[Init] Initial commit - NetMesh terminal manager

lib/textZip.ts

@@ -0,0 +1,110 @@
+export interface TextZipFile {
+  name: string;
+  content: string;
+}
+
+const ZIP_UTF8_FLAG = 0x0800;
+
+const crcTable = Array.from({ length: 256 }, (_, index) => {
+  let value = index;
+  for (let bit = 0; bit < 8; bit += 1) {
+    value = value & 1 ? 0xedb88320 ^ (value >>> 1) : value >>> 1;
+  }
+  return value >>> 0;
+});
+
+const crc32 = (bytes: Uint8Array): number => {
+  let crc = 0xffffffff;
+  bytes.forEach((byte) => {
+    crc = crcTable[(crc ^ byte) & 0xff] ^ (crc >>> 8);
+  });
+  return (crc ^ 0xffffffff) >>> 0;
+};
+
+const pushUint16 = (parts: number[], value: number) => {
+  parts.push(value & 0xff, (value >>> 8) & 0xff);
+};
+
+const pushUint32 = (parts: number[], value: number) => {
+  parts.push(value & 0xff, (value >>> 8) & 0xff, (value >>> 16) & 0xff, (value >>> 24) & 0xff);
+};
+
+const concatZipParts = (header: number[], ...parts: Uint8Array[]): Uint8Array => {
+  const headerBytes = Uint8Array.from(header);
+  const chunk = new Uint8Array(
+    headerBytes.length + parts.reduce((total, part) => total + part.length, 0),
+  );
+  let offset = 0;
+  chunk.set(headerBytes, offset);
+  offset += headerBytes.length;
+  parts.forEach((part) => {
+    chunk.set(part, offset);
+    offset += part.length;
+  });
+  return chunk;
+};
+
+export const buildTextFilesZipBlob = (files: TextZipFile[]): Blob => {
+  const encoder = new TextEncoder();
+  const chunks: Uint8Array[] = [];
+  const centralDirectory: Uint8Array[] = [];
+  let offset = 0;
+
+  files.forEach((file) => {
+    const nameBytes = encoder.encode(file.name);
+    const contentBytes = encoder.encode(file.content);
+    const checksum = crc32(contentBytes);
+
+    const localHeader: number[] = [];
+    pushUint32(localHeader, 0x04034b50);
+    pushUint16(localHeader, 20);
+    pushUint16(localHeader, ZIP_UTF8_FLAG);
+    pushUint16(localHeader, 0);
+    pushUint16(localHeader, 0);
+    pushUint16(localHeader, 0);
+    pushUint32(localHeader, checksum);
+    pushUint32(localHeader, contentBytes.length);
+    pushUint32(localHeader, contentBytes.length);
+    pushUint16(localHeader, nameBytes.length);
+    pushUint16(localHeader, 0);
+    const localChunk = concatZipParts(localHeader, nameBytes, contentBytes);
+    chunks.push(localChunk);
+
+    const centralHeader: number[] = [];
+    pushUint32(centralHeader, 0x02014b50);
+    pushUint16(centralHeader, 20);
+    pushUint16(centralHeader, 20);
+    pushUint16(centralHeader, ZIP_UTF8_FLAG);
+    pushUint16(centralHeader, 0);
+    pushUint16(centralHeader, 0);
+    pushUint16(centralHeader, 0);
+    pushUint32(centralHeader, checksum);
+    pushUint32(centralHeader, contentBytes.length);
+    pushUint32(centralHeader, contentBytes.length);
+    pushUint16(centralHeader, nameBytes.length);
+    pushUint16(centralHeader, 0);
+    pushUint16(centralHeader, 0);
+    pushUint16(centralHeader, 0);
+    pushUint16(centralHeader, 0);
+    pushUint32(centralHeader, 0);
+    pushUint32(centralHeader, offset);
+    centralDirectory.push(concatZipParts(centralHeader, nameBytes));
+
+    offset += localChunk.length;
+  });
+
+  const centralDirectorySize = centralDirectory.reduce((total, chunk) => total + chunk.length, 0);
+  const endRecord: number[] = [];
+  pushUint32(endRecord, 0x06054b50);
+  pushUint16(endRecord, 0);
+  pushUint16(endRecord, 0);
+  pushUint16(endRecord, files.length);
+  pushUint16(endRecord, files.length);
+  pushUint32(endRecord, centralDirectorySize);
+  pushUint32(endRecord, offset);
+  pushUint16(endRecord, 0);
+
+  return new Blob([...chunks, ...centralDirectory, new Uint8Array(endRecord)], {
+    type: "application/zip",
+  });
+};