refactoring

Resolve #7779

packages/backend/src/misc/get-file-info.ts

@@ -0,0 +1,196 @@
+import * as fs from 'fs';
+import * as crypto from 'crypto';
+import * as stream from 'stream';
+import * as util from 'util';
+import * as fileType from 'file-type';
+import isSvg from 'is-svg';
+import * as probeImageSize from 'probe-image-size';
+import * as sharp from 'sharp';
+import { encode } from 'blurhash';
+
+const pipeline = util.promisify(stream.pipeline);
+
+export type FileInfo = {
+	size: number;
+	md5: string;
+	type: {
+		mime: string;
+		ext: string | null;
+	};
+	width?: number;
+	height?: number;
+	blurhash?: string;
+	warnings: string[];
+};
+
+const TYPE_OCTET_STREAM = {
+	mime: 'application/octet-stream',
+	ext: null
+};
+
+const TYPE_SVG = {
+	mime: 'image/svg+xml',
+	ext: 'svg'
+};
+
+/**
+ * Get file information
+ */
+export async function getFileInfo(path: string): Promise<FileInfo> {
+	const warnings = [] as string[];
+
+	const size = await getFileSize(path);
+	const md5 = await calcHash(path);
+
+	let type = await detectType(path);
+
+	// image dimensions
+	let width: number | undefined;
+	let height: number | undefined;
+
+	if (['image/jpeg', 'image/gif', 'image/png', 'image/apng', 'image/webp', 'image/bmp', 'image/tiff', 'image/svg+xml', 'image/vnd.adobe.photoshop'].includes(type.mime)) {
+		const imageSize = await detectImageSize(path).catch(e => {
+			warnings.push(`detectImageSize failed: ${e}`);
+			return undefined;
+		});
+
+		// うまく判定できない画像は octet-stream にする
+		if (!imageSize) {
+			warnings.push(`cannot detect image dimensions`);
+			type = TYPE_OCTET_STREAM;
+		} else if (imageSize.wUnits === 'px') {
+			width = imageSize.width;
+			height = imageSize.height;
+
+			// 制限を超えている画像は octet-stream にする
+			if (imageSize.width > 16383 || imageSize.height > 16383) {
+				warnings.push(`image dimensions exceeds limits`);
+				type = TYPE_OCTET_STREAM;
+			}
+		} else {
+			warnings.push(`unsupported unit type: ${imageSize.wUnits}`);
+		}
+	}
+
+	let blurhash: string | undefined;
+
+	if (['image/jpeg', 'image/gif', 'image/png', 'image/apng', 'image/webp', 'image/svg+xml'].includes(type.mime)) {
+		blurhash = await getBlurhash(path).catch(e => {
+			warnings.push(`getBlurhash failed: ${e}`);
+			return undefined;
+		});
+	}
+
+	return {
+		size,
+		md5,
+		type,
+		width,
+		height,
+		blurhash,
+		warnings,
+	};
+}
+
+/**
+ * Detect MIME Type and extension
+ */
+export async function detectType(path: string) {
+	// Check 0 byte
+	const fileSize = await getFileSize(path);
+	if (fileSize === 0) {
+		return TYPE_OCTET_STREAM;
+	}
+
+	const type = await fileType.fromFile(path);
+
+	if (type) {
+		// XMLはSVGかもしれない
+		if (type.mime === 'application/xml' && await checkSvg(path)) {
+			return TYPE_SVG;
+		}
+
+		return {
+			mime: type.mime,
+			ext: type.ext
+		};
+	}
+
+	// 種類が不明でもSVGかもしれない
+	if (await checkSvg(path)) {
+		return TYPE_SVG;
+	}
+
+	// それでも種類が不明なら application/octet-stream にする
+	return TYPE_OCTET_STREAM;
+}
+
+/**
+ * Check the file is SVG or not
+ */
+export async function checkSvg(path: string) {
+	try {
+		const size = await getFileSize(path);
+		if (size > 1 * 1024 * 1024) return false;
+		return isSvg(fs.readFileSync(path));
+	} catch {
+		return false;
+	}
+}
+
+/**
+ * Get file size
+ */
+export async function getFileSize(path: string): Promise<number> {
+	const getStat = util.promisify(fs.stat);
+	return (await getStat(path)).size;
+}
+
+/**
+ * Calculate MD5 hash
+ */
+async function calcHash(path: string): Promise<string> {
+	const hash = crypto.createHash('md5').setEncoding('hex');
+	await pipeline(fs.createReadStream(path), hash);
+	return hash.read();
+}
+
+/**
+ * Detect dimensions of image
+ */
+async function detectImageSize(path: string): Promise<{
+	width: number;
+	height: number;
+	wUnits: string;
+	hUnits: string;
+}> {
+	const readable = fs.createReadStream(path);
+	const imageSize = await probeImageSize(readable);
+	readable.destroy();
+	return imageSize;
+}
+
+/**
+ * Calculate average color of image
+ */
+function getBlurhash(path: string): Promise<string> {
+	return new Promise((resolve, reject) => {
+		sharp(path)
+			.raw()
+			.ensureAlpha()
+			.resize(64, 64, { fit: 'inside' })
+			.toBuffer((err, buffer, { width, height }) => {
+				if (err) return reject(err);
+
+				let hash;
+
+				try {
+					hash = encode(new Uint8ClampedArray(buffer), width, height, 7, 7);
+				} catch (e) {
+					return reject(e);
+				}
+
+				resolve(hash);
+			});
+	});
+}