]).get('ResourceTypes'):
            self.resource_property_types.append(resource_type_spec)
        for property_type_spec in RESOURCE_SPECS.get(cfn.regions[0]).get('PropertyTypes'):
            self.resource_sub_property_types.append(property_type_spec)

    def _check_duplicates(self, values, path, scenario=None):
        """ Check for Duplicates """
        matches = []

        list_items = []
        if isinstance(values, list):
            for index, value in enumerate(values):
                value_hash = hashlib.sha1(json.dumps(
                    value, sort_keys=True).encode('utf-8')).hexdigest()
                if value_hash in list_items:
                    if not scenario:
                        message = 'List has a duplicate value at {0}'
                        matches.append(
                            RuleMatch(path + [index], message.format('/'.join(map(str, path + [index])))))
                    else:
                        scenario_text = ' and '.join(
                            ['condition "%s" is %s' % (k, v) for (k, v) in scenario.items()])
                        message = 'List has a duplicate value at {0} when {1}'
                        matches.append(RuleMatch(path, message.format(
                            '/'.join(map(str, path)), scenario_text)))

                list_items.append(value_hash)

        return matches

    def check_duplicates(self, values, path, cfn):
        """ Check for duplicates """
        matches = []

        if isinstance(values, list):
            matches.extend(self._check_duplicates(values, path))
        elif isinstance(values, dict):
            props = cfn.get_object_without_conditions(values)
            for prop in props:
                matches.extend(self._check_duplicates(
                    prop.get('Object'), path, prop.get('Scenario')))

        return matches

    def check(self, cfn, properties, value_specs, path):
        """Check itself"""
        matches = list()
        for p_value, p_path in properties.items_safe(path[:]):
            for prop in p_value:
                if prop in value_specs:
                    property_type = value_specs.get(prop).get('Type')
                    duplicates_allowed = value_specs.get(prop).get('DuplicatesAllowed', True)
                    if property_type == 'List' and not duplicates_allowed:
                        matches.extend(
                            self.check_duplicates(
                                p_value[prop], p_path + [prop], cfn
                            )
                        )

        return matches

    def match_resource_sub_properties(self, properties, property_type, path, cfn):
        """Match for sub properties"""
        matches = list()

        specs = RESOURCE_SPECS.get(cfn.regions[0]).get(
            'PropertyTypes').get(property_type, {}).get('Properties', {})
        matches.extend(self.check(cfn, properties, specs, path))

        return matches

    def match_resource_properties(self, properties, resource_type, path, cfn):
        """Check CloudFormation Properties"""
        matches = list()

        specs = RESOURCE_SPECS.get(cfn.regions[0]).get(
            'ResourceTypes').get(resource_type, {}).get('Properties', {})
        matches.extend(self.check(cfn, properties, specs, path))

        return matches
