/*
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 rancher_credentials

import (
	"os"
	"time"

	"github.com/golang/glog"
	"github.com/rancher/go-rancher/client"
	"k8s.io/kubernetes/pkg/credentialprovider"
)

// rancher provider
type rancherProvider struct {
	credGetter credentialsGetter
}

// credentials getter from Rancher private registry
type rancherCredentialsGetter struct {
	client *client.RancherClient
}

type rConfig struct {
	Global configGlobal
}

// An interface for testing purposes.
type credentialsGetter interface {
	getCredentials() []registryCredential
}

type configGlobal struct {
	CattleURL       string `gcfg:"cattle-url"`
	CattleAccessKey string `gcfg:"cattle-access-key"`
	CattleSecretKey string `gcfg:"cattle-secret-key"`
}

type registryCredential struct {
	credential *client.RegistryCredential
	serverIP   string
}

var rancherGetter = &rancherCredentialsGetter{}

func init() {
	credentialprovider.RegisterCredentialProvider("rancher-registry-creds",
		&credentialprovider.CachingDockerConfigProvider{
			Provider: &rancherProvider{rancherGetter},
			Lifetime: 30 * time.Second,
		})
}

func (p *rancherProvider) Enabled() bool {
	client, err := getRancherClient()
	if err != nil {
		return false
	}
	if client == nil {
		return false
	}

	rancherGetter.client = client
	return true
}

// LazyProvide implements DockerConfigProvider. Should never be called.
func (p *rancherProvider) LazyProvide() *credentialprovider.DockerConfigEntry {
	return nil
}

// Provide implements DockerConfigProvider.Provide, refreshing Rancher tokens on demand
func (p *rancherProvider) Provide() credentialprovider.DockerConfig {
	cfg := credentialprovider.DockerConfig{}
	for _, cred := range p.credGetter.getCredentials() {
		entry := credentialprovider.DockerConfigEntry{
			Username: cred.credential.PublicValue,
			Password: cred.credential.SecretValue,
			Email:    cred.credential.Email,
		}
		cfg[cred.serverIP] = entry
	}

	return cfg
}

func (g *rancherCredentialsGetter) getCredentials() []registryCredential {
	var registryCreds []registryCredential
	credColl, err := g.client.RegistryCredential.List(client.NewListOpts())
	if err != nil {
		glog.Errorf("Failed to pull registry credentials from rancher %v", err)
		return registryCreds
	}
	for _, cred := range credColl.Data {
		registry := &client.Registry{}
		if err = g.client.GetLink(cred.Resource, "registry", registry); err != nil {
			glog.Errorf("Failed to pull registry from rancher %v", err)
			return registryCreds
		}
		registryCred := registryCredential{
			credential: &cred,
			serverIP:   registry.ServerAddress,
		}
		registryCreds = append(registryCreds, registryCred)
	}
	return registryCreds
}

func getRancherClient() (*client.RancherClient, error) {
	url := os.Getenv("CATTLE_URL")
	accessKey := os.Getenv("CATTLE_ACCESS_KEY")
	secretKey := os.Getenv("CATTLE_SECRET_KEY")

	if url == "" || accessKey == "" || secretKey == "" {
		return nil, nil
	}

	conf := rConfig{
		Global: configGlobal{
			CattleURL:       url,
			CattleAccessKey: accessKey,
			CattleSecretKey: secretKey,
		},
	}

	return client.NewRancherClient(&client.ClientOpts{
		Url:       conf.Global.CattleURL,
		AccessKey: conf.Global.CattleAccessKey,
		SecretKey: conf.Global.CattleSecretKey,
	})
}