Switch to discordgo upstream again (#1759)

* Switch to upstream discordgo again

* Fix discord api changes

1 files changed, 1277 insertions, 0 deletions

diff --git a/vendor/github.com/bwmarrin/discordgo/state.go b/vendor/github.com/bwmarrin/discordgo/state.go
new file mode 100644
index 00000000..e75be895
--- /dev/null
+++ b/vendor/github.com/bwmarrin/discordgo/state.go
@@ -0,0 +1,1277 @@
+// Discordgo - Discord bindings for Go
+// Available at https://github.com/bwmarrin/discordgo
+
+// Copyright 2015-2016 Bruce Marriner <bruce@sqls.net>.  All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// This file contains code related to state tracking.  If enabled, state
+// tracking will capture the initial READY packet and many other websocket
+// events and maintain an in-memory state of of guilds, channels, users, and
+// so forth.  This information can be accessed through the Session.State struct.
+
+package discordgo
+
+import (
+	"errors"
+	"sort"
+	"sync"
+)
+
+// ErrNilState is returned when the state is nil.
+var ErrNilState = errors.New("state not instantiated, please use discordgo.New() or assign Session.State")
+
+// ErrStateNotFound is returned when the state cache
+// requested is not found
+var ErrStateNotFound = errors.New("state cache not found")
+
+// ErrMessageIncompletePermissions is returned when the message
+// requested for permissions does not contain enough data to
+// generate the permissions.
+var ErrMessageIncompletePermissions = errors.New("message incomplete, unable to determine permissions")
+
+// A State contains the current known state.
+// As discord sends this in a READY blob, it seems reasonable to simply
+// use that struct as the data store.
+type State struct {
+	sync.RWMutex
+	Ready
+
+	// MaxMessageCount represents how many messages per channel the state will store.
+	MaxMessageCount    int
+	TrackChannels      bool
+	TrackThreads       bool
+	TrackEmojis        bool
+	TrackMembers       bool
+	TrackThreadMembers bool
+	TrackRoles         bool
+	TrackVoice         bool
+	TrackPresences     bool
+
+	guildMap   map[string]*Guild
+	channelMap map[string]*Channel
+	memberMap  map[string]map[string]*Member
+}
+
+// NewState creates an empty state.
+func NewState() *State {
+	return &State{
+		Ready: Ready{
+			PrivateChannels: []*Channel{},
+			Guilds:          []*Guild{},
+		},
+		TrackChannels:      true,
+		TrackThreads:       true,
+		TrackEmojis:        true,
+		TrackMembers:       true,
+		TrackThreadMembers: true,
+		TrackRoles:         true,
+		TrackVoice:         true,
+		TrackPresences:     true,
+		guildMap:           make(map[string]*Guild),
+		channelMap:         make(map[string]*Channel),
+		memberMap:          make(map[string]map[string]*Member),
+	}
+}
+
+func (s *State) createMemberMap(guild *Guild) {
+	members := make(map[string]*Member)
+	for _, m := range guild.Members {
+		members[m.User.ID] = m
+	}
+	s.memberMap[guild.ID] = members
+}
+
+// GuildAdd adds a guild to the current world state, or
+// updates it if it already exists.
+func (s *State) GuildAdd(guild *Guild) error {
+	if s == nil {
+		return ErrNilState
+	}
+
+	s.Lock()
+	defer s.Unlock()
+
+	// Update the channels to point to the right guild, adding them to the channelMap as we go
+	for _, c := range guild.Channels {
+		s.channelMap[c.ID] = c
+	}
+
+	// Add all the threads to the state in case of thread sync list.
+	for _, t := range guild.Threads {
+		s.channelMap[t.ID] = t
+	}
+
+	// If this guild contains a new member slice, we must regenerate the member map so the pointers stay valid
+	if guild.Members != nil {
+		s.createMemberMap(guild)
+	} else if _, ok := s.memberMap[guild.ID]; !ok {
+		// Even if we have no new member slice, we still initialize the member map for this guild if it doesn't exist
+		s.memberMap[guild.ID] = make(map[string]*Member)
+	}
+
+	if g, ok := s.guildMap[guild.ID]; ok {
+		// We are about to replace `g` in the state with `guild`, but first we need to
+		// make sure we preserve any fields that the `guild` doesn't contain from `g`.
+		if guild.MemberCount == 0 {
+			guild.MemberCount = g.MemberCount
+		}
+		if guild.Roles == nil {
+			guild.Roles = g.Roles
+		}
+		if guild.Emojis == nil {
+			guild.Emojis = g.Emojis
+		}
+		if guild.Members == nil {
+			guild.Members = g.Members
+		}
+		if guild.Presences == nil {
+			guild.Presences = g.Presences
+		}
+		if guild.Channels == nil {
+			guild.Channels = g.Channels
+		}
+		if guild.Threads == nil {
+			guild.Threads = g.Threads
+		}
+		if guild.VoiceStates == nil {
+			guild.VoiceStates = g.VoiceStates
+		}
+		*g = *guild
+		return nil
+	}
+
+	s.Guilds = append(s.Guilds, guild)
+	s.guildMap[guild.ID] = guild
+
+	return nil
+}
+
+// GuildRemove removes a guild from current world state.
+func (s *State) GuildRemove(guild *Guild) error {
+	if s == nil {
+		return ErrNilState
+	}
+
+	_, err := s.Guild(guild.ID)
+	if err != nil {
+		return err
+	}
+
+	s.Lock()
+	defer s.Unlock()
+
+	delete(s.guildMap, guild.ID)
+
+	for i, g := range s.Guilds {
+		if g.ID == guild.ID {
+			s.Guilds = append(s.Guilds[:i], s.Guilds[i+1:]...)
+			return nil
+		}
+	}
+
+	return nil
+}
+
+// Guild gets a guild by ID.
+// Useful for querying if @me is in a guild:
+//     _, err := discordgo.Session.State.Guild(guildID)
+//     isInGuild := err == nil
+func (s *State) Guild(guildID string) (*Guild, error) {
+	if s == nil {
+		return nil, ErrNilState
+	}
+
+	s.RLock()
+	defer s.RUnlock()
+
+	if g, ok := s.guildMap[guildID]; ok {
+		return g, nil
+	}
+
+	return nil, ErrStateNotFound
+}
+
+func (s *State) presenceAdd(guildID string, presence *Presence) error {
+	guild, ok := s.guildMap[guildID]
+	if !ok {
+		return ErrStateNotFound
+	}
+
+	for i, p := range guild.Presences {
+		if p.User.ID == presence.User.ID {
+			//guild.Presences[i] = presence
+
+			//Update status
+			guild.Presences[i].Activities = presence.Activities
+			if presence.Status != "" {
+				guild.Presences[i].Status = presence.Status
+			}
+
+			//Update the optionally sent user information
+			//ID Is a mandatory field so you should not need to check if it is empty
+			guild.Presences[i].User.ID = presence.User.ID
+
+			if presence.User.Avatar != "" {
+				guild.Presences[i].User.Avatar = presence.User.Avatar
+			}
+			if presence.User.Discriminator != "" {
+				guild.Presences[i].User.Discriminator = presence.User.Discriminator
+			}
+			if presence.User.Email != "" {
+				guild.Presences[i].User.Email = presence.User.Email
+			}
+			if presence.User.Token != "" {
+				guild.Presences[i].User.Token = presence.User.Token
+			}
+			if presence.User.Username != "" {
+				guild.Presences[i].User.Username = presence.User.Username
+			}
+
+			return nil
+		}
+	}
+
+	guild.Presences = append(guild.Presences, presence)
+	return nil
+}
+
+// PresenceAdd adds a presence to the current world state, or
+// updates it if it already exists.
+func (s *State) PresenceAdd(guildID string, presence *Presence) error {
+	if s == nil {
+		return ErrNilState
+	}
+
+	s.Lock()
+	defer s.Unlock()
+
+	return s.presenceAdd(guildID, presence)
+}
+
+// PresenceRemove removes a presence from the current world state.
+func (s *State) PresenceRemove(guildID string, presence *Presence) error {
+	if s == nil {
+		return ErrNilState
+	}
+
+	guild, err := s.Guild(guildID)
+	if err != nil {
+		return err
+	}
+
+	s.Lock()
+	defer s.Unlock()
+
+	for i, p := range guild.Presences {
+		if p.User.ID == presence.User.ID {
+			guild.Presences = append(guild.Presences[:i], guild.Presences[i+1:]...)
+			return nil
+		}
+	}
+
+	return ErrStateNotFound
+}
+
+// Presence gets a presence by ID from a guild.
+func (s *State) Presence(guildID, userID string) (*Presence, error) {
+	if s == nil {
+		return nil, ErrNilState
+	}
+
+	guild, err := s.Guild(guildID)
+	if err != nil {
+		return nil, err
+	}
+
+	for _, p := range guild.Presences {
+		if p.User.ID == userID {
+			return p, nil
+		}
+	}
+
+	return nil, ErrStateNotFound
+}
+
+// TODO: Consider moving Guild state update methods onto *Guild.
+
+func (s *State) memberAdd(member *Member) error {
+	guild, ok := s.guildMap[member.GuildID]
+	if !ok {
+		return ErrStateNotFound
+	}
+
+	members, ok := s.memberMap[member.GuildID]
+	if !ok {
+		return ErrStateNotFound
+	}
+
+	m, ok := members[member.User.ID]
+	if !ok {
+		members[member.User.ID] = member
+		guild.Members = append(guild.Members, member)
+	} else {
+		// We are about to replace `m` in the state with `member`, but first we need to
+		// make sure we preserve any fields that the `member` doesn't contain from `m`.
+		if member.JoinedAt.IsZero() {
+			member.JoinedAt = m.JoinedAt
+		}
+		*m = *member
+	}
+	return nil
+}
+
+// MemberAdd adds a member to the current world state, or
+// updates it if it already exists.
+func (s *State) MemberAdd(member *Member) error {
+	if s == nil {
+		return ErrNilState
+	}
+
+	s.Lock()
+	defer s.Unlock()
+
+	return s.memberAdd(member)
+}
+
+// MemberRemove removes a member from current world state.
+func (s *State) MemberRemove(member *Member) error {
+	if s == nil {
+		return ErrNilState
+	}
+
+	guild, err := s.Guild(member.GuildID)
+	if err != nil {
+		return err
+	}
+
+	s.Lock()
+	defer s.Unlock()
+
+	members, ok := s.memberMap[member.GuildID]
+	if !ok {
+		return ErrStateNotFound
+	}
+
+	_, ok = members[member.User.ID]
+	if !ok {
+		return ErrStateNotFound
+	}
+	delete(members, member.User.ID)
+
+	for i, m := range guild.Members {
+		if m.User.ID == member.User.ID {
+			guild.Members = append(guild.Members[:i], guild.Members[i+1:]...)
+			return nil
+		}
+	}
+
+	return ErrStateNotFound
+}
+
+// Member gets a member by ID from a guild.
+func (s *State) Member(guildID, userID string) (*Member, error) {
+	if s == nil {
+		return nil, ErrNilState
+	}
+
+	s.RLock()
+	defer s.RUnlock()
+
+	members, ok := s.memberMap[guildID]
+	if !ok {
+		return nil, ErrStateNotFound
+	}
+
+	m, ok := members[userID]
+	if ok {
+		return m, nil
+	}
+
+	return nil, ErrStateNotFound
+}
+
+// RoleAdd adds a role to the current world state, or
+// updates it if it already exists.
+func (s *State) RoleAdd(guildID string, role *Role) error {
+	if s == nil {
+		return ErrNilState
+	}
+
+	guild, err := s.Guild(guildID)
+	if err != nil {
+		return err
+	}
+
+	s.Lock()
+	defer s.Unlock()
+
+	for i, r := range guild.Roles {
+		if r.ID == role.ID {
+			guild.Roles[i] = role
+			return nil
+		}
+	}
+
+	guild.Roles = append(guild.Roles, role)
+	return nil
+}
+
+// RoleRemove removes a role from current world state by ID.
+func (s *State) RoleRemove(guildID, roleID string) error {
+	if s == nil {
+		return ErrNilState
+	}
+
+	guild, err := s.Guild(guildID)
+	if err != nil {
+		return err
+	}
+
+	s.Lock()
+	defer s.Unlock()
+
+	for i, r := range guild.Roles {
+		if r.ID == roleID {
+			guild.Roles = append(guild.Roles[:i], guild.Roles[i+1:]...)
+			return nil
+		}
+	}
+
+	return ErrStateNotFound
+}
+
+// Role gets a role by ID from a guild.
+func (s *State) Role(guildID, roleID string) (*Role, error) {
+	if s == nil {
+		return nil, ErrNilState
+	}
+
+	guild, err := s.Guild(guildID)
+	if err != nil {
+		return nil, err
+	}
+
+	s.RLock()
+	defer s.RUnlock()
+
+	for _, r := range guild.Roles {
+		if r.ID == roleID {
+			return r, nil
+		}
+	}
+
+	return nil, ErrStateNotFound
+}
+
+// ChannelAdd adds a channel to the current world state, or
+// updates it if it already exists.
+// Channels may exist either as PrivateChannels or inside
+// a guild.
+func (s *State) ChannelAdd(channel *Channel) error {
+	if s == nil {
+		return ErrNilState
+	}
+
+	s.Lock()
+	defer s.Unlock()
+
+	// If the channel exists, replace it
+	if c, ok := s.channelMap[channel.ID]; ok {
+		if channel.Messages == nil {
+			channel.Messages = c.Messages
+		}
+		if channel.PermissionOverwrites == nil {
+			channel.PermissionOverwrites = c.PermissionOverwrites
+		}
+		if channel.ThreadMetadata == nil {
+			channel.ThreadMetadata = c.ThreadMetadata
+		}
+
+		*c = *channel
+		return nil
+	}
+
+	if channel.Type == ChannelTypeDM || channel.Type == ChannelTypeGroupDM {
+		s.PrivateChannels = append(s.PrivateChannels, channel)
+		s.channelMap[channel.ID] = channel
+		return nil
+	}
+
+	guild, ok := s.guildMap[channel.GuildID]
+	if !ok {
+		return ErrStateNotFound
+	}
+
+	if channel.IsThread() {
+		guild.Threads = append(guild.Threads, channel)
+	} else {
+		guild.Channels = append(guild.Channels, channel)
+	}
+
+	s.channelMap[channel.ID] = channel
+
+	return nil
+}
+
+// ChannelRemove removes a channel from current world state.
+func (s *State) ChannelRemove(channel *Channel) error {
+	if s == nil {
+		return ErrNilState
+	}
+
+	_, err := s.Channel(channel.ID)
+	if err != nil {
+		return err
+	}
+
+	if channel.Type == ChannelTypeDM || channel.Type == ChannelTypeGroupDM {
+		s.Lock()
+		defer s.Unlock()
+
+		for i, c := range s.PrivateChannels {
+			if c.ID == channel.ID {
+				s.PrivateChannels = append(s.PrivateChannels[:i], s.PrivateChannels[i+1:]...)
+				break
+			}
+		}
+		delete(s.channelMap, channel.ID)
+		return nil
+	}
+
+	guild, err := s.Guild(channel.GuildID)
+	if err != nil {
+		return err
+	}
+
+	s.Lock()
+	defer s.Unlock()
+
+	if channel.IsThread() {
+		for i, t := range guild.Threads {
+			if t.ID == channel.ID {
+				guild.Threads = append(guild.Threads[:i], guild.Threads[i+1:]...)
+				break
+			}
+		}
+	} else {
+		for i, c := range guild.Channels {
+			if c.ID == channel.ID {
+				guild.Channels = append(guild.Channels[:i], guild.Channels[i+1:]...)
+				break
+			}
+		}
+	}
+
+	delete(s.channelMap, channel.ID)
+
+	return nil
+}
+
+// ThreadListSync syncs guild threads with provided ones.
+func (s *State) ThreadListSync(tls *ThreadListSync) error {
+	guild, err := s.Guild(tls.GuildID)
+	if err != nil {
+		return err
+	}
+
+	s.Lock()
+	defer s.Unlock()
+
+	// This algorithm filters out archived or
+	// threads which are children of channels in channelIDs
+	// and then it adds all synced threads to guild threads and cache
+	index := 0
+outer:
+	for _, t := range guild.Threads {
+		if !t.ThreadMetadata.Archived && tls.ChannelIDs != nil {
+			for _, v := range tls.ChannelIDs {
+				if t.ParentID == v {
+					delete(s.channelMap, t.ID)
+					continue outer
+				}
+			}
+			guild.Threads[index] = t
+			index++
+		} else {
+			delete(s.channelMap, t.ID)
+		}
+	}
+	guild.Threads = guild.Threads[:index]
+	for _, t := range tls.Threads {
+		s.channelMap[t.ID] = t
+		guild.Threads = append(guild.Threads, t)
+	}
+
+	for _, m := range tls.Members {
+		if c, ok := s.channelMap[m.ID]; ok {
+			c.Member = m
+		}
+	}
+
+	return nil
+}
+
+// ThreadMembersUpdate updates thread members list
+func (s *State) ThreadMembersUpdate(tmu *ThreadMembersUpdate) error {
+	thread, err := s.Channel(tmu.ID)
+	if err != nil {
+		return err
+	}
+	s.Lock()
+	defer s.Unlock()
+
+	for idx, member := range thread.Members {
+		for _, removedMember := range tmu.RemovedMembers {
+			if member.ID == removedMember {
+				thread.Members = append(thread.Members[:idx], thread.Members[idx+1:]...)
+				break
+			}
+		}
+	}
+
+	for _, addedMember := range tmu.AddedMembers {
+		thread.Members = append(thread.Members, addedMember.ThreadMember)
+		if addedMember.Member != nil {
+			err = s.memberAdd(addedMember.Member)
+			if err != nil {
+				return err
+			}
+		}
+		if addedMember.Presence != nil {
+			err = s.presenceAdd(tmu.GuildID, addedMember.Presence)
+			if err != nil {
+				return err
+			}
+		}
+	}
+	thread.MemberCount = tmu.MemberCount
+
+	return nil
+}
+
+// ThreadMemberUpdate sets or updates member data for the current user.
+func (s *State) ThreadMemberUpdate(mu *ThreadMemberUpdate) error {
+	thread, err := s.Channel(mu.ID)
+	if err != nil {
+		return err
+	}
+
+	thread.Member = mu.ThreadMember
+	return nil
+}
+
+// GuildChannel gets a channel by ID from a guild.
+// This method is Deprecated, use Channel(channelID)
+func (s *State) GuildChannel(guildID, channelID string) (*Channel, error) {
+	return s.Channel(channelID)
+}
+
+// PrivateChannel gets a private channel by ID.
+// This method is Deprecated, use Channel(channelID)
+func (s *State) PrivateChannel(channelID string) (*Channel, error) {
+	return s.Channel(channelID)
+}
+
+// Channel gets a channel by ID, it will look in all guilds and private channels.
+func (s *State) Channel(channelID string) (*Channel, error) {
+	if s == nil {
+		return nil, ErrNilState
+	}
+
+	s.RLock()
+	defer s.RUnlock()
+
+	if c, ok := s.channelMap[channelID]; ok {
+		return c, nil
+	}
+
+	return nil, ErrStateNotFound
+}
+
+// Emoji returns an emoji for a guild and emoji id.
+func (s *State) Emoji(guildID, emojiID string) (*Emoji, error) {
+	if s == nil {
+		return nil, ErrNilState
+	}
+
+	guild, err := s.Guild(guildID)
+	if err != nil {
+		return nil, err
+	}
+
+	s.RLock()
+	defer s.RUnlock()
+
+	for _, e := range guild.Emojis {
+		if e.ID == emojiID {
+			return e, nil
+		}
+	}
+
+	return nil, ErrStateNotFound
+}
+
+// EmojiAdd adds an emoji to the current world state.
+func (s *State) EmojiAdd(guildID string, emoji *Emoji) error {
+	if s == nil {
+		return ErrNilState
+	}
+
+	guild, err := s.Guild(guildID)
+	if err != nil {
+		return err
+	}
+
+	s.Lock()
+	defer s.Unlock()
+
+	for i, e := range guild.Emojis {
+		if e.ID == emoji.ID {
+			guild.Emojis[i] = emoji
+			return nil
+		}
+	}
+
+	guild.Emojis = append(guild.Emojis, emoji)
+	return nil
+}
+
+// EmojisAdd adds multiple emojis to the world state.
+func (s *State) EmojisAdd(guildID string, emojis []*Emoji) error {
+	for _, e := range emojis {
+		if err := s.EmojiAdd(guildID, e); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+// MessageAdd adds a message to the current world state, or updates it if it exists.
+// If the channel cannot be found, the message is discarded.
+// Messages are kept in state up to s.MaxMessageCount per channel.
+func (s *State) MessageAdd(message *Message) error {
+	if s == nil {
+		return ErrNilState
+	}
+
+	c, err := s.Channel(message.ChannelID)
+	if err != nil {
+		return err
+	}
+
+	s.Lock()
+	defer s.Unlock()
+
+	// If the message exists, merge in the new message contents.
+	for _, m := range c.Messages {
+		if m.ID == message.ID {
+			if message.Content != "" {
+				m.Content = message.Content
+			}
+			if message.EditedTimestamp != nil {
+				m.EditedTimestamp = message.EditedTimestamp
+			}
+			if message.Mentions != nil {
+				m.Mentions = message.Mentions
+			}
+			if message.Embeds != nil {
+				m.Embeds = message.Embeds
+			}
+			if message.Attachments != nil {
+				m.Attachments = message.Attachments
+			}
+			if !message.Timestamp.IsZero() {
+				m.Timestamp = message.Timestamp
+			}
+			if message.Author != nil {
+				m.Author = message.Author
+			}
+			if message.Components != nil {
+				m.Components = message.Components
+			}
+
+			return nil
+		}
+	}
+
+	c.Messages = append(c.Messages, message)
+
+	if len(c.Messages) > s.MaxMessageCount {
+		c.Messages = c.Messages[len(c.Messages)-s.MaxMessageCount:]
+	}
+
+	return nil
+}
+
+// MessageRemove removes a message from the world state.
+func (s *State) MessageRemove(message *Message) error {
+	if s == nil {
+		return ErrNilState
+	}
+
+	return s.messageRemoveByID(message.ChannelID, message.ID)
+}
+
+// messageRemoveByID removes a message by channelID and messageID from the world state.
+func (s *State) messageRemoveByID(channelID, messageID string) error {
+	c, err := s.Channel(channelID)
+	if err != nil {
+		return err
+	}
+
+	s.Lock()
+	defer s.Unlock()
+
+	for i, m := range c.Messages {
+		if m.ID == messageID {
+			c.Messages = append(c.Messages[:i], c.Messages[i+1:]...)
+
+			return nil
+		}
+	}
+
+	return ErrStateNotFound
+}
+
+func (s *State) voiceStateUpdate(update *VoiceStateUpdate) error {
+	guild, err := s.Guild(update.GuildID)
+	if err != nil {
+		return err
+	}
+
+	s.Lock()
+	defer s.Unlock()
+
+	// Handle Leaving Channel
+	if update.ChannelID == "" {
+		for i, state := range guild.VoiceStates {
+			if state.UserID == update.UserID {
+				guild.VoiceStates = append(guild.VoiceStates[:i], guild.VoiceStates[i+1:]...)
+				return nil
+			}
+		}
+	} else {
+		for i, state := range guild.VoiceStates {
+			if state.UserID == update.UserID {
+				guild.VoiceStates[i] = update.VoiceState
+				return nil
+			}
+		}
+
+		guild.VoiceStates = append(guild.VoiceStates, update.VoiceState)
+	}
+
+	return nil
+}
+
+// VoiceState gets a VoiceState by guild and user ID.
+func (s *State) VoiceState(guildID, userID string) (*VoiceState, error) {
+	if s == nil {
+		return nil, ErrNilState
+	}
+
+	guild, err := s.Guild(guildID)
+	if err != nil {
+		return nil, err
+	}
+
+	for _, state := range guild.VoiceStates {
+		if state.UserID == userID {
+			return state, nil
+		}
+	}
+
+	return nil, ErrStateNotFound
+}
+
+// Message gets a message by channel and message ID.
+func (s *State) Message(channelID, messageID string) (*Message, error) {
+	if s == nil {
+		return nil, ErrNilState
+	}
+
+	c, err := s.Channel(channelID)
+	if err != nil {
+		return nil, err
+	}
+
+	s.RLock()
+	defer s.RUnlock()
+
+	for _, m := range c.Messages {
+		if m.ID == messageID {
+			return m, nil
+		}
+	}
+
+	return nil, ErrStateNotFound
+}
+
+// OnReady takes a Ready event and updates all internal state.
+func (s *State) onReady(se *Session, r *Ready) (err error) {
+	if s == nil {
+		return ErrNilState
+	}
+
+	s.Lock()
+	defer s.Unlock()
+
+	// We must track at least the current user for Voice, even
+	// if state is disabled, store the bare essentials.
+	if !se.StateEnabled {
+		ready := Ready{
+			Version:   r.Version,
+			SessionID: r.SessionID,
+			User:      r.User,
+		}
+
+		s.Ready = ready
+
+		return nil
+	}
+
+	s.Ready = *r
+
+	for _, g := range s.Guilds {
+		s.guildMap[g.ID] = g
+		s.createMemberMap(g)
+
+		for _, c := range g.Channels {
+			s.channelMap[c.ID] = c
+		}
+	}
+
+	for _, c := range s.PrivateChannels {
+		s.channelMap[c.ID] = c
+	}
+
+	return nil
+}
+
+// OnInterface handles all events related to states.
+func (s *State) OnInterface(se *Session, i interface{}) (err error) {
+	if s == nil {
+		return ErrNilState
+	}
+
+	r, ok := i.(*Ready)
+	if ok {
+		return s.onReady(se, r)
+	}
+
+	if !se.StateEnabled {
+		return nil
+	}
+
+	switch t := i.(type) {
+	case *GuildCreate:
+		err = s.GuildAdd(t.Guild)
+	case *GuildUpdate:
+		err = s.GuildAdd(t.Guild)
+	case *GuildDelete:
+		var old *Guild
+		old, err = s.Guild(t.ID)
+		if err == nil {
+			oldCopy := *old
+			t.BeforeDelete = &oldCopy
+		}
+
+		err = s.GuildRemove(t.Guild)
+	case *GuildMemberAdd:
+		// Updates the MemberCount of the guild.
+		guild, err := s.Guild(t.Member.GuildID)
+		if err != nil {
+			return err
+		}
+		guild.MemberCount++
+
+		// Caches member if tracking is enabled.
+		if s.TrackMembers {
+			err = s.MemberAdd(t.Member)
+		}
+	case *GuildMemberUpdate:
+		if s.TrackMembers {
+			err = s.MemberAdd(t.Member)
+		}
+	case *GuildMemberRemove:
+		// Updates the MemberCount of the guild.
+		guild, err := s.Guild(t.Member.GuildID)
+		if err != nil {
+			return err
+		}
+		guild.MemberCount--
+
+		// Removes member from the cache if tracking is enabled.
+		if s.TrackMembers {
+			err = s.MemberRemove(t.Member)
+		}
+	case *GuildMembersChunk:
+		if s.TrackMembers {
+			for i := range t.Members {
+				t.Members[i].GuildID = t.GuildID
+				err = s.MemberAdd(t.Members[i])
+			}
+		}
+
+		if s.TrackPresences {
+			for _, p := range t.Presences {
+				err = s.PresenceAdd(t.GuildID, p)
+			}
+		}
+	case *GuildRoleCreate:
+		if s.TrackRoles {
+			err = s.RoleAdd(t.GuildID, t.Role)
+		}
+	case *GuildRoleUpdate:
+		if s.TrackRoles {
+			err = s.RoleAdd(t.GuildID, t.Role)
+		}
+	case *GuildRoleDelete:
+		if s.TrackRoles {
+			err = s.RoleRemove(t.GuildID, t.RoleID)
+		}
+	case *GuildEmojisUpdate:
+		if s.TrackEmojis {
+			err = s.EmojisAdd(t.GuildID, t.Emojis)
+		}
+	case *ChannelCreate:
+		if s.TrackChannels {
+			err = s.ChannelAdd(t.Channel)
+		}
+	case *ChannelUpdate:
+		if s.TrackChannels {
+			err = s.ChannelAdd(t.Channel)
+		}
+	case *ChannelDelete:
+		if s.TrackChannels {
+			err = s.ChannelRemove(t.Channel)
+		}
+	case *ThreadCreate:
+		if s.TrackThreads {
+			err = s.ChannelAdd(t.Channel)
+		}
+	case *ThreadUpdate:
+		if s.TrackThreads {
+			old, err := s.Channel(t.ID)
+			if err == nil {
+				oldCopy := *old
+				t.BeforeUpdate = &oldCopy
+			}
+			err = s.ChannelAdd(t.Channel)
+		}
+	case *ThreadDelete:
+		if s.TrackThreads {
+			err = s.ChannelRemove(t.Channel)
+		}
+	case *ThreadMemberUpdate:
+		if s.TrackThreads {
+			err = s.ThreadMemberUpdate(t)
+		}
+	case *ThreadMembersUpdate:
+		if s.TrackThreadMembers {
+			err = s.ThreadMembersUpdate(t)
+		}
+	case *ThreadListSync:
+		if s.TrackThreads {
+			err = s.ThreadListSync(t)
+		}
+	case *MessageCreate:
+		if s.MaxMessageCount != 0 {
+			err = s.MessageAdd(t.Message)
+		}
+	case *MessageUpdate:
+		if s.MaxMessageCount != 0 {
+			var old *Message
+			old, err = s.Message(t.ChannelID, t.ID)
+			if err == nil {
+				oldCopy := *old
+				t.BeforeUpdate = &oldCopy
+			}
+
+			err = s.MessageAdd(t.Message)
+		}
+	case *MessageDelete:
+		if s.MaxMessageCount != 0 {
+			var old *Message
+			old, err = s.Message(t.ChannelID, t.ID)
+			if err == nil {
+				oldCopy := *old
+				t.BeforeDelete = &oldCopy
+			}
+
+			err = s.MessageRemove(t.Message)
+		}
+	case *MessageDeleteBulk:
+		if s.MaxMessageCount != 0 {
+			for _, mID := range t.Messages {
+				s.messageRemoveByID(t.ChannelID, mID)
+			}
+		}
+	case *VoiceStateUpdate:
+		if s.TrackVoice {
+			var old *VoiceState
+			old, err = s.VoiceState(t.GuildID, t.UserID)
+			if err == nil {
+				oldCopy := *old
+				t.BeforeUpdate = &oldCopy
+			}
+
+			err = s.voiceStateUpdate(t)
+		}
+	case *PresenceUpdate:
+		if s.TrackPresences {
+			s.PresenceAdd(t.GuildID, &t.Presence)
+		}
+		if s.TrackMembers {
+			if t.Status == StatusOffline {
+				return
+			}
+
+			var m *Member
+			m, err = s.Member(t.GuildID, t.User.ID)
+
+			if err != nil {
+				// Member not found; this is a user coming online
+				m = &Member{
+					GuildID: t.GuildID,
+					User:    t.User,
+				}
+			} else {
+				if t.User.Username != "" {
+					m.User.Username = t.User.Username
+				}
+			}
+
+			err = s.MemberAdd(m)
+		}
+
+	}
+
+	return
+}
+
+// UserChannelPermissions returns the permission of a user in a channel.
+// userID    : The ID of the user to calculate permissions for.
+// channelID : The ID of the channel to calculate permission for.
+func (s *State) UserChannelPermissions(userID, channelID string) (apermissions int64, err error) {
+	if s == nil {
+		return 0, ErrNilState
+	}
+
+	channel, err := s.Channel(channelID)
+	if err != nil {
+		return
+	}
+
+	guild, err := s.Guild(channel.GuildID)
+	if err != nil {
+		return
+	}
+
+	member, err := s.Member(guild.ID, userID)
+	if err != nil {
+		return
+	}
+
+	return memberPermissions(guild, channel, userID, member.Roles), nil
+}
+
+// MessagePermissions returns the permissions of the author of the message
+// in the channel in which it was sent.
+func (s *State) MessagePermissions(message *Message) (apermissions int64, err error) {
+	if s == nil {
+		return 0, ErrNilState
+	}
+
+	if message.Author == nil || message.Member == nil {
+		return 0, ErrMessageIncompletePermissions
+	}
+
+	channel, err := s.Channel(message.ChannelID)
+	if err != nil {
+		return
+	}
+
+	guild, err := s.Guild(channel.GuildID)
+	if err != nil {
+		return
+	}
+
+	return memberPermissions(guild, channel, message.Author.ID, message.Member.Roles), nil
+}
+
+// UserColor returns the color of a user in a channel.
+// While colors are defined at a Guild level, determining for a channel is more useful in message handlers.
+// 0 is returned in cases of error, which is the color of @everyone.
+// userID    : The ID of the user to calculate the color for.
+// channelID   : The ID of the channel to calculate the color for.
+func (s *State) UserColor(userID, channelID string) int {
+	if s == nil {
+		return 0
+	}
+
+	channel, err := s.Channel(channelID)
+	if err != nil {
+		return 0
+	}
+
+	guild, err := s.Guild(channel.GuildID)
+	if err != nil {
+		return 0
+	}
+
+	member, err := s.Member(guild.ID, userID)
+	if err != nil {
+		return 0
+	}
+
+	return firstRoleColorColor(guild, member.Roles)
+}
+
+// MessageColor returns the color of the author's name as displayed
+// in the client associated with this message.
+func (s *State) MessageColor(message *Message) int {
+	if s == nil {
+		return 0
+	}
+
+	if message.Member == nil || message.Member.Roles == nil {
+		return 0
+	}
+
+	channel, err := s.Channel(message.ChannelID)
+	if err != nil {
+		return 0
+	}
+
+	guild, err := s.Guild(channel.GuildID)
+	if err != nil {
+		return 0
+	}
+
+	return firstRoleColorColor(guild, message.Member.Roles)
+}
+
+func firstRoleColorColor(guild *Guild, memberRoles []string) int {
+	roles := Roles(guild.Roles)
+	sort.Sort(roles)
+
+	for _, role := range roles {
+		for _, roleID := range memberRoles {
+			if role.ID == roleID {
+				if role.Color != 0 {
+					return role.Color
+				}
+			}
+		}
+	}
+
+	for _, role := range roles {
+		if role.ID == guild.ID {
+			return role.Color
+		}
+	}
+
+	return 0
+}