# ###################################
##       Rule Specification        ##
#####################################
# 
# Rule Identifier:
#   docdb_cluster_backup_retention_check
# 
# Description:
#   This control checks whether an Amazon DocumentDB cluster retention period is set to seven or more days (>=7).
# 
# Reports on:
#   AWS::DocDB::DBCluster
# 
# 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 Document DB cluster resources
#      Then: SKIP
#   Scenario: 2
#     Given: The input document is an AWS CloudFormation or CloudFormation hook document
#       And: The input document contains a Document DB cluster resource
#       And: 'BackupRetentionPeriod' 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 a Document DB cluster resource
#       And: 'BackupRetentionPeriod' has been provided and set to an integer value less than seven (<7)
#      Then: FAIL
#   Scenario: 4
#     Given: The input document is an AWS CloudFormation or CloudFormation hook document
#       And: The input document contains a Document DB cluster resource
#       And: 'BackupRetentionPeriod' has been provided and set to an integer value greater than or equal to seven (>=7)
#      Then: PASS

#
# Constants
#
let DOCUMENT_DB_CLUSTER_TYPE = "AWS::DocDB::DBCluster"
let INPUT_DOCUMENT = this

#
# Assignments
#
let document_db_clusters = Resources.*[ Type == %DOCUMENT_DB_CLUSTER_TYPE ]

#
# Primary Rules
#
rule docdb_cluster_backup_retention_check when is_cfn_template(%INPUT_DOCUMENT)
                                               %document_db_clusters not empty {
    check(%document_db_clusters.Properties)
        <<
        [CT.DOCUMENTDB.PR.2]: Require an Amazon DocumentDB cluster to have automatic backups enabled
        [FIX]: Set the value of the 'BackupRetentionPeriod' parameter to an integer value between 7 and 35 days (inclusive).
        >>
}

rule docdb_cluster_backup_retention_check when is_cfn_hook(%INPUT_DOCUMENT, %DOCUMENT_DB_CLUSTER_TYPE) {
    check(%INPUT_DOCUMENT.%DOCUMENT_DB_CLUSTER_TYPE.resourceProperties)
        <<
        [CT.DOCUMENTDB.PR.2]: Require an Amazon DocumentDB cluster to have automatic backups enabled
        [FIX]: Set the value of the 'BackupRetentionPeriod' parameter to an integer value between 7 and 35 days (inclusive).
        >>
}

#
# Parameterized Rules
#
rule check(document_db_cluster) {
    %document_db_cluster {
        # Scenario 2
        BackupRetentionPeriod exists
        # Scenarios 3 and 4
        BackupRetentionPeriod >= 7
    }
}

#
# 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
}