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88 lines
3.2 KiB
JavaScript
88 lines
3.2 KiB
JavaScript
import Q from 'q';
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import SparkMD5 from 'spark-md5';
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import Moment from 'moment';
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import { getLangText } from './lang';
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// Re-export related utilities from js-utility-belt for easier access
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export { extractFileExtensionFromString, extractFileExtensionFromUrl } from 'js-utility-belt/es6/file';
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/**
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* Takes a file Object, computes the MD5 hash and returns the URL of the textfile with the hash
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*
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* @param {File} file javascript File object
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* @return {string} regular javascript string
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*/
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export function computeHashOfFile(file) {
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return Q.Promise((resolve, reject, notify) => {
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const blobSlice = File.prototype.slice || File.prototype.mozSlice || File.prototype.webkitSlice;
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const chunkSize = 2097152; // Read in chunks of 2MB
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const chunks = Math.ceil(file.size / chunkSize);
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const spark = new SparkMD5.ArrayBuffer();
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const fileReader = new FileReader();
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const startTime = new Moment();
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let currentChunk = 0;
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// comment: We should convert this to es6 at some point, however if so please consider that
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// an arrow function will get rid of the function's scope...
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fileReader.onload = (e) => {
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// console.log('read chunk nr', currentChunk + 1, 'of', chunks);
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spark.append(e.target.result); // Append array buffer
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currentChunk++;
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if (currentChunk < chunks) {
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loadNext();
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} else {
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const fileHash = spark.end();
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console.info('computed hash %s (took %d s)',
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fileHash,
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Math.round(((new Moment() - startTime) / 1000) % 60)); // Compute hash
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resolve(makeTextFile(fileHash, file));
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}
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};
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fileReader.onerror = () => {
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reject(new Error(getLangText("We weren't able to hash your file locally. Try to " +
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'upload it manually or consider contact us.')));
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};
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function loadNext() {
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const start = currentChunk * chunkSize;
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const end = ((start + chunkSize) >= file.size) ? file.size : start + chunkSize;
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// send progress
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// Due to the fact that progressHandler and notify are going to be removed in v2
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// of Q, the functionality of throwing errors in the progressHandler will not be implemented
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// anymore. To still be able to throw an error however, we can just expose the promise's reject
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// method to the .progress function to stop the execution immediately.
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notify({
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progress: start / file.size,
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reject
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});
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fileReader.readAsArrayBuffer(blobSlice.call(file, start, end));
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}
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loadNext();
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});
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}
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/**
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* Takes a string, creates a text file and returns the URL
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*
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* @param {string} text regular javascript string
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* @return {string} regular javascript string
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*/
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function makeTextFile(text, file) {
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const textFileBlob = new Blob([text], { type: 'text/plain' });
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const textFile = new File([textFileBlob], `hash-of-${file.name}.txt`, {
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lastModifiedDate: file.lastModifiedDate,
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lastModified: file.lastModified,
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type: 'text/plain'
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});
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return textFile;
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}
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