# ###################################
##       Rule Specification        ##
#####################################
# 
# Rule Identifier:
#   s3_bucket_versioning_enabled_check
# 
# Description:
#   This control checks whether an Amazon Simple Storage Service (Amazon S3) bucket has versioning enabled.
# 
# Reports on:
#   AWS::S3::Bucket
# 
# 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 S3 bucket resources
#      Then: SKIP
#   Scenario: 2
#     Given: The input document is an AWS CloudFormation or CloudFormation hook document
#       And: The input document contains an S3 bucket resource
#       And: 'VersioningConfiguration' 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 an S3 bucket resource
#       And: 'VersioningConfiguration' has been provided
#       And: 'Status' in 'VersioningConfiguration' has not been provided or has been provided
#            and set to a value other than 'Enabled'
#      Then: FAIL
#   Scenario: 4
#     Given: The input document is an AWS CloudFormation or CloudFormation hook document
#       And: The input document contains an S3 bucket resource
#       And: 'VersioningConfiguration' has been provided
#       And: 'Status' in 'VersioningConfiguration' has been provided and set to 'Enabled'
#      Then: PASS

#
# Constants
#
let S3_BUCKET_TYPE = "AWS::S3::Bucket"
let INPUT_DOCUMENT = this

#
# Assignments
#
let s3_buckets = Resources.*[ Type == %S3_BUCKET_TYPE ]

#
# Primary Rules
#
rule s3_bucket_versioning_enabled_check when is_cfn_template(%INPUT_DOCUMENT)
                                            %s3_buckets not empty {
    check(%s3_buckets.Properties)
        <<
        [CT.S3.PR.11]: Require an Amazon S3 bucket to have versioning enabled
        [FIX]: Set the 'Status' in 'VersioningConfiguration' to Enabled.
        >>
}

rule s3_bucket_versioning_enabled_check when is_cfn_hook(%INPUT_DOCUMENT, %S3_BUCKET_TYPE) {
    check(%INPUT_DOCUMENT.%S3_BUCKET_TYPE.resourceProperties)
        <<
        [CT.S3.PR.11]: Require an Amazon S3 bucket to have versioning enabled
        [FIX]: Set the 'Status' in 'VersioningConfiguration' to Enabled.
        >>
}

#
# Parameterized Rules
#
rule check(s3_bucket) {
    %s3_bucket {
        # Scenario 2
        VersioningConfiguration exists

        # Scenarios 3 and 4
        VersioningConfiguration is_struct
        VersioningConfiguration {
            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
}