from aws_cdk import RemovalPolicy, Stack
from aws_cdk.aws_appsync import (
    CfnGraphQLSchema,
    CfnGraphQLApi,
    CfnApiKey,
    CfnDataSource,
    CfnResolver
)
from aws_cdk.aws_dynamodb import (
    Table,
    Attribute,
    AttributeType,
    StreamViewType,
    BillingMode
)
from aws_cdk.aws_iam import (
    Role,
    ServicePrincipal,
    ManagedPolicy
)
from constructs import Construct


class AppSyncCdkStack(Stack):

    def __init__(self, scope: Construct, id: str, **kwargs) -> None:
        super().__init__(scope, id, **kwargs)

        table_name = 'items'

        items_graphql_api = CfnGraphQLApi(
            self, 'ItemsApi',
            name='items-api',
            authentication_type='API_KEY'
        )

        CfnApiKey(
            self, 'ItemsApiKey',
            api_id=items_graphql_api.attr_api_id
        )

        api_schema = CfnGraphQLSchema(
            self, 'ItemsSchema',
            api_id=items_graphql_api.attr_api_id,
            definition=f"""\
                type {table_name} {{
                    {table_name}Id: ID!
                    name: String
                }}
                type Paginated{table_name} {{
                    items: [{table_name}!]!
                    nextToken: String
                }}
                type Query {{
                    all(limit: Int, nextToken: String): Paginated{table_name}!
                    getOne({table_name}Id: ID!): {table_name}
                }}
                type Mutation {{
                    save(name: String!): {table_name}
                    delete({table_name}Id: ID!): {table_name}
                }}
                type Schema {{
                    query: Query
                    mutation: Mutation
                }}"""
        )

        items_table = Table(
            self, 'ItemsTable',
            table_name=table_name,
            partition_key=Attribute(
                name=f'{table_name}Id',
                type=AttributeType.STRING
            ),
            billing_mode=BillingMode.PAY_PER_REQUEST,
            stream=StreamViewType.NEW_IMAGE,

            # The default removal policy is RETAIN, which means that cdk
            # destroy will not attempt to delete the new table, and it will
            # remain in your account until manually deleted. By setting the
            # policy to DESTROY, cdk destroy will delete the table (even if it
            # has data in it)
            removal_policy=RemovalPolicy.DESTROY # NOT recommended for production code
        )

        items_table_role = Role(
            self, 'ItemsDynamoDBRole',
            assumed_by=ServicePrincipal('appsync.amazonaws.com')
        )

        items_table_role.add_managed_policy(
            ManagedPolicy.from_aws_managed_policy_name(
                'AmazonDynamoDBFullAccess'
            )
        )

        data_source = CfnDataSource(
            self, 'ItemsDataSource',
            api_id=items_graphql_api.attr_api_id,
            name='ItemsDynamoDataSource',
            type='AMAZON_DYNAMODB',
            dynamo_db_config=CfnDataSource.DynamoDBConfigProperty(
                table_name=items_table.table_name,
                aws_region=self.region
            ),
            service_role_arn=items_table_role.role_arn
        )

        get_one_resolver = CfnResolver(
            self, 'GetOneQueryResolver',
            api_id=items_graphql_api.attr_api_id,
            type_name='Query',
            field_name='getOne',
            data_source_name=data_source.name,
            request_mapping_template=f"""\
            {{
                "version": "2017-02-28",
                "operation": "GetItem",
                "key": {{
                "{table_name}Id": $util.dynamodb.toDynamoDBJson($ctx.args.{table_name}Id)
                }}
            }}""",
            response_mapping_template="$util.toJson($ctx.result)"
        )

        get_one_resolver.add_depends_on(api_schema)

        get_all_resolver = CfnResolver(
            self, 'GetAllQueryResolver',
            api_id=items_graphql_api.attr_api_id,
            type_name='Query',
            field_name='all',
            data_source_name=data_source.name,
            request_mapping_template=f"""\
            {{
                "version": "2017-02-28",
                "operation": "Scan",
                "limit": $util.defaultIfNull($ctx.args.limit, 20),
                "nextToken": $util.toJson($util.defaultIfNullOrEmpty($ctx.args.nextToken, null))
            }}""",
            response_mapping_template="$util.toJson($ctx.result)"
        )

        get_all_resolver.add_depends_on(api_schema)

        save_resolver = CfnResolver(
            self, 'SaveMutationResolver',
            api_id=items_graphql_api.attr_api_id,
            type_name='Mutation',
            field_name='save',
            data_source_name=data_source.name,
            request_mapping_template=f"""\
            {{
                "version": "2017-02-28",
                "operation": "PutItem",
                "key": {{
                    "{table_name}Id": {{ "S": "$util.autoId()" }}
                }},
                "attributeValues": {{
                    "name": $util.dynamodb.toDynamoDBJson($ctx.args.name)
                }}
            }}""",
            response_mapping_template="$util.toJson($ctx.result)"
        )

        save_resolver.add_depends_on(api_schema)

        delete_resolver = CfnResolver(
            self, 'DeleteMutationResolver',
            api_id=items_graphql_api.attr_api_id,
            type_name='Mutation',
            field_name='delete',
            data_source_name=data_source.name,
            request_mapping_template=f"""\
            {{
                "version": "2017-02-28",
                "operation": "DeleteItem",
                "key": {{
                "{table_name}Id": $util.dynamodb.toDynamoDBJson($ctx.args.{table_name}Id)
                }}
            }}""",
            response_mapping_template="$util.toJson($ctx.result)"
        )

        delete_resolver.add_depends_on(api_schema)