/*
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 vsphere

import (
	"fmt"
	"strings"
	"sync"

	"github.com/golang/glog"
	"golang.org/x/net/context"
	"k8s.io/api/core/v1"
	k8stypes "k8s.io/apimachinery/pkg/types"
	"k8s.io/kubernetes/pkg/cloudprovider/providers/vsphere/vclib"
)

// Stores info about the kubernetes node
type NodeInfo struct {
	dataCenter *vclib.Datacenter
	vm         *vclib.VirtualMachine
	vcServer   string
}

type NodeManager struct {
	// TODO: replace map with concurrent map when k8s supports go v1.9

	// Maps the VC server to VSphereInstance
	vsphereInstanceMap map[string]*VSphereInstance
	// Maps node name to node info.
	nodeInfoMap map[string]*NodeInfo
	// Maps node name to node structure
	registeredNodes map[string]*v1.Node

	// Mutexes
	registeredNodesLock sync.RWMutex
	nodeInfoLock        sync.RWMutex
}

type NodeDetails struct {
	NodeName string
	vm       *vclib.VirtualMachine
}

// TODO: Make it configurable in vsphere.conf
const (
	POOL_SIZE  = 8
	QUEUE_SIZE = POOL_SIZE * 10
)

func (nm *NodeManager) DiscoverNode(node *v1.Node) error {
	type VmSearch struct {
		vc         string
		datacenter *vclib.Datacenter
	}

	var mutex = &sync.Mutex{}
	var globalErrMutex = &sync.Mutex{}
	var queueChannel chan *VmSearch
	var wg sync.WaitGroup
	var globalErr *error

	queueChannel = make(chan *VmSearch, QUEUE_SIZE)
	nodeUUID := node.Status.NodeInfo.SystemUUID
	vmFound := false
	globalErr = nil

	setGlobalErr := func(err error) {
		globalErrMutex.Lock()
		globalErr = &err
		globalErrMutex.Unlock()
	}

	setVMFound := func(found bool) {
		mutex.Lock()
		vmFound = found
		mutex.Unlock()
	}

	getVMFound := func() bool {
		mutex.Lock()
		found := vmFound
		mutex.Unlock()
		return found
	}

	go func() {
		var datacenterObjs []*vclib.Datacenter
		for vc, vsi := range nm.vsphereInstanceMap {

			found := getVMFound()
			if found == true {
				break
			}

			// Create context
			ctx, cancel := context.WithCancel(context.Background())
			defer cancel()

			err := vsi.conn.Connect(ctx)
			if err != nil {
				glog.V(4).Info("Discovering node error vc:", err)
				setGlobalErr(err)
				continue
			}

			if vsi.cfg.Datacenters == "" {
				datacenterObjs, err = vclib.GetAllDatacenter(ctx, vsi.conn)
				if err != nil {
					glog.V(4).Info("Discovering node error dc:", err)
					setGlobalErr(err)
					continue
				}
			} else {
				datacenters := strings.Split(vsi.cfg.Datacenters, ",")
				for _, dc := range datacenters {
					dc = strings.TrimSpace(dc)
					if dc == "" {
						continue
					}
					datacenterObj, err := vclib.GetDatacenter(ctx, vsi.conn, dc)
					if err != nil {
						glog.V(4).Info("Discovering node error dc:", err)
						setGlobalErr(err)
						continue
					}
					datacenterObjs = append(datacenterObjs, datacenterObj)
				}
			}

			for _, datacenterObj := range datacenterObjs {
				found := getVMFound()
				if found == true {
					break
				}

				glog.V(4).Infof("Finding node %s in vc=%s and datacenter=%s", node.Name, vc, datacenterObj.Name())
				queueChannel <- &VmSearch{
					vc:         vc,
					datacenter: datacenterObj,
				}
			}
		}
		close(queueChannel)
	}()

	for i := 0; i < POOL_SIZE; i++ {
		go func() {
			for res := range queueChannel {
				ctx, cancel := context.WithCancel(context.Background())
				defer cancel()
				vm, err := res.datacenter.GetVMByUUID(ctx, nodeUUID)
				if err != nil {
					glog.V(4).Infof("Error %q while looking for vm=%+v in vc=%s and datacenter=%s",
						err, node.Name, vm, res.vc, res.datacenter.Name())
					if err != vclib.ErrNoVMFound {
						setGlobalErr(err)
					} else {
						glog.V(4).Infof("Did not find node %s in vc=%s and datacenter=%s",
							node.Name, res.vc, res.datacenter.Name(), err)
					}
					continue
				}
				if vm != nil {
					glog.V(4).Infof("Found node %s as vm=%+v in vc=%s and datacenter=%s",
						node.Name, vm, res.vc, res.datacenter.Name())

					nodeInfo := &NodeInfo{dataCenter: res.datacenter, vm: vm, vcServer: res.vc}
					nm.addNodeInfo(node.ObjectMeta.Name, nodeInfo)
					for range queueChannel {
					}
					setVMFound(true)
					break
				}
			}
			wg.Done()
		}()
		wg.Add(1)
	}
	wg.Wait()
	if vmFound {
		return nil
	}
	if globalErr != nil {
		return *globalErr
	}

	glog.V(4).Infof("Discovery Node: %q vm not found", node.Name)
	return vclib.ErrNoVMFound
}

func (nm *NodeManager) RegisterNode(node *v1.Node) error {
	nm.addNode(node)
	nm.DiscoverNode(node)
	return nil
}

func (nm *NodeManager) UnRegisterNode(node *v1.Node) error {
	nm.removeNode(node)
	return nil
}

func (nm *NodeManager) RediscoverNode(nodeName k8stypes.NodeName) error {
	node, err := nm.GetNode(nodeName)

	if err != nil {
		return err
	}
	return nm.DiscoverNode(&node)
}

func (nm *NodeManager) GetNode(nodeName k8stypes.NodeName) (v1.Node, error) {
	nm.registeredNodesLock.RLock()
	node := nm.registeredNodes[convertToString(nodeName)]
	nm.registeredNodesLock.RUnlock()
	if node == nil {
		return v1.Node{}, vclib.ErrNoVMFound
	}
	return *node, nil
}

func (nm *NodeManager) addNode(node *v1.Node) {
	nm.registeredNodesLock.Lock()
	nm.registeredNodes[node.ObjectMeta.Name] = node
	nm.registeredNodesLock.Unlock()
}

func (nm *NodeManager) removeNode(node *v1.Node) {
	nm.registeredNodesLock.Lock()
	delete(nm.registeredNodes, node.ObjectMeta.Name)
	nm.registeredNodesLock.Unlock()

	nm.nodeInfoLock.Lock()
	delete(nm.nodeInfoMap, node.ObjectMeta.Name)
	nm.nodeInfoLock.Unlock()
}

// GetNodeInfo returns a NodeInfo which datacenter, vm and vc server ip address.
// This method returns an error if it is unable find node VCs and DCs listed in vSphere.conf
// NodeInfo returned may not be updated to reflect current VM location.
//
// This method is a getter but it can cause side-effect of updating NodeInfo object.
func (nm *NodeManager) GetNodeInfo(nodeName k8stypes.NodeName) (NodeInfo, error) {
	getNodeInfo := func(nodeName k8stypes.NodeName) *NodeInfo {
		nm.nodeInfoLock.RLock()
		nodeInfo := nm.nodeInfoMap[convertToString(nodeName)]
		nm.nodeInfoLock.RUnlock()
		return nodeInfo
	}
	nodeInfo := getNodeInfo(nodeName)
	var err error
	if nodeInfo == nil {
		// Rediscover node if no NodeInfo found.
		glog.V(4).Infof("No VM found for node %q. Initiating rediscovery.", convertToString(nodeName))
		err = nm.RediscoverNode(nodeName)
		if err != nil {
			glog.Errorf("Error %q node info for node %q not found", err, convertToString(nodeName))
			return NodeInfo{}, err
		}
		nodeInfo = getNodeInfo(nodeName)
	} else {
		// Renew the found NodeInfo to avoid stale vSphere connection.
		glog.V(4).Infof("Renewing NodeInfo %+v for node %q", nodeInfo, convertToString(nodeName))
		nodeInfo, err = nm.renewNodeInfo(nodeInfo, true)
		if err != nil {
			glog.Errorf("Error %q occurred while renewing NodeInfo for %q", err, convertToString(nodeName))
			return NodeInfo{}, err
		}
		nm.addNodeInfo(convertToString(nodeName), nodeInfo)
	}
	return *nodeInfo, nil
}

// GetNodeDetails returns NodeDetails for all the discovered nodes.
//
// This method is a getter but it can cause side-effect of updating NodeInfo objects.
func (nm *NodeManager) GetNodeDetails() ([]NodeDetails, error) {
	nm.nodeInfoLock.RLock()
	defer nm.nodeInfoLock.RUnlock()
	var nodeDetails []NodeDetails
	vsphereSessionRefreshMap := make(map[string]bool)

	for nodeName, nodeInfo := range nm.nodeInfoMap {
		var n *NodeInfo
		var err error
		if vsphereSessionRefreshMap[nodeInfo.vcServer] {
			// vSphere connection already refreshed. Just refresh VM and Datacenter.
			glog.V(4).Infof("Renewing NodeInfo %+v for node %q. No new connection needed.", nodeInfo, nodeName)
			n, err = nm.renewNodeInfo(nodeInfo, false)
		} else {
			// Refresh vSphere connection, VM and Datacenter.
			glog.V(4).Infof("Renewing NodeInfo %+v for node %q with new vSphere connection.", nodeInfo, nodeName)
			n, err = nm.renewNodeInfo(nodeInfo, true)
			vsphereSessionRefreshMap[nodeInfo.vcServer] = true
		}
		if err != nil {
			return nil, err
		}
		nm.nodeInfoMap[nodeName] = n
		glog.V(4).Infof("Updated NodeInfo %q for node %q.", nodeInfo, nodeName)
		nodeDetails = append(nodeDetails, NodeDetails{nodeName, n.vm})
	}
	return nodeDetails, nil
}

func (nm *NodeManager) addNodeInfo(nodeName string, nodeInfo *NodeInfo) {
	nm.nodeInfoLock.Lock()
	nm.nodeInfoMap[nodeName] = nodeInfo
	nm.nodeInfoLock.Unlock()
}

func (nm *NodeManager) GetVSphereInstance(nodeName k8stypes.NodeName) (VSphereInstance, error) {
	nodeInfo, err := nm.GetNodeInfo(nodeName)
	if err != nil {
		glog.V(4).Infof("node info for node %q not found", convertToString(nodeName))
		return VSphereInstance{}, err
	}
	vsphereInstance := nm.vsphereInstanceMap[nodeInfo.vcServer]
	if vsphereInstance == nil {
		return VSphereInstance{}, fmt.Errorf("vSphereInstance for vc server %q not found while looking for node %q", nodeInfo.vcServer, convertToString(nodeName))
	}
	return *vsphereInstance, nil
}

// renewNodeInfo renews vSphere connection, VirtualMachine and Datacenter for NodeInfo instance.
func (nm *NodeManager) renewNodeInfo(nodeInfo *NodeInfo, reconnect bool) (*NodeInfo, error) {
	ctx, cancel := context.WithCancel(context.Background())
	defer cancel()

	vsphereInstance := nm.vsphereInstanceMap[nodeInfo.vcServer]
	if vsphereInstance == nil {
		err := fmt.Errorf("vSphereInstance for vSphere %q not found while refershing NodeInfo for VM %q", nodeInfo.vcServer, nodeInfo.vm)
		return nil, err
	}
	if reconnect {
		err := vsphereInstance.conn.Connect(ctx)
		if err != nil {
			return nil, err
		}
	}
	vm := nodeInfo.vm.RenewVM(vsphereInstance.conn.GoVmomiClient)
	return &NodeInfo{vm: &vm, dataCenter: vm.Datacenter, vcServer: nodeInfo.vcServer}, nil
}

func (nodeInfo *NodeInfo) VM() *vclib.VirtualMachine {
	if nodeInfo == nil {
		return nil
	}
	return nodeInfo.vm
}