// Copyright 2019 Yunion
//
// 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 pleg

// PodLifecycleEventType define the event type of pod life cycle events.
type PodLifecycleEventType string

const (
	// ContainerStarted - event type when the new state of container is running
	ContainerStarted PodLifecycleEventType = "ContainerStarted"
	// ContainerDied - event type when the new state of container is exited.
	ContainerDied PodLifecycleEventType = "ContainerDied"
	// ContainerRemoved - event type when the old state of container is exited.
	ContainerRemoved PodLifecycleEventType = "ContainerRemoved"
	// PodSync is used to trigger syncing of a pod when the observed change of
	// the state of the pod cannot be captured by any single event above.
	PodSync PodLifecycleEventType = "PodSync"
	// ContainerChanged - event type when the new state of container is unknown.
	ContainerChanged PodLifecycleEventType = "ContainerChanged"
)

// PodLifecycleEvent is an event that reflects the change of the pod state.
type PodLifecycleEvent struct {
	// The pod ID.
	Id string
	// The type of the event.
	Type PodLifecycleEventType
	// The accompanied data which varies based on the event type.
	// 	 - ContainerStarted/ContainerStopped: the container name (string).
	//   - All other event types: unused.
	Data interface{}
}

// PodLifecycleEventGenerator contains functions for generating pod life cycle events.
type PodLifecycleEventGenerator interface {
	Start()
	Watch() chan *PodLifecycleEvent
}