memegoat/backend/src/messages/messages.service.ts

import { ForbiddenException, Injectable } 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);
	}
}