/*
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 (
	"errors"
	"net/http"
	"sync"
	"time"

	"github.com/Azure/azure-sdk-for-go/arm/compute"
	"github.com/Azure/azure-sdk-for-go/arm/network"
	"github.com/Azure/go-autorest/autorest"
	"github.com/golang/glog"
	"k8s.io/apimachinery/pkg/types"
	"k8s.io/kubernetes/pkg/cloudprovider"
)

var (
	// ErrorNotVmssInstance indicates an instance is not belongint to any vmss.
	ErrorNotVmssInstance = errors.New("not a vmss instance")
)

// checkExistsFromError inspects an error and returns a true if err is nil,
// false if error is an autorest.Error with StatusCode=404 and will return the
// error back if error is another status code or another type of error.
func checkResourceExistsFromError(err error) (bool, error) {
	if err == nil {
		return true, nil
	}
	v, ok := err.(autorest.DetailedError)
	if !ok {
		return false, err
	}
	if v.StatusCode == http.StatusNotFound {
		return false, nil
	}
	return false, v
}

// If it is StatusNotFound return nil,
// Otherwise, return what it is
func ignoreStatusNotFoundFromError(err error) error {
	if err == nil {
		return nil
	}
	v, ok := err.(autorest.DetailedError)
	if ok && v.StatusCode == http.StatusNotFound {
		return nil
	}
	return err
}

// cache used by getVirtualMachine
// 15s for expiration duration
var vmCache = newTimedcache(15 * time.Second)

type vmRequest struct {
	lock *sync.Mutex
	vm   *compute.VirtualMachine
}

/// getVirtualMachine calls 'VirtualMachinesClient.Get' with a timed cache
/// The service side has throttling control that delays responses if there're multiple requests onto certain vm
/// resource request in short period.
func (az *Cloud) getVirtualMachine(nodeName types.NodeName) (vm compute.VirtualMachine, err error) {
	vmName := string(nodeName)

	cachedRequest, err := vmCache.GetOrCreate(vmName, func() interface{} {
		return &vmRequest{
			lock: &sync.Mutex{},
			vm:   nil,
		}
	})
	if err != nil {
		return compute.VirtualMachine{}, err
	}
	request := cachedRequest.(*vmRequest)

	if request.vm == nil {
		request.lock.Lock()
		defer request.lock.Unlock()
		if request.vm == nil {
			// Currently InstanceView request are used by azure_zones, while the calls come after non-InstanceView
			// request. If we first send an InstanceView request and then a non InstanceView request, the second
			// request will still hit throttling. This is what happens now for cloud controller manager: In this
			// case we do get instance view every time to fulfill the azure_zones requirement without hitting
			// throttling.
			// Consider adding separate parameter for controlling 'InstanceView' once node update issue #56276 is fixed
			az.operationPollRateLimiter.Accept()
			glog.V(10).Infof("VirtualMachinesClient.Get(%s): start", vmName)
			vm, err = az.VirtualMachinesClient.Get(az.ResourceGroup, vmName, compute.InstanceView)
			glog.V(10).Infof("VirtualMachinesClient.Get(%s): end", vmName)

			exists, realErr := checkResourceExistsFromError(err)
			if realErr != nil {
				return vm, realErr
			}

			if !exists {
				return vm, cloudprovider.InstanceNotFound
			}

			request.vm = &vm
		}
		return *request.vm, nil
	}

	glog.V(6).Infof("getVirtualMachine hits cache for(%s)", vmName)
	return *request.vm, nil
}

func (az *Cloud) getVmssVirtualMachine(nodeName types.NodeName) (vm compute.VirtualMachineScaleSetVM, exists bool, err error) {
	var realErr error

	vmName := string(nodeName)
	instanceID, err := getVmssInstanceID(vmName)
	if err != nil {
		return vm, false, err
	}

	az.operationPollRateLimiter.Accept()
	glog.V(10).Infof("VirtualMachineScaleSetVMsClient.Get(%s): start", vmName)
	vm, err = az.VirtualMachineScaleSetVMsClient.Get(az.ResourceGroup, az.PrimaryScaleSetName, instanceID)
	glog.V(10).Infof("VirtualMachineScaleSetVMsClient.Get(%s): end", vmName)

	exists, realErr = checkResourceExistsFromError(err)
	if realErr != nil {
		return vm, false, realErr
	}

	if !exists {
		return vm, false, nil
	}

	return vm, exists, err
}

func (az *Cloud) getRouteTable() (routeTable network.RouteTable, exists bool, err error) {
	var realErr error

	az.operationPollRateLimiter.Accept()
	glog.V(10).Infof("RouteTablesClient.Get(%s): start", az.RouteTableName)
	routeTable, err = az.RouteTablesClient.Get(az.ResourceGroup, az.RouteTableName, "")
	glog.V(10).Infof("RouteTablesClient.Get(%s): end", az.RouteTableName)

	exists, realErr = checkResourceExistsFromError(err)
	if realErr != nil {
		return routeTable, false, realErr
	}

	if !exists {
		return routeTable, false, nil
	}

	return routeTable, exists, err
}

func (az *Cloud) getSecurityGroup() (sg network.SecurityGroup, exists bool, err error) {
	var realErr error

	az.operationPollRateLimiter.Accept()
	glog.V(10).Infof("SecurityGroupsClient.Get(%s): start", az.SecurityGroupName)
	sg, err = az.SecurityGroupsClient.Get(az.ResourceGroup, az.SecurityGroupName, "")
	glog.V(10).Infof("SecurityGroupsClient.Get(%s): end", az.SecurityGroupName)

	exists, realErr = checkResourceExistsFromError(err)
	if realErr != nil {
		return sg, false, realErr
	}

	if !exists {
		return sg, false, nil
	}

	return sg, exists, err
}

func (az *Cloud) getAzureLoadBalancer(name string) (lb network.LoadBalancer, exists bool, err error) {
	var realErr error
	az.operationPollRateLimiter.Accept()
	glog.V(10).Infof("LoadBalancerClient.Get(%s): start", name)
	lb, err = az.LoadBalancerClient.Get(az.ResourceGroup, name, "")
	glog.V(10).Infof("LoadBalancerClient.Get(%s): end", name)

	exists, realErr = checkResourceExistsFromError(err)
	if realErr != nil {
		return lb, false, realErr
	}

	if !exists {
		return lb, false, nil
	}

	return lb, exists, err
}

func (az *Cloud) listLoadBalancers() (lbListResult network.LoadBalancerListResult, exists bool, err error) {
	var realErr error

	az.operationPollRateLimiter.Accept()
	glog.V(10).Infof("LoadBalancerClient.List(%s): start", az.ResourceGroup)
	lbListResult, err = az.LoadBalancerClient.List(az.ResourceGroup)
	glog.V(10).Infof("LoadBalancerClient.List(%s): end", az.ResourceGroup)
	exists, realErr = checkResourceExistsFromError(err)
	if realErr != nil {
		return lbListResult, false, realErr
	}

	if !exists {
		return lbListResult, false, nil
	}

	return lbListResult, exists, err
}

func (az *Cloud) getPublicIPAddress(name string) (pip network.PublicIPAddress, exists bool, err error) {
	var realErr error

	az.operationPollRateLimiter.Accept()
	glog.V(10).Infof("PublicIPAddressesClient.Get(%s): start", name)
	pip, err = az.PublicIPAddressesClient.Get(az.ResourceGroup, name, "")
	glog.V(10).Infof("PublicIPAddressesClient.Get(%s): end", name)

	exists, realErr = checkResourceExistsFromError(err)
	if realErr != nil {
		return pip, false, realErr
	}

	if !exists {
		return pip, false, nil
	}

	return pip, exists, err
}

func (az *Cloud) getSubnet(virtualNetworkName string, subnetName string) (subnet network.Subnet, exists bool, err error) {
	var realErr error
	var rg string

	if len(az.VnetResourceGroup) > 0 {
		rg = az.VnetResourceGroup
	} else {
		rg = az.ResourceGroup
	}

	az.operationPollRateLimiter.Accept()
	glog.V(10).Infof("SubnetsClient.Get(%s): start", subnetName)
	subnet, err = az.SubnetsClient.Get(rg, virtualNetworkName, subnetName, "")
	glog.V(10).Infof("SubnetsClient.Get(%s): end", subnetName)

	exists, realErr = checkResourceExistsFromError(err)
	if realErr != nil {
		return subnet, false, realErr
	}

	if !exists {
		return subnet, false, nil
	}

	return subnet, exists, err
}