bridgecord/WatchedGuild.js

import { EventEmitter } from "events";
import { wait } from "./common.js";

class WatchedGuild extends EventEmitter {
    constructor() {
        super();

        this.knownWebhooks = new Map();
        this.upstreamGuildId = null;
    }

    pushEvent(e) {
        this.emit("pushed", e);
    }

    holdForEvent(timeout) {
        return new Promise((outerResolve, outerReject) => {
            let handler;
            Promise.race([
                new Promise((resolve, reject) => {
                    // potential memory leak here when too many promises are created and waiting
                    handler = (event) => {
                        resolve(event);
                    };
                    this.once("pushed", handler);
                }),
                wait(timeout, true)
            ]).then((result) => {
                if (handler)
                    this.removeListener("pushed", handler);
                outerResolve(result);
            }).catch(() => {
                if (handler)
                    this.removeListener("pushed", handler);
                outerResolve(null);
            });
        });
    }

    discordConnect(bot) {
        this.bot = bot;
        this.guildObject = this.bot.guilds.find(e => e.id === this.upstreamGuildId);

        if (!this.guildObject) {
            throw new Error("Could not find guild object from bot cache by id (is the upstreamGuildId valid and does the bot have access to it?)");
        }
        
        this.bot.on("GUILD_CREATE", (guild) => {
            if (guild.id === this.upstreamGuildId)
                this.guildObject = guild;
        });

        this.bot.on("GUILD_UPDATE", (guild) => {
            if (guild.id === this.upstreamGuildId)
                this.guildObject = guild;
        });

        this.bot.on("MESSAGE_CREATE", (message) => {
            if (message.guild_id !== this.upstreamGuildId)
                return;

            const maybeKnownWebhook = this.knownWebhooks.get(message.channel_id);
            if (maybeKnownWebhook && maybeKnownWebhook.id === message.webhook_id)
                return; // ignore messages coming from our webhook

            this.pushEvent({
                eventType: "MESSAGE_CREATE",
                message: message
            });
        });
    }

    userFacingChannelList() {
        return this.guildObject.channels.map(channel => ({ id: channel.id, name: channel.name, position: channel.position, type: channel.type, nsfw: channel.nsfw }));
    }

    async discordSendMessage(content, channelId, username, avatarURL=undefined) {
        let webhook = this.knownWebhooks.get(channelId);
        if (!webhook) {
            webhook = (await this.bot.api(["GET", `/channels/${channelId}/webhooks`]))
                .find(e => e.name === "well_known__bridge");
 
            if (!webhook)
                webhook = await this.bot.api(["POST", `/channels/${channelId}/webhooks`], {
                    name: "well_known__bridge"
                });

            this.knownWebhooks.set(channelId, webhook);
        }

        await this.bot.api(["POST", `/webhooks/${webhook.id}/${webhook.token}?wait=true`], {
            content,
            username,
            avatar_url: avatarURL,
            tts: false,
            allowed_mentions: {
                parse: ["users"]
            }
        });
    }
}

export default WatchedGuild;