# ###################################
##       Rule Specification        ##
#####################################
# 
# Rule Identifier:
#   efs_automatic_backups_enabled_check
# 
# Description:
#   This control checks whether your Amazon EFS file system has been configured with automatic backups through AWS Backup.
# 
# Reports on:
#   AWS::EFS::FileSystem
# 
# 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 EFS file system resources
#      Then: SKIP
#   Scenario: 2
#     Given: The input document is an AWS CloudFormation or CloudFormation hook document
#       And: The input document contains an EFS file system resource
#       And: 'BackupPolicy' is not present
#      Then: FAIL
#   Scenario: 3
#     Given: The input document is an AWS CloudFormation or CloudFormation hook document
#       And: The input document contains an EFS file system resource
#       And: 'BackupPolicy' is present and 'Status' is set to 'DISABLED'
#      Then: FAIL
#   Scenario: 4
#     Given: The input document is an AWS CloudFormation or CloudFormation hook document
#       And: The input document contains an EFS file system resource
#       And: 'BackupPolicy' is present and 'Status' is set to 'ENABLED'
#      Then: PASS

#
# Constants
#
let RESOURCE_TYPE = "AWS::EFS::FileSystem"
let INPUT_DOCUMENT = this

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

#
# Primary Rules
#
rule efs_automatic_backups_enabled_check when is_cfn_template(this)
                                              %efs_file_systems not empty {
    check(%efs_file_systems.Properties)
        <<
        [CT.ELASTICFILESYSYSTEM.PR.2]: Require an Amazon EFS volume to have an automated backup plan
        [FIX]: Enable automatic backups by setting 'BackupPolicy.Status' to 'ENABLED'.
        >>

}

rule efs_automatic_backups_enabled_check when is_cfn_hook(%INPUT_DOCUMENT, %RESOURCE_TYPE) {
    check(%INPUT_DOCUMENT.%RESOURCE_TYPE.resourceProperties)
        <<
        [CT.ELASTICFILESYSYSTEM.PR.2]: Require an Amazon EFS volume to have an automated backup plan
        [FIX]: Enable automatic backups by setting 'BackupPolicy.Status' to 'ENABLED'.
        >>
}

#
# Parameterized Rules
#
rule check(efs_file_systems) {
    %efs_file_systems {
        # Scenario 2
        BackupPolicy exists
        BackupPolicy is_struct
        BackupPolicy {
            # Scenario 3 and 4
            Status exists
            Status == "ENABLED"
        }
    }
}

#
# 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
}