ara-context/index.js

ARA context to encapsulate things like Web3, etc

const thunky = require('thunky')
const pify = require('pify')

const web3 = require('./web3')

const PROVIDER_TIMEOUT = 3000

module.exports = context

/**
 * Creates an ARA context that wraps useful
 * instances like `Web3'
 *
 * @public
 * @default
 * @param {Object} opts
 * @return {Object}
 */
function context(opts) {
  if (null === opts || (undefined !== opts && 'object' !== typeof opts)) {
    throw new TypeError('Expecting options to be an object.')
  } else if ('object' !== typeof opts) {
    // eslint-disable-next-line no-param-reassign
    opts = {}
  }

  if (false === opts.provider) {
    if (opts.web3) {
      opts.web3.provider = false
    } else {
      opts.web3 = {
        provider: false
      }
    }
  }

  const ctx = {
    web3: web3.load(opts.web3)
  }

  ctx.close = () => {
    if (!ctx.web3) { return }
    if (ctx.web3.currentProvider && ctx.web3.currentProvider.connection) {
      try {
        ctx.web3.currentProvider.connection.close()
      } catch (err) {
        void err
      }
    }
  }

  process.nextTick(() => {
    if (ctx.web3.currentProvider && ctx.web3.currentProvider.connection) {
      if ('function' === typeof ctx.web3.currentProvider.connection.connect) {
        ctx.web3.currentProvider.connection.connect()
      }
    }
  })

  ctx.ready = pify(thunky((done) => {
    let connected = Boolean(ctx.web3.currentProvider.connected)
    setTimeout(() => {
      if (!connected) {
        ctx.close()
        done(new Error('Could not connect to a provider.'))
      } else {
        done(null)
      }
    }, PROVIDER_TIMEOUT)

    if (ctx.web3 && ctx.web3.currentProvider) {
      if ('function' === typeof ctx.web3.currentProvider.once) {
        ctx.web3.currentProvider.once('connect', onconnect)
      } else if (
        ctx.web3.currentProvider.connection
        && 'function' === typeof ctx.web3.currentProvider.connection.once
      ) {
        ctx.web3.currentProvider.connection.once('connect', onconnect)
      }
    }

    function onconnect() {
      connected = true
      done()
    }
  }))

  return ctx
}