Add support for Web notifications

assets/js/sse.js

@@ -0,0 +1,200 @@
+/**
+ * Copyright (C) 2016 Maxime Petazzoni <maxime.petazzoni@bulix.org>.
+ * All rights reserved.
+ */
+
+var SSE = function (url, options) {
+  if (!(this instanceof SSE)) {
+    return new SSE(url, options);
+  }
+
+  this.INITIALIZING = -1;
+  this.CONNECTING = 0;
+  this.OPEN = 1;
+  this.CLOSED = 2;
+
+  this.url = url;
+
+  options = options || {};
+  this.headers = options.headers || {};
+  this.payload = options.payload !== undefined ? options.payload : '';
+  this.method = options.method || (this.payload && 'POST' || 'GET');
+
+  this.FIELD_SEPARATOR = ':';
+  this.listeners = {};
+
+  this.xhr = null;
+  this.readyState = this.INITIALIZING;
+  this.progress = 0;
+  this.chunk = '';
+
+  this.addEventListener = function(type, listener) {
+    if (this.listeners[type] === undefined) {
+      this.listeners[type] = [];
+    }
+
+    if (this.listeners[type].indexOf(listener) === -1) {
+      this.listeners[type].push(listener);
+    }
+  };
+
+  this.removeEventListener = function(type, listener) {
+    if (this.listeners[type] === undefined) {
+      return;
+    }
+
+    var filtered = [];
+    this.listeners[type].forEach(function(element) {
+      if (element !== listener) {
+        filtered.push(element);
+      }
+    });
+    if (filtered.length === 0) {
+      delete this.listeners[type];
+    } else {
+      this.listeners[type] = filtered;
+    }
+  };
+
+  this.dispatchEvent = function(e) {
+    if (!e) {
+      return true;
+    }
+
+    e.source = this;
+
+    var onHandler = 'on' + e.type;
+    if (this.hasOwnProperty(onHandler)) {
+      this[onHandler].call(this, e);
+      if (e.defaultPrevented) {
+        return false;
+      }
+    }
+
+    if (this.listeners[e.type]) {
+      return this.listeners[e.type].every(function(callback) {
+        callback(e);
+        return !e.defaultPrevented;
+      });
+    }
+
+    return true;
+  };
+
+  this._setReadyState = function (state) {
+    var event = new CustomEvent('readystatechange');
+    event.readyState = state;
+    this.readyState = state;
+    this.dispatchEvent(event);
+  };
+
+  this._onStreamFailure = function(e) {
+    this.dispatchEvent(new CustomEvent('error'));
+    this.close();
+  }
+
+  this._onStreamProgress = function(e) {
+    if (this.xhr.status !== 200) {
+      this._onStreamFailure(e);
+      return;
+    }
+
+    if (this.readyState == this.CONNECTING) {
+      this.dispatchEvent(new CustomEvent('open'));
+      this._setReadyState(this.OPEN);
+    }
+
+    var data = this.xhr.responseText.substring(this.progress);
+    this.progress += data.length;
+    data.split(/(\r\n|\r|\n){2}/g).forEach(function(part) {
+      if (part.trim().length === 0) {
+        this.dispatchEvent(this._parseEventChunk(this.chunk.trim()));
+        this.chunk = '';
+      } else {
+        this.chunk += part;
+      }
+    }.bind(this));
+  };
+
+  this._onStreamLoaded = function(e) {
+    this._onStreamProgress(e);
+
+    // Parse the last chunk.
+    this.dispatchEvent(this._parseEventChunk(this.chunk));
+    this.chunk = '';
+  };
+
+  /**
+   * Parse a received SSE event chunk into a constructed event object.
+   */
+  this._parseEventChunk = function(chunk) {
+    if (!chunk || chunk.length === 0) {
+      return null;
+    }
+
+    var e = {'id': null, 'retry': null, 'data': '', 'event': 'message'};
+    chunk.split(/\n|\r\n|\r/).forEach(function(line) {
+      line = line.trimRight();
+      var index = line.indexOf(this.FIELD_SEPARATOR);
+      if (index <= 0) {
+        // Line was either empty, or started with a separator and is a comment.
+        // Either way, ignore.
+        return;
+      }
+
+      var field = line.substring(0, index);
+      if (!(field in e)) {
+        return;
+      }
+
+      var value = line.substring(index + 1).trimLeft();
+      if (field === 'data') {
+        e[field] += value;
+      } else {
+        e[field] = value;
+      }
+    }.bind(this));
+
+    var event = new CustomEvent(e.event);
+    event.data = e.data;
+    event.id = e.id;
+    return event;
+  };
+
+  this._checkStreamClosed = function() {
+    if (this.xhr.readyState === XMLHttpRequest.DONE) {
+      this._setReadyState(this.CLOSED);
+    }
+  };
+
+  this.stream = function() {
+    this._setReadyState(this.CONNECTING);
+
+    this.xhr = new XMLHttpRequest();
+    this.xhr.addEventListener('progress', this._onStreamProgress.bind(this));
+    this.xhr.addEventListener('load', this._onStreamLoaded.bind(this));
+    this.xhr.addEventListener('readystatechange', this._checkStreamClosed.bind(this));
+    this.xhr.addEventListener('error', this._onStreamFailure.bind(this));
+    this.xhr.addEventListener('abort', this._onStreamFailure.bind(this));
+    this.xhr.open(this.method, this.url);
+    for (var header in this.headers) {
+      this.xhr.setRequestHeader(header, this.headers[header]);
+    }
+    this.xhr.send(this.payload);
+  };
+
+  this.close = function() {
+    if (this.readyState === this.CLOSED) {
+      return;
+    }
+
+    this.xhr.abort();
+    this.xhr = null;
+    this._setReadyState(this.CLOSED);
+  };
+};
+
+// Export our SSE module for npm.js
+if (typeof exports !== 'undefined') {
+  exports.SSE = SSE;
+}