/*
Copyright 2014 Google Inc. All rights reserved.

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 registry

import (
	"errors"
	"fmt"
	"time"

	"code.google.com/p/go-uuid/uuid"
	"github.com/GoogleCloudPlatform/kubernetes/pkg/api"
	"github.com/GoogleCloudPlatform/kubernetes/pkg/apiserver"
	"github.com/GoogleCloudPlatform/kubernetes/pkg/labels"
	"github.com/GoogleCloudPlatform/kubernetes/pkg/watch"
)

// ControllerRegistryStorage is an implementation of RESTStorage for the api server.
type ControllerRegistryStorage struct {
	registry    ControllerRegistry
	podRegistry PodRegistry
	// Period in between polls when waiting for a controller to complete
	pollPeriod time.Duration
}

func NewControllerRegistryStorage(registry ControllerRegistry, podRegistry PodRegistry) apiserver.RESTStorage {
	return &ControllerRegistryStorage{
		registry:    registry,
		podRegistry: podRegistry,
		pollPeriod:  time.Second * 10,
	}
}

// List obtains a list of ReplicationControllers that match selector.
func (storage *ControllerRegistryStorage) List(selector labels.Selector) (interface{}, error) {
	result := api.ReplicationControllerList{}
	controllers, err := storage.registry.ListControllers()
	if err == nil {
		for _, controller := range controllers {
			if selector.Matches(labels.Set(controller.Labels)) {
				result.Items = append(result.Items, controller)
			}
		}
	}
	return result, err
}

// Get obtains the ReplicationController specified by its id.
func (storage *ControllerRegistryStorage) Get(id string) (interface{}, error) {
	controller, err := storage.registry.GetController(id)
	if err != nil {
		return nil, err
	}
	return controller, err
}

// Delete asynchronously deletes the ReplicationController specified by its id.
func (storage *ControllerRegistryStorage) Delete(id string) (<-chan interface{}, error) {
	return apiserver.MakeAsync(func() (interface{}, error) {
		return api.Status{Status: api.StatusSuccess}, storage.registry.DeleteController(id)
	}), nil
}

// New creates a new ReplicationController for use with Create and Update
func (storage *ControllerRegistryStorage) New() interface{} {
	return &api.ReplicationController{}
}

// Create registers a given new ReplicationController instance to storage.registry.
func (storage *ControllerRegistryStorage) Create(obj interface{}) (<-chan interface{}, error) {
	controller, ok := obj.(*api.ReplicationController)
	if !ok {
		return nil, fmt.Errorf("not a replication controller: %#v", obj)
	}
	if len(controller.ID) == 0 {
		controller.ID = uuid.NewUUID().String()
	}
	// Pod Manifest ID should be assigned by the pod API
	controller.DesiredState.PodTemplate.DesiredState.Manifest.ID = ""

	if errs := api.ValidateReplicationController(controller); len(errs) > 0 {
		return nil, fmt.Errorf("Validation errors: %v", errs)
	}

	return apiserver.MakeAsync(func() (interface{}, error) {
		err := storage.registry.CreateController(*controller)
		if err != nil {
			return nil, err
		}
		return storage.waitForController(*controller)
	}), nil
}

// Update replaces a given ReplicationController instance with an existing instance in storage.registry.
func (storage *ControllerRegistryStorage) Update(obj interface{}) (<-chan interface{}, error) {
	controller, ok := obj.(*api.ReplicationController)
	if !ok {
		return nil, fmt.Errorf("not a replication controller: %#v", obj)
	}
	if errs := api.ValidateReplicationController(controller); len(errs) > 0 {
		return nil, fmt.Errorf("Validation errors: %v", errs)
	}
	return apiserver.MakeAsync(func() (interface{}, error) {
		err := storage.registry.UpdateController(*controller)
		if err != nil {
			return nil, err
		}
		return storage.waitForController(*controller)
	}), nil
}

func (storage *ControllerRegistryStorage) waitForController(ctrl api.ReplicationController) (interface{}, error) {
	for {
		pods, err := storage.podRegistry.ListPods(labels.Set(ctrl.DesiredState.ReplicaSelector).AsSelector())
		if err != nil {
			return ctrl, err
		}
		if len(pods) == ctrl.DesiredState.Replicas {
			break
		}
		time.Sleep(storage.pollPeriod)
	}
	return ctrl, nil
}

// WatchAll returns ReplicationController events via a watch.Interface, implementing
// apiserver.ResourceWatcher.
func (storage *ControllerRegistryStorage) WatchAll() (watch.Interface, error) {
	return storage.registry.WatchControllers()
}

// WatchSingle returns events for a single ReplicationController via a watch.Interface,
// implementing apiserver.ResourceWatcher.
func (storage *ControllerRegistryStorage) WatchSingle(id string) (watch.Interface, error) {
	return nil, errors.New("unimplemented")
}