Implemented multi-file upload/download

app/zip.js

@@ -0,0 +1,186 @@
+import crc32 from 'crc/crc32';
+
+const encoder = new TextEncoder();
+
+function dosDateTime(dateTime = new Date()) {
+  const year = (dateTime.getFullYear() - 1980) << 9;
+  const month = (dateTime.getMonth() + 1) << 5;
+  const day = dateTime.getDate();
+  const date = year | month | day;
+  const hour = dateTime.getHours() << 11;
+  const minute = dateTime.getMinutes() << 5;
+  const second = Math.floor(dateTime.getSeconds() / 2);
+  const time = hour | minute | second;
+
+  return { date, time };
+}
+
+class File {
+  constructor(info) {
+    this.name = encoder.encode(info.name);
+    this.size = info.size;
+    this.bytesRead = 0;
+    this.crc = null;
+    this.dateTime = dosDateTime();
+  }
+
+  get header() {
+    const h = new ArrayBuffer(30 + this.name.byteLength);
+    const v = new DataView(h);
+    v.setUint32(0, 0x04034b50, true); // sig
+    v.setUint16(4, 20, true); // version
+    v.setUint16(6, 8, true); // bit flags (8 = use data descriptor)
+    v.setUint16(8, 0, true); // compression
+    v.setUint16(10, this.dateTime.time, true); // modified time
+    v.setUint16(12, this.dateTime.date, true); // modified date
+    v.setUint32(14, 0, true); // crc32 (in descriptor)
+    v.setUint32(18, 0, true); // compressed size (in descriptor)
+    v.setUint32(22, 0, true); // uncompressed size (in descriptor)
+    v.setUint16(26, this.name.byteLength, true); // name length
+    v.setUint16(28, 0, true); // extra field length
+    for (let i = 0; i < this.name.byteLength; i++) {
+      v.setUint8(30 + i, this.name[i]);
+    }
+    return new Uint8Array(h);
+  }
+
+  get dataDescriptor() {
+    const dd = new ArrayBuffer(16);
+    const v = new DataView(dd);
+    v.setUint32(0, 0x08074b50, true); // sig
+    v.setUint32(4, this.crc, true); // crc32
+    v.setUint32(8, this.size, true); // compressed size
+    v.setUint16(12, this.size, true); // uncompressed size
+    return new Uint8Array(dd);
+  }
+
+  directoryRecord(offset) {
+    const dr = new ArrayBuffer(46 + this.name.byteLength);
+    const v = new DataView(dr);
+    v.setUint32(0, 0x02014b50, true); // sig
+    v.setUint16(4, 20, true); // version made
+    v.setUint16(6, 20, true); // version required
+    v.setUint16(8, 0, true); // bit flags
+    v.setUint16(10, 0, true); // compression
+    v.setUint16(12, this.dateTime.time, true); // modified time
+    v.setUint16(14, this.dateTime.date, true); // modified date
+    v.setUint32(16, this.crc, true); // crc
+    v.setUint32(20, this.size, true); // compressed size
+    v.setUint32(24, this.size, true); // uncompressed size
+    v.setUint16(28, this.name.byteLength, true); // name length
+    v.setUint16(30, 0, true); // extra length
+    v.setUint16(32, 0, true); // comment length
+    v.setUint16(34, 0, true); // disk number
+    v.setUint16(36, 0, true); // internal file attrs
+    v.setUint32(38, 0, true); // external file attrs
+    v.setUint32(42, offset, true); // file offset
+    for (let i = 0; i < this.name.byteLength; i++) {
+      v.setUint8(46 + i, this.name[i]);
+    }
+    return new Uint8Array(dr);
+  }
+
+  get byteLength() {
+    return this.size + this.name.byteLength + 30 + 16;
+  }
+
+  append(data, controller) {
+    this.bytesRead += data.byteLength;
+    const endIndex = data.byteLength - Math.max(this.bytesRead - this.size, 0);
+    const buf = data.slice(0, endIndex);
+    this.crc = crc32(buf, this.crc);
+    controller.enqueue(buf);
+    if (endIndex < data.byteLength) {
+      return data.slice(endIndex, data.byteLength);
+    }
+  }
+}
+
+function centralDirectory(files, controller) {
+  let directoryOffset = 0;
+  let directorySize = 0;
+  for (let i = 0; i < files.length; i++) {
+    const file = files[i];
+    const record = file.directoryRecord(directoryOffset);
+    directoryOffset += file.byteLength;
+    controller.enqueue(record);
+    directorySize += record.byteLength;
+  }
+  controller.enqueue(eod(files.length, directorySize, directoryOffset));
+}
+
+function eod(fileCount, directorySize, directoryOffset) {
+  const e = new ArrayBuffer(22);
+  const v = new DataView(e);
+  v.setUint32(0, 0x06054b50, true); // sig
+  v.setUint16(4, 0, true); // disk number
+  v.setUint16(6, 0, true); // directory disk
+  v.setUint16(8, fileCount, true); // number of records
+  v.setUint16(10, fileCount, true); // total records
+  v.setUint32(12, directorySize, true); // size of directory
+  v.setUint32(16, directoryOffset, true); // offset of directory
+  v.setUint16(20, 0, true); // comment length
+  return new Uint8Array(e);
+}
+
+class ZipStreamController {
+  constructor(files, source) {
+    this.files = files;
+    this.fileIndex = 0;
+    this.file = null;
+    this.reader = source.getReader();
+    this.nextFile();
+    this.extra = null;
+  }
+
+  nextFile() {
+    this.file = this.files[this.fileIndex++];
+  }
+
+  async pull(controller) {
+    if (!this.file) {
+      // end of archive
+      centralDirectory(this.files, controller);
+      return controller.close();
+    }
+    if (this.file.bytesRead === 0) {
+      // beginning of file
+      controller.enqueue(this.file.header);
+      if (this.extra) {
+        this.extra = this.file.append(this.extra, controller);
+      }
+    }
+    if (this.file.bytesRead >= this.file.size) {
+      // end of file
+      controller.enqueue(this.file.dataDescriptor);
+      this.nextFile();
+      return this.pull(controller);
+    }
+    const data = await this.reader.read();
+    if (data.done) {
+      this.nextFile();
+      return this.pull(controller);
+    }
+    this.extra = this.file.append(data.value, controller);
+  }
+}
+
+export default class Zip {
+  constructor(manifest, source) {
+    this.files = manifest.files.map(info => new File(info));
+    this.source = source;
+  }
+
+  get stream() {
+    return new ReadableStream(new ZipStreamController(this.files, this.source));
+  }
+
+  get size() {
+    const entries = this.files.reduce(
+      (total, file) => total + file.byteLength * 2 - file.size,
+      0
+    );
+    const eod = 22;
+    return entries + eod;
+  }
+}