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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);
});
});
}
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