@uprtcl/ipfs-provider/src/support.ts

_Prtcl provider wrappers around ipfs-http-client

import CID from 'cids';

const constants: [string, number][] = [
  ['base8', 37],
  ['base10', 39],
  ['base16', 66],
  ['base32', 62],
  ['base32pad', 63],
  ['base32hex', 76],
  ['base32hexpad', 74],
  ['base32z', 68],
  ['base58flickr', 90],
  ['base58btc', 122],
  ['base64', 109],
  ['base64pad', 77],
  ['base64url', 75],
  ['Ubase64urlpad', 55],
];

const multibaseToUint = (multibaseName: string): number => {
  return constants.filter((e) => e[0] == multibaseName)[0][1];
};

const uintToMultibase = (number: number): string => {
  return constants.filter((e) => e[1] == number)[0][0];
};

export const cidToHex32 = (cidStr) => {
  /** store the encoded cids as they are, including the multibase bytes */
  const cid = new CID(cidStr);
  const bytes = cid.bytes;

  /* push the code of the multibse (UTF8 number of the string) */
  const bytesWithMultibase = new Uint8Array(bytes.length + 1);
  bytesWithMultibase.set(Uint8Array.from([multibaseToUint(cid.multibaseName)]));
  bytesWithMultibase.set(bytes, 1);

  /** convert to hex */
  let cidEncoded16 = Buffer.from(bytesWithMultibase).toString('hex');
  /** pad with zeros */
  cidEncoded16 = cidEncoded16.padStart(128, '0');

  const cidHex0 = cidEncoded16.slice(-64); /** LSB */
  const cidHex1 = cidEncoded16.slice(-128, -64);

  return ['0x' + cidHex1, '0x' + cidHex0];
};

export const bytes32ToCid = (bytes: [string, string]) => {
  const cidHex1 = bytes[0].substring(2);
  const cidHex0 = bytes[1].substring(2); /** LSB */

  const cidHex = cidHex1.concat(cidHex0).replace(/^0+/, '');
  if (cidHex === '') return '';

  const cidBufferWithBase = Buffer.from(cidHex, 'hex');

  const multibaseCode = cidBufferWithBase[0];
  const cidBuffer = cidBufferWithBase.slice(1);

  const multibaseName = uintToMultibase(multibaseCode);

  /** Force Buffer class */
  const cid = new CID(cidBuffer);

  return cid.toBaseEncodedString(multibaseName as any);
};