src/chat/SupportChat.ts

import {User} from '../session/User';

import {Chat} from './Chat';

type SupportChatParticipant = Pick<User, 'domain' | 'id' | 'username'>;

export interface SupportChatService {
	leaveSupportChat(id: string): Promise<void>;
	transferSupportChat(id: string, destination: SupportChatParticipant): Promise<void>;
}

// eslint-disable-next-line
export interface SupportChat extends Chat {}

export class SupportChat {
	private supportChatId: string;
	private chatService: SupportChatService;

	private constructor(supportChatId: string, chatService: SupportChatService) {
		this.supportChatId = supportChatId;
		this.chatService = chatService;
	}

	public static create(
		supportChatId: string,
		chatService: SupportChatService,
		chat: Chat,
	): SupportChat {
		const supportChat = new SupportChat(supportChatId, chatService);
		return Object.assign(Object.create(chat), {
			leave: supportChat.leave.bind(supportChat),
			transfer: supportChat.transfer.bind(supportChat),
		});
	}

	/**
	 * Leaves the current Support Chat
	 *
	 * If leaving participant is the chat's agent, the support chat is finished.
	 *
	 * @return {Promise<void>}
     */
	public async leave(): Promise<void> {
		await this.chatService.leaveSupportChat(this.supportChatId);
	}

	/**
	 * Transfers the current Support Chat to another agent
	 *
	 * Changes the agent who is assigned to this support chat.  The backend
	 * will generate an XMPP invitation to that destination agent.
	 *
	 * @param {object} destination The agent we want to transfer this chat to
	 * @param {string} destination.id The ID of the agent
	 * @param {string} destination.username The username of the agent
	 * @param {string} destination domain The domain of the agent
	 *
	 * @return {Promise<void>}
     */
	public async transfer(destination: SupportChatParticipant): Promise<void> {
		await this.chatService.transferSupportChat(this.supportChatId, destination);
	}
}