/*
Copyright 2014 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 json

import (
	"encoding/json"
	"fmt"
	"reflect"

	"k8s.io/apimachinery/pkg/runtime"
	"k8s.io/apimachinery/pkg/watch"
)

// WatchEvent objects are streamed from the api server in response to a watch request.
// These are not API objects and may not be changed in a backward-incompatible way.
// TODO: move to a public, versioned object now that RawExtension conversions are possible
// in the schema.
type WatchEvent struct {
	// The type of the watch event; added, modified, deleted, or error.
	// +optional
	Type watch.EventType `json:"type,omitempty" description:"the type of watch event; may be ADDED, MODIFIED, DELETED, or ERROR"`

	// For added or modified objects, this is the new object; for deleted objects,
	// it's the state of the object immediately prior to its deletion.
	// For errors, it's an api.Status.
	// +optional
	Object runtime.RawExtension `json:"object,omitempty" description:"the object being watched; will match the type of the resource endpoint or be a Status object if the type is ERROR"`
}

// Object converts a watch.Event into an appropriately serializable JSON object
func Object(encoder runtime.Encoder, event *watch.Event) (interface{}, error) {
	obj, ok := event.Object.(runtime.Object)
	if !ok {
		return nil, fmt.Errorf("the event object cannot be safely converted to JSON: %v", reflect.TypeOf(event.Object).Name())
	}
	data, err := runtime.Encode(encoder, obj)
	if err != nil {
		return nil, err
	}
	return &WatchEvent{event.Type, runtime.RawExtension{Raw: json.RawMessage(data)}}, nil
}
