import { zlibSync } from "fflate";

function textEncode(str: string) {
  return new TextEncoder().encode(str);
}

function strFromU8(dat: Uint8Array): string {
  const s = 2 ** 14;
  const chunks = [];
  for (let i = 0; i < dat.length; i += s) {
    chunks.push(String.fromCharCode(...dat.subarray(i, i + s)));
  }
  return chunks.join("");
}

async function zlib_fflate(data: Uint8Array): Promise<Uint8Array> {
  return await zlibSync(data, { level: 9 });
}

export async function zlib(str: string): Promise<string> {
  const data = textEncode(str);
  // const res = typeof CompressionStream !== typeof undefined
  //   ? zlib_CompressStream(data)
  //   : zlib_fflate(data);
  const res = zlib_fflate(data);
  return strFromU8(await res);
}

// async function zlib_CompressStream(data: Uint8Array): Promise<Uint8Array> {
//   const compressionStream = new CompressionStream("deflate");

//   // 创建一个Readable Stream
//   const stream = new ReadableStream<Uint8Array>({
//     start(controller) {
//       controller.enqueue(data);
//       controller.close();
//     },
//   }).pipeThrough<Uint8Array>(compressionStream);

//   const chunks = await readData(stream);

//   return mergeUint8Arrays(chunks);
// }

// function mergeUint8Arrays(arrays: Uint8Array[]): Uint8Array {
//   const totalSize = arrays.map((it) => it.length).reduce((a, b) => a + b, 0);

//   const merged = new Uint8Array(totalSize);
//   let offset = 0;
//   for (const array of arrays) {
//     merged.set(array, offset);
//     offset += array.length;
//   }

//   return merged;
// }

// async function readData(stream: ReadableStream<Uint8Array>) {
//   const reader = stream.getReader();
//   const chunks = [];
//   while (true) {
//     const { done, value } = await reader.read();
//     if (value) {
//       chunks.push(value);
//     }
//     if (done) {
//       return chunks;
//     }
//   }
// }