feat: implement messaging functionality with real-time updates

- Introduced a messaging module on the backend using NestJS, including repository, service, controller, DTOs, and WebSocket Gateway.
- Developed a frontend messaging page with conversation management, real-time message handling, and chat UI.
- Implemented `MessageService` for API integrations and `SocketProvider` for real-time WebSocket updates.
- Enhanced database schema to support conversations, participants, and messages with Drizzle ORM.

backend/src/messages/messages.service.ts

@@ -0,0 +1,60 @@
+import {
+	ForbiddenException,
+	Injectable,
+	NotFoundException,
+} from "@nestjs/common";
+import { EventsGateway } from "../realtime/events.gateway";
+import type { CreateMessageDto } from "./dto/create-message.dto";
+import { MessagesRepository } from "./repositories/messages.repository";
+
+@Injectable()
+export class MessagesService {
+	constructor(
+		private readonly messagesRepository: MessagesRepository,
+		private readonly eventsGateway: EventsGateway,
+	) {}
+
+	async sendMessage(senderId: string, dto: CreateMessageDto) {
+		let conversation = await this.messagesRepository.findConversationBetweenUsers(
+			senderId,
+			dto.recipientId,
+		);
+
+		if (!conversation) {
+			const newConv = await this.messagesRepository.createConversation();
+			await this.messagesRepository.addParticipant(newConv.id, senderId);
+			await this.messagesRepository.addParticipant(newConv.id, dto.recipientId);
+			conversation = newConv;
+		}
+
+		const message = await this.messagesRepository.createMessage({
+			conversationId: conversation.id,
+			senderId,
+			text: dto.text,
+		});
+
+		// Notify recipient via WebSocket
+		this.eventsGateway.sendToUser(dto.recipientId, "new_message", {
+			conversationId: conversation.id,
+			message,
+		});
+
+		return message;
+	}
+
+	async getConversations(userId: string) {
+		return this.messagesRepository.findAllConversations(userId);
+	}
+
+	async getMessages(userId: string, conversationId: string) {
+		const isParticipant = await this.messagesRepository.isParticipant(
+			conversationId,
+			userId,
+		);
+		if (!isParticipant) {
+			throw new ForbiddenException("You are not part of this conversation");
+		}
+
+		return this.messagesRepository.findMessagesByConversationId(conversationId);
+	}
+}