support rich replies, support basic m.mentions

d2m/converters/message-to-event.js

@@ -2,6 +2,7 @@
 
 const assert = require("assert").strict
 const markdown = require("discord-markdown")
+const DiscordTypes = require("discord-api-types/v10")
 
 const passthrough = require("../../passthrough")
 const { sync, db, discord } = passthrough
@@ -39,10 +40,56 @@ function getDiscordParseCallbacks(message, useHTML) {
 /**
  * @param {import("discord-api-types/v10").APIMessage} message
  * @param {import("discord-api-types/v10").APIGuild} guild
+ * @param {import("../../matrix/api")} api simple-as-nails dependency injection for the matrix API
  */
-async function messageToEvent(message, guild) {
+async function messageToEvent(message, guild, api) {
 	const events = []
 
+	/**
+	   @type {{room?: boolean, user_ids?: string[]}}
+		We should consider the following scenarios for mentions:
+		1. TODO 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. TODO 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
+			+ 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. TODO 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 repliedToEventId = null
+	let repliedToEventRoomId = null
+	let repliedToEventSenderMxid = null
+	let repliedToEventOriginallyFromMatrix = false
+
+	function addMention(mxid) {
+		if (!mentions.user_ids) mentions.user_ids = []
+		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 = db.prepare("SELECT event_id, room_id, source FROM event_message INNER JOIN channel_room USING (channel_id) WHERE message_id = ? AND part = 0").get(message.message_reference.message_id)
+		if (row) {
+			repliedToEventId = row.event_id
+			repliedToEventRoomId = row.room_id
+			repliedToEventOriginallyFromMatrix = row.source === 0 // source 0 = matrix
+		}
+	}
+	if (repliedToEventOriginallyFromMatrix) {
+		// Need to figure out who sent that event...
+		const event = await api.getEvent(repliedToEventRoomId, repliedToEventId)
+		repliedToEventSenderMxid = event.sender
+		// Need to add the sender to m.mentions
+		addMention(repliedToEventSenderMxid)
+	}
+
 	// Text content appears first
 	if (message.content) {
 		let content = message.content
@@ -55,33 +102,63 @@ async function messageToEvent(message, guild) {
 			}
 		})
 
-		const html = markdown.toHTML(content, {
+		let html = markdown.toHTML(content, {
 			discordCallback: getDiscordParseCallbacks(message, true)
 		}, null, null)
 
-		const body = markdown.toHTML(content, {
+		let body = markdown.toHTML(content, {
 			discordCallback: getDiscordParseCallbacks(message, false),
 			discordOnly: true,
 			escapeHTML: false,
 		}, null, null)
 
+		// Fallback body/formatted_body for replies
+		if (repliedToEventId) {
+			let repliedToDisplayName
+			let repliedToUserHtml
+			if (repliedToEventOriginallyFromMatrix && 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
+			}
+			const repliedToContent = message.referenced_message?.content || "[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/#/${repliedToEventRoomId}/${repliedToEventId}">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: "m.text",
+			body: body
+		}
+
 		const isPlaintext = body === html
 
-		if (isPlaintext) {
-			events.push({
-				$type: "m.room.message",
-				msgtype: "m.text",
-				body: body
-			})
-		} else {
-			events.push({
-				$type: "m.room.message",
-				msgtype: "m.text",
-				body: body,
+		if (!isPlaintext) {
+			Object.assign(newTextMessageEvent, {
 				format: "org.matrix.custom.html",
 				formatted_body: html
 			})
 		}
+
+		events.push(newTextMessageEvent)
 	}
 
 	// Then attachments
@@ -90,6 +167,7 @@ async function messageToEvent(message, guild) {
 		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,
@@ -105,6 +183,7 @@ async function messageToEvent(message, guild) {
 		} else {
 			return {
 				$type: "m.room.message",
+				"m.mentions": mentions,
 				msgtype: "m.text",
 				body: "Unsupported attachment:\n" + JSON.stringify(attachment, null, 2)
 			}
@@ -122,6 +201,7 @@ async function messageToEvent(message, guild) {
 				if (sticker && sticker.description) body += ` - ${sticker.description}`
 				return {
 					$type: "m.sticker",
+					"m.mentions": mentions,
 					body,
 					info: {
 						mimetype: format.mime
@@ -131,6 +211,7 @@ async function messageToEvent(message, guild) {
 			} else {
 				return {
 					$type: "m.room.message",
+					"m.mentions": mentions,
 					msgtype: "m.text",
 					body: "Unsupported sticker format. Name: " + stickerItem.name
 				}
@@ -139,6 +220,17 @@ async function messageToEvent(message, guild) {
 		events.push(...stickerEvents)
 	}
 
+	// Rich replies
+	if (repliedToEventId) {
+		Object.assign(events[0], {
+			"m.relates_to": {
+				"m.in_reply_to": {
+					event_id: repliedToEventId
+				}
+			}
+		})
+	}
+
 	return events
 }