# ###################################
##       Rule Specification        ##
#####################################
# 
# Rule Identifier:
#   redshift_cluster_allow_version_upgrade_check
# 
# Description:
#   This control checks whether automatic major version upgrades are enabled for your Amazon Redshift cluster.
# 
# 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: 'AllowVersionUpgrade' has been provided
#       And: 'AllowVersionUpgrade' has been set to bool(false)
#      Then: FAIL
#   Scenario: 3
#     Given: The input document is an AWS CloudFormation or CloudFormation hook document
#       And: The input document contains a Redshift cluster resource
#       And: 'AllowVersionUpgrade' has not been provided
#      Then: PASS
#   Scenario: 4
#     Given: The input document is an AWS CloudFormation or CloudFormation hook document
#       And: The input document contains a Redshift cluster resource
#       And: 'AllowVersionUpgrade' has been provided
#       And: 'AllowVersionUpgrade' has been set to bool(true)
#      Then: PASS

#
# Constants
#
let REDSHIFT_CLUSTER_TYPE = "AWS::Redshift::Cluster"
let INPUT_DOCUMENT = this

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

#
# Primary Rules
#
rule redshift_cluster_allow_version_upgrade_check when is_cfn_template(%INPUT_DOCUMENT)
                                                       %redshift_clusters not empty  {
    check(%redshift_clusters.Properties)
        <<
        [CT.REDSHIFT.PR.4]: Require an Amazon Redshift cluster to have automatic upgrades to major versions configured
        [FIX]: Set the 'AllowVersionUpgrade' property to true or do not specify it (default).
        >>
}

rule redshift_cluster_allow_version_upgrade_check when is_cfn_hook(%INPUT_DOCUMENT, %REDSHIFT_CLUSTER_TYPE) {
    check(%INPUT_DOCUMENT.%REDSHIFT_CLUSTER_TYPE.resourceProperties)
        <<
        [CT.REDSHIFT.PR.4]: Require an Amazon Redshift cluster to have automatic upgrades to major versions configured
        [FIX]: Set the 'AllowVersionUpgrade' property to true or do not specify it (default).
        >>
}

#
# Parameterized Rules
#
rule check(redshift_cluster) {
    %redshift_cluster {
        # Scenario 3
        AllowVersionUpgrade not exists or
        # Scenario 2 & 4
        AllowVersionUpgrade == true
    }
}

#
# 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
}