# ###################################
##       Rule Specification        ##
#####################################
# 
# Rule Identifier:
#   codebuild_project_artifact_encryption_check
# 
# Description:
#   This control checks whether AWS CodeBuild projects are configured to encrypt artifacts.
# 
# Reports on:
#   AWS::CodeBuild::Project
# 
# 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 CodeBuild project resources
#      Then: SKIP
#   Scenario 2:
#     Given: The input document is an AWS CloudFormation or CloudFormation hook document
#       And: The input document contains a CodeBuild project resource
#       And: 'Artifacts' configuration is provided and is of 'Type' 'NO_ARTIFACTS'
#       And: 'SecondaryArtifacts' configuration is not provided or provided with an empty list
#      Then: SKIP
#   Scenario 3:
#     Given: The input document is an AWS CloudFormation or CloudFormation hook document
#       And: The input document contains a CodeBuild project resource
#       And: 'Artifacts' configuration is provided and is of 'Type' 'NO_ARTIFACTS'
#       And: 'SecondaryArtifacts' configuration is provided as a non-empty list
#       And: All 'SecondaryArtifacts' entries have 'Type' set to 'NO_ARTIFACTS'
#      Then: SKIP
#   Scenario 4:
#     Given: The input document is an AWS CloudFormation or CloudFormation hook document
#       And: The input document contains a CodeBuild project resource
#       And: 'Artifacts' configuration is provided and is not of 'Type' 'NO_ARTIFACTS'
#       And: 'EncryptionDisabled' within 'Artifacts' configuration is provided and set to bool(true)
#      Then: FAIL
#   Scenario 5:
#     Given: The input document is an AWS CloudFormation or CloudFormation hook document
#       And: The input document contains a CodeBuild project resource
#       And: 'SecondaryArtifacts' configuration is provided
#       And: There exists one or more items in 'SecondaryArtifacts' which have 'EncryptionDisabled' set to bool(true)
#      Then: FAIL
#   Scenario 6:
#     Given: The input document is an AWS CloudFormation or CloudFormation hook document
#       And: The input document contains a CodeBuild project resource
#       And: 'Artifacts.EncryptionDisabled' is not provided, or is set to bool(false)
#       And: There exists no item in 'SecondaryArtifacts' which has 'EncryptionDisabled' set to bool(true)
#      Then: PASS

#
# Constants
#
let CODEBUILD_PROJECT_TYPE = "AWS::CodeBuild::Project"
let INPUT_DOCUMENT = this

#
# Assignments
#
let codebuild_project = Resources.*[ Type == %CODEBUILD_PROJECT_TYPE ]

#
# Primary Rules
#
rule codebuild_project_artifact_encryption_check when is_cfn_template(%INPUT_DOCUMENT)
                                                      %codebuild_project not empty {
    check(%codebuild_project.Properties)
        <<
        [CT.CODEBUILD.PR.5]: Require encryption on all AWS CodeBuild project artifacts
        [FIX]: Set the 'EncryptionDisabled' property in 'Artifacts' and any 'SecondaryArtifacts' to 'false', or omit the 'EncryptionDisabled' property.
        >>
}

rule codebuild_project_artifact_encryption_check when is_cfn_hook(%INPUT_DOCUMENT, %CODEBUILD_PROJECT_TYPE) {
    check(%INPUT_DOCUMENT.%CODEBUILD_PROJECT_TYPE.resourceProperties)
        <<
        [CT.CODEBUILD.PR.5]: Require encryption on all AWS CodeBuild project artifacts
        [FIX]: Set the 'EncryptionDisabled' property in 'Artifacts' and any 'SecondaryArtifacts' to 'false', or omit the 'EncryptionDisabled' property.
        >>
}

#
# Parameterized Rules
#
rule check(codebuild_project) {
    %codebuild_project [
        filter_codebuild_projects(this)
    ] {
        Artifacts {
            # Scenario 4 and 6
            check_artifact(this)
        }
        # Scenario 5
        SecondaryArtifacts not exists or
        check_secondary_artifacts(this)
    }
}

rule check_secondary_artifacts(codebuild_project) {
    %codebuild_project {
        SecondaryArtifacts is_list
        SecondaryArtifacts[*] {
            # Scenario 5 and 6
            check_artifact(this)
        }
    }
}

rule check_artifact(artifact) {
    %artifact {
        EncryptionDisabled not exists or
        EncryptionDisabled == false
    }
}

rule filter_codebuild_projects(codebuild_project) {
    %codebuild_project {
        # Scenario 2 and 3
        Artifacts exists
        Artifacts is_struct
        Artifacts {
            filter_artifact(this)
        } or
        filter_secondary_artifacts(this)
    }
}

rule filter_secondary_artifacts(codebuild_project) {
    %codebuild_project {
        # Scenario 2
        SecondaryArtifacts exists
        SecondaryArtifacts is_list
        SecondaryArtifacts not empty
        SecondaryArtifacts[*] {
            # Scenario 3
            filter_artifact(this)
        }
    }
}

rule filter_artifact(artifact) {
    %artifact {
       Type exists
       Type != "NO_ARTIFACTS"
    }
}

#
# 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
}