import { ethers } from "ethers";

const BlobTxBytesPerFieldElement = 32; // Size in bytes of a field element
const BlobTxFieldElementsPerBlob = 4096;
export const BLOB_SIZE =
  BlobTxBytesPerFieldElement * BlobTxFieldElementsPerBlob;
export const BLOB_DATA_SIZE = 31 * BlobTxFieldElementsPerBlob;

export function EncodeBlobs(data: Uint8Array) {
  const len = data.length;
  if (len === 0) {
    throw Error("invalid blob data");
  }

  let blobIndex = 0;
  let fieldIndex = -1;

  const blobs = [new Uint8Array(BLOB_SIZE).fill(0)];
  for (let i = 0; i < len; i += 31) {
    fieldIndex++;
    if (fieldIndex === BlobTxFieldElementsPerBlob) {
      blobs.push(new Uint8Array(BLOB_SIZE).fill(0));
      blobIndex++;
      fieldIndex = 0;
    }
    let max = i + 31;
    if (max > len) {
      max = len;
    }
    blobs[blobIndex].set(data.subarray(i, max), fieldIndex * 32 + 1);
  }
  return blobs;
}

export function DecodeBlob(blob: Uint8Array) {
  if (!blob) {
    throw Error("invalid blob data");
  }

  blob = ethers.getBytes(blob);
  if (blob.length < BLOB_SIZE) {
    const newBlob = new Uint8Array(BLOB_SIZE).fill(0);
    newBlob.set(blob);
    blob = newBlob;
  }

  let data: any[] = [];
  let j = 0;
  for (let i = 0; i < BlobTxFieldElementsPerBlob; i++) {
    const chunk = blob.subarray(j + 1, j + 32);
    data = [...data, ...chunk];
    j += 32;
  }
  let i = data.length - 1;
  for (; i >= 0; i--) {
    if (data[i] !== 0x00) {
      break;
    }
  }
  return data.slice(0, i + 1);
}

export function DecodeBlobs(blobs: Uint8Array) {
  if (!blobs) {
    throw Error("invalid blobs");
  }

  blobs = ethers.getBytes(blobs);
  const len = blobs.length;
  if (len === 0) {
    throw Error("invalid blobs");
  }

  let buf: any[] = [];
  for (let i = 0; i < len; i += BLOB_SIZE) {
    let max = i + BLOB_SIZE;
    if (max > len) {
      max = len;
    }
    const blob = blobs.subarray(i, max);
    const blobBuf = DecodeBlob(blob);
    buf = [...buf, ...blobBuf];
  }
  return Buffer.from(buf);
}