/*
Copyright 2016 The Kubernetes Authors.

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 genericapiserver

import (
	"k8s.io/apimachinery/pkg/runtime/schema"
	"k8s.io/apimachinery/pkg/util/sets"
)

// APIResourceConfigSource is the interface to determine which versions and resources are enabled
type APIResourceConfigSource interface {
	AnyVersionOfResourceEnabled(resource schema.GroupResource) bool
	ResourceEnabled(resource schema.GroupVersionResource) bool
	AllResourcesForVersionEnabled(version schema.GroupVersion) bool
	AnyResourcesForVersionEnabled(version schema.GroupVersion) bool
	AnyResourcesForGroupEnabled(group string) bool
}

// Specifies the overrides for various API group versions.
// This can be used to enable/disable entire group versions or specific resources.
type GroupVersionResourceConfig struct {
	// Whether to enable or disable this entire group version.  This dominates any enablement check.
	// Enable=true means the group version is enabled, and EnabledResources/DisabledResources are considered.
	// Enable=false means the group version is disabled, and EnabledResources/DisabledResources are not considered.
	Enable bool

	// DisabledResources lists the resources that are specifically disabled for a group/version
	// DisabledResources trumps EnabledResources
	DisabledResources sets.String

	// EnabledResources lists the resources that should be enabled by default.  This is a little
	// unusual, but we need it for compatibility with old code for now.  An empty set means
	// enable all, a non-empty set means that all other resources are disabled.
	EnabledResources sets.String
}

var _ APIResourceConfigSource = &ResourceConfig{}

type ResourceConfig struct {
	GroupVersionResourceConfigs map[schema.GroupVersion]*GroupVersionResourceConfig
}

func NewResourceConfig() *ResourceConfig {
	return &ResourceConfig{GroupVersionResourceConfigs: map[schema.GroupVersion]*GroupVersionResourceConfig{}}
}

func NewGroupVersionResourceConfig() *GroupVersionResourceConfig {
	return &GroupVersionResourceConfig{Enable: true, DisabledResources: sets.String{}, EnabledResources: sets.String{}}
}

// DisableVersions disables the versions entirely.  No resources (even those whitelisted in EnabledResources) will be enabled
func (o *ResourceConfig) DisableVersions(versions ...schema.GroupVersion) {
	for _, version := range versions {
		_, versionExists := o.GroupVersionResourceConfigs[version]
		if !versionExists {
			o.GroupVersionResourceConfigs[version] = NewGroupVersionResourceConfig()
		}

		o.GroupVersionResourceConfigs[version].Enable = false
	}
}

func (o *ResourceConfig) EnableVersions(versions ...schema.GroupVersion) {
	for _, version := range versions {
		_, versionExists := o.GroupVersionResourceConfigs[version]
		if !versionExists {
			o.GroupVersionResourceConfigs[version] = NewGroupVersionResourceConfig()
		}

		o.GroupVersionResourceConfigs[version].Enable = true
	}
}

func (o *ResourceConfig) DisableResources(resources ...schema.GroupVersionResource) {
	for _, resource := range resources {
		version := resource.GroupVersion()
		_, versionExists := o.GroupVersionResourceConfigs[version]
		if !versionExists {
			o.GroupVersionResourceConfigs[version] = NewGroupVersionResourceConfig()
		}

		o.GroupVersionResourceConfigs[version].DisabledResources.Insert(resource.Resource)
	}
}

func (o *ResourceConfig) EnableResources(resources ...schema.GroupVersionResource) {
	for _, resource := range resources {
		version := resource.GroupVersion()
		_, versionExists := o.GroupVersionResourceConfigs[version]
		if !versionExists {
			o.GroupVersionResourceConfigs[version] = NewGroupVersionResourceConfig()
		}

		o.GroupVersionResourceConfigs[version].EnabledResources.Insert(resource.Resource)
		o.GroupVersionResourceConfigs[version].DisabledResources.Delete(resource.Resource)
	}
}

// AnyResourcesForVersionEnabled only considers matches based on exactly group/resource lexical matching.  This means that
// resource renames across versions are NOT considered to be the same resource by this method. You'll need to manually check
// using the ResourceEnabled function.
func (o *ResourceConfig) AnyVersionOfResourceEnabled(resource schema.GroupResource) bool {
	for version := range o.GroupVersionResourceConfigs {
		if version.Group != resource.Group {
			continue
		}

		if o.ResourceEnabled(version.WithResource(resource.Resource)) {
			return true
		}
	}

	return false
}

func (o *ResourceConfig) ResourceEnabled(resource schema.GroupVersionResource) bool {
	versionOverride, versionExists := o.GroupVersionResourceConfigs[resource.GroupVersion()]
	if !versionExists {
		return false
	}
	if !versionOverride.Enable {
		return false
	}

	if versionOverride.DisabledResources.Has(resource.Resource) {
		return false
	}

	if len(versionOverride.EnabledResources) > 0 {
		return versionOverride.EnabledResources.Has(resource.Resource)
	}

	return true
}

func (o *ResourceConfig) AllResourcesForVersionEnabled(version schema.GroupVersion) bool {
	versionOverride, versionExists := o.GroupVersionResourceConfigs[version]
	if !versionExists {
		return false
	}
	if !versionOverride.Enable {
		return false
	}

	if len(versionOverride.EnabledResources) == 0 && len(versionOverride.DisabledResources) == 0 {
		return true
	}

	return false
}

func (o *ResourceConfig) AnyResourcesForVersionEnabled(version schema.GroupVersion) bool {
	versionOverride, versionExists := o.GroupVersionResourceConfigs[version]
	if !versionExists {
		return false
	}

	return versionOverride.Enable
}

func (o *ResourceConfig) AnyResourcesForGroupEnabled(group string) bool {
	for version := range o.GroupVersionResourceConfigs {
		if version.Group == group {
			if o.AnyResourcesForVersionEnabled(version) {
				return true
			}
		}
	}

	return false
}