arikawa/state/store.go

package state

import (
	"errors"

	"github.com/diamondburned/arikawa/discord"
)

// Store is the state storage. It should handle mutex itself, and it should only
// concern itself with the local state.
// type Store interface {
// 	StoreMe
// 	StoreChannel
// 	StoreEmoji
// 	StoreGuild
// 	StoreMember
// 	StoreMessage
// 	StorePresence
// 	StoreRole

// 	// This should reset all the state to zero/null.
// 	Reset() error
// }

// Resetter is an optional state reset function that stores could implement.
type Resetter interface {
	Reset() error
}

// All methods in StoreGetter will be wrapped by the State. If the State can't
// find anything in the storage, it will call the API itself and automatically
// add what's missing into the storage.
//
// Methods that return with a slice should pay attention to race conditions that
// would mutate the underlying slice (and as a result the returned slice as
// well). The best way to avoid this is to copy the whole slice, like
// DefaultStore does.
type (
	StoreMe interface {
		Me() (*discord.User, error)
		MyselfSet(me *discord.User) error
	}

	StoreChannel interface {
		Channel(id discord.Snowflake) (*discord.Channel, error)
		Channels(guildID discord.Snowflake) ([]discord.Channel, error)
		PrivateChannels() ([]discord.Channel, error)

		// ChannelSet should switch on Type to know if it's a private channel or
		// not.
		ChannelSet(*discord.Channel) error
		ChannelRemove(*discord.Channel) error
	}

	StoreEmoji interface {
		Emoji(guildID, emojiID discord.Snowflake) (*discord.Emoji, error)
		Emojis(guildID discord.Snowflake) ([]discord.Emoji, error)
		EmojiSet(guildID discord.Snowflake, emojis []discord.Emoji) error
	}

	StoreGuild interface {
		Guild(id discord.Snowflake) (*discord.Guild, error)
		Guilds() ([]discord.Guild, error)
		GuildSet(*discord.Guild) error
		GuildRemove(id discord.Snowflake) error
	}

	StoreMember interface {
		Member(guildID, userID discord.Snowflake) (*discord.Member, error)
		Members(guildID discord.Snowflake) ([]discord.Member, error)
		MemberSet(guildID discord.Snowflake, member *discord.Member) error
		MemberRemove(guildID, userID discord.Snowflake) error
	}

	StoreMessage interface {
		Message(channelID, messageID discord.Snowflake) (*discord.Message, error)
		Messages(channelID discord.Snowflake) ([]discord.Message, error)
		MaxMessages() int // used to know if the state is filled or not.
		MessageSet(*discord.Message) error
		MessageRemove(channelID, messageID discord.Snowflake) error
	}

	StorePresence interface {
		// These don't get fetched from the API, it's Gateway only.
		Presence(guildID, userID discord.Snowflake) (*discord.Presence, error)
		Presences(guildID discord.Snowflake) ([]discord.Presence, error)
		PresenceSet(guildID discord.Snowflake, presence *discord.Presence) error
		PresenceRemove(guildID, userID discord.Snowflake) error
	}

	StoreRole interface {
		Role(guildID, roleID discord.Snowflake) (*discord.Role, error)
		Roles(guildID discord.Snowflake) ([]discord.Role, error)
		RoleSet(guildID discord.Snowflake, role *discord.Role) error
		RoleRemove(guildID, roleID discord.Snowflake) error
	}
)

// ErrStoreNotFound is an error that a store can use to return when something
// isn't in the storage. There is no strict restrictions on what uses this (the
// default one does, though), so be advised.
var ErrStoreNotFound = errors.New("item not found in store")