component-remotes/lib/remotes.js

Normalize remote end points

var EventEmitter = require('events').EventEmitter;
var inherits = require('util').inherits;

inherits(Remotes, EventEmitter);

module.exports = Remotes;

/**
 * Create an a remote object.
 * Each remote can be added as an array on initialization,
 * or one by one with `.use()`.
 * The array can be either instances of Remote,
 * or strings of names of known remotes.
 * `.local` is special as you can just pass `local: true` as an option.
 * Note that both arguments are optional.
 *
 * @param {Array} remotes
 * @param {Object} options
 * @api public
 */

function Remotes(remotes, options) {
  if (!(this instanceof Remotes)) return new Remotes(remotes, options);

  if (Array.isArray(remotes)) {
    options = options || {};
  } else {
    options = remotes || {};
    remotes = null;
  }

  // list of remotes
  this.remotes = [];
  // look up remotes by `remote.name`
  this.remote = Object.create(null);

  // If `local` is a remote, it __must__ be first,
  // otherwise it doesn't make any sense!
  if (options.local) this.use(Remotes.local(options));

  if (remotes) remotes.forEach(function (remote) {
    var Remote = Remotes[remote];
    if (!Remote) throw new Error('no remote by the name of "' + remote + '"');
    this.use(new Remote(options));
  }, this);
}

/**
 * Use a remote. At least one is required.
 * Must inherit from `Remote`.
 *
 * @param {Object} remote
 * @api public
 */

Remotes.prototype.use = function (remote) {
  if (!(remote instanceof Remotes.Remote)) throw new TypeError('You may only use .Remote\'s');

  this.remotes.push(remote)
  this.remote[remote.name] = remote

  return this;
}

/**
 * Resolve a component from [remotes].
 * Internally, this will just look up the `component.json`.
 * Returns the remote instance if there's a match, otherwise null.
 * If there's only one remote, then it'll just return that remote.
 *
 * @param {Array} remotes
 * @param {String} component name
 * @param {String} component reference
 * @return {Object} remote
 * @api public
 */

Remotes.prototype.check = function* (remotes, name, reference) {
  var length = this.remotes.length;
  if (!length) throw new Error('no remotes');

  // resolve(name, [reference])
  if (typeof remotes === 'string') {
    reference = name;
    name = remotes;
    remotes = null;
  }

  remotes = remotes || this.remotes.map(toName);

  // map to remote instances
  var instances = remotes.map(function (name) {
    return this.remote[name];
  }, this).filter(Boolean);
  remotes = instances.map(toName);

  // loop through
  for (var i = 0; i < instances.length; i++) {
    if (yield* instances[i].isValid(remotes, name, reference)) {
      return instances[i];
    }
  }
};

Remotes.prototype.resolve = function* (remotes, name, reference) {
  var length = this.remotes.length;
  if (!length) throw new Error('no remotes');

  // resolve(name, [reference])
  if (typeof remotes === 'string') {
    reference = name;
    name = remotes;
    remotes = null;
  }

  remotes = remotes || this.remotes.map(toName);

  // map to remote instances
  var instances = remotes.map(function (name) {
    return this.remote[name];
  }, this).filter(Boolean);
  remotes = instances.map(toName);

  // loop through
  for (var i = 0; i < instances.length; i++) {
    if (yield* instances[i].resolve(remotes, name, reference))
      return instances[i];
  }
};

function toName(x) {
  return x.name;
}