Link instead of upload emoji sprite sheets

src/m2d/converters/event-to-message.js

@@ -348,25 +348,44 @@ function getUserOrProxyOwnerMention(mxid) {
 
 /**
  * At the time of this executing, we know what the end of message emojis are, and we know that at least one of them is unknown.
- * This function will strip them from the content and generate the correct pending file of the sprite sheet.
+ * This function will strip them from the content and generate a link in it's place for proxying a sprite sheet that discord previews.
  * @param {string} content
- * @param {{id: string, filename: string}[]} attachments
- * @param {({name: string, mxc: string} | {name: string, mxc: string, key: string, iv: string} | {name: string, buffer: Buffer})[]} pendingFiles
- * @param {(mxc: string) => Promise<Buffer | undefined>} mxcDownloader function that will download the mxc URLs and convert to uncompressed PNG data. use `getAndConvertEmoji` or a mock.
  */
-async function uploadEndOfMessageSpriteSheet(content, attachments, pendingFiles, mxcDownloader) {
+async function uploadEndOfMessageSpriteSheet(content) {
 	if (!content.includes("<::>")) return content // No unknown emojis, nothing to do
 	// Remove known and unknown emojis from the end of the message
 	const r = /<a?:[a-zA-Z0-9_]*:[0-9]*>\s*$/
+
 	while (content.match(r)) {
 		content = content.replace(r, "")
 	}
-	// Create a sprite sheet of known and unknown emojis from the end of the message
-	const buffer = await emojiSheet.compositeMatrixEmojis(endOfMessageEmojis, mxcDownloader)
-	// Attach it
-	const filename = "emojis.png"
-	attachments.push({id: String(attachments.length), filename})
-	pendingFiles.push({name: filename, buffer})
+
+	let emojiSheetUrl = new URL('emoji/matrix', reg.ooye.bridge_origin)
+	for(let mxc of endOfMessageEmojis) {
+		const emojiSheetUrlString = emojiSheetUrl.toString()
+
+		// Discord will not preview the URL if it is longer than 2000 characters. 
+		// Longer URLs can preview but it's very inconsistant so ignoring any additional emojis
+		if(emojiSheetUrlString.length + mxc.length > 2000) {
+			break
+		}
+
+		// Ignoring any additional emojis if it would exceed discords message length
+		if(emojiSheetUrlString.length + mxc.length + content.length > 4000) {
+			break
+		}
+
+		mxUtils.generatePermittedMediaHash(mxc)
+		emojiSheetUrl.searchParams.append('e', mxc)
+	}
+
+	const emojiSheetUrlString = emojiSheetUrl.toString()
+
+	// Discord message length check. Using markdown link with placeholder text since discord displays 
+	// the link when there is preceeding text to the emoji
+	const placeholderText = '.'
+	content = content.concat(`[${placeholderText}](${emojiSheetUrlString})`)
+
 	return content
 }
 
@@ -937,7 +956,7 @@ async function eventToMessage(event, guild, channel, di) {
 				if (replyLine && content.startsWith("> ")) content = "\n" + content
 
 				// SPRITE SHEET EMOJIS FEATURE:
-				content = await uploadEndOfMessageSpriteSheet(content, attachments, pendingFiles, di?.mxcDownloader)
+				content = await uploadEndOfMessageSpriteSheet(content)
 			} else {
 				// Looks like we're using the plaintext body!
 				content = event.content.body

src/matrix/utils.js

@@ -205,6 +205,19 @@ async function getViaServersQuery(roomID, api) {
 	return qs
 }
 
+function generatePermittedMediaHash(mxc) {
+	assert(hasher, "xxhash is not ready yet")
+	const mediaParts = mxc?.match(/^mxc:\/\/([^/]+)\/(\w+)$/)
+	if (!mediaParts) return undefined
+
+	const serverAndMediaID = `${mediaParts[1]}/${mediaParts[2]}`
+	const unsignedHash = hasher.h64(serverAndMediaID)
+	const signedHash = unsignedHash - 0x8000000000000000n // shifting down to signed 64-bit range
+	db.prepare("INSERT OR IGNORE INTO media_proxy (permitted_hash) VALUES (?)").run(signedHash)
+
+	return serverAndMediaID
+}
+
 /**
  * Since the introduction of authenticated media, this can no longer just be the /_matrix/media/r0/download URL
  * because Discord and Discord users cannot use those URLs. Media now has to be proxied through the bridge.
@@ -219,15 +232,8 @@ async function getViaServersQuery(roomID, api) {
  * @returns {string | undefined}
  */
 function getPublicUrlForMxc(mxc) {
-	assert(hasher, "xxhash is not ready yet")
-	const mediaParts = mxc?.match(/^mxc:\/\/([^/]+)\/(\w+)$/)
-	if (!mediaParts) return undefined
-
-	const serverAndMediaID = `${mediaParts[1]}/${mediaParts[2]}`
-	const unsignedHash = hasher.h64(serverAndMediaID)
-	const signedHash = unsignedHash - 0x8000000000000000n // shifting down to signed 64-bit range
-	db.prepare("INSERT OR IGNORE INTO media_proxy (permitted_hash) VALUES (?)").run(signedHash)
-
+	const serverAndMediaID = generatePermittedMediaHash(mxc);
+	if(!serverAndMediaID) return undefined
 	return `${reg.ooye.bridge_origin}/download/matrix/${serverAndMediaID}`
 }
 
@@ -358,6 +364,7 @@ async function setUserPowerCascade(spaceID, mxid, power, api) {
 module.exports.bot = bot
 module.exports.BLOCK_ELEMENTS = BLOCK_ELEMENTS
 module.exports.eventSenderIsFromDiscord = eventSenderIsFromDiscord
+module.exports.generatePermittedMediaHash = generatePermittedMediaHash
 module.exports.getPublicUrlForMxc = getPublicUrlForMxc
 module.exports.getEventIDHash = getEventIDHash
 module.exports.MatrixStringBuilder = MatrixStringBuilder

src/web/routes/download-matrix.js

@@ -1,7 +1,7 @@
 // @ts-check
 
 const assert = require("assert/strict")
-const {defineEventHandler, getValidatedRouterParams, setResponseStatus, setResponseHeader, sendStream, createError, H3Event} = require("h3")
+const {defineEventHandler, getValidatedRouterParams, setResponseStatus, setResponseHeader, createError, H3Event, getValidatedQuery} = require("h3")
 const {z} = require("zod")
 
 /** @type {import("xxhash-wasm").XXHashAPI} */ // @ts-ignore
@@ -27,10 +27,8 @@ function getAPI(event) {
 	return event.context.api || sync.require("../../matrix/api")
 }
 
-as.router.get(`/download/matrix/:server_name/:media_id`, defineEventHandler(async event => {
-	const params = await getValidatedRouterParams(event, schema.params.parse)
-
-	const serverAndMediaID = `${params.server_name}/${params.media_id}`
+function verifyMediaHash(serverName, mediaId) {
+	const serverAndMediaID = `${serverName}/${mediaId}`
 	const unsignedHash = hasher.h64(serverAndMediaID)
 	const signedHash = unsignedHash - 0x8000000000000000n // shifting down to signed 64-bit range
 
@@ -41,7 +39,12 @@ as.router.get(`/download/matrix/:server_name/:media_id`, defineEventHandler(asyn
 			data: `The file you requested isn't permitted by this media proxy.`
 		})
 	}
+}
 
+as.router.get(`/download/matrix/:server_name/:media_id`, defineEventHandler(async event => {
+	const params = await getValidatedRouterParams(event, schema.params.parse)
+
+	verifyMediaHash(params.server_name, params.media_id)
 	const api = getAPI(event)
 	const res = await api.getMedia(`mxc://${params.server_name}/${params.media_id}`)
 
@@ -53,3 +56,34 @@ as.router.get(`/download/matrix/:server_name/:media_id`, defineEventHandler(asyn
 	setResponseHeader(event, "Transfer-Encoding", "chunked")
 	return res.body
 }))
+
+const emojiSchema = z.object({
+	'e': z.array(z.string()).or(z.string())
+})
+
+const emojiSheet = sync.require("../../m2d/actions/emoji-sheet")
+const emojiSheetConverter = sync.require("../../m2d/converters/emoji-sheet")
+
+as.router.get(`/emoji/matrix`, defineEventHandler(async event => {
+
+	const query = await getValidatedQuery(event, emojiSchema.parse)
+
+	let mxcs = query.e
+	if(!Array.isArray(mxcs)) {
+		mxcs = [mxcs]
+	}
+
+	for(let mxc of mxcs) {
+		const mediaParts = mxc.match(/^mxc:\/\/([^/]+)\/(\w+)$/)
+		if (!mediaParts) return undefined
+		verifyMediaHash(mediaParts[1], mediaParts[2])
+	}
+	const buffer = await emojiSheetConverter.compositeMatrixEmojis(mxcs, emojiSheet.getAndConvertEmoji)
+
+	const contentType = 'image/png'
+
+	setResponseStatus(event, 200)
+	setResponseHeader(event, "Content-Type", contentType)
+	setResponseHeader(event, "Transfer-Encoding", "chunked")
+	return buffer
+}))