/*
Copyright 2017 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 admissionregistration

import (
	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
)

// Rule is a tuple of APIGroups, APIVersion, and Resources.It is recommended
// to make sure that all the tuple expansions are valid.
type Rule struct {
	// APIGroups is the API groups the resources belong to. '*' is all groups.
	// If '*' is present, the length of the slice must be one.
	// Required.
	APIGroups []string

	// APIVersions is the API versions the resources belong to. '*' is all versions.
	// If '*' is present, the length of the slice must be one.
	// Required.
	APIVersions []string

	// Resources is a list of resources this rule applies to.
	//
	// For example:
	// 'pods' means pods.
	// 'pods/log' means the log subresource of pods.
	// '*' means all resources, but not subresources.
	// 'pods/*' means all subresources of pods.
	// '*/scale' means all scale subresources.
	// '*/*' means all resources and their subresources.
	//
	// If wildcard is present, the validation rule will ensure resources do not
	// overlap with each other.
	//
	// Depending on the enclosing object, subresources might not be allowed.
	// Required.
	Resources []string

	// scope specifies the scope of this rule.
	// Valid values are "Cluster", "Namespaced", and "*"
	// "Cluster" means that only cluster-scoped resources will match this rule.
	// Namespace API objects are cluster-scoped.
	// "Namespaced" means that only namespaced resources will match this rule.
	// "*" means that there are no scope restrictions.
	// Subresources match the scope of their parent resource.
	// Default is "*".
	//
	// +optional
	Scope *ScopeType
}

type ScopeType string

const (
	// ClusterScope means that scope is limited to cluster-scoped objects.
	// Namespace objects are cluster-scoped.
	ClusterScope ScopeType = "Cluster"
	// NamespacedScope means that scope is limited to namespaced objects.
	NamespacedScope ScopeType = "Namespaced"
	// AllScopes means that all scopes are included.
	AllScopes ScopeType = "*"
)

type FailurePolicyType string

const (
	// Ignore means that an error calling the webhook is ignored.
	Ignore FailurePolicyType = "Ignore"
	// Fail means that an error calling the webhook causes the admission to fail.
	Fail FailurePolicyType = "Fail"
)

type SideEffectClass string

const (
	// SideEffectClassUnknown means that no information is known about the side effects of calling the webhook.
	// If a request with the dry-run attribute would trigger a call to this webhook, the request will instead fail.
	SideEffectClassUnknown SideEffectClass = "Unknown"
	// SideEffectClassNone means that calling the webhook will have no side effects.
	SideEffectClassNone SideEffectClass = "None"
	// SideEffectClassSome means that calling the webhook will possibly have side effects.
	// If a request with the dry-run attribute would trigger a call to this webhook, the request will instead fail.
	SideEffectClassSome SideEffectClass = "Some"
	// SideEffectClassNoneOnDryRun means that calling the webhook will possibly have side effects, but if the
	// request being reviewed has the dry-run attribute, the side effects will be suppressed.
	SideEffectClassNoneOnDryRun SideEffectClass = "NoneOnDryRun"
)

// +genclient
// +genclient:nonNamespaced
// +k8s:deepcopy-gen:interfaces=k8s.io/apimachinery/pkg/runtime.Object

// ValidatingWebhookConfiguration describes the configuration of an admission webhook that accepts or rejects and object without changing it.
type ValidatingWebhookConfiguration struct {
	metav1.TypeMeta
	// Standard object metadata; More info: https://git.k8s.io/community/contributors/devel/api-conventions.md#metadata.
	// +optional
	metav1.ObjectMeta
	// Webhooks is a list of webhooks and the affected resources and operations.
	// +optional
	Webhooks []Webhook
}

// +k8s:deepcopy-gen:interfaces=k8s.io/apimachinery/pkg/runtime.Object

// ValidatingWebhookConfigurationList is a list of ValidatingWebhookConfiguration.
type ValidatingWebhookConfigurationList struct {
	metav1.TypeMeta
	// Standard list metadata.
	// More info: https://git.k8s.io/community/contributors/devel/api-conventions.md#types-kinds
	// +optional
	metav1.ListMeta
	// List of ValidatingWebhookConfigurations.
	Items []ValidatingWebhookConfiguration
}

// +genclient
// +genclient:nonNamespaced
// +k8s:deepcopy-gen:interfaces=k8s.io/apimachinery/pkg/runtime.Object

// MutatingWebhookConfiguration describes the configuration of and admission webhook that accept or reject and may change the object.
type MutatingWebhookConfiguration struct {
	metav1.TypeMeta
	// Standard object metadata; More info: https://git.k8s.io/community/contributors/devel/api-conventions.md#metadata.
	// +optional
	metav1.ObjectMeta
	// Webhooks is a list of webhooks and the affected resources and operations.
	// +optional
	Webhooks []Webhook
}

// +k8s:deepcopy-gen:interfaces=k8s.io/apimachinery/pkg/runtime.Object

// MutatingWebhookConfigurationList is a list of MutatingWebhookConfiguration.
type MutatingWebhookConfigurationList struct {
	metav1.TypeMeta
	// Standard list metadata.
	// More info: https://git.k8s.io/community/contributors/devel/api-conventions.md#types-kinds
	// +optional
	metav1.ListMeta
	// List of MutatingWebhookConfiguration.
	Items []MutatingWebhookConfiguration
}

// Webhook describes an admission webhook and the resources and operations it applies to.
type Webhook struct {
	// The name of the admission webhook.
	// Name should be fully qualified, e.g., imagepolicy.kubernetes.io, where
	// "imagepolicy" is the name of the webhook, and kubernetes.io is the name
	// of the organization.
	// Required.
	Name string

	// ClientConfig defines how to communicate with the hook.
	// Required
	ClientConfig WebhookClientConfig

	// Rules describes what operations on what resources/subresources the webhook cares about.
	// The webhook cares about an operation if it matches _any_ Rule.
	Rules []RuleWithOperations

	// FailurePolicy defines how unrecognized errors from the admission endpoint are handled -
	// allowed values are Ignore or Fail. Defaults to Ignore.
	// +optional
	FailurePolicy *FailurePolicyType

	// NamespaceSelector decides whether to run the webhook on an object based
	// on whether the namespace for that object matches the selector. If the
	// object itself is a namespace, the matching is performed on
	// object.metadata.labels. If the object is another cluster scoped resource,
	// it never skips the webhook.
	//
	// For example, to run the webhook on any objects whose namespace is not
	// associated with "runlevel" of "0" or "1";  you will set the selector as
	// follows:
	// "namespaceSelector": {
	//   "matchExpressions": [
	//     {
	//       "key": "runlevel",
	//       "operator": "NotIn",
	//       "values": [
	//         "0",
	//         "1"
	//       ]
	//     }
	//   ]
	// }
	//
	// If instead you want to only run the webhook on any objects whose
	// namespace is associated with the "environment" of "prod" or "staging";
	// you will set the selector as follows:
	// "namespaceSelector": {
	//   "matchExpressions": [
	//     {
	//       "key": "environment",
	//       "operator": "In",
	//       "values": [
	//         "prod",
	//         "staging"
	//       ]
	//     }
	//   ]
	// }
	//
	// See
	// https://kubernetes.io/docs/concepts/overview/working-with-objects/labels/
	// for more examples of label selectors.
	//
	// Default to the empty LabelSelector, which matches everything.
	// +optional
	NamespaceSelector *metav1.LabelSelector

	// SideEffects states whether this webhookk has side effects.
	// Acceptable values are: Unknown, None, Some, NoneOnDryRun
	// Webhooks with side effects MUST implement a reconciliation system, since a request may be
	// rejected by a future step in the admission change and the side effects therefore need to be undone.
	// Requests with the dryRun attribute will be auto-rejected if they match a webhook with
	// sideEffects == Unknown or Some. Defaults to Unknown.
	// +optional
	SideEffects *SideEffectClass

	// TimeoutSeconds specifies the timeout for this webhook. After the timeout passes,
	// the webhook call will be ignored or the API call will fail based on the
	// failure policy.
	// The timeout value must be between 1 and 30 seconds.
	// +optional
	TimeoutSeconds *int32

	// AdmissionReviewVersions is an ordered list of preferred `AdmissionReview`
	// versions the Webhook expects. API server will try to use first version in
	// the list which it supports. If none of the versions specified in this list
	// supported by API server, validation will fail for this object.
	// If the webhook configuration has already been persisted with a version apiserver
	// does not understand, calls to the webhook will fail and be subject to the failure policy.
	// +optional
	AdmissionReviewVersions []string
}

// RuleWithOperations is a tuple of Operations and Resources. It is recommended to make
// sure that all the tuple expansions are valid.
type RuleWithOperations struct {
	// Operations is the operations the admission hook cares about - CREATE, UPDATE, or *
	// for all operations.
	// If '*' is present, the length of the slice must be one.
	// Required.
	Operations []OperationType
	// Rule is embedded, it describes other criteria of the rule, like
	// APIGroups, APIVersions, Resources, etc.
	Rule
}

type OperationType string

// The constants should be kept in sync with those defined in k8s.io/kubernetes/pkg/admission/interface.go.
const (
	OperationAll OperationType = "*"
	Create       OperationType = "CREATE"
	Update       OperationType = "UPDATE"
	Delete       OperationType = "DELETE"
	Connect      OperationType = "CONNECT"
)

// WebhookClientConfig contains the information to make a TLS
// connection with the webhook
type WebhookClientConfig struct {
	// `url` gives the location of the webhook, in standard URL form
	// (`scheme://host:port/path`). Exactly one of `url` or `service`
	// must be specified.
	//
	// The `host` should not refer to a service running in the cluster; use
	// the `service` field instead. The host might be resolved via external
	// DNS in some apiservers (e.g., `kube-apiserver` cannot resolve
	// in-cluster DNS as that would be a layering violation). `host` may
	// also be an IP address.
	//
	// Please note that using `localhost` or `127.0.0.1` as a `host` is
	// risky unless you take great care to run this webhook on all hosts
	// which run an apiserver which might need to make calls to this
	// webhook. Such installs are likely to be non-portable, i.e., not easy
	// to turn up in a new cluster.
	//
	// The scheme must be "https"; the URL must begin with "https://".
	//
	// A path is optional, and if present may be any string permissible in
	// a URL. You may use the path to pass an arbitrary string to the
	// webhook, for example, a cluster identifier.
	//
	// Attempting to use a user or basic auth e.g. "user:password@" is not
	// allowed. Fragments ("#...") and query parameters ("?...") are not
	// allowed, either.
	//
	// +optional
	URL *string

	// `service` is a reference to the service for this webhook. Either
	// `service` or `url` must be specified.
	//
	// If the webhook is running within the cluster, then you should use `service`.
	//
	// Port 443 will be used if it is open, otherwise it is an error.
	//
	// +optional
	Service *ServiceReference

	// `caBundle` is a PEM encoded CA bundle which will be used to validate the webhook's server certificate.
	// If unspecified, system trust roots on the apiserver are used.
	// +optional
	CABundle []byte
}

// ServiceReference holds a reference to Service.legacy.k8s.io
type ServiceReference struct {
	// `namespace` is the namespace of the service.
	// Required
	Namespace string
	// `name` is the name of the service.
	// Required
	Name string

	// `path` is an optional URL path which will be sent in any request to
	// this service.
	// +optional
	Path *string
}