Move everything to src folder... it had to happen

src/m2d/converters/emoji-sheet.js

@@ -0,0 +1,114 @@
+// @ts-check
+
+const assert = require("assert").strict
+const {pipeline} = require("stream").promises
+const sharp = require("sharp")
+const {GIFrame} = require("@cloudrac3r/giframe")
+const {PNG} = require("@cloudrac3r/pngjs")
+const streamMimeType = require("stream-mime-type")
+
+const SIZE = 48
+const RESULT_WIDTH = 400
+const IMAGES_ACROSS = Math.floor(RESULT_WIDTH / SIZE)
+
+/**
+ * Composite a bunch of Matrix emojis into a kind of spritesheet image to upload to Discord.
+ * @param {string[]} mxcs mxc URLs, in order
+ * @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.
+ * @returns {Promise<Buffer>} PNG image
+ */
+async function compositeMatrixEmojis(mxcs, mxcDownloader) {
+	const buffers = await Promise.all(mxcs.map(mxcDownloader))
+
+	// Calculate the size of the final composited image
+	const totalWidth = Math.min(buffers.length, IMAGES_ACROSS) * SIZE
+	const imagesDown = Math.ceil(buffers.length / IMAGES_ACROSS)
+	const totalHeight = imagesDown * SIZE
+	const comp = []
+	let left = 0, top = 0
+	for (const buffer of buffers) {
+		if (Buffer.isBuffer(buffer)) {
+			// Composite the current buffer into the sprite sheet
+			comp.push({left, top, input: buffer})
+			// The next buffer should be placed one slot to the right
+			left += SIZE
+			// If we're out of space to fit the entire next buffer there, wrap to the next line
+			if (left + SIZE > RESULT_WIDTH) {
+				left = 0
+				top += SIZE
+			}
+		}
+	}
+
+	const output = await sharp({create: {width: totalWidth, height: totalHeight, channels: 4, background: {r: 0, g: 0, b: 0, alpha: 0}}})
+		.composite(comp)
+		.png()
+		.toBuffer({resolveWithObject: true})
+	return output.data
+}
+
+/**
+ * @param {import("node-fetch").Response["body"]} streamIn
+ * @param {() => any} stopStream
+ * @returns {Promise<Buffer | undefined>} Uncompressed PNG image
+ */
+async function convertImageStream(streamIn, stopStream) {
+	const {stream, mime} = await streamMimeType.getMimeType(streamIn)
+	assert(["image/png", "image/jpeg", "image/webp", "image/gif", "image/apng"].includes(mime), `Mime type ${mime} is impossible for emojis`)
+
+	try {
+		if (mime === "image/png" || mime === "image/jpeg" || mime === "image/webp") {
+			/** @type {{info: sharp.OutputInfo, buffer: Buffer}} */
+			const result = await new Promise((resolve, reject) => {
+				const transformer = sharp()
+					.resize(SIZE, SIZE, {fit: "contain", background: {r: 0, g: 0, b: 0, alpha: 0}})
+					.png({compressionLevel: 0})
+					.toBuffer((err, buffer, info) => {
+						/* c8 ignore next */
+						if (err) return reject(err)
+						resolve({info, buffer})
+					})
+				pipeline(
+					stream,
+					transformer
+				)
+			})
+			return result.buffer
+
+		} else if (mime === "image/gif") {
+			const giframe = new GIFrame(0)
+			stream.on("data", chunk => {
+				giframe.feed(chunk)
+			})
+			const frame = await giframe.getFrame()
+			const pixels = Uint8Array.from(frame.pixels)
+			stopStream()
+
+			const buffer = await sharp(pixels, {raw: {width: frame.width, height: frame.height, channels: 4}})
+				.resize(SIZE, SIZE, {fit: "contain", background: {r: 0, g: 0, b: 0, alpha: 0}})
+				.png({compressionLevel: 0})
+				.toBuffer({resolveWithObject: true})
+			return buffer.data
+
+		} else if (mime === "image/apng") {
+			const png = new PNG({maxFrames: 1})
+			// @ts-ignore
+			stream.pipe(png)
+			/** @type {Buffer} */ // @ts-ignore
+			const frame = await new Promise(resolve => png.on("parsed", resolve))
+			stopStream()
+
+			const buffer = await sharp(frame, {raw: {width: png.width, height: png.height, channels: 4}})
+				.resize(SIZE, SIZE, {fit: "contain", background: {r: 0, g: 0, b: 0, alpha: 0}})
+				.png({compressionLevel: 0})
+				.toBuffer({resolveWithObject: true})
+			return buffer.data
+
+		}
+	} finally {
+		stopStream()
+	}
+}
+
+module.exports.compositeMatrixEmojis = compositeMatrixEmojis
+module.exports.convertImageStream = convertImageStream