Made SendMessage optional, extended ServerMessageSender

README.md

@@ -52,6 +52,11 @@ easily extend the API.
 The identifier interface forces whatever interface that embeds this one to be
 uniquely identifiable.
 
+### Configurator
+
+The configurator interface is a way for the frontend to display configuration
+options that the backend has.
+
 ### Server
 
 A server is any entity that is usually a channel or a guild.
@@ -61,11 +66,21 @@ A server is any entity that is usually a channel or a guild.
 - ServerList and/or ServerMessage
 - ServerIcon (optional)
 
+### ServerMessage
+
+A server message is an entity that contains messages to be displayed. An example
+would be channels in Discord and IRC.
+
+#### Interfaces
+
+- ServerMessageSender (optional): adds message sending capability.
+- ServerMessageSendCompleter (optional): adds message completion capability.
+
 ### Messages
 
 #### Interfaces
 
-- MessageHeader
+- MessageHeader: the minimum for a proper message.
 - MessageCreate or MessageUpdate or MessageDelete
 - MessageNonce (optional)
 - MessageAuthorAvatar (optional)

cchat.go

@@ -141,10 +141,21 @@ type ServerMessage interface {
 	// LeaveServer indicates the backend to stop calling the controller over.
 	// This should be called before any other JoinServer() calls are made.
 	LeaveServer() error
+}
+
+// ServerMessageSender optionally extends ServerMessage to add message sending
+// capability to the server.
+type ServerMessageSender interface {
 	// SendMessage is called by the frontend to send a message to this channel.
 	SendMessage(SendableMessage) error
 }
 
+// ServerMessageSendCompleter optionally extends ServerMessageSender to add
+// autocompletion into the message composer.
+type ServerMessageSendCompleter interface {
+	CompleteMessage(words []string, wordIndex int) []string
+}
+
 // SendableMessage is the bare minimum interface of a sendable message, that is,
 // a message that can be sent with SendMessage().
 type SendableMessage interface {