From 437f04682c0490b3fe94e679195f6466f2045abe Mon Sep 17 00:00:00 2001
From: Cadence Ember <cadence@disroot.org>
Date: Tue, 11 Jul 2023 17:27:40 +1200
Subject: [PATCH] support written @mentions (scenario 3)

---
 d2m/converters/message-to-event.js      | 21 +++++++++++-
 d2m/converters/message-to-event.test.js | 43 +++++++++++++++++++++++++
 test/data.js                            | 31 ++++++++++++++++++
 3 files changed, 94 insertions(+), 1 deletion(-)

diff --git a/d2m/converters/message-to-event.js b/d2m/converters/message-to-event.js
index 0e94a70..daa0a3c 100644
--- a/d2m/converters/message-to-event.js
+++ b/d2m/converters/message-to-event.js
@@ -8,6 +8,9 @@ const passthrough = require("../../passthrough")
 const { sync, db, discord } = passthrough
 /** @type {import("../../matrix/file")} */
 const file = sync.require("../../matrix/file")
+const reg = require("../../matrix/read-registration")
+
+const userRegex = reg.namespaces.users.map(u => new RegExp(u.regex))
 
 function getDiscordParseCallbacks(message, useHTML) {
 	return {
@@ -69,7 +72,7 @@ async function messageToEvent(message, guild, api) {
 
 	function addMention(mxid) {
 		if (!mentions.user_ids) mentions.user_ids = []
-		mentions.user_ids.push(mxid)
+		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
@@ -106,12 +109,28 @@ async function messageToEvent(message, guild, api) {
 			discordCallback: getDiscordParseCallbacks(message, true)
 		}, null, null)
 
+		// TODO: add a string return type to my discord-markdown library
 		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
+		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 = db.prepare("SELECT room_id FROM channel_room WHERE channel_id = ?").pluck().get(message.channel_id)
+			const {joined} = await api.getJoinedMembers(roomID)
+			for (const [mxid, member] of Object.entries(joined)) {
+				if (!userRegex.some(rx => mxid.match(rx))) {
+					const localpart = mxid.match(/@([^:]*)/)
+					assert(localpart)
+					if (writtenMentionsText.includes(localpart[1].toLowerCase()) || writtenMentionsText.includes(member.display_name.toLowerCase())) addMention(mxid)
+				}
+			}
+		}
+
 		// Fallback body/formatted_body for replies
 		if (repliedToEventId) {
 			let repliedToDisplayName
diff --git a/d2m/converters/message-to-event.test.js b/d2m/converters/message-to-event.test.js
index 5fa16f8..58093ca 100644
--- a/d2m/converters/message-to-event.test.js
+++ b/d2m/converters/message-to-event.test.js
@@ -215,4 +215,47 @@ test("message2event: simple reply to matrix user", async t => {
 	}])
 })
 
+test("message2event: simple written @mention for matrix user", async t => {
+	const events = await messageToEvent(data.message.simple_written_at_mention_for_matrix, data.guild.general, {
+		async getJoinedMembers(roomID) {
+			t.equal(roomID, "!kLRqKKUQXcibIMtOpl:cadence.moe")
+			return new Promise(resolve => {
+				setTimeout(() => {
+					resolve({
+						joined: {
+							"@cadence:cadence.moe": {
+								display_name: "cadence [they]",
+								avatar_url: "whatever"
+							},
+							"@huckleton:cadence.moe": {
+								display_name: "huck",
+								avatar_url: "whatever"
+							},
+							"@_ooye_botrac4r:cadence.moe": {
+								display_name: "botrac4r",
+								avatar_url: "whatever"
+							},
+							"@_ooye_bot:cadence.moe": {
+								display_name: "Out Of Your Element",
+								avatar_url: "whatever"
+							}
+						}
+					})
+				})
+			})
+		}
+	})
+	t.deepEqual(events, [{
+		$type: "m.room.message",
+		"m.mentions": {
+			user_ids: [
+				"@cadence:cadence.moe",
+				"@huckleton:cadence.moe"
+			]
+		},
+		msgtype: "m.text",
+		body: "@Cadence, tell me about @Phil, the creator of the Chin Trick, who has become ever more powerful under the mentorship of @botrac4r and @huck"
+	}])
+})
+
 // TODO: read "edits of replies" in the spec
diff --git a/test/data.js b/test/data.js
index 7c8fadc..a5ca95e 100644
--- a/test/data.js
+++ b/test/data.js
@@ -304,6 +304,37 @@ module.exports = {
 			flags: 0,
 			components: []
 		},
+		simple_written_at_mention_for_matrix: {
+			id: "1126739682080858234",
+			type: 0,
+			content: "@Cadence, tell me about @Phil, the creator of the Chin Trick, who has become ever more powerful under the mentorship of @botrac4r and @huck",
+			channel_id: "112760669178241024",
+			author: {
+				id: "114147806469554185",
+				username: "extremity",
+				avatar: "6628aaf6b27219c36e2d3b5cfd6d0ee6",
+				discriminator: "0",
+				public_flags: 768,
+				flags: 768,
+				banner: null,
+				accent_color: null,
+				global_name: "Extremity",
+				avatar_decoration: null,
+				display_name: "Extremity",
+				banner_color: null
+			},
+			attachments: [],
+			embeds: [],
+			mentions: [],
+			mention_roles: [],
+			pinned: false,
+			mention_everyone: false,
+			tts: false,
+			timestamp: "2023-07-07T05:01:14.019000+00:00",
+			edited_timestamp: null,
+			flags: 0,
+			components: []
+		},
 		simple_reply: {
 			id: "1126604870762369124",
 			type: 19,