Use zip archives for company export

Co-Authored-By: Paperclip <noreply@paperclip.ing>

ui/src/lib/zip.test.ts

@@ -0,0 +1,53 @@
+// @vitest-environment node
+
+import { describe, expect, it } from "vitest";
+import { createZipArchive } from "./zip";
+
+function readUint16(bytes: Uint8Array, offset: number) {
+  return bytes[offset]! | (bytes[offset + 1]! << 8);
+}
+
+function readUint32(bytes: Uint8Array, offset: number) {
+  return (
+    bytes[offset]! |
+    (bytes[offset + 1]! << 8) |
+    (bytes[offset + 2]! << 16) |
+    (bytes[offset + 3]! << 24)
+  ) >>> 0;
+}
+
+function readString(bytes: Uint8Array, offset: number, length: number) {
+  return new TextDecoder().decode(bytes.slice(offset, offset + length));
+}
+
+describe("createZipArchive", () => {
+  it("writes a zip archive with the export root path prefixed into each entry", () => {
+    const archive = createZipArchive(
+      {
+        "COMPANY.md": "# Company\n",
+        "agents/ceo/AGENTS.md": "# CEO\n",
+      },
+      "paperclip-demo",
+    );
+
+    expect(readUint32(archive, 0)).toBe(0x04034b50);
+
+    const firstNameLength = readUint16(archive, 26);
+    const firstBodyLength = readUint32(archive, 18);
+    expect(readString(archive, 30, firstNameLength)).toBe("paperclip-demo/agents/ceo/AGENTS.md");
+    expect(readString(archive, 30 + firstNameLength, firstBodyLength)).toBe("# CEO\n");
+
+    const secondOffset = 30 + firstNameLength + firstBodyLength;
+    expect(readUint32(archive, secondOffset)).toBe(0x04034b50);
+
+    const secondNameLength = readUint16(archive, secondOffset + 26);
+    const secondBodyLength = readUint32(archive, secondOffset + 18);
+    expect(readString(archive, secondOffset + 30, secondNameLength)).toBe("paperclip-demo/COMPANY.md");
+    expect(readString(archive, secondOffset + 30 + secondNameLength, secondBodyLength)).toBe("# Company\n");
+
+    const endOffset = archive.length - 22;
+    expect(readUint32(archive, endOffset)).toBe(0x06054b50);
+    expect(readUint16(archive, endOffset + 8)).toBe(2);
+    expect(readUint16(archive, endOffset + 10)).toBe(2);
+  });
+});

ui/src/lib/zip.ts

@@ -0,0 +1,131 @@
+const textEncoder = new TextEncoder();
+
+const crcTable = new Uint32Array(256);
+for (let i = 0; i < 256; i++) {
+  let crc = i;
+  for (let bit = 0; bit < 8; bit++) {
+    crc = (crc & 1) === 1 ? (crc >>> 1) ^ 0xedb88320 : crc >>> 1;
+  }
+  crcTable[i] = crc >>> 0;
+}
+
+function normalizeArchivePath(pathValue: string) {
+  return pathValue
+    .replace(/\\/g, "/")
+    .split("/")
+    .filter(Boolean)
+    .join("/");
+}
+
+function crc32(bytes: Uint8Array) {
+  let crc = 0xffffffff;
+  for (const byte of bytes) {
+    crc = (crc >>> 8) ^ crcTable[(crc ^ byte) & 0xff]!;
+  }
+  return (crc ^ 0xffffffff) >>> 0;
+}
+
+function writeUint16(target: Uint8Array, offset: number, value: number) {
+  target[offset] = value & 0xff;
+  target[offset + 1] = (value >>> 8) & 0xff;
+}
+
+function writeUint32(target: Uint8Array, offset: number, value: number) {
+  target[offset] = value & 0xff;
+  target[offset + 1] = (value >>> 8) & 0xff;
+  target[offset + 2] = (value >>> 16) & 0xff;
+  target[offset + 3] = (value >>> 24) & 0xff;
+}
+
+function getDosDateTime(date: Date) {
+  const year = Math.min(Math.max(date.getFullYear(), 1980), 2107);
+  const month = date.getMonth() + 1;
+  const day = date.getDate();
+  const hours = date.getHours();
+  const minutes = date.getMinutes();
+  const seconds = Math.floor(date.getSeconds() / 2);
+
+  return {
+    time: (hours << 11) | (minutes << 5) | seconds,
+    date: ((year - 1980) << 9) | (month << 5) | day,
+  };
+}
+
+function concatChunks(chunks: Uint8Array[]) {
+  const totalLength = chunks.reduce((sum, chunk) => sum + chunk.length, 0);
+  const archive = new Uint8Array(totalLength);
+  let offset = 0;
+  for (const chunk of chunks) {
+    archive.set(chunk, offset);
+    offset += chunk.length;
+  }
+  return archive;
+}
+
+export function createZipArchive(files: Record<string, string>, rootPath: string): Uint8Array {
+  const normalizedRoot = normalizeArchivePath(rootPath);
+  const localChunks: Uint8Array[] = [];
+  const centralChunks: Uint8Array[] = [];
+  const archiveDate = getDosDateTime(new Date());
+  let localOffset = 0;
+  let entryCount = 0;
+
+  for (const [relativePath, contents] of Object.entries(files).sort(([left], [right]) => left.localeCompare(right))) {
+    const archivePath = normalizeArchivePath(`${normalizedRoot}/${relativePath}`);
+    const fileName = textEncoder.encode(archivePath);
+    const body = textEncoder.encode(contents);
+    const checksum = crc32(body);
+
+    const localHeader = new Uint8Array(30 + fileName.length);
+    writeUint32(localHeader, 0, 0x04034b50);
+    writeUint16(localHeader, 4, 20);
+    writeUint16(localHeader, 6, 0x0800);
+    writeUint16(localHeader, 8, 0);
+    writeUint16(localHeader, 10, archiveDate.time);
+    writeUint16(localHeader, 12, archiveDate.date);
+    writeUint32(localHeader, 14, checksum);
+    writeUint32(localHeader, 18, body.length);
+    writeUint32(localHeader, 22, body.length);
+    writeUint16(localHeader, 26, fileName.length);
+    writeUint16(localHeader, 28, 0);
+    localHeader.set(fileName, 30);
+
+    const centralHeader = new Uint8Array(46 + fileName.length);
+    writeUint32(centralHeader, 0, 0x02014b50);
+    writeUint16(centralHeader, 4, 20);
+    writeUint16(centralHeader, 6, 20);
+    writeUint16(centralHeader, 8, 0x0800);
+    writeUint16(centralHeader, 10, 0);
+    writeUint16(centralHeader, 12, archiveDate.time);
+    writeUint16(centralHeader, 14, archiveDate.date);
+    writeUint32(centralHeader, 16, checksum);
+    writeUint32(centralHeader, 20, body.length);
+    writeUint32(centralHeader, 24, body.length);
+    writeUint16(centralHeader, 28, fileName.length);
+    writeUint16(centralHeader, 30, 0);
+    writeUint16(centralHeader, 32, 0);
+    writeUint16(centralHeader, 34, 0);
+    writeUint16(centralHeader, 36, 0);
+    writeUint32(centralHeader, 38, 0);
+    writeUint32(centralHeader, 42, localOffset);
+    centralHeader.set(fileName, 46);
+
+    localChunks.push(localHeader, body);
+    centralChunks.push(centralHeader);
+    localOffset += localHeader.length + body.length;
+    entryCount += 1;
+  }
+
+  const centralDirectory = concatChunks(centralChunks);
+  const endOfCentralDirectory = new Uint8Array(22);
+  writeUint32(endOfCentralDirectory, 0, 0x06054b50);
+  writeUint16(endOfCentralDirectory, 4, 0);
+  writeUint16(endOfCentralDirectory, 6, 0);
+  writeUint16(endOfCentralDirectory, 8, entryCount);
+  writeUint16(endOfCentralDirectory, 10, entryCount);
+  writeUint32(endOfCentralDirectory, 12, centralDirectory.length);
+  writeUint32(endOfCentralDirectory, 16, localOffset);
+  writeUint16(endOfCentralDirectory, 20, 0);
+
+  return concatChunks([...localChunks, centralDirectory, endOfCentralDirectory]);
+}