/*
Copyright 2020 The Knative 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 v1

import (
	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
	"k8s.io/apimachinery/pkg/runtime"
	"knative.dev/pkg/apis"
	duckv1 "knative.dev/pkg/apis/duck/v1"
	"knative.dev/pkg/kmeta"
)

const (
	// DependencyAnnotation is the annotation key used to mark the sources that the Trigger depends on.
	// This will be used when the kn client creates a source and trigger pair for the user such that the trigger only receives events produced by the paired source.
	DependencyAnnotation = "knative.dev/dependency"

	// InjectionAnnotation is the annotation key used to enable knative eventing
	// injection for a namespace to automatically create a broker.
	InjectionAnnotation = "eventing.knative.dev/injection"
)

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

// Trigger represents a request to have events delivered to a subscriber from a
// Broker's event pool.
type Trigger struct {
	metav1.TypeMeta `json:",inline"`
	// +optional
	metav1.ObjectMeta `json:"metadata,omitempty"`

	// Spec defines the desired state of the Trigger.
	Spec TriggerSpec `json:"spec,omitempty"`

	// Status represents the current state of the Trigger. This data may be out of
	// date.
	// +optional
	Status TriggerStatus `json:"status,omitempty"`
}

var (
	// Check that Trigger can be validated, can be defaulted, and has immutable fields.
	_ apis.Validatable = (*Trigger)(nil)
	_ apis.Defaultable = (*Trigger)(nil)

	// Check that Trigger can return its spec untyped.
	_ apis.HasSpec = (*Trigger)(nil)

	_ runtime.Object = (*Trigger)(nil)

	// Check that we can create OwnerReferences to a Trigger.
	_ kmeta.OwnerRefable = (*Trigger)(nil)

	// Check that the type conforms to the duck Knative Resource shape.
	_ duckv1.KRShaped = (*Trigger)(nil)
)

type TriggerSpec struct {
	// Broker is the broker that this trigger receives events from.
	Broker string `json:"broker,omitempty"`

	// Filter is the filter to apply against all events from the Broker. Only events that pass this
	// filter will be sent to the Subscriber. If not specified, will default to allowing all events.
	//
	// +optional
	Filter *TriggerFilter `json:"filter,omitempty"`

	// Subscriber is the addressable that receives events from the Broker that pass the Filter. It
	// is required.
	Subscriber duckv1.Destination `json:"subscriber"`
}

type TriggerFilter struct {
	// Attributes filters events by exact match on event context attributes.
	// Each key in the map is compared with the equivalent key in the event
	// context. An event passes the filter if all values are equal to the
	// specified values.
	//
	// Nested context attributes are not supported as keys. Only string values are supported.
	//
	// +optional
	Attributes TriggerFilterAttributes `json:"attributes,omitempty"`
}

// TriggerFilterAttributes is a map of context attribute names to values for
// filtering by equality. Only exact matches will pass the filter. You can use the value ''
// to indicate all strings match.
type TriggerFilterAttributes map[string]string

// TriggerStatus represents the current state of a Trigger.
type TriggerStatus struct {
	// inherits duck/v1 Status, which currently provides:
	// * ObservedGeneration - the 'Generation' of the Trigger that was last processed by the controller.
	// * Conditions - the latest available observations of a resource's current state.
	duckv1.Status `json:",inline"`

	// SubscriberURI is the resolved URI of the receiver for this Trigger.
	SubscriberURI *apis.URL `json:"subscriberUri,omitempty"`
}

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

// TriggerList is a collection of Triggers.
type TriggerList struct {
	metav1.TypeMeta `json:",inline"`
	// +optional
	metav1.ListMeta `json:"metadata,omitempty"`
	Items           []Trigger `json:"items"`
}

// GetStatus retrieves the status of the Trigger. Implements the KRShaped interface.
func (t *Trigger) GetStatus() *duckv1.Status {
	return &t.Status.Status
}
