out-of-your-element/m2d/actions/add-reaction.js

// @ts-check

const assert = require("assert").strict
const Ty = require("../../types")

const passthrough = require("../../passthrough")
const {discord, sync, db, select} = passthrough
/** @type {import("../converters/utils")} */
const utils = sync.require("../converters/utils")

/**
 * @param {Ty.Event.Outer<Ty.Event.M_Reaction>} event
 */
async function addReaction(event) {
	const channelID = select("channel_room", "channel_id", "WHERE room_id = ?").pluck().get(event.room_id)
	if (!channelID) return // We just assume the bridge has already been created
	const messageID = select("event_message", "message_id", "WHERE event_id = ? AND part = 0").pluck().get(event.content["m.relates_to"].event_id) // 0 = primary
	if (!messageID) return // Nothing can be done if the parent message was never bridged.

	const emoji = event.content["m.relates_to"].key // TODO: handle custom text or emoji reactions
	let discordPreferredEncoding
	if (emoji.startsWith("mxc://")) {
		// Custom emoji
		let row = select("emoji", ["id", "name"], "WHERE mxc_url = ?").get(emoji)
		if (!row && event.content.shortcode) {
			// Use the name to try to find a known emoji with the same name.
			const name = event.content.shortcode.replace(/^:|:$/g, "")
			row = select("emoji", ["id", "name"], "WHERE name = ?").get(name)
		}
		if (!row) {
			// We don't have this emoji and there's no realistic way to just-in-time upload a new emoji somewhere.
			// Sucks!
			return
		}
		// Cool, we got an exact or a candidate emoji.
		discordPreferredEncoding = encodeURIComponent(`${row.name}:${row.id}`)
	} else {
		// Default emoji
		// https://github.com/discord/discord-api-docs/issues/2723#issuecomment-807022205 ????????????
		const encoded = encodeURIComponent(emoji)
		const encodedTrimmed = encoded.replace(/%EF%B8%8F/g, "")

		const forceTrimmedList = [
			"%F0%9F%91%8D", // 👍
			"%E2%AD%90" // ⭐
		]

		discordPreferredEncoding =
			( forceTrimmedList.includes(encodedTrimmed) ? encodedTrimmed
			: encodedTrimmed !== encoded && [...emoji].length === 2 ? encoded
			: encodedTrimmed)

		console.log("add reaction from matrix:", emoji, encoded, encodedTrimmed, "chosen:", discordPreferredEncoding)
	}

	await discord.snow.channel.createReaction(channelID, messageID, discordPreferredEncoding) // acting as the discord bot itself

	db.prepare("REPLACE INTO reaction (hashed_event_id, message_id, encoded_emoji) VALUES (?, ?, ?)").run(utils.getEventIDHash(event.event_id), messageID, discordPreferredEncoding)
}

module.exports.addReaction = addReaction