// Create node
func (c *UpdateCommand) Apply(context raft.Context) (interface{}, error) {
	s, _ := context.Server().StateMachine().(store.Store)

	e, err := s.Update(c.Key, c.Value, c.ExpireTime)

	if err != nil {
		log.Debug(err)
		return nil, err
	}

	return e, nil
}

// Set the key-value pair if the current value of the key equals to the given prevValue
func (c *CompareAndSwapCommand) Apply(context raft.Context) (interface{}, error) {
	s, _ := context.Server().StateMachine().(store.Store)

	e, err := s.CompareAndSwap(c.Key, c.PrevValue, c.PrevIndex, c.Value, c.ExpireTime)

	if err != nil {
		log.Debug(err)
		return nil, err
	}

	return e, nil
}

// Create node
func (c *SetCommand) Apply(context raft.Context) (interface{}, error) {
	s, _ := context.Server().StateMachine().(store.Store)

	// create a new node or replace the old node.
	e, err := s.Set(c.Key, c.Dir, c.Value, c.ExpireTime)

	if err != nil {
		log.Debug(err)
		return nil, err
	}

	return e, nil
}

// Join a server to the cluster
func (c *JoinCommand) 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 _, ok := ps.registry.ClientURL(c.Name); ok {
		return b, nil
	}

	// Check peer number in the cluster
	if ps.registry.Count() == ps.Config.MaxClusterSize {
		log.Debug("Reject join request from ", c.Name)
		return []byte{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
	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
}

// Delete the key
func (c *DeleteCommand) Apply(context raft.Context) (interface{}, error) {
	s, _ := context.Server().StateMachine().(store.Store)

	if c.Recursive {
		// recursive implies dir
		c.Dir = true
	}

	e, err := s.Delete(c.Key, c.Dir, c.Recursive)

	if err != nil {
		log.Debug(err)
		return nil, err
	}

	return e, nil
}

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

	// Remove node from the shared registry.
	err := ps.registry.Unregister(c.Name)

	// Delete from stats
	delete(ps.followersStats.Followers, c.Name)

	if err != nil {
		log.Debugf("Error while unregistering: %s (%v)", c.Name, err)
		return []byte{0}, err
	}

	// Remove peer in raft
	err = context.Server().RemovePeer(c.Name)
	if err != nil {
		log.Debugf("Unable to remove peer: %s (%v)", c.Name, err)
		return []byte{0}, err
	}

	if c.Name == context.Server().Name() {
		// the removed node is this node

		// if the node is not replaying the previous logs
		// and the node has sent out a join request in this
		// start. It is sure that this node received a new remove
		// command and need to be removed
		if context.CommitIndex() > ps.joinIndex && ps.joinIndex != 0 {
			log.Debugf("server [%s] is removed", context.Server().Name())
			os.Exit(0)
		} else {
			// else ignore remove
			log.Debugf("ignore previous remove command.")
		}
	}

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

	return b, err
}

func (c SyncCommand) Apply(context raft.Context) (interface{}, error) {
	s, _ := context.Server().StateMachine().(store.Store)
	s.DeleteExpiredKeys(c.Time)

	return nil, nil
}