# Copyright 2021 Google LLC
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     https://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
#
apiVersion: templates.gatekeeper.sh/v1alpha1
kind: ConstraintTemplate
metadata:
  name: gcp-sql-maintenance-window-v1
spec:
  crd:
    spec:
      names:
        kind: GCPSQLMaintenanceWindowConstraintV1
      validation:
        openAPIV3Schema:
          properties:
            hours:
              type: array
              items:
                type: number
              description: "Array of UTC hours when the maintenance window is authorised. Example night hours
              Optional, when not specified any hour is authorized from 0 to 23"
            exemptions:
              type: array
              items:
                type: string
              description: "Array of Cloud SQL instances to exempt from maintenance window restriction. String values in the array
              should correspond to the full name values of exempted Cloud SQL instances. Optional"
  targets:
    validation.gcp.forsetisecurity.org:
      rego: | #INLINE("validator/sql_maintenance_window.rego")
        #
        # Copyright 2021 Google LLC
        #
        # Licensed under the Apache License, Version 2.0 (the "License");
        # you may not use this file except in compliance with the License.
        # You may obtain a copy of the License at
        #
        #      http://www.apache.org/licenses/LICENSE-2.0
        #
        # Unless required by applicable law or agreed to in writing, software
        # distributed under the License is distributed on an "AS IS" BASIS,
        # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
        # See the License for the specific language governing permissions and
        # limitations under the License.
        #

        package templates.gcp.GCPSQLMaintenanceWindowConstraintV1

        import data.validator.gcp.lib as lib

        # A violation is generated only when the rule body evaluates to true.
        deny[{
        	"msg": message,
        	"details": metadata,
        }] {
        	# by default any hour accepted
        	default_hours := {0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23}
        	spec := lib.get_default(input.constraint, "spec", "")
        	parameters := lib.get_default(spec, "parameters", "")
        	maintenance_window_hours := lib.get_default(parameters, "hours", default_hours)
        	desired_maintenance_window_hours := get_default_when_empty(maintenance_window_hours, default_hours)
        	exempt_list := lib.get_default(parameters, "exemptions", [])

        	# Verify that resource is Cloud SQL instance and is not a first gen
        	# Maintenance window is supported only on 2nd generation instances
        	asset := input.asset
        	asset.asset_type == "sqladmin.googleapis.com/Instance"
        	asset.resource.data.backendType != "FIRST_GEN"

        	# Check if resource is in exempt list
        	matches := {asset.name} & cast_set(exempt_list)
        	count(matches) == 0

        	# get instance settings
        	settings := lib.get_default(asset.resource.data, "settings", {})
        	instance_maintenance_window := lib.get_default(settings, "maintenanceWindow", {})
        	instance_maintenance_window_hour := lib.get_default(instance_maintenance_window, "hour", "")

        	# check compliance
        	hour_matches := {instance_maintenance_window_hour} & cast_set(desired_maintenance_window_hours)
        	count(hour_matches) == 0

        	message := sprintf("%v missing or incorrect maintenance window. Hour: '%v'", [asset.name, instance_maintenance_window_hour])
        	metadata := {"resource": asset.name}
        }

        # Rule utilities
        get_default_when_empty(value, default_value) = output {
        	count(value) != 0
        	output := value
        }

        get_default_when_empty(value, default_value) = output {
        	count(value) == 0
        	output := default_value
        }
        #ENDINLINE
