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


class Ref(CloudFormationLintRule):
    """Check if Ref value is a string"""

    id = "E1020"
    shortdesc = "Ref validation of value"
    description = (
        "Making sure the Ref has a String value (no other functions are supported)"
    )
    source_url = "https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/intrinsic-function-reference-ref.html"
    tags = ["functions", "ref"]

    def match(self, cfn):
        matches = []

        ref_objs = cfn.search_deep_keys("Ref")
        for ref_obj in ref_objs:
            value = ref_obj[-1]
            if not isinstance(value, (str)):
                message = "Ref can only be a string for {0}"
                matches.append(
                    RuleMatch(
                        ref_obj[:-1], message.format("/".join(map(str, ref_obj[:-1])))
                    )
                )

        return matches
