Function parseUmd

packages/core/src/utils/umd-parser.ts:132–283

(bytes: Uint8Array, inflate: UmdInflate)

 * use `fflate.unzlibSync`; on mobile use `pako.inflate`.
 */
export function parseUmd(bytes: Uint8Array, inflate: UmdInflate): UmdParsed {
  checkMagic(bytes);

  const fileLen = bytes.length;
  let offset = 4;

  let bookTitle = "";
  let author = "";
  let year = "";
  let month = "";
  let day = "";
  let bookType = "";
  let publisher = "";
  let retailer = "";

  let contentLen = 0;
  let idContentBlocks = 0;
  let idTitleList = 0;
  let idChapterList = 0;
  let idCover = 0;
  let hasCover = false;

  // data-block id list, in file order — content reassembly walks this
  const dataOrder: number[] = [];
  // data-block id → raw payload
  const dataById = new Map<number, Uint8Array>();

  while (offset + 5 <= fileLen) {
    const blockType = bytes[offset]!;

    if (blockType === 0x23) {
      // Functional block: '#' funcID ?? ?? funcLen content...
      const funcID = bytes[offset + 1]!;
      const funcLen = bytes[offset + 4]!;
      if (funcLen < 5 || offset + funcLen > fileLen) break;

      const content = bytes.subarray(offset + 5, offset + funcLen);

      switch (funcID) {
        case 0x01: {
          // 1 = text, 2 = comic
          if (content.length === 0 || content[0] !== 1) {
            throw new Error("UMD: non-text variant not supported");
          }
          break;
        }
        case 0x02:
          bookTitle = decodeUtf16LE(content);
          break;
        case 0x03:
          author = decodeUtf16LE(content);
          break;
        case 0x04:
          year = decodeUtf16LE(content);
          break;
        case 0x05:
          month = decodeUtf16LE(content);
          break;