/*
Copyright 2016 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 azure

import (
	"fmt"
	"io"
	"io/ioutil"

	"k8s.io/kubernetes/pkg/cloudprovider"
	"k8s.io/kubernetes/pkg/version"

	"github.com/Azure/azure-sdk-for-go/arm/compute"
	"github.com/Azure/azure-sdk-for-go/arm/network"
	"github.com/Azure/azure-sdk-for-go/arm/storage"
	"github.com/Azure/go-autorest/autorest"
	"github.com/Azure/go-autorest/autorest/azure"
	"github.com/ghodss/yaml"
	"time"
)

// CloudProviderName is the value used for the --cloud-provider flag
const CloudProviderName = "azure"

// Config holds the configuration parsed from the --cloud-config flag
// All fields are required unless otherwise specified
type Config struct {
	// The cloud environment identifier. Takes values from https://github.com/Azure/go-autorest/blob/ec5f4903f77ed9927ac95b19ab8e44ada64c1356/autorest/azure/environments.go#L13
	Cloud string `json:"cloud" yaml:"cloud"`
	// The AAD Tenant ID for the Subscription that the cluster is deployed in
	TenantID string `json:"tenantId" yaml:"tenantId"`
	// The ID of the Azure Subscription that the cluster is deployed in
	SubscriptionID string `json:"subscriptionId" yaml:"subscriptionId"`
	// The name of the resource group that the cluster is deployed in
	ResourceGroup string `json:"resourceGroup" yaml:"resourceGroup"`
	// The location of the resource group that the cluster is deployed in
	Location string `json:"location" yaml:"location"`
	// The name of the VNet that the cluster is deployed in
	VnetName string `json:"vnetName" yaml:"vnetName"`
	// The name of the subnet that the cluster is deployed in
	SubnetName string `json:"subnetName" yaml:"subnetName"`
	// The name of the security group attached to the cluster's subnet
	SecurityGroupName string `json:"securityGroupName" yaml:"securityGroupName"`
	// (Optional in 1.6) The name of the route table attached to the subnet that the cluster is deployed in
	RouteTableName string `json:"routeTableName" yaml:"routeTableName"`
	// (Optional) The name of the availability set that should be used as the load balancer backend
	// If this is set, the Azure cloudprovider will only add nodes from that availability set to the load
	// balancer backend pool. If this is not set, and multiple agent pools (availability sets) are used, then
	// the cloudprovider will try to add all nodes to a single backend pool which is forbidden.
	// In other words, if you use multiple agent pools (availability sets), you MUST set this field.
	PrimaryAvailabilitySetName string `json:"primaryAvailabilitySetName" yaml:"primaryAvailabilitySetName"`

	// The ClientID for an AAD application with RBAC access to talk to Azure RM APIs
	AADClientID string `json:"aadClientId" yaml:"aadClientId"`
	// The ClientSecret for an AAD application with RBAC access to talk to Azure RM APIs
	AADClientSecret string `json:"aadClientSecret" yaml:"aadClientSecret"`
}

// Cloud holds the config and clients
type Cloud struct {
	Config
	Environment             azure.Environment
	RoutesClient            network.RoutesClient
	SubnetsClient           network.SubnetsClient
	InterfacesClient        network.InterfacesClient
	RouteTablesClient       network.RouteTablesClient
	LoadBalancerClient      network.LoadBalancersClient
	PublicIPAddressesClient network.PublicIPAddressesClient
	SecurityGroupsClient    network.SecurityGroupsClient
	VirtualMachinesClient   compute.VirtualMachinesClient
	StorageAccountClient    storage.AccountsClient
}

func init() {
	cloudprovider.RegisterCloudProvider(CloudProviderName, NewCloud)
}

// NewCloud returns a Cloud with initialized clients
func NewCloud(configReader io.Reader) (cloudprovider.Interface, error) {
	var az Cloud

	configContents, err := ioutil.ReadAll(configReader)
	if err != nil {
		return nil, err
	}
	err = yaml.Unmarshal(configContents, &az)
	if err != nil {
		return nil, err
	}

	if az.Cloud == "" {
		az.Environment = azure.PublicCloud
	} else {
		az.Environment, err = azure.EnvironmentFromName(az.Cloud)
		if err != nil {
			return nil, err
		}
	}

	oauthConfig, err := az.Environment.OAuthConfigForTenant(az.TenantID)
	if err != nil {
		return nil, err
	}

	servicePrincipalToken, err := azure.NewServicePrincipalToken(
		*oauthConfig,
		az.AADClientID,
		az.AADClientSecret,
		az.Environment.ServiceManagementEndpoint)
	if err != nil {
		return nil, err
	}

	az.SubnetsClient = network.NewSubnetsClient(az.SubscriptionID)
	az.SubnetsClient.BaseURI = az.Environment.ResourceManagerEndpoint
	az.SubnetsClient.Authorizer = servicePrincipalToken
	az.SubnetsClient.PollingDelay = 5 * time.Second
	configureUserAgent(&az.SubnetsClient.Client)

	az.RouteTablesClient = network.NewRouteTablesClient(az.SubscriptionID)
	az.RouteTablesClient.BaseURI = az.Environment.ResourceManagerEndpoint
	az.RouteTablesClient.Authorizer = servicePrincipalToken
	az.RouteTablesClient.PollingDelay = 5 * time.Second
	configureUserAgent(&az.RouteTablesClient.Client)

	az.RoutesClient = network.NewRoutesClient(az.SubscriptionID)
	az.RoutesClient.BaseURI = az.Environment.ResourceManagerEndpoint
	az.RoutesClient.Authorizer = servicePrincipalToken
	az.RoutesClient.PollingDelay = 5 * time.Second
	configureUserAgent(&az.RoutesClient.Client)

	az.InterfacesClient = network.NewInterfacesClient(az.SubscriptionID)
	az.InterfacesClient.BaseURI = az.Environment.ResourceManagerEndpoint
	az.InterfacesClient.Authorizer = servicePrincipalToken
	az.InterfacesClient.PollingDelay = 5 * time.Second
	configureUserAgent(&az.InterfacesClient.Client)

	az.LoadBalancerClient = network.NewLoadBalancersClient(az.SubscriptionID)
	az.LoadBalancerClient.BaseURI = az.Environment.ResourceManagerEndpoint
	az.LoadBalancerClient.Authorizer = servicePrincipalToken
	az.LoadBalancerClient.PollingDelay = 5 * time.Second
	configureUserAgent(&az.LoadBalancerClient.Client)

	az.VirtualMachinesClient = compute.NewVirtualMachinesClient(az.SubscriptionID)
	az.VirtualMachinesClient.BaseURI = az.Environment.ResourceManagerEndpoint
	az.VirtualMachinesClient.Authorizer = servicePrincipalToken
	az.VirtualMachinesClient.PollingDelay = 5 * time.Second
	configureUserAgent(&az.VirtualMachinesClient.Client)

	az.PublicIPAddressesClient = network.NewPublicIPAddressesClient(az.SubscriptionID)
	az.PublicIPAddressesClient.BaseURI = az.Environment.ResourceManagerEndpoint
	az.PublicIPAddressesClient.Authorizer = servicePrincipalToken
	az.PublicIPAddressesClient.PollingDelay = 5 * time.Second
	configureUserAgent(&az.PublicIPAddressesClient.Client)

	az.SecurityGroupsClient = network.NewSecurityGroupsClient(az.SubscriptionID)
	az.SecurityGroupsClient.BaseURI = az.Environment.ResourceManagerEndpoint
	az.SecurityGroupsClient.Authorizer = servicePrincipalToken
	az.SecurityGroupsClient.PollingDelay = 5 * time.Second
	configureUserAgent(&az.SecurityGroupsClient.Client)

	az.StorageAccountClient = storage.NewAccountsClientWithBaseURI(az.Environment.ResourceManagerEndpoint, az.SubscriptionID)
	az.StorageAccountClient.Authorizer = servicePrincipalToken

	return &az, nil
}

// LoadBalancer returns a balancer interface. Also returns true if the interface is supported, false otherwise.
func (az *Cloud) LoadBalancer() (cloudprovider.LoadBalancer, bool) {
	return az, true
}

// Instances returns an instances interface. Also returns true if the interface is supported, false otherwise.
func (az *Cloud) Instances() (cloudprovider.Instances, bool) {
	return az, true
}

// Zones returns a zones interface. Also returns true if the interface is supported, false otherwise.
func (az *Cloud) Zones() (cloudprovider.Zones, bool) {
	return az, true
}

// Clusters returns a clusters interface.  Also returns true if the interface is supported, false otherwise.
func (az *Cloud) Clusters() (cloudprovider.Clusters, bool) {
	return nil, false
}

// Routes returns a routes interface along with whether the interface is supported.
func (az *Cloud) Routes() (cloudprovider.Routes, bool) {
	return az, true
}

// ScrubDNS provides an opportunity for cloud-provider-specific code to process DNS settings for pods.
func (az *Cloud) ScrubDNS(nameservers, searches []string) (nsOut, srchOut []string) {
	return nameservers, searches
}

// ProviderName returns the cloud provider ID.
func (az *Cloud) ProviderName() string {
	return CloudProviderName
}

func configureUserAgent(client *autorest.Client) {
	k8sVersion := version.Get().GitVersion
	client.UserAgent = fmt.Sprintf("%s; %s", client.UserAgent, k8sVersion)
}