App protocol handler to map directory

app-protocol-handler.js

const { utils: Cu, classes: Cc, interfaces: Ci, manager: Cm } = Components;
const io = Cc["@mozilla.org/network/io-service;1"]
  .getService(Ci.nsIIOService)
Cm.QueryInterface(Ci.nsIComponentRegistrar)

if (typeof(Symbol) === "undefined") {
  var Symbol = String
}
const SubstitutionProtocol = function(scheme) {
  this[SubstitutionProtocol.hosts] = Object.create(null)
  this.scheme = scheme
  this.contract = `@mozilla.org/network/protocol;1?name=${scheme}`
}
SubstitutionProtocol.hosts = Symbol("substitution/protocol/hosts")
SubstitutionProtocol.prototype = {
  constructor: SubstitutionProtocol,
  description: "Custom substitution protocol implemantion",
  classID: Components.ID("{e368b52a-3af0-4585-811c-80a8b020dd24}"),
  QueryInterface(iid) {
    if (iid.equals(Ci.nsISupports) ||
        iid.equals(Ci.nsIProtocolHandler) ||
        iid.equals(Ci.nsIResProtocolHandler) ||
        iid.equals(Ci.nsIFactory))
    {
      return this
    }
    
    throw Cr.NS_ERROR_NO_INTERFACE
  },
  
  // nsIResProtocolHandler
  getSubstitution(host) {
    return this[SubstitutionProtocol.hosts][host]
  },
  hasSubstitution(host) {
    return !!this.getSubstitution(host)
  },
  setSubstitution(host, uri) {
    this[SubstitutionProtocol.hosts][host] = uri
  },
  resolveURI({host, path}) {
    let uri = this.getSubstitution(host)
    if (!uri) {
      throw Cr.NS_ERROR_NOT_AVAILABLE
    }
    return uri.resolve(path.substr(1))
  },
  
  // nsIProtocolHandler
  defaultPort: -1,
  protocolFlags: Ci.nsIProtocolHandler.URI_NOAUTH |
                 Ci.nsIProtocolHandler.URI_DANGEROUS_TO_LOAD |
                 Ci.nsIProtocolHandler.URI_IS_UI_RESOURCE |
                 Ci.nsIProtocolHandler.URI_CROSS_ORIGIN_NEEDS_WEBAPPS_PERM,
  scheme: null,
  newURI(spec, originCharset, baseURI) {
    let uri = Cc["@mozilla.org/network/standard-url;1"]
               .createInstance(Ci.nsIStandardURL)
    uri.init(Ci.nsIStandardURL.URLTYPE_STANDARD,
             -1, spec, originCharset, baseURI)
    return uri.QueryInterface(Ci.nsIURI)
  },
  
  newChannel(uri) {
    let channel = io.newChannel(this.resolveURI(uri), null, null);
    channel.QueryInterface(Ci.nsIChannel).originalURI = uri
    return channel
  },
  
  // nsIFactory
  createInstance(outer, iid) {
   if (outer) {
     throw Cr.NS_ERROR_NO_AGGREGATION
   }
   return this
  },
  lockFactory: function(aLock) {
    throw Cr.NS_ERROR_NOT_IMPLEMENTED
  },
    
  // component
  register() {
      Cm.registerFactory(this.classID,
                         this.description,
                         this.contract,
                         this)

  },
  unregister() {
    Cm.unregisterFactory(this.classID,
                         this)
  }
}

// In e10s registered protocol handlers does not seem to content processes there for
// urls aren't loaded as one would expect. To overcome that limitation import this
// module via message manager in every frameManager.
//
// Todo: figure out a better way to propagate registered protocol handlers.
Cc["@mozilla.org/globalmessagemanager;1"].
  getService(Ci.nsIMessageListenerManager).
  loadFrameScript(`data:,Components.utils.import("${__URI__}", {})`, true);

var EXPORTED_SYMBOLS = ["SubstitutionProtocol"]


let app = new SubstitutionProtocol("app")
app.register()
app.setSubstitution("firefox.html",
                    io.newURI("file:///Users/gozala/Projects/firefox.html/", null, null))