# ###################################
##       Rule Specification        ##
#####################################
# 
# Rule Identifier:
#   waf_global_rule_not_empty_check
# 
# Description:
#   This control checks whether an AWS WAF Classic global rule contains any conditions.
# 
# Reports on:
#   AWS::WAF::Rule
# 
# 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 WAF Classic global rule resources
#      Then: SKIP
#   Scenario: 2
#     Given: The input document is an AWS CloudFormation or CloudFormation hook document
#       And: The input document contains a WAF Classic global rule resource
#       And: 'Predicates' 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 WAF Classic global rule resource
#       And: 'Predicates' has been provided as an empty list
#      Then: FAIL
#   Scenario: 4
#     Given: The input document is an AWS CloudFormation or CloudFormation hook document
#       And: The input document contains a WAF Classic global rule resource
#       And: 'Predicates' has been provided as a non-empty list
#      Then: PASS

#
# Constants
#
let WAF_GLOBAL_RULE_TYPE = "AWS::WAF::Rule"
let INPUT_DOCUMENT = this

#
# Assignments
#
let waf_global_rules = Resources.*[ Type == %WAF_GLOBAL_RULE_TYPE ]

#
# Primary Rules
#
rule waf_global_rule_not_empty_check when is_cfn_template(%INPUT_DOCUMENT)
                                          %waf_global_rules not empty {
    check(%waf_global_rules.Properties)
        <<
        [CT.WAF.PR.1]: Require any AWS WAF Classic global rule to have a condition
        [FIX]: Provide one or more AWS WAF Classic rule conditions within the 'Predicates' property.
        >>
}

rule waf_global_rule_not_empty_check when is_cfn_hook(%INPUT_DOCUMENT, %WAF_GLOBAL_RULE_TYPE) {
    check(%INPUT_DOCUMENT.%WAF_GLOBAL_RULE_TYPE.resourceProperties)
        <<
        [CT.WAF.PR.1]: Require any AWS WAF Classic global rule to have a condition
        [FIX]: Provide one or more AWS WAF Classic rule conditions within the 'Predicates' property.
        >>
}

#
# Parameterized Rules
#
rule check(waf_global_rule) {
    %waf_global_rule {
        # Scenario 2, 3 and 4
        Predicates exists
        Predicates is_list
        Predicates not empty
    }
}

#
# 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
}