// Dispatch the command to leader
func dispatch(c Command, w http.ResponseWriter, req *http.Request, etcd bool) error {

	if r.State() == raft.Leader {
		if body, err := r.Do(c); err != nil {
			return err
		} else {
			if body == nil {
				return etcdErr.NewError(300, "Empty result from raft")
			} else {
				body, _ := body.([]byte)
				w.WriteHeader(http.StatusOK)
				w.Write(body)
				return nil
			}
		}

	} else {
		leader := r.Leader()
		// current no leader
		if leader == "" {
			return etcdErr.NewError(300, "")
		}

		redirect(leader, etcd, w, req)

		return nil
	}
	return etcdErr.NewError(300, "")
}

// Set the value of the key to the value if the given prevValue is equal to the value of the key
func (s *Store) TestAndSet(key string, prevValue string, value string, expireTime time.Time, index uint64) ([]byte, error) {
	s.mutex.Lock()
	defer s.mutex.Unlock()

	// Update stats
	s.BasicStats.TestAndSets++

	resp := s.internalGet(key)

	if resp == nil {
		if prevValue != "" {
			errmsg := fmt.Sprintf("TestAndSet: key not found and previousValue is not empty %s:%s ", key, prevValue)
			return nil, etcdErr.NewError(100, errmsg)
		}
		return s.internalSet(key, value, expireTime, index)
	}

	if resp.Value == prevValue {

		// If test succeed, do set
		return s.internalSet(key, value, expireTime, index)
	} else {

		// If fails, return err
		return nil, etcdErr.NewError(101, fmt.Sprintf("TestAndSet: %s!=%s",
			resp.Value, prevValue))
	}

}

// Set the value of the key to the value if the given prevValue is equal to the value of the key
func (s *Store) TestAndSet(key string, prevValue string, value string, expireTime time.Time, index uint64) ([]byte, error) {
	s.mutex.Lock()
	defer s.mutex.Unlock()

	// Update stats
	s.BasicStats.TestAndSets++

	resp := s.internalGet(key)

	if resp == nil {
		return nil, etcdErr.NewError(100, "testandset: "+key)
	}

	if resp.Value == prevValue {

		// If test success, do set
		return s.internalSet(key, value, expireTime, index)
	} else {

		// If fails, return err
		return nil, etcdErr.NewError(101, fmt.Sprintf("TestAndSet: %s!=%s",
			resp.Value, prevValue))
	}

}

// InternalGet gets the node of the given nodePath.
func (s *store) internalGet(nodePath string) (*node, *etcdErr.Error) {
	nodePath = path.Clean(path.Join("/", nodePath))

	walkFunc := func(parent *node, name string) (*node, *etcdErr.Error) {

		if !parent.IsDir() {
			err := etcdErr.NewError(etcdErr.EcodeNotDir, parent.Path, s.CurrentIndex)
			return nil, err
		}

		child, ok := parent.Children[name]
		if ok {
			return child, nil
		}

		return nil, etcdErr.NewError(etcdErr.EcodeKeyNotFound, path.Join(parent.Path, name), s.CurrentIndex)
	}

	f, err := s.walk(nodePath, walkFunc)

	if err != nil {
		return nil, err
	}
	return f, nil
}

// Watches a given key prefix for changes.
func WatchKeyHandler(w http.ResponseWriter, req *http.Request, s Server) error {
	var err error
	vars := mux.Vars(req)
	key := "/" + vars["key"]

	// Create a command to watch from a given index (default 0).
	var sinceIndex uint64 = 0
	if req.Method == "POST" {
		sinceIndex, err = strconv.ParseUint(string(req.FormValue("index")), 10, 64)
		if err != nil {
			return etcdErr.NewError(203, "Watch From Index", s.Store().Index())
		}
	}

	// Start the watcher on the store.
	watcher, err := s.Store().Watch(key, false, false, sinceIndex)
	if err != nil {
		return etcdErr.NewError(500, key, s.Store().Index())
	}
	event := <-watcher.EventChan

	// Convert event to a response and write to client.
	w.WriteHeader(http.StatusOK)
	if req.Method == "HEAD" {
		return nil
	}
	b, _ := json.Marshal(event.Response(s.Store().Index()))
	w.Write(b)
	return nil
}

// Update updates the value/ttl of the node.
// If the node is a file, the value and the ttl can be updated.
// If the node is a directory, only the ttl can be updated.
func (s *store) Update(nodePath string, newValue string, expireTime time.Time) (*Event, error) {
	var err *etcdErr.Error

	s.worldLock.Lock()
	defer s.worldLock.Unlock()

	defer func() {
		if err == nil {
			s.Stats.Inc(UpdateSuccess)
			reportWriteSuccess(Update)
			return
		}

		s.Stats.Inc(UpdateFail)
		reportWriteFailure(Update)
	}()

	nodePath = path.Clean(path.Join("/", nodePath))
	// we do not allow the user to change "/"
	if s.readonlySet.Contains(nodePath) {
		return nil, etcdErr.NewError(etcdErr.EcodeRootROnly, "/", s.CurrentIndex)
	}

	currIndex, nextIndex := s.CurrentIndex, s.CurrentIndex+1

	n, err := s.internalGet(nodePath)
	if err != nil { // if the node does not exist, return error
		return nil, err
	}
	if n.IsDir() && len(newValue) != 0 {
		// if the node is a directory, we cannot update value to non-empty
		return nil, etcdErr.NewError(etcdErr.EcodeNotFile, nodePath, currIndex)
	}

	e := newEvent(Update, nodePath, nextIndex, n.CreatedIndex)
	e.EtcdIndex = nextIndex
	e.PrevNode = n.Repr(false, false, s.clock)
	eNode := e.Node

	n.Write(newValue, nextIndex)

	if n.IsDir() {
		eNode.Dir = true
	} else {
		// copy the value for safety
		newValueCopy := newValue
		eNode.Value = &newValueCopy
	}

	// update ttl
	n.UpdateTTL(expireTime)

	eNode.Expiration, eNode.TTL = n.expirationAndTTL(s.clock)

	s.WatcherHub.notify(e)

	s.CurrentIndex = nextIndex

	return e, nil
}

// Sets the value for a given key.
func SetKeyHandler(w http.ResponseWriter, req *http.Request, s Server) error {
	vars := mux.Vars(req)
	key := "/" + vars["key"]

	req.ParseForm()

	// Parse non-blank value.
	value := req.Form.Get("value")
	if len(value) == 0 {
		return etcdErr.NewError(200, "Set", s.Store().Index())
	}

	// Convert time-to-live to an expiration time.
	expireTime, err := store.TTL(req.Form.Get("ttl"))
	if err != nil {
		return etcdErr.NewError(202, "Set", s.Store().Index())
	}

	// If the "prevValue" is specified then test-and-set. Otherwise create a new key.
	var c raft.Command
	if prevValueArr, ok := req.Form["prevValue"]; ok {
		if len(prevValueArr[0]) > 0 {
			// test against previous value
			c = s.Store().CommandFactory().CreateCompareAndSwapCommand(key, value, prevValueArr[0], 0, expireTime)
		} else {
			// test against existence
			c = s.Store().CommandFactory().CreateCreateCommand(key, value, expireTime, false)
		}

	} else {
		c = s.Store().CommandFactory().CreateSetCommand(key, value, expireTime)
	}

	return s.Dispatch(c, w, req)
}

// applyJoin attempts to join a machine to the cluster.
func applyJoin(c *JoinCommand, context raft.Context) (uint64, error) {
	ps, _ := context.Server().Context().(*PeerServer)
	commitIndex := context.CommitIndex()

	// Make sure we're not getting a cached value from the registry.
	ps.registry.Invalidate(c.Name)

	// Check if the join command is from a previous peer, who lost all its previous log.
	if peerURL, ok := ps.registry.PeerURL(c.Name); ok {
		// If previous node restarts with different peer URL,
		// update its information.
		if peerURL != c.RaftURL {
			log.Infof("Rejoin with %v instead of %v from %v", c.RaftURL, peerURL, c.Name)
			if err := updatePeerURL(c, ps); err != nil {
				return 0, err
			}
		}
		if c.Name == context.Server().Name() {
			ps.removedInLog = false
		}
		return commitIndex, nil
	}

	// Check if the join command adds an instance that collides with existing one on peer URL.
	peerURLs := ps.registry.PeerURLs(ps.raftServer.Leader(), c.Name)
	for _, peerURL := range peerURLs {
		if peerURL == c.RaftURL {
			log.Warnf("%v tries to join the cluster with existing URL %v", c.Name, c.EtcdURL)
			return 0, etcdErr.NewError(etcdErr.EcodeExistingPeerAddr, c.EtcdURL, context.CommitIndex())
		}
	}

	// Check peer number in the cluster
	count := ps.registry.Count()
	// ClusterConfig doesn't init until first machine is added
	if count > 0 && count >= ps.ClusterConfig().ActiveSize {
		log.Debug("Reject join request from ", c.Name)
		return 0, etcdErr.NewError(etcdErr.EcodeNoMorePeer, "", context.CommitIndex())
	}

	// Add to shared peer registry.
	ps.registry.Register(c.Name, c.RaftURL, c.EtcdURL)

	// Add peer in raft
	if err := context.Server().AddPeer(c.Name, ""); err != nil {
		return 0, err
	}

	// Add peer stats
	if c.Name != ps.RaftServer().Name() {
		ps.followersStats.Followers[c.Name] = &raftFollowerStats{}
		ps.followersStats.Followers[c.Name].Latency.Minimum = 1 << 63
	}

	if c.Name == context.Server().Name() {
		ps.removedInLog = false
	}
	return commitIndex, nil
}

func (s *store) CompareAndSwap(nodePath string, prevValue string, prevIndex uint64,
	value string, expireTime time.Time) (*Event, error) {

	s.worldLock.Lock()
	defer s.worldLock.Unlock()

	nodePath = path.Clean(path.Join("/", nodePath))
	// we do not allow the user to change "/"
	if s.readonlySet.Contains(nodePath) {
		return nil, etcdErr.NewError(etcdErr.EcodeRootROnly, "/", s.CurrentIndex)
	}

	n, err := s.internalGet(nodePath)

	if err != nil {
		s.Stats.Inc(CompareAndSwapFail)
		reportWriteFailure(CompareAndSwap)
		return nil, err
	}

	if n.IsDir() { // can only compare and swap file
		s.Stats.Inc(CompareAndSwapFail)
		reportWriteFailure(CompareAndSwap)
		return nil, etcdErr.NewError(etcdErr.EcodeNotFile, nodePath, s.CurrentIndex)
	}

	// If both of the prevValue and prevIndex are given, we will test both of them.
	// Command will be executed, only if both of the tests are successful.
	if ok, which := n.Compare(prevValue, prevIndex); !ok {
		cause := getCompareFailCause(n, which, prevValue, prevIndex)
		s.Stats.Inc(CompareAndSwapFail)
		reportWriteFailure(CompareAndSwap)
		return nil, etcdErr.NewError(etcdErr.EcodeTestFailed, cause, s.CurrentIndex)
	}

	// update etcd index
	s.CurrentIndex++

	e := newEvent(CompareAndSwap, nodePath, s.CurrentIndex, n.CreatedIndex)
	e.EtcdIndex = s.CurrentIndex
	e.PrevNode = n.Repr(false, false, s.clock)
	eNode := e.Node

	// if test succeed, write the value
	n.Write(value, s.CurrentIndex)
	n.UpdateTTL(expireTime)

	// copy the value for safety
	valueCopy := value
	eNode.Value = &valueCopy
	eNode.Expiration, eNode.TTL = n.expirationAndTTL(s.clock)

	s.WatcherHub.notify(e)
	s.Stats.Inc(CompareAndSwapSuccess)
	reportWriteSuccess(CompareAndSwap)

	return e, nil
}

// Remove function remove the node.
func (n *node) Remove(dir, recursive bool, callback func(path string)) *etcdErr.Error {

	if n.IsDir() {
		if !dir {
			// cannot delete a directory without recursive set to true
			return etcdErr.NewError(etcdErr.EcodeNotFile, n.Path, n.store.CurrentIndex)
		}

		if len(n.Children) != 0 && !recursive {
			// cannot delete a directory if it is not empty and the operation
			// is not recursive
			return etcdErr.NewError(etcdErr.EcodeDirNotEmpty, n.Path, n.store.CurrentIndex)
		}
	}

	if !n.IsDir() { // key-value pair
		_, name := path.Split(n.Path)

		// find its parent and remove the node from the map
		if n.Parent != nil && n.Parent.Children[name] == n {
			delete(n.Parent.Children, name)
		}

		if callback != nil {
			callback(n.Path)
		}

		if !n.IsPermanent() {
			n.store.ttlKeyHeap.remove(n)
		}

		return nil
	}

	for _, child := range n.Children { // delete all children
		child.Remove(true, true, callback)
	}

	// delete self
	_, name := path.Split(n.Path)
	if n.Parent != nil && n.Parent.Children[name] == n {
		delete(n.Parent.Children, name)

		if callback != nil {
			callback(n.Path)
		}

		if !n.IsPermanent() {
			n.store.ttlKeyHeap.remove(n)
		}

	}

	return nil
}

// acquireHandler attempts to acquire a lock on the given key.
// The "key" parameter specifies the resource to lock.
// The "value" parameter specifies a value to associate with the lock.
// The "ttl" parameter specifies how long the lock will persist for.
// The "timeout" parameter specifies how long the request should wait for the lock.
func (h *handler) acquireHandler(w http.ResponseWriter, req *http.Request) error {
	h.client.SyncCluster()

	// Setup connection watcher.
	closeNotifier, _ := w.(http.CloseNotifier)
	closeChan := closeNotifier.CloseNotify()
	stopChan := make(chan bool)

	// Parse the lock "key".
	vars := mux.Vars(req)
	keypath := path.Join(prefix, vars["key"])
	value := req.FormValue("value")

	// Parse "timeout" parameter.
	var timeout int
	var err error
	if req.FormValue("timeout") == "" {
		timeout = -1
	} else if timeout, err = strconv.Atoi(req.FormValue("timeout")); err != nil {
		return etcdErr.NewError(etcdErr.EcodeTimeoutNaN, "Acquire", 0)
	}
	timeout = timeout + 1

	// Parse TTL.
	ttl, err := strconv.Atoi(req.FormValue("ttl"))
	if err != nil {
		return etcdErr.NewError(etcdErr.EcodeTTLNaN, "Acquire", 0)
	}

	// If node exists then just watch it. Otherwise create the node and watch it.
	node, index, pos := h.findExistingNode(keypath, value)
	if index > 0 {
		if pos == 0 {
			// If lock is already acquired then update the TTL.
			h.client.Update(node.Key, node.Value, uint64(ttl))
		} else {
			// Otherwise watch until it becomes acquired (or errors).
			err = h.watch(keypath, index, nil)
		}
	} else {
		index, err = h.createNode(keypath, value, ttl, closeChan, stopChan)
	}

	// Stop all goroutines.
	close(stopChan)

	// Check for an error.
	if err != nil {
		return err
	}

	// Write response.
	w.Write([]byte(strconv.Itoa(index)))
	return nil
}

func (s *store) CompareAndDelete(nodePath string, prevValue string, prevIndex uint64) (*Event, error) {
	var err *etcdErr.Error

	s.worldLock.Lock()
	defer s.worldLock.Unlock()

	defer func() {
		if err == nil {
			s.Stats.Inc(CompareAndDeleteSuccess)
			reportWriteSuccess(CompareAndDelete)
			return
		}

		s.Stats.Inc(CompareAndDeleteFail)
		reportWriteFailure(CompareAndDelete)
	}()

	nodePath = path.Clean(path.Join("/", nodePath))

	n, err := s.internalGet(nodePath)
	if err != nil { // if the node does not exist, return error
		return nil, err
	}
	if n.IsDir() { // can only compare and delete file
		return nil, etcdErr.NewError(etcdErr.EcodeNotFile, nodePath, s.CurrentIndex)
	}

	// If both of the prevValue and prevIndex are given, we will test both of them.
	// Command will be executed, only if both of the tests are successful.
	if ok, which := n.Compare(prevValue, prevIndex); !ok {
		cause := getCompareFailCause(n, which, prevValue, prevIndex)
		return nil, etcdErr.NewError(etcdErr.EcodeTestFailed, cause, s.CurrentIndex)
	}

	// update etcd index
	s.CurrentIndex++

	e := newEvent(CompareAndDelete, nodePath, s.CurrentIndex, n.CreatedIndex)
	e.EtcdIndex = s.CurrentIndex
	e.PrevNode = n.Repr(false, false, s.clock)

	callback := func(path string) { // notify function
		// notify the watchers with deleted set true
		s.WatcherHub.notifyWatchers(e, path, true)
	}

	err = n.Remove(false, false, callback)
	if err != nil {
		return nil, err
	}

	s.WatcherHub.notify(e)

	return e, nil
}

func (s *store) CompareAndSwap(nodePath string, prevValue string, prevIndex uint64,
	value string, expireTime time.Time) (*Event, error) {

	nodePath = path.Clean(path.Join("/", nodePath))
	// we do not allow the user to change "/"
	if nodePath == "/" {
		return nil, etcdErr.NewError(etcdErr.EcodeRootROnly, "/", s.CurrentIndex)
	}

	s.worldLock.Lock()
	defer s.worldLock.Unlock()

	n, err := s.internalGet(nodePath)

	if err != nil {
		s.Stats.Inc(CompareAndSwapFail)
		return nil, err
	}

	if n.IsDir() { // can only compare and swap file
		s.Stats.Inc(CompareAndSwapFail)
		return nil, etcdErr.NewError(etcdErr.EcodeNotFile, nodePath, s.CurrentIndex)
	}

	// If both of the prevValue and prevIndex are given, we will test both of them.
	// Command will be executed, only if both of the tests are successful.
	if !n.Compare(prevValue, prevIndex) {
		cause := fmt.Sprintf("[%v != %v] [%v != %v]", prevValue, n.Value, prevIndex, n.ModifiedIndex)
		s.Stats.Inc(CompareAndSwapFail)
		return nil, etcdErr.NewError(etcdErr.EcodeTestFailed, cause, s.CurrentIndex)
	}

	// update etcd index
	s.CurrentIndex++

	e := newEvent(CompareAndSwap, nodePath, s.CurrentIndex, n.CreatedIndex)
	e.PrevNode = n.Repr(false, false)
	eNode := e.Node

	// if test succeed, write the value
	n.Write(value, s.CurrentIndex)
	n.UpdateTTL(expireTime)

	// copy the value for safety
	valueCopy := ustrings.Clone(value)
	eNode.Value = &valueCopy
	eNode.Expiration, eNode.TTL = n.ExpirationAndTTL()

	s.WatcherHub.notify(e)
	s.Stats.Inc(CompareAndSwapSuccess)
	return e, nil
}

// Update function updates the value/ttl of the node.
// If the node is a file, the value and the ttl can be updated.
// If the node is a directory, only the ttl can be updated.
func (s *store) Update(nodePath string, newValue string, expireTime time.Time) (*Event, error) {
	nodePath = path.Clean(path.Join("/", nodePath))
	// we do not allow the user to change "/"
	if nodePath == "/" {
		return nil, etcdErr.NewError(etcdErr.EcodeRootROnly, "/", s.CurrentIndex)
	}

	s.worldLock.Lock()
	defer s.worldLock.Unlock()

	currIndex, nextIndex := s.CurrentIndex, s.CurrentIndex+1

	n, err := s.internalGet(nodePath)

	if err != nil { // if the node does not exist, return error
		s.Stats.Inc(UpdateFail)
		return nil, err
	}

	e := newEvent(Update, nodePath, nextIndex, n.CreatedIndex)
	eNode := e.Node

	if len(newValue) != 0 {
		if n.IsDir() {
			// if the node is a directory, we cannot update value
			s.Stats.Inc(UpdateFail)
			return nil, etcdErr.NewError(etcdErr.EcodeNotFile, nodePath, currIndex)
		}

		eNode.PrevValue = n.Value
		n.Write(newValue, nextIndex)
		eNode.Value = newValue

	} else {
		// do not update value
		eNode.Value = n.Value
	}

	// update ttl
	n.UpdateTTL(expireTime)

	eNode.Expiration, eNode.TTL = n.ExpirationAndTTL()

	s.WatcherHub.notify(e)

	s.Stats.Inc(UpdateSuccess)

	s.CurrentIndex = nextIndex

	return e, nil
}

// Join a server to the cluster
func (c *JoinCommandV1) Apply(context raft.Context) (interface{}, error) {
	ps, _ := context.Server().Context().(*PeerServer)

	b := make([]byte, 8)
	binary.PutUvarint(b, context.CommitIndex())

	// Make sure we're not getting a cached value from the registry.
	ps.registry.Invalidate(c.Name)

	// Check if the join command is from a previous peer, who lost all its previous log.
	if peerURL, ok := ps.registry.PeerURL(c.Name); ok {
		// If previous node restarts with different peer URL,
		// update its information.
		if peerURL != c.RaftURL {
			log.Infof("Rejoin with %v instead of %v from %v", c.RaftURL, peerURL, c.Name)
			if err := c.updatePeerURL(ps); err != nil {
				return []byte{0}, err
			}
		}
		return b, nil
	}

	// Check if the join command adds an instance that collides with existing one on peer URL.
	peerURLs := ps.registry.PeerURLs(ps.raftServer.Leader(), c.Name)
	for _, peerURL := range peerURLs {
		if peerURL == c.RaftURL {
			log.Warnf("%v tries to join the cluster with existing URL %v", c.Name, c.EtcdURL)
			return []byte{0}, etcdErr.NewError(etcdErr.EcodeExistingPeerAddr, c.EtcdURL, context.CommitIndex())
		}
	}

	// Check peer number in the cluster
	if ps.registry.PeerCount() >= ps.ClusterConfig().ActiveSize {
		log.Debug("Reject join request from ", c.Name)
		return []byte{0}, etcdErr.NewError(etcdErr.EcodeNoMorePeer, "", context.CommitIndex())
	}

	// Add to shared peer registry.
	ps.registry.RegisterPeer(c.Name, c.RaftURL, c.EtcdURL)

	// Add peer in raft
	err := context.Server().AddPeer(c.Name, "")

	// Add peer stats
	if c.Name != ps.RaftServer().Name() {
		ps.followersStats.Followers[c.Name] = &raftFollowerStats{}
		ps.followersStats.Followers[c.Name].Latency.Minimum = 1 << 63
	}

	return b, err
}

// renewLockHandler attempts to update the TTL on an existing lock.
// Returns a 200 OK if successful. Returns non-200 on error.
func (h *handler) renewLockHandler(w http.ResponseWriter, req *http.Request) error {
	h.client.SyncCluster()

	// Read the lock path.
	vars := mux.Vars(req)
	keypath := path.Join(prefix, vars["key"])

	// Parse new TTL parameter.
	ttl, err := strconv.Atoi(req.FormValue("ttl"))
	if err != nil {
		return etcdErr.NewError(etcdErr.EcodeTTLNaN, "Renew", 0)
	}

	// Read and set defaults for index and value.
	index := req.FormValue("index")
	value := req.FormValue("value")
	if len(index) == 0 && len(value) == 0 {
		return etcdErr.NewError(etcdErr.EcodeIndexOrValueRequired, "Renew", 0)
	}

	if len(index) == 0 {
		// If index is not specified then look it up by value.
		resp, err := h.client.Get(keypath, true, true)
		if err != nil {
			return err
		}
		nodes := lockNodes{resp.Node.Nodes}
		node, _ := nodes.FindByValue(value)
		if node == nil {
			return etcdErr.NewError(etcdErr.EcodeKeyNotFound, "Renew", 0)
		}
		index = path.Base(node.Key)

	} else if len(value) == 0 {
		// If value is not specified then default it to the previous value.
		resp, err := h.client.Get(path.Join(keypath, index), true, false)
		if err != nil {
			return err
		}
		value = resp.Node.Value
	}

	// Renew the lock, if it exists.
	if _, err = h.client.Update(path.Join(keypath, index), value, uint64(ttl)); err != nil {
		return err
	}

	return nil
}

// Add function adds a node to the receiver node.
// If the receiver is not a directory, a "Not A Directory" error will be returned.
// If there is an existing node with the same name under the directory, a "Already Exist"
// error will be returned
func (n *node) Add(child *node) *etcdErr.Error {
	if !n.IsDir() {
		return etcdErr.NewError(etcdErr.EcodeNotDir, "", n.store.CurrentIndex)
	}

	_, name := path.Split(child.Path)

	if _, ok := n.Children[name]; ok {
		return etcdErr.NewError(etcdErr.EcodeNodeExist, "", n.store.CurrentIndex)
	}

	n.Children[name] = child

	return nil
}

// deleteHandler remove a given leader.
func (h *handler) deleteHandler(w http.ResponseWriter, req *http.Request) error {
	vars := mux.Vars(req)
	name := req.FormValue("name")
	if name == "" {
		return etcdErr.NewError(etcdErr.EcodeNameRequired, "Delete", 0)
	}

	// Proxy the request to the the lock service.
	u, err := url.Parse(fmt.Sprintf("%s/mod/v2/lock/%s", h.addr, vars["key"]))
	if err != nil {
		return err
	}
	q := u.Query()
	q.Set("value", name)
	u.RawQuery = q.Encode()

	r, err := http.NewRequest("DELETE", u.String(), nil)
	if err != nil {
		return err
	}

	// Read from the leader lock.
	resp, err := h.client.Do(r)
	if err != nil {
		return err
	}
	defer resp.Body.Close()
	w.WriteHeader(resp.StatusCode)
	io.Copy(w, resp.Body)

	return nil
}

// Handler to return the basic stats of etcd
func StatsHttpHandler(w http.ResponseWriter, req *http.Request) error {
	option := req.URL.Path[len("/v1/stats/"):]

	switch option {
	case "self":
		w.WriteHeader(http.StatusOK)
		w.Write(r.Stats())
	case "leader":
		if r.State() == raft.Leader {
			w.Write(r.PeerStats())
		} else {
			leader := r.Leader()
			// current no leader
			if leader == "" {
				return etcdErr.NewError(300, "")
			}
			redirect(leader, true, w, req)
		}
	case "store":
		w.WriteHeader(http.StatusOK)
		w.Write(etcdStore.Stats())
	}

	return nil
}

// Adds a server handler to the router.
func (s *Server) handleFunc(r *mux.Router, path string, f func(http.ResponseWriter, *http.Request) error) *mux.Route {

	// Wrap the standard HandleFunc interface to pass in the server reference.
	return r.HandleFunc(path, func(w http.ResponseWriter, req *http.Request) {
		if req.Method == "HEAD" {
			w = &HEADResponseWriter{w}
		}

		// Log request.
		log.Debugf("[recv] %s %s %s [%s]", req.Method, s.URL(), req.URL.Path, req.RemoteAddr)

		// Forward request along if the server is a standby.
		if s.peerServer.Mode() == StandbyMode {
			if s.peerServer.standbyClientURL == "" {
				w.Header().Set("Content-Type", "application/json")
				etcdErr.NewError(402, "", 0).Write(w)
				return
			}
			uhttp.Redirect(s.peerServer.standbyClientURL, w, req)
			return
		}

		// Execute handler function and return error if necessary.
		if err := f(w, req); err != nil {
			if etcdErr, ok := err.(*etcdErr.Error); ok {
				log.Debug("Return error: ", (*etcdErr).Error())
				w.Header().Set("Content-Type", "application/json")
				etcdErr.Write(w)
			} else {
				http.Error(w, err.Error(), http.StatusInternalServerError)
			}
		}
	})
}