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arikawa/state/state.go
2021-12-25 15:08:01 -08:00

811 lines
20 KiB
Go

// Package state provides interfaces for a local or remote state, as well as
// abstractions around the REST API and Gateway events.
package state
import (
"context"
"sync"
"github.com/diamondburned/arikawa/v3/api"
"github.com/diamondburned/arikawa/v3/discord"
"github.com/diamondburned/arikawa/v3/gateway"
"github.com/diamondburned/arikawa/v3/session"
"github.com/diamondburned/arikawa/v3/session/shard"
"github.com/diamondburned/arikawa/v3/state/store"
"github.com/diamondburned/arikawa/v3/state/store/defaultstore"
"github.com/diamondburned/arikawa/v3/utils/handler"
"github.com/pkg/errors"
)
var (
MaxFetchMembers uint = 1000
MaxFetchGuilds uint = 100
)
// NewShardFunc creates a shard constructor with its own state registry and
// handlers. The given opts function is called everytime the State is created.
// The user should initialize handlers and intents in the opts function.
func NewShardFunc(opts func(*shard.Manager, *State)) shard.NewShardFunc {
return func(m *shard.Manager, id *gateway.Identifier) (shard.Shard, error) {
sessn := session.NewCustom(*id, api.NewClient(id.Token), handler.New())
state := NewFromSession(sessn, defaultstore.New())
opts(m, state)
return state, nil
}
}
// State is the cache to store events coming from Discord as well as data from
// API calls.
//
// Store
//
// The state basically provides abstractions on top of the API and the state
// storage (Store). The state storage is effectively a set of interfaces which
// allow arbitrary backends to be implemented.
//
// The default storage backend is a typical in-memory structure consisting of
// maps and slices. Custom backend implementations could embed this storage
// backend as an in-memory fallback. A good example of this would be embedding
// the default store for messages only, while handling everything else in Redis.
//
// The package also provides a no-op store (NoopStore) that implementations
// could embed. This no-op store will always return an error, which makes the
// state fetch information from the API. The setters are all no-ops, so the
// fetched data won't be updated.
//
// Handler
//
// The state uses its own handler over session's to make all handlers run after
// the state updates itself. A PreHandler is exposed in any case the user needs
// the handlers to run before the state updates itself. Refer to that field's
// documentation.
//
// The state also provides extra events and overrides to make up for Discord's
// inconsistencies in data. The following are known instances of such.
//
// The Guild Create event is split up to make the state's Guild Available, Guild
// Ready and Guild Join events. Refer to these events' documentations for more
// information.
//
// The Message Create and Message Update events with the Member field provided
// will have the User field copied from Author. This is because the User field
// will be empty, while the Member structure expects it to be there.
type State struct {
*session.Session
*store.Cabinet
// *: State doesn't actually keep track of pinned messages.
readyMu *sync.Mutex
ready gateway.ReadyEvent
// StateLog logs all errors that come from the state cache. This includes
// not found errors. Defaults to a no-op, as state errors aren't that
// important.
StateLog func(error)
// PreHandler is the manual hook that is executed before the State handler
// is. This should only be used for low-level operations.
// It's recommended to set Synchronous to true if you mutate the events.
PreHandler *handler.Handler // default nil
// Command handler with inherited methods. Ran after PreHandler. You should
// most of the time use this instead of Session's, to avoid race conditions
// with the State.
*handler.Handler
// List of channels with few messages, so it doesn't bother hitting the API
// again.
fewMessages map[discord.ChannelID]struct{}
fewMutex *sync.Mutex
// unavailableGuilds is a set of discord.GuildIDs of guilds that became
// unavailable after connecting to the gateway, i.e. they were sent in a
// GuildUnavailableEvent.
unavailableGuilds map[discord.GuildID]struct{}
// unreadyGuilds is a set of discord.GuildIDs of the guilds received during
// the Ready event. After receiving guild create events for those guilds,
// they will be removed.
unreadyGuilds map[discord.GuildID]struct{}
guildMutex *sync.Mutex
}
// New creates a new state.
func New(token string) *State {
return NewWithStore(token, defaultstore.New())
}
// NewWithIntents creates a new state with the given gateway intents. For more
// information, refer to gateway.Intents.
func NewWithIntents(token string, intents ...gateway.Intents) *State {
s := session.NewWithIntents(token, intents...)
return NewFromSession(s, defaultstore.New())
}
// NewWithIdentifier creates a new state with the given gateway identifier.
func NewWithIdentifier(id gateway.Identifier) *State {
s := session.NewWithIdentifier(id)
return NewFromSession(s, defaultstore.New())
}
// NewWithStore creates a new state with the given store cabinet.
func NewWithStore(token string, cabinet *store.Cabinet) *State {
s := session.New(token)
return NewFromSession(s, cabinet)
}
// NewFromSession creates a new State from the passed Session and Cabinet.
func NewFromSession(s *session.Session, cabinet *store.Cabinet) *State {
state := &State{
Session: s,
Cabinet: cabinet,
Handler: handler.New(),
StateLog: func(err error) {},
readyMu: new(sync.Mutex),
fewMessages: map[discord.ChannelID]struct{}{},
fewMutex: new(sync.Mutex),
unavailableGuilds: make(map[discord.GuildID]struct{}),
unreadyGuilds: make(map[discord.GuildID]struct{}),
guildMutex: new(sync.Mutex),
}
state.hookSession()
return state
}
// WithContext returns a shallow copy of State with the context replaced in the
// API client. All methods called on the State will use this given context. This
// method is thread-safe.
func (s *State) WithContext(ctx context.Context) *State {
copied := *s
copied.Session = s.Session.WithContext(ctx)
return &copied
}
// Ready returns a copy of the Ready event. Although this function is safe to
// call concurrently, its values should still not be changed, as certain types
// like slices are not concurrent-safe.
//
// Note that if Ready events are not received yet, then the returned event will
// be a zero-value Ready instance.
func (s *State) Ready() gateway.ReadyEvent {
s.readyMu.Lock()
r := s.ready
s.readyMu.Unlock()
return r
}
//// Helper methods
func (s *State) AuthorDisplayName(message *gateway.MessageCreateEvent) string {
if !message.GuildID.IsValid() {
return message.Author.Username
}
if message.Member != nil {
if message.Member.Nick != "" {
return message.Member.Nick
}
return message.Author.Username
}
n, err := s.MemberDisplayName(message.GuildID, message.Author.ID)
if err != nil {
return message.Author.Username
}
return n
}
func (s *State) MemberDisplayName(guildID discord.GuildID, userID discord.UserID) (string, error) {
member, err := s.Member(guildID, userID)
if err != nil {
return "", err
}
if member.Nick == "" {
return member.User.Username, nil
}
return member.Nick, nil
}
func (s *State) AuthorColor(message *gateway.MessageCreateEvent) (discord.Color, error) {
if !message.GuildID.IsValid() { // this is a dm
return discord.DefaultMemberColor, nil
}
if message.Member != nil {
guild, err := s.Guild(message.GuildID)
if err != nil {
return 0, err
}
return discord.MemberColor(*guild, *message.Member), nil
}
return s.MemberColor(message.GuildID, message.Author.ID)
}
func (s *State) MemberColor(guildID discord.GuildID, userID discord.UserID) (discord.Color, error) {
var wg sync.WaitGroup
var (
g *discord.Guild
m *discord.Member
gerr = store.ErrNotFound
merr = store.ErrNotFound
)
if s.HasIntents(gateway.IntentGuilds) {
g, gerr = s.Cabinet.Guild(guildID)
}
if s.HasIntents(gateway.IntentGuildMembers) {
m, merr = s.Cabinet.Member(guildID, userID)
}
switch {
case gerr != nil && merr != nil:
wg.Add(1)
go func() {
g, gerr = s.fetchGuild(guildID)
wg.Done()
}()
m, merr = s.fetchMember(guildID, userID)
case gerr != nil:
g, gerr = s.fetchGuild(guildID)
case merr != nil:
m, merr = s.fetchMember(guildID, userID)
}
wg.Wait()
if gerr != nil {
return 0, errors.Wrap(merr, "failed to get guild")
}
if merr != nil {
return 0, errors.Wrap(merr, "failed to get member")
}
return discord.MemberColor(*g, *m), nil
}
////
// Permissions gets the user's permissions in the given channel. If the channel
// is not in any guild, then an error is returned.
func (s *State) Permissions(
channelID discord.ChannelID, userID discord.UserID) (discord.Permissions, error) {
ch, err := s.Channel(channelID)
if err != nil {
return 0, errors.Wrap(err, "failed to get channel")
}
if !ch.GuildID.IsValid() {
return 0, errors.New("channel is not in a guild")
}
var wg sync.WaitGroup
var (
g *discord.Guild
m *discord.Member
gerr = store.ErrNotFound
merr = store.ErrNotFound
)
if s.HasIntents(gateway.IntentGuilds) {
g, gerr = s.Cabinet.Guild(ch.GuildID)
}
if s.HasIntents(gateway.IntentGuildMembers) {
m, merr = s.Cabinet.Member(ch.GuildID, userID)
}
switch {
case gerr != nil && merr != nil:
wg.Add(1)
go func() {
g, gerr = s.fetchGuild(ch.GuildID)
wg.Done()
}()
m, merr = s.fetchMember(ch.GuildID, userID)
case gerr != nil:
g, gerr = s.fetchGuild(ch.GuildID)
case merr != nil:
m, merr = s.fetchMember(ch.GuildID, userID)
}
wg.Wait()
if gerr != nil {
return 0, errors.Wrap(merr, "failed to get guild")
}
if merr != nil {
return 0, errors.Wrap(merr, "failed to get member")
}
return discord.CalcOverwrites(*g, *ch, *m), nil
}
////
func (s *State) Me() (*discord.User, error) {
u, err := s.Cabinet.Me()
if err == nil {
return u, nil
}
u, err = s.Session.Me()
if err != nil {
return nil, err
}
s.Cabinet.MyselfSet(*u, false)
return u, nil
}
////
func (s *State) Channel(id discord.ChannelID) (c *discord.Channel, err error) {
c, err = s.Cabinet.Channel(id)
if err == nil && s.tracksChannel(c) {
return
}
c, err = s.Session.Channel(id)
if err != nil {
return
}
if s.tracksChannel(c) {
s.Cabinet.ChannelSet(c, false)
}
return
}
func (s *State) Channels(guildID discord.GuildID) (cs []discord.Channel, err error) {
if s.HasIntents(gateway.IntentGuilds) {
cs, err = s.Cabinet.Channels(guildID)
if err == nil {
return
}
}
cs, err = s.Session.Channels(guildID)
if err != nil {
return
}
if s.HasIntents(gateway.IntentGuilds) {
for i := range cs {
s.Cabinet.ChannelSet(&cs[i], false)
}
}
return
}
func (s *State) CreatePrivateChannel(recipient discord.UserID) (*discord.Channel, error) {
c, err := s.Cabinet.CreatePrivateChannel(recipient)
if err == nil {
return c, nil
}
c, err = s.Session.CreatePrivateChannel(recipient)
if err != nil {
return nil, err
}
s.Cabinet.ChannelSet(c, false)
return c, nil
}
// PrivateChannels gets the direct messages of the user.
// This is not supported for bots.
func (s *State) PrivateChannels() ([]discord.Channel, error) {
cs, err := s.Cabinet.PrivateChannels()
if err == nil {
return cs, nil
}
cs, err = s.Session.PrivateChannels()
if err != nil {
return nil, err
}
for i := range cs {
s.Cabinet.ChannelSet(&cs[i], false)
}
return cs, nil
}
////
func (s *State) Emoji(
guildID discord.GuildID, emojiID discord.EmojiID) (e *discord.Emoji, err error) {
if s.HasIntents(gateway.IntentGuildEmojis) {
e, err = s.Cabinet.Emoji(guildID, emojiID)
if err == nil {
return
}
} else { // Fast path
return s.Session.Emoji(guildID, emojiID)
}
es, err := s.Session.Emojis(guildID)
if err != nil {
return nil, err
}
s.Cabinet.EmojiSet(guildID, es, false)
for _, e := range es {
if e.ID == emojiID {
return &e, nil
}
}
return nil, store.ErrNotFound
}
func (s *State) Emojis(guildID discord.GuildID) (es []discord.Emoji, err error) {
if s.HasIntents(gateway.IntentGuildEmojis) {
es, err = s.Cabinet.Emojis(guildID)
if err == nil {
return
}
}
es, err = s.Session.Emojis(guildID)
if err != nil {
return
}
if s.HasIntents(gateway.IntentGuildEmojis) {
s.Cabinet.EmojiSet(guildID, es, false)
}
return
}
////
func (s *State) Guild(id discord.GuildID) (*discord.Guild, error) {
if s.HasIntents(gateway.IntentGuilds) {
c, err := s.Cabinet.Guild(id)
if err == nil {
return c, nil
}
}
return s.fetchGuild(id)
}
// Guilds will only fill a maximum of 100 guilds from the API.
func (s *State) Guilds() (gs []discord.Guild, err error) {
if s.HasIntents(gateway.IntentGuilds) {
gs, err = s.Cabinet.Guilds()
if err == nil {
return
}
}
gs, err = s.Session.Guilds(MaxFetchGuilds)
if err != nil {
return
}
if s.HasIntents(gateway.IntentGuilds) {
for i := range gs {
s.Cabinet.GuildSet(&gs[i], false)
}
}
return
}
////
func (s *State) Member(guildID discord.GuildID, userID discord.UserID) (*discord.Member, error) {
if s.HasIntents(gateway.IntentGuildMembers) {
m, err := s.Cabinet.Member(guildID, userID)
if err == nil {
return m, nil
}
}
return s.fetchMember(guildID, userID)
}
func (s *State) Members(guildID discord.GuildID) (ms []discord.Member, err error) {
if s.HasIntents(gateway.IntentGuildMembers) {
ms, err = s.Cabinet.Members(guildID)
if err == nil {
return
}
}
ms, err = s.Session.Members(guildID, MaxFetchMembers)
if err != nil {
return
}
if s.HasIntents(gateway.IntentGuildMembers) {
for i := range ms {
s.Cabinet.MemberSet(guildID, &ms[i], false)
}
}
return
}
////
func (s *State) Message(
channelID discord.ChannelID, messageID discord.MessageID) (*discord.Message, error) {
m, err := s.Cabinet.Message(channelID, messageID)
if err == nil && s.tracksMessage(m) {
return m, nil
}
var (
wg sync.WaitGroup
c *discord.Channel
cerr = store.ErrNotFound
)
c, cerr = s.Cabinet.Channel(channelID)
if cerr != nil || !s.tracksChannel(c) {
wg.Add(1)
go func() {
c, cerr = s.Session.Channel(channelID)
if cerr == nil && s.HasIntents(gateway.IntentGuilds) {
s.Cabinet.ChannelSet(c, false)
}
wg.Done()
}()
}
m, err = s.Session.Message(channelID, messageID)
if err != nil {
return nil, errors.Wrap(err, "unable to fetch message")
}
wg.Wait()
if cerr != nil {
return nil, errors.Wrap(cerr, "unable to fetch channel")
}
m.ChannelID = c.ID
m.GuildID = c.GuildID
return m, err
}
// Messages returns a slice filled with the most recent messages sent in the
// channel with the passed ID. The method automatically paginates until it
// reaches the passed limit, or, if the limit is set to 0, has fetched all
// messages in the channel.
//
// As the underlying endpoint is capped at a maximum of 100 messages per
// request, at maximum a total of limit/100 rounded up requests will be made,
// although they may be less, if no more messages are available or there are
// cached messages.
// When fetching the messages, those with the highest ID, will be fetched
// first. The returned slice will be sorted from latest to oldest.
func (s *State) Messages(channelID discord.ChannelID, limit uint) ([]discord.Message, error) {
storeMessages, err := s.Cabinet.Messages(channelID)
if err == nil && s.tracksMessage(&storeMessages[0]) {
// Is the channel tiny?
s.fewMutex.Lock()
if _, ok := s.fewMessages[channelID]; ok {
s.fewMutex.Unlock()
return storeMessages, nil
}
// No, fetch from the API.
s.fewMutex.Unlock()
} else {
// Something wrong with the cached messages, make sure they aren't
// returned.
storeMessages = nil
}
// Store already has enough messages.
if len(storeMessages) >= int(limit) && limit > 0 {
return storeMessages[:limit], nil
}
// Decrease the limit, if we aren't fetching all messages.
if limit > 0 {
limit -= uint(len(storeMessages))
}
var before discord.MessageID = 0
if len(storeMessages) > 0 {
before = storeMessages[len(storeMessages)-1].ID
}
apiMessages, err := s.Session.MessagesBefore(channelID, before, limit)
if err != nil {
return nil, err
}
if len(storeMessages)+len(apiMessages) < s.MaxMessages() {
// Tiny channel, store this.
s.fewMutex.Lock()
s.fewMessages[channelID] = struct{}{}
s.fewMutex.Unlock()
}
if len(apiMessages) == 0 {
return storeMessages, nil
}
// New messages fetched weirdly does not have GuildID filled. If we have
// cached messages, we can use their GuildID. Otherwise, we need to fetch
// it from the api.
var guildID discord.GuildID
if len(storeMessages) > 0 {
guildID = storeMessages[0].GuildID
} else {
c, err := s.Channel(channelID)
if err == nil {
// If it's 0, it's 0 anyway. We don't need a check here.
guildID = c.GuildID
}
}
for _, m := range apiMessages {
m.GuildID = guildID
}
if s.tracksMessage(&apiMessages[0]) && len(storeMessages) < s.MaxMessages() {
// Only add as many messages as the store can hold.
i := s.MaxMessages() - len(storeMessages)
if i > len(apiMessages) {
i = len(apiMessages)
}
msgs := apiMessages[:i]
for i := range msgs {
s.Cabinet.MessageSet(&msgs[i], false)
}
}
return append(storeMessages, apiMessages...), nil
}
////
// Presence checks the state for user presences. If no guildID is given, it
// will look for the presence in all cached guilds.
func (s *State) Presence(gID discord.GuildID, uID discord.UserID) (*discord.Presence, error) {
if !s.HasIntents(gateway.IntentGuildPresences) {
return nil, store.ErrNotFound
}
// If there's no guild ID, look in all guilds
if !gID.IsValid() {
if !s.HasIntents(gateway.IntentGuilds) {
return nil, store.ErrNotFound
}
g, err := s.Cabinet.Guilds()
if err != nil {
return nil, err
}
for _, g := range g {
if p, err := s.Cabinet.Presence(g.ID, uID); err == nil {
return p, nil
}
}
return nil, store.ErrNotFound
}
return s.Cabinet.Presence(gID, uID)
}
////
func (s *State) Role(guildID discord.GuildID, roleID discord.RoleID) (target *discord.Role, err error) {
if s.HasIntents(gateway.IntentGuilds) {
target, err = s.Cabinet.Role(guildID, roleID)
if err == nil {
return
}
}
rs, err := s.Session.Roles(guildID)
if err != nil {
return
}
for i, r := range rs {
if r.ID == roleID {
r := r // copy to prevent mem aliasing
target = &r
}
if s.HasIntents(gateway.IntentGuilds) {
s.RoleSet(guildID, &rs[i], false)
}
}
if target == nil {
return nil, store.ErrNotFound
}
return
}
func (s *State) Roles(guildID discord.GuildID) ([]discord.Role, error) {
rs, err := s.Cabinet.Roles(guildID)
if err == nil {
return rs, nil
}
rs, err = s.Session.Roles(guildID)
if err != nil {
return nil, err
}
if s.HasIntents(gateway.IntentGuilds) {
for i := range rs {
s.RoleSet(guildID, &rs[i], false)
}
}
return rs, nil
}
func (s *State) fetchGuild(id discord.GuildID) (g *discord.Guild, err error) {
g, err = s.Session.Guild(id)
if err == nil && s.HasIntents(gateway.IntentGuilds) {
s.Cabinet.GuildSet(g, false)
}
return
}
func (s *State) fetchMember(gID discord.GuildID, uID discord.UserID) (m *discord.Member, err error) {
m, err = s.Session.Member(gID, uID)
if err == nil && s.HasIntents(gateway.IntentGuildMembers) {
s.Cabinet.MemberSet(gID, m, false)
}
return
}
// tracksMessage reports whether the state would track the passed message and
// messages from the same channel.
func (s *State) tracksMessage(m *discord.Message) bool {
return (m.GuildID.IsValid() && s.HasIntents(gateway.IntentGuildMessages)) ||
(!m.GuildID.IsValid() && s.HasIntents(gateway.IntentDirectMessages))
}
// tracksChannel reports whether the state would track the passed channel.
func (s *State) tracksChannel(c *discord.Channel) bool {
return (c.GuildID.IsValid() && s.HasIntents(gateway.IntentGuilds)) ||
!c.GuildID.IsValid()
}