import { ethers, Contract } from "ethers";
import { HexString } from "ethers/lib.commonjs/utils/data";

const contractABI = [
  "function countChunks(bytes memory name) external view returns (uint256)",
  "function readChunk(bytes memory name, uint256 chunkId) external view returns (bytes memory, bool)",
];

const stringToHex = (s: string) => ethers.hexlify(ethers.toUtf8Bytes(s));

async function readChunk(
  ethStorageRpc: string,
  ethStorageAddress: HexString,
  hexName: HexString,
  index: number
) {
  let result;
  try {
    const provider = new ethers.JsonRpcProvider(ethStorageRpc);
    const contract = new Contract(ethStorageAddress, contractABI, provider);
    result = await contract.readChunk(hexName, index);
  } catch (e) {
    const provider = new ethers.JsonRpcProvider(ethStorageRpc);
    const contract = new Contract(ethStorageAddress, contractABI, provider);
    result = await contract.readChunk(hexName, index);
  }
  return ethers.getBytes(result[0]);
}

export async function Download(
  ethStorageRpc: string,
  ethStorageAddress: HexString,
  fileName: string
) {
  const hexName = stringToHex(fileName);

  const provider = new ethers.JsonRpcProvider(ethStorageRpc);
  const contract = new Contract(ethStorageAddress, contractABI, provider);
  const blobCount = await contract.countChunks(hexName);

  let buff: any[] = [];
  for (let i = 0; i < blobCount; i++) {
    const chunk = await readChunk(ethStorageRpc, ethStorageAddress, hexName, i);
    buff = [...buff, ...chunk];
  }
  return Buffer.from(buff);
}