out-of-your-element/d2m/converters/message-to-event.js

// @ts-check

const assert = require("assert").strict
const markdown = require("discord-markdown")
const pb = require("prettier-bytes")
const DiscordTypes = require("discord-api-types/v10")

const passthrough = require("../../passthrough")
const {sync, db, discord, select, from} = passthrough
/** @type {import("../../matrix/file")} */
const file = sync.require("../../matrix/file")
/** @type {import("./lottie")} */
const lottie = sync.require("./lottie")
const reg = require("../../matrix/read-registration")

const userRegex = reg.namespaces.users.map(u => new RegExp(u.regex))

function getDiscordParseCallbacks(message, useHTML) {
	return {
		/** @param {{id: string, type: "discordUser"}} node */
		user: node => {
			const mxid = select("sim", "mxid", {user_id: node.id}).pluck().get()
			const username = message.mentions.find(ment => ment.id === node.id)?.username || node.id
			if (mxid && useHTML) {
				return `<a href="https://matrix.to/#/${mxid}">@${username}</a>`
			} else {
				return `@${username}:`
			}
		},
		/** @param {{id: string, type: "discordChannel"}} node */
		channel: node => {
			const row = select("channel_room", ["room_id", "name", "nick"], {channel_id: node.id}).get()
			if (!row) {
				return `<#${node.id}>` // fallback for when this channel is not bridged
			} else if (useHTML) {
				return `<a href="https://matrix.to/#/${row.room_id}">#${row.nick || row.name}</a>`
			} else {
				return `#${row.nick || row.name}`
			}
		},
		/** @param {{animated: boolean, name: string, id: string, type: "discordEmoji"}} node */
		emoji: node => {
			if (useHTML) {
				const mxc = select("emoji", "mxc_url", {emoji_id: node.id}).pluck().get()
				if (mxc) {
					return `<img data-mx-emoticon height="32" src="${mxc}" title=":${node.name}:" alt=":${node.name}:">`
				} else { // We shouldn't get here since all emojis should have been added ahead of time in the messageToEvent function.
					return `<img src="mxc://cadence.moe/${node.id}" data-mx-emoticon alt=":${node.name}:" title=":${node.name}:" height="24">`
				}
			} else {
				return `:${node.name}:`
			}
		},
		role: node =>
			"@&" + node.id,
		everyone: node =>
			"@room",
		here: node =>
			"@here"
	}
}

/**
 * @param {import("discord-api-types/v10").APIMessage} message
 * @param {import("discord-api-types/v10").APIGuild} guild
 * @param {{includeReplyFallback?: boolean, includeEditFallbackStar?: boolean}} options default values:
 * - includeReplyFallback: true
 * - includeEditFallbackStar: false
 * @param {{api: import("../../matrix/api")}} di simple-as-nails dependency injection for the matrix API
 */
async function messageToEvent(message, guild, options = {}, di) {
	const events = []

	if (message.type === DiscordTypes.MessageType.ThreadCreated) {
		// This is the kind of message that appears when somebody makes a thread which isn't close enough to the message it's based off.
		// It lacks the lines and the pill, so it looks kind of like a member join message, and it says:
		// [#] NICKNAME started a thread: __THREAD NAME__. __See all threads__
		// We're already bridging the THREAD_CREATED gateway event to make a comparable message, so drop this one.
		return []
	}

	if (message.type === DiscordTypes.MessageType.ThreadStarterMessage) {
		// This is the message that appears at the top of a thread when the thread was based off an existing message.
		// It's just a message reference, no content.
		const ref = message.message_reference
		assert(ref)
		assert(ref.message_id)
		const eventID = select("event_message", "event_id", {message_id: ref.message_id}).pluck().get()
		const roomID = select("channel_room", "room_id", {channel_id: ref.channel_id}).pluck().get()
		if (!eventID || !roomID) return []
		const event = await di.api.getEvent(roomID, eventID)
		return [{
			...event.content,
			$type: event.type
		}]
	}

	/**
	   @type {{room?: boolean, user_ids?: string[]}}
		We should consider the following scenarios for mentions:
		1. A discord user rich-replies to a matrix user with a text post
			+ The matrix user needs to be m.mentioned in the text event
			+ The matrix user needs to have their name/mxid/link in the text event (notification fallback)
				- So prepend their `@name:` to the start of the plaintext body
		2. A discord user rich-replies to a matrix user with an image event only
			+ The matrix user needs to be m.mentioned in the image event
			+ TODO The matrix user needs to have their name/mxid in the image event's body field, alongside the filename (notification fallback)
				- So append their name to the filename body, I guess!!!
		3. A discord user `@`s a matrix user in the text body of their text box
			+ The matrix user needs to be m.mentioned in the text event
			+ No change needed to the text event content: it already has their name
				- So make sure we don't do anything in this case.
	*/
	const mentions = {}
	let repliedToEventRow = null
	let repliedToEventSenderMxid = null

	function addMention(mxid) {
		if (!mentions.user_ids) mentions.user_ids = []
		if (!mentions.user_ids.includes(mxid)) mentions.user_ids.push(mxid)
	}

	// Mentions scenarios 1 and 2, part A. i.e. translate relevant message.mentions to m.mentions
	// (Still need to do scenarios 1 and 2 part B, and scenario 3.)
	if (message.type === DiscordTypes.MessageType.Reply && message.message_reference?.message_id) {
		const row = from("event_message").join("message_channel", "message_id").join("channel_room", "channel_id").select("event_id", "room_id", "source").and("WHERE message_id = ? AND part = 0").get(message.message_reference.message_id)
		if (row) {
			repliedToEventRow = row
		}
	}
	if (repliedToEventRow && repliedToEventRow.source === 0) { // reply was originally from Matrix
		// Need to figure out who sent that event...
		const event = await di.api.getEvent(repliedToEventRow.room_id, repliedToEventRow.event_id)
		repliedToEventSenderMxid = event.sender
		// Need to add the sender to m.mentions
		addMention(repliedToEventSenderMxid)
	}

	async function addTextEvent(content, msgtype, {scanMentions}) {
		content = content.replace(/https:\/\/(?:ptb\.|canary\.|www\.)?discord(?:app)?\.com\/channels\/([0-9]+)\/([0-9]+)\/([0-9]+)/, (whole, guildID, channelID, messageID) => {
			const eventID = select("event_message", "event_id", {message_id: messageID}).pluck().get()
			const roomID = select("channel_room", "room_id", {channel_id: channelID}).pluck().get()
			if (eventID && roomID) {
				return `https://matrix.to/#/${roomID}/${eventID}`
			} else {
				return `${whole} [event not found]`
			}
		})

		// Handling emojis that we don't know about. The emoji has to be present in the DB for it to be picked up in the emoji markdown converter.
		// So we scan the message ahead of time for all its emojis and ensure they are in the DB.
		const emojiMatches = [...content.matchAll(/<(a?):([^:>]{2,64}):([0-9]+)>/g)]
		const emojiDownloads = []
		for (const match of emojiMatches) {
			const id = match[3]
			const name = match[2]
			const animated = +!!match[1]
			const exists = select("emoji", "emoji_id", {emoji_id: id}).pluck().get()
			if (!exists) {
				// The custom emoji is not registered. We will register it and then add it.
				emojiDownloads.push(
					file.uploadDiscordFileToMxc(file.emoji(id, animated)).then(mxc => {
						db.prepare("INSERT OR IGNORE INTO emoji (id, name, animated, mxc_url) VALUES (?, ?, ?, ?)").run(id, name, animated, mxc)
					})
				)
			}
		}
		await Promise.all(emojiDownloads)

		let html = markdown.toHTML(content, {
			discordCallback: getDiscordParseCallbacks(message, true)
		}, null, null)

		let body = markdown.toHTML(content, {
			discordCallback: getDiscordParseCallbacks(message, false),
			discordOnly: true,
			escapeHTML: false,
		}, null, null)

		// Mentions scenario 3: scan the message content for written @mentions of matrix users. Allows for up to one space between @ and mention.
		if (scanMentions) {
			const matches = [...content.matchAll(/@ ?([a-z0-9._]+)\b/gi)]
			if (matches.length && matches.some(m => m[1].match(/[a-z]/i))) {
				const writtenMentionsText = matches.map(m => m[1].toLowerCase())
				const roomID = select("channel_room", "room_id", {channel_id: message.channel_id}).pluck().get()
				assert(roomID)
				const {joined} = await di.api.getJoinedMembers(roomID)
				for (const [mxid, member] of Object.entries(joined)) {
					if (!userRegex.some(rx => mxid.match(rx))) {
						const localpart = mxid.match(/@([^:]*)/)
						assert(localpart)
						const displayName = member.display_name || localpart[1]
						if (writtenMentionsText.includes(localpart[1].toLowerCase()) || writtenMentionsText.includes(displayName.toLowerCase())) addMention(mxid)
					}
				}
			}
		}

		// Star * prefix for fallback edits
		if (options.includeEditFallbackStar) {
			body = "* " + body
			html = "* " + html
		}

		// Fallback body/formatted_body for replies
		// This branch is optional - do NOT change anything apart from the reply fallback, since it may not be run
		if (repliedToEventRow && options.includeReplyFallback !== false) {
			let repliedToDisplayName
			let repliedToUserHtml
			if (repliedToEventRow?.source === 0 && repliedToEventSenderMxid) {
				const match = repliedToEventSenderMxid.match(/^@([^:]*)/)
				assert(match)
				repliedToDisplayName = match[1] || "a Matrix user" // grab the localpart as the display name, whatever
				repliedToUserHtml = `<a href="https://matrix.to/#/${repliedToEventSenderMxid}">${repliedToDisplayName}</a>`
			} else {
				repliedToDisplayName = message.referenced_message?.author.global_name || message.referenced_message?.author.username || "a Discord user"
				repliedToUserHtml = repliedToDisplayName
			}
			let repliedToContent = message.referenced_message?.content
			if (repliedToContent == "") repliedToContent = "[Media]"
			else if (!repliedToContent) repliedToContent = "[Replied-to message content wasn't provided by Discord]"
			const repliedToHtml = markdown.toHTML(repliedToContent, {
				discordCallback: getDiscordParseCallbacks(message, true)
			}, null, null)
			const repliedToBody = markdown.toHTML(repliedToContent, {
				discordCallback: getDiscordParseCallbacks(message, false),
				discordOnly: true,
				escapeHTML: false,
			}, null, null)
			html = `<mx-reply><blockquote><a href="https://matrix.to/#/${repliedToEventRow.room_id}/${repliedToEventRow.event_id}">In reply to</a> ${repliedToUserHtml}`
				+ `<br>${repliedToHtml}</blockquote></mx-reply>`
				+ html
			body = (`${repliedToDisplayName}: ` // scenario 1 part B for mentions
				+ repliedToBody).split("\n").map(line => "> " + line).join("\n")
				+ "\n\n" + body
		}

		const newTextMessageEvent = {
			$type: "m.room.message",
			"m.mentions": mentions,
			msgtype,
			body: body
		}

		const isPlaintext = body === html

		if (!isPlaintext) {
			Object.assign(newTextMessageEvent, {
				format: "org.matrix.custom.html",
				formatted_body: html
			})
		}

		events.push(newTextMessageEvent)
	}


	let msgtype = "m.text"
	// Handle message type 4, channel name changed
	if (message.type === DiscordTypes.MessageType.ChannelNameChange) {
		msgtype = "m.emote"
		message.content = "changed the channel name to **" + message.content + "**"
	}

	// Text content appears first
	if (message.content) {
		await addTextEvent(message.content, msgtype, {scanMentions: true})
	}

	// Then attachments
	const attachmentEvents = await Promise.all(message.attachments.map(async attachment => {
		const emoji =
			attachment.content_type?.startsWith("image/jp") ? "📸"
			: attachment.content_type?.startsWith("image/") ? "🖼️"
			: attachment.content_type?.startsWith("video/") ? "🎞️"
			: attachment.content_type?.startsWith("text/") ? "📝"
			: attachment.content_type?.startsWith("audio/") ? "🎶"
			: "📄"
		// no native media spoilers in Element, so we'll post a link instead, forcing it to not preview using a blockquote
		if (attachment.filename.startsWith("SPOILER_")) {
			return {
				$type: "m.room.message",
				"m.mentions": mentions,
				msgtype: "m.text",
				body: `${emoji} Uploaded SPOILER file: ${attachment.url} (${pb(attachment.size)})`,
				format: "org.matrix.custom.html",
				formatted_body: `<blockquote>${emoji} Uploaded SPOILER file: <span data-mx-spoiler><a href="${attachment.url}">View</a></span> (${pb(attachment.size)})</blockquote>`
			}
		}
		// for large files, always link them instead of uploading so I don't use up all the space in the content repo
		else if (attachment.size > reg.ooye.max_file_size) {
			return {
				$type: "m.room.message",
				"m.mentions": mentions,
				msgtype: "m.text",
				body: `${emoji} Uploaded file: ${attachment.url} (${pb(attachment.size)})`,
				format: "org.matrix.custom.html",
				formatted_body: `${emoji} Uploaded file: <a href="${attachment.url}">${attachment.filename}</a> (${pb(attachment.size)})`
			}
		} else if (attachment.content_type?.startsWith("image/") && attachment.width && attachment.height) {
			return {
				$type: "m.room.message",
				"m.mentions": mentions,
				msgtype: "m.image",
				url: await file.uploadDiscordFileToMxc(attachment.url),
				external_url: attachment.url,
				body: attachment.filename,
				filename: attachment.filename,
				info: {
					mimetype: attachment.content_type,
					w: attachment.width,
					h: attachment.height,
					size: attachment.size
				}
			}
		} else if (attachment.content_type?.startsWith("video/") && attachment.width && attachment.height) {
			return {
				$type: "m.room.message",
				"m.mentions": mentions,
				msgtype: "m.video",
				url: await file.uploadDiscordFileToMxc(attachment.url),
				external_url: attachment.url,
				body: attachment.description || attachment.filename,
				filename: attachment.filename,
				info: {
					mimetype: attachment.content_type,
					w: attachment.width,
					h: attachment.height,
					size: attachment.size
				}
			}
		} else if (attachment.content_type?.startsWith("audio/")) {
			return {
				$type: "m.room.message",
				"m.mentions": mentions,
				msgtype: "m.audio",
				url: await file.uploadDiscordFileToMxc(attachment.url),
				external_url: attachment.url,
				body: attachment.description || attachment.filename,
				filename: attachment.filename,
				info: {
					mimetype: attachment.content_type,
					size: attachment.size,
					duration: attachment.duration_secs ? attachment.duration_secs * 1000 : undefined
				}
			}
		} else {
			return {
				$type: "m.room.message",
				"m.mentions": mentions,
				msgtype: "m.file",
				url: await file.uploadDiscordFileToMxc(attachment.url),
				external_url: attachment.url,
				body: attachment.filename,
				filename: attachment.filename,
				info: {
					mimetype: attachment.content_type,
					size: attachment.size
				}
			}
		}
	}))
	events.push(...attachmentEvents)

	// Then embeds
	for (const embed of message.embeds || []) {
		if (embed.type === "image") {
			continue // Matrix already does a fine enough job of providing image embeds.
		}

		// Start building up a replica ("rep") of the embed in Discord-markdown format, which we will convert into both plaintext and formatted body at once
		let repParagraphs = []
		const makeUrlTitle = (text, url) =>
			( text && url ? `[**${text}**](${url})`
			: text ? `**${text}**`
			: url ? `**${url}**`
			: "")

		let authorNameText = embed.author?.name || ""
		if (authorNameText && embed.author?.icon_url) authorNameText = `⏺️ ${authorNameText}` // not using the real image
		let authorTitle = makeUrlTitle(authorNameText, embed.author?.url)
		if (authorTitle) repParagraphs.push(authorTitle)

		let title = makeUrlTitle(embed.title, embed.url)
		if (title) repParagraphs.push(title)

		if (embed.image?.url) repParagraphs.push(`📸 ${embed.image.url}`)
		if (embed.video?.url) repParagraphs.push(`🎞️ ${embed.video.url}`)

		if (embed.description) repParagraphs.push(embed.description)
		for (const field of embed.fields || []) {
			repParagraphs.push(`**${field.name}**\n${field.value}`)
		}
		if (embed.footer?.text) repParagraphs.push(`— ${embed.footer.text}`)
		const repContent = repParagraphs.join("\n\n")
		const repContentQuoted = repContent.split("\n").map(l => "> " + l).join("\n")

		// Send as m.notice to apply the usual automated/subtle appearance, showing this wasn't actually typed by the person
		await addTextEvent(repContentQuoted, "m.notice", {scanMentions: false})
	}

	// Then stickers
	if (message.sticker_items) {
		const stickerEvents = await Promise.all(message.sticker_items.map(async stickerItem => {
			const format = file.stickerFormat.get(stickerItem.format_type)
			if (format?.mime === "lottie") {
				try {
					const {mxc_url, info} = await lottie.convert(stickerItem)
					return {
						$type: "m.sticker",
						"m.mentions": mentions,
						body: stickerItem.name,
						info,
						url: mxc_url
					}
				} catch (e) {
					return {
						$type: "m.room.message",
						"m.mentions": mentions,
						msgtype: "m.notice",
						body: `Failed to convert Lottie sticker:\n${e.toString()}\n${e.stack}`
					}
				}
			} else if (format?.mime) {
				let body = stickerItem.name
				const sticker = guild.stickers.find(sticker => sticker.id === stickerItem.id)
				if (sticker && sticker.description) body += ` - ${sticker.description}`
				return {
					$type: "m.sticker",
					"m.mentions": mentions,
					body,
					info: {
						mimetype: format.mime
					},
					url: await file.uploadDiscordFileToMxc(file.sticker(stickerItem))
				}
			}
			return {
				$type: "m.room.message",
				"m.mentions": mentions,
				msgtype: "m.notice",
				body: `Unsupported sticker format ${format?.mime}. Name: ${stickerItem.name}`
			}
		}))
		events.push(...stickerEvents)
	}

	// Rich replies
	if (repliedToEventRow) {
		Object.assign(events[0], {
			"m.relates_to": {
				"m.in_reply_to": {
					event_id: repliedToEventRow.event_id
				}
			}
		})
	}

	return events
}

module.exports.messageToEvent = messageToEvent