(function() {
'use strict';

Elm.fullscreen = function(module, ports) {
    var style = document.createElement('style');
    style.type = 'text/css';
    style.innerHTML = "html,head,body { padding:0; margin:0; }" +
        "body { font-family: calibri, helvetica, arial, sans-serif; }";
    document.head.appendChild(style);
    var container = document.createElement('div');
    document.body.appendChild(container);
    return init(ElmRuntime.Display.FULLSCREEN, container, module, ports || {});
};

Elm.embed = function(module, container, ports) {
    var tag = container.tagName;
    if (tag !== 'DIV') {
        throw new Error('Elm.node must be given a DIV, not a ' + tag + '.');
    } else if (container.hasChildNodes()) {
        throw new Error('Elm.node must be given an empty DIV. No children allowed!');
    }
    return init(ElmRuntime.Display.COMPONENT, container, module, ports || {});
};

Elm.worker = function(module, ports) {
    return init(ElmRuntime.Display.NONE, {}, module, ports || {});
};

function init(display, container, module, ports, moduleToReplace) {
  // defining state needed for an instance of the Elm RTS
  var inputs = [];

  var updateInProgress = false;
  function notify(id, v) {
      if (updateInProgress) {
          throw new Error(
              'The notify function has been called synchronously!\n' +
              'This can lead to frames being dropped.\n' +
              'Definitely report this to <https://github.com/evancz/Elm/issues>\n');
      }
      updateInProgress = true;
      var timestep = Date.now();
      for (var i = inputs.length; i--; ) {
          inputs[i].recv(timestep, id, v);
      }
      updateInProgress = false;
  }

  var listeners = [];
  function addListener(relevantInputs, domNode, eventName, func) {
      domNode.addEventListener(eventName, func);
      var listener = {
          relevantInputs: relevantInputs,
          domNode: domNode,
          eventName: eventName,
          func: func
      };
      listeners.push(listener);
  }

  var portUses = {}
  for (var key in ports) {
      portUses[key] = 0;
  }
  // create the actual RTS. Any impure modules will attach themselves to this
  // object. This permits many Elm programs to be embedded per document.
  var elm = {
      notify:notify,
      node:container,
      display:display,
      id:ElmRuntime.guid(),
      addListener:addListener,
      inputs:inputs,
      ports: { incoming:ports, outgoing:{}, uses:portUses }
  };

  function swap(newModule) {
      removeListeners(listeners);
      var div = document.createElement('div');
      var newElm = init(display, div, newModule, ports, elm);
      inputs = [];
      // elm.swap = newElm.swap;
      return newElm;
  }

  var Module = {};
  var reportAnyErrors = function() {};
  try {
      Module = module.make(elm);
      checkPorts(elm);
  } catch(e) {
      var directions = "<br/>&nbsp; &nbsp; Open the developer console for more details."
      Module.main = Elm.Text.make(elm).leftAligned('<code>' + e.message + directions + '</code>');
      reportAnyErrors = function() { throw e; }
  }
  inputs = ElmRuntime.filterDeadInputs(inputs);
  filterListeners(inputs, listeners);
  addReceivers(elm.ports.outgoing);
  if (display !== ElmRuntime.Display.NONE) {
      var graphicsNode = initGraphics(elm, Module);
  }
  if (typeof moduleToReplace !== 'undefined') {
      ElmRuntime.swap(moduleToReplace, elm);

      // rerender scene if graphics are enabled.
      if (typeof graphicsNode !== 'undefined') {
          graphicsNode.recv(0, true, 0);
      }
  }

  reportAnyErrors();
  return { swap:swap, ports:elm.ports.outgoing };
};

function checkPorts(elm) {
    var portUses = elm.ports.uses;
    for (var key in portUses) {
        var uses = portUses[key]
        if (uses === 0) {
            throw new Error(
                "Initialization Error: provided port '" + key +
                "' to a module that does not take it as in input.\n" +
                "Remove '" + key + "' from the module initialization code.");
        } else if (uses > 1) {
            throw new Error(
                "Initialization Error: port '" + key +
                "' has been declared multiple times in the Elm code.\n" +
                "Remove declarations until there is exactly one.");
        }
    }
}
    
function filterListeners(inputs, listeners) {
    loop:
    for (var i = listeners.length; i--; ) {
        var listener = listeners[i];
        for (var j = inputs.length; j--; ) {
            if (listener.relevantInputs.indexOf(inputs[j].id) >= 0) {
                continue loop;
            }
        }
        listener.domNode.removeEventListener(listener.eventName, listener.func);
    }
}

function removeListeners(listeners) {
    for (var i = listeners.length; i--; ) {
        var listener = listeners[i];
        listener.domNode.removeEventListener(listener.eventName, listener.func);
    }
}

// add receivers for built-in ports if they are defined
function addReceivers(ports) {
    if ('log' in ports) {
        ports.log.subscribe(function(v) { console.log(v) });
    }
    if ('stdout' in ports) {
        var process = process || {};
        var handler = process.stdout
            ? function(v) { process.stdout.write(v); }
            : function(v) { console.log(v); };
        ports.stdout.subscribe(handler);
    }
    if ('stderr' in ports) {
        var process = process || {};
        var handler = process.stderr
            ? function(v) { process.stderr.write(v); }
            : function(v) { console.log('Error:' + v); };
        ports.stderr.subscribe(handler);
    }
    if ('title' in ports) {
        if (typeof ports.title === 'string') {
            document.title = ports.title;
        } else {
            ports.title.subscribe(function(v) { document.title = v; });
        }
    }
    if ('redirect' in ports) {
        ports.redirect.subscribe(function(v) {
            if (v.length > 0) window.location = v;
        });
    }
    if ('favicon' in ports) {
        if (typeof ports.favicon === 'string') {
            changeFavicon(ports.favicon);
        } else {
            ports.favicon.subscribe(changeFavicon);
        }
    }
    function changeFavicon(src) {
        var link = document.createElement('link');
        var oldLink = document.getElementById('elm-favicon');
        link.id = 'elm-favicon';
        link.rel = 'shortcut icon';
        link.href = src;
        if (oldLink) {
            document.head.removeChild(oldLink);
        }
        document.head.appendChild(link);
    }
}

function initGraphics(elm, Module) {
  if (!('main' in Module))
      throw new Error("'main' is missing! What do I display?!");

  var signalGraph = Module.main;

  // make sure the signal graph is actually a signal & extract the visual model
  var Signal = Elm.Signal.make(elm);
  if (!('recv' in signalGraph)) {
      signalGraph = Signal.constant(signalGraph);
  }
  var currentScene = signalGraph.value;

 // Add the currentScene to the DOM
  var Render = ElmRuntime.use(ElmRuntime.Render.Element);
  elm.node.appendChild(Render.render(currentScene));

  // set up updates so that the DOM is adjusted as necessary.
  var savedScene = currentScene;
  function domUpdate(newScene) {
      ElmRuntime.draw(function(_) {
          Render.update(elm.node.firstChild, savedScene, newScene);
          if (elm.Native.Window) elm.Native.Window.values.resizeIfNeeded();
          savedScene = newScene;
      });
  }
  var renderer = A2(Signal.lift, domUpdate, signalGraph);

  // must check for resize after 'renderer' is created so
  // that changes show up.
  if (elm.Native.Window) elm.Native.Window.values.resizeIfNeeded();

  return renderer;
}

}());