package connector

/*
	A generic connector framework for instant messaging protocols.

	Model:

	- A connector represents a connection to an outgoing service (IRC, XMPP, etc)
	  It satisfies a generic interface representing the actions that can be called
	  (send messages, join room, etc)
	
	- A handler represents a consumer of events happening on a connection
	  It satisfies a generic interface representing the events that can happend
	  (message received, rooms autojoined, etc)
	
	- A connector implements a given protocol that has an identifier
	  Each protocol identifier determines a namespace for user identifiers
	  and room identifiers which are globally unique for all connections using
	  this protocol.
	  For instance, a user can have two IRC conections to different servers.
	  Internally used user names and room identifiers must contain
	  the server name to be able to differentiate.
*/

type UserID string
type RoomID string

type Connector interface {
	// Set the handler that will receive events happening on this connection
	SetHandler(handler Handler)

	// Configure (or reconfigure) the connector and attempt to connect
	Configure(conf Configuration) error

	// Get the identifier of the protocol that is implemented by this connector
	Protocol() string

	// Get the user id of the connected user
	User() UserID

	// Set user information (nickname, picture, etc)
	SetUserInfo(info *UserInfo) error

	// Set room information (name, description, picture, etc)
	SetRoomInfo(roomId RoomID, info *RoomInfo) error

	// Try to join a channel
	// If no error happens, it must fire a Handler.Joined event
	Join(roomId RoomID) error

	// Leave a channel
	Leave(roomId RoomID)

	// Send an event
	Send(event *Event) error

	// Close the connection
	Close()
}

type Handler interface {
	// Called when a room was joined (automatically or by call to Connector.Join)
	Joined(roomId RoomID)

	// Called when the user left a room
	Left(roomId RoomID)

	// Called when a user's info is updated (changed their nickname, status, etc)
	// Can also be called with our own user ID when first loaded our user info
	UserInfoUpdated(user UserID, info *UserInfo)

	// Called when a room's info was updated,
	// or the first tome a room's info is retreived
	RoomInfoUpdated(roomId RoomID, info *RoomInfo)

	// Called when an event occurs in a room
	// This must not be called for events authored by the user of the connection
	Event(event *Event)
}

type EventType int
const (
	EVENT_JOIN EventType = iota
	EVENT_LEAVE
	EVENT_MESSAGE
	EVENT_ACTION
)

type Event struct {
	Type EventType

	// UserID of the user that sent the event
	// If this is a direct message event, this event can only have been authored
	// by the user we are talking to (and not by ourself)
	Author UserID

	// UserID of the targetted user in the case of a direct message,
	// empty if targetting a room
	Recipient UserID

	// RoomID of the room where the event happenned or of the targetted room,
	// or empty string if it happenned by direct message
	Room RoomID

	// Message text or action text
	Message string

	// Attached files such as images
	Attachements map[string]MediaObject
}

type UserInfo struct {
	Nickname string
	Status string
	Avatar MediaObject
}

type RoomInfo struct {
	Name string
	Description string
	Picture MediaObject
}

type MediaObject interface {
	Size() int
	MimeType() string

	// AsBytes: must always be implemented
	AsBytes() ([]byte, error)

	// AsString: not mandatory, may return an empty string
	// If so, AsBytes() is the only way to retrieve the object
	AsURL() string
}