index.js

'use strict'

const { Buffer } = require('buffer')
const CID = require('cids')
const withIs = require('class-is')

/**
 * Represents an immutable block of data that is uniquely referenced with a cid.
 *
 * @constructor
 * @param {Buffer} data - The data to be stored in the block as a buffer.
 * @param {CID} cid - The cid of the data
 *
 * @example
 * const block = new Block(new Buffer('a012d83b20f9371...'))
 */
class Block {
  constructor (data, cid) {
    if (!data || !ArrayBuffer.isView(data)) {
      throw new Error('first argument  must be a buffer or typed array')
    } else if (!Buffer.isBuffer(data)) {
      data = Buffer.from(data.buffer, data.byteOffset, data.byteLength)
    }

    if (!cid || !CID.isCID(cid)) {
      throw new Error('second argument must be a CID')
    }

    this._data = data
    this._cid = cid
  }

  /**
   * The data of this block.
   *
   * @type {Buffer}
   */
  get data () {
    return this._data
  }

  set data (val) {
    throw new Error('Tried to change an immutable block')
  }

  /**
   * The cid of the data this block represents.
   *
   * @type {CID}
   */
  get cid () {
    return this._cid
  }

  set cid (val) {
    throw new Error('Tried to change an immutable block')
  }
}

module.exports = withIs(Block, { className: 'Block', symbolName: '@ipld/js-ipld-block/block' })