# ###################################
##       Rule Specification        ##
#####################################
# 
# Rule Identifier:
#   redshift_default_db_name_check
# 
# Description:
#   This control checks whether an Amazon Redshift cluster has changed its database name from the default value.
# 
# Reports on:
#   AWS::Redshift::Cluster
# 
# Evaluates:
#   AWS CloudFormation, AWS CloudFormation hook
# 
# Rule Parameters:
#   None
# 
# Scenarios:
#   Scenario: 1
#     Given: The input document is an AWS CloudFormation or CloudFormation hook document
#       And: The input document does not contain any Redshift cluster resources
#      Then: SKIP
#   Scenario: 2
#     Given: The input document is an AWS CloudFormation or CloudFormation hook document
#       And: The input document contains a Redshift cluster resource
#       And: The 'DBName' property has not been provided
#      Then: FAIL
#   Scenario: 3
#     Given: The input document is an AWS CloudFormation or CloudFormation hook document
#       And: The input document contains Redshift cluster resource
#       And: The 'DBName' property has been provided with a value of 'dev' or an empty string
#      Then: FAIL
#   Scenario: 4
#     Given: The input document is an AWS CloudFormation or CloudFormation hook document
#       And: The input document contains Redshift cluster resource
#       And: The 'DBName' property has been provided with a non-empty string that is not equal to 'dev'
#      Then: PASS

#
# Constants
#
let RESOURCE_TYPE = "AWS::Redshift::Cluster"
let INPUT_DOCUMENT = this
let INVALID_DB_NAME_STRING = "dev"

#
# Assignments
#
let redshift_clusters = Resources.*[ Type == %RESOURCE_TYPE ]

#
# Primary Rules
#
rule redshift_default_db_name_check when is_cfn_template(%INPUT_DOCUMENT)
                                         %redshift_clusters not empty {
    check_db_name(%redshift_clusters.Properties)
        <<
        [CT.REDSHIFT.PR.7]: Require an Amazon Redshift cluster to have a unique database name
        [FIX]: Set 'DBName' to a database name that is different from the default value of 'dev'.
        >>
}

rule redshift_default_db_name_check when is_cfn_hook(%INPUT_DOCUMENT, %RESOURCE_TYPE) {
    check_db_name(%INPUT_DOCUMENT.%RESOURCE_TYPE.resourceProperties)
        <<
        [CT.REDSHIFT.PR.7]: Require an Amazon Redshift cluster to have a unique database name
        [FIX]: Set 'DBName' to a database name that is different from the default value of 'dev'.
        >>
}

#
# Parameterized Rules
#
rule check_db_name(redshift_cluster) {
    %redshift_cluster {
        # Scenario 2
        DBName exists

        # Scenario 3 and 4
        check_is_string_and_not_empty(DBName)
        DBName != %INVALID_DB_NAME_STRING
    }
}

#
# Utility Rules
#
rule is_cfn_template(doc) {
    %doc {
        AWSTemplateFormatVersion exists  or
        Resources exists
    }
}

rule is_cfn_hook(doc, RESOURCE_TYPE) {
    %doc.%RESOURCE_TYPE.resourceProperties exists
}

rule check_is_string_and_not_empty(value) {
    %value {
        this is_string
        this != /\A\s*\z/
    }
}