comunicapiv2/src/helpers/ConversationsHelper.ts

import { Conversation, BaseConversation } from "../entities/Conversation";
import { DatabaseHelper } from "./DatabaseHelper";
import { time } from "../utils/DateUtils";

/**
 * Conversations helper
 * 
 * @author Pierre HUBERT
 */

const LIST_TABLE = "comunic_conversations_list";
const USERS_TABLE = "comunic_conversations_users";
const MESSAGES_TABLE = "comunic_conversations_messages";

export class ConversationsHelper {

	/**
	 * Create a new conversation
	 * 
	 * @param conv Information about the conversation to create
	 */
	public static async Create(conv : BaseConversation) : Promise<number> {

		// Create the conversation in the main table
		const convID = await DatabaseHelper.InsertRow(LIST_TABLE, {
			"user_id": conv.ownerID,
			"name": conv.name,
			"last_active": time(),
			"creation_time": time()
		});

		// Add the members to the conversation
		for (const userID of conv.members) {
			await this.AddMember(
				convID, 
				userID, 
				conv.ownerID == userID ? conv.following : true);
		}

		return convID;
	}

	/**
	 * Add a member to a conversation
	 * 
	 * @param convID Conversation ID
	 * @param userID User ID
	 * @param following Specify whether the user is following
	 * the conversation or not
	 */
	private static async AddMember(convID : number, userID: number, following : boolean = true) {
		await DatabaseHelper.InsertRow(
			USERS_TABLE,
			{
				"conv_id": convID,
				"user_id": userID,
				"time_add": time(),
				"following": following ? 1 : 0,
				"saw_last_message": 1
			}
		);
	}

	/**
	 * Get the list of conversations of the user
	 * 
	 * @param userID Target user ID
	 */
	public static async GetListUser(userID: number) : Promise<Array<Conversation>> {
		
		// Fetch the list of conversations
		const result = await DatabaseHelper.Query({
			fields: [
				"*",
				"l.id as id",
				"l.user_id as owner_id" // The field conflits with user.user_id
			],
			table: LIST_TABLE + " l",
			joins: [

				// Joins with conversation members table
				{
					table: USERS_TABLE + " u",
					condition: "l.id = u.conv_id"
				}

			],
			where: {
				"u.user_id": userID
			},
			order: "l.last_active DESC"
		});

		const list = [];
		for (const el of result) {
			list.push(await this.DBToConversationInfo(el));
		}
		return list;
	}

	/**
	 * Get information about a single conversation
	 * 
	 * @param convID  The ID of the conversation to get
	 */
	public static async GetSingle(convID : number, userID: number) : Promise<Conversation | null> {
		const result = await DatabaseHelper.QueryRow({
			fields: [
				"*",
				"l.id as id",
				"l.user_id as owner_id",
			],
			table: LIST_TABLE + " l",
			joins: [
				// Joins with conversation members table
				{
					table: USERS_TABLE + " u",
					condition: "l.id = u.conv_id"
				}
			],
			where: {
				"l.id": convID,
				"u.user_id": userID
			}
		});

		if(!result)
			return null;
		
		return await this.DBToConversationInfo(result);
	}

	/**
	 * Check out whether a user is the member of a conversation or not
	 * 
	 * @param userID Target user ID
	 * @param convID Target conversation
	 */
	public static async DoesUsersBelongsTo(userID: number, convID: number) : Promise<boolean> {
		return await DatabaseHelper.Count({
			table: USERS_TABLE,
			where: {
				conv_id: convID,
				user_id: userID
			}
		}) == 1;
	}

	/**
	 * Update following state of the conversation
	 * 
	 * @param userID User to update
	 * @param convID Target conversation ID
	 * @param following New status
	 */
	public static async SetFollowing(userID: number, convID: number, following: boolean) {
		await DatabaseHelper.UpdateRows({
			table: USERS_TABLE,
			set: {
				"following": following ? 1 : 0
			},
			where: {
				"conv_id": convID,
				"user_id": userID
			}
		});
	}

	/**
	 * Get the list of members of a conversation
	 * 
	 * @param convID The ID of the target conversation
	 */
	private static async GetConversationMembers(convID : number): Promise<Array<number>> {
		const result = await DatabaseHelper.Query({
			table: USERS_TABLE,
			where: {
				"conv_id": convID
			},
			fields: ["user_id"]
		});

		return result.map((e) => e.user_id);
	}

	/**
	 * Turn a database entry into a conversation object
	 * 
	 * @param row 
	 */
	private static async DBToConversationInfo(row: any) : Promise<Conversation> {
		return {
			id: row.id,
			ownerID: row.owner_id,
			name: row.name,
			lastActive: row.last_active,
			timeCreate: row.time_add,
			following: row.following,
			sawLastMessage: row.saw_last_message == 1,
			members: await this.GetConversationMembers(row.id)
		}
	}
}