ipfs-http-client/src/lib/resolve.js

A client library for the IPFS HTTP API

'use strict'

const { CID } = require('multiformats/cid')
const errCode = require('err-code')

/**
 * @typedef {import('ipfs-core-types/src/utils').AbortOptions} AbortOptions
 */

/**
 * Retrieves IPLD Nodes along the `path` that is rooted at `cid`.
 *
 * @param {CID} cid - the CID where the resolving starts
 * @param {string} path - the path that should be resolved
 * @param {import('ipfs-core-utils/src/multicodecs')} codecs
 * @param {(cid: CID, options?: AbortOptions) => Promise<Uint8Array>} getBlock
 * @param {AbortOptions} [options]
 */
const resolve = async function * (cid, path, codecs, getBlock, options) {
  /**
   * @param {CID} cid
   */
  const load = async (cid) => {
    const codec = await codecs.getCodec(cid.code)
    const block = await getBlock(cid, options)

    return codec.decode(block)
  }

  const parts = path.split('/').filter(Boolean)
  let value = await load(cid)
  let lastCid = cid

  if (!parts.length) {
    yield {
      value,
      remainderPath: ''
    }
  }

  // End iteration if there isn't a CID to follow any more
  while (parts.length) {
    const key = parts.shift()

    if (!key) {
      throw errCode(new Error(`Could not resolve path "${path}"`), 'ERR_INVALID_PATH')
    }

    if (Object.prototype.hasOwnProperty.call(value, key)) {
      value = value[key]

      yield {
        value,
        remainderPath: parts.join('/')
      }
    } else {
      throw errCode(new Error(`no link named "${key}" under ${lastCid}`), 'ERR_NO_LINK')
    }

    if (value instanceof CID) {
      lastCid = value
      value = await load(value)
    }
  }
}

module.exports = resolve