var canvas;
  
  var delta = [0,0];
  var stage = [window.screenX,window.screenY,window.innerWidth,window.innerHeight];
  getBrowserDimensions();
  
  var isRunning = false;
  var isMouseDown = false;
  
  var worldAABB;
  var world;
  var iterations = 1;
  var timeStep = 1/25; 
  
  var walls = new Array();
  var wall_thickness = 200;
  var wallsSetted = false;
  
  var mouseJoint;
  var mouseX = 0;
  var mouseY = 0;
  
  var mouseOnClick = new Array();
  
  var timer = 0;
  
  var elements = new Array();
  var bodies = new Array();
  var properties = new Array();
  
  var gWebSearch;
  var imFeelingLuckyMode = false;
  var resultBodies = new Array();
  
  init();
  
  if (location.search != "")
  {
          var params = location.search.substr(1).split("&")
  
          for (var i = 0; i < params.length; i++)
          {
                  var param = params[i].split("=");
  
                  if (param[0] == "q")
                  {
                          document.getElementById('q').value = param[1];
                          run();
                          break;
                  }
          }
  }
  
  // GOOGLE API
  
  function onLoad()
  {
          gWebSearch = new GwebSearch();
          gWebSearch.setResultSetSize(GSearch.SMALL_RESULTSET);
          gWebSearch.setSearchCompleteCallback(null, onWebSearch);
  
          if (document.getElementById('q').value != '')
                  search();
  }
  
  function onWebSearch()
  {
          if(imFeelingLuckyMode)
          {
                  location.href = gWebSearch.results[0].unescapedUrl;
                  return;
          }
          
          for (var i = 0; i < gWebSearch.results.length; i++)
                  addResult(gWebSearch.results[i]);
  }
  
  //
  
  function init()
  {
          canvas = document.getElementById('canvas');
          
          document.onmousedown = onDocumentMouseDown;
          document.onmouseup = onDocumentMouseUp;
          document.onmousemove = onDocumentMouseMove;
          document.ondblclick = onDocumentDoubleClick;
          
          document.onkeypress = onDocumentKeyPress;
  
          document.addEventListener('touchstart', onDocumentTouchStart, false);
          document.addEventListener('touchmove', onDocumentTouchMove, false);
          document.addEventListener('touchend', onDocumentTouchEnd, false)
  
          // init box2d
          
          worldAABB = new b2AABB();
          worldAABB.minVertex.Set(-200, -200);
          worldAABB.maxVertex.Set( screen.width + 200, screen.height + 200);
  
          world = new b2World(worldAABB, new b2Vec2(0, 0), true);
          
          // walls        
          setWalls();
  
          // Get box2d elements
          
          elements = getElementsByClass("box2d");
                  
          for (i = 0; i < elements.length; i++) {
  
                  var element = elements[i];
                  properties[i] = findPos(element);
                  properties[i][2] = element.offsetWidth;
                  properties[i][3] = element.offsetHeight;
          }
          
          for (i = 0; i < elements.length; i++) {
                  var element = elements[i];
                  element.style.position = 'absolute';
                  element.style.left = properties[i][0] + 'px';
                  element.style.top = properties[i][1] + 'px';
                  // element.style.backgroundColor = '#ffff00';
                  element.onmousedown = onElementMouseDown;
                  element.onmouseup = onElementMouseUp;
                  element.onclick = onElementClick;
                  
                  bodies[i] = createBox(world, properties[i][0] + (properties[i][2] >> 1), properties[i][1] + (properties[i][3] >> 1), properties[i][2] / 2, properties[i][3] / 2, false);                
          }
  }
  
  function run() {
  
          isRunning = true;
          setInterval(loop, 25);        
  }
  
  //
  
  function onDocumentMouseDown() {
  
          isMouseDown = true;
          return false;
  }
  
  function onDocumentMouseUp() {
  
          isMouseDown = false;
          return false;
  }
  
  function onDocumentMouseMove() {
  
          if (!isRunning)
                  run();
  
          mouseX = window.event.clientX;
          mouseY = window.event.clientY;
  }
  
  function onDocumentDoubleClick() {
  
          reset();
  }
  
  function onDocumentKeyPress(event) {
  
          if (event.charCode == 13)
                  search();
  }
  
  function onDocumentTouchStart( event ) {
  
          if(event.touches.length == 1) {
  
                  event.preventDefault();
  
                  if (!isRunning)
                          run();
  
                  // Faking double click for touch devices
  
                  var now = new Date().getTime();
  
                  if (now - timeOfLastTouch  < 250) {
  
                          reset();
                          return;
                  }
  
                  timeOfLastTouch = now;
  
                  mouseX = event.touches[0].pageX;
                  mouseY = event.touches[0].pageY;
                  isMouseDown = true;
          }
  }
  
  function onDocumentTouchMove( event ) {
  
          if(event.touches.length == 1) {
  
                  event.preventDefault();
                  
                  mouseX = event.touches[0].pageX;
                  mouseY = event.touches[0].pageY;
          }
  }
  
  function onDocumentTouchEnd( event ) {
  
          if(event.touches.length == 0) {
  
                  event.preventDefault();
                  isMouseDown = false;
          }
  }
  
  //
  
  function onElementMouseDown() {
  
          mouseOnClick[0] = window.event.clientX;
          mouseOnClick[1] = window.event.clientY;        
          return false;
  }
  
  function onElementMouseUp() {
  
          return false;
  }
  
  function onElementClick() {
  
          var range = 5;
          
          if (mouseOnClick[0] > window.event.clientX + range || mouseOnClick[0] < window.event.clientX - range && mouseOnClick[1] > window.event.clientY + range || mouseOnClick[1] < window.event.clientY - range)
                  return false;
          
          if (this == document.getElementById('btnG')) search();
          if (this == document.getElementById('btnI')) imFeelingLucky();
          if (this == document.getElementById('q')) document.f.q.focus();
  }
  
  // API STUFF
  
  function search() {
  
          if (!isRunning)
                  run();
          
          onDocumentDoubleClick(); // clean
          gWebSearch.execute(document.getElementById('q').value);
          return false;
  }
  
  function imFeelingLucky() {
  
          imFeelingLuckyMode = true;
          gWebSearch.execute(document.getElementById('q').value);
          return false;        
  }
  
  function addResult(data) {
  
          var element = document.createElement('div');
          element.innerHTML = '<div><h3 class=r><a href="' + data.unescapedUrl + '" class=l onmousedown="return clk(this.href,\'\',\'\',\'res\',\'1\',\'&amp;sig2=3Ti89FTuSYfE6a-5k1jjKQ\')">' + data.title + '</a></h3><span style=display:inline-block><button class=w10 title="Promote"></button><button class=w20 title="Remove"></button></span><div class="s">' + data.content + '<br><cite>' + data.visibleUrl + '</cite></div>';
          
          canvas.appendChild(element);
          properties.push([Math.random() * (window.innerWidth / 2),-200,600,element.offsetHeight]);
          
          var i = properties.length - 1;
  
          element.style.position = 'absolute';
          element.style.left = 0 + 'px';
          element.style.top = -100 + 'px';
          element.style.backgroundColor = '#ffffff';
          element.onmousedown = onElementMouseDown;
          element.onmouseup = onElementMouseUp;
          element.onclick = onElementClick;
  
          elements[i] = element;
  
          resultBodies.push( bodies[i] = createBox(world, properties[i][0] + (properties[i][2] >> 1), properties[i][1] + (properties[i][3] >> 1), properties[i][2] / 2, properties[i][3] / 2, false, element) );
          
  }
  
  function reset() {
  
          for (i = 0; i < resultBodies.length; i++) {
  
                  var body = resultBodies[i]
                  canvas.removeChild( body.GetUserData().element );
                  world.DestroyBody(body);
                  body = null;
          }
          
          resultBodies = new Array();
  }
  
  //
  
  function loop() {
  
          if (getBrowserDimensions())
                  setWalls();
  
          delta[0] += (0 - delta[0]) * .5;
          delta[1] += (0 - delta[1]) * .5;
          
          world.m_gravity.x = 0 + delta[0];
          world.m_gravity.y = 350 + delta[1];
  
          mouseDrag();
          world.Step(timeStep, iterations);        
          
          for (i = 0; i < elements.length; i++) {
  
                  var body = bodies[i];
                  var element = elements[i];
                  
                  element.style.left = (body.m_position0.x - (properties[i][2] >> 1)) + 'px';
                  element.style.top = (body.m_position0.y - (properties[i][3] >> 1)) + 'px';
  
                  var rotationStyle = 'rotate(' + (body.m_rotation0 * 57.2957795) + 'deg)';
  
                  element.style.WebkitTransform = rotationStyle;
                  element.style.MozTransform = rotationStyle;
                  element.style.OTransform = rotationStyle;
          }
  }
  
  // .. BOX2D UTILS
  
  function createBox(world, x, y, width, height, fixed, element) {
  
          if (typeof(fixed) == 'undefined')
                  fixed = true;
  
          var boxSd = new b2BoxDef();
  
          if (!fixed)
                  boxSd.density = 1.0;
  
          boxSd.extents.Set(width, height);
  
          var boxBd = new b2BodyDef();
          boxBd.AddShape(boxSd);
          boxBd.position.Set(x,y);
          boxBd.userData = {element: element};
  
          return world.CreateBody(boxBd)
  }
  
  function mouseDrag() {
  
          // mouse press
          if (isMouseDown && !mouseJoint) {
  
                  var body = getBodyAtMouse();
                  
                  if (body) {
  
                          var md = new b2MouseJointDef();
                          md.body1 = world.m_groundBody;
                          md.body2 = body;
                          md.target.Set(mouseX, mouseY);
                          md.maxForce = 30000.0 * body.m_mass;
                          md.timeStep = timeStep;
                          mouseJoint = world.CreateJoint(md);
                          body.WakeUp();
                  }
          }
          
          // mouse release
          if (!isMouseDown) {
  
                  if (mouseJoint) {
  
                          world.DestroyJoint(mouseJoint);
                          mouseJoint = null;
                  }
          }
          
          // mouse move
          if (mouseJoint) {
  
                  var p2 = new b2Vec2(mouseX, mouseY);
                  mouseJoint.SetTarget(p2);
          }
  }
  
  function getBodyAtMouse() {
  
          // Make a small box.
          var mousePVec = new b2Vec2();
          mousePVec.Set(mouseX, mouseY);
          
          var aabb = new b2AABB();
          aabb.minVertex.Set(mouseX - 1, mouseY - 1);
          aabb.maxVertex.Set(mouseX + 1, mouseY + 1);
  
          // Query the world for overlapping shapes.
          var k_maxCount = 10;
          var shapes = new Array();
          var count = world.Query(aabb, shapes, k_maxCount);
          var body = null;
          
          for (var i = 0; i < count; ++i) {
  
                  if (shapes[i].m_body.IsStatic() == false) {
  
                          if ( shapes[i].TestPoint(mousePVec) ) {
  
                                  body = shapes[i].m_body;
                                  break;
                          }
                  }
          }
  
          return body;
  }
  
  function setWalls() {
  
          if (wallsSetted) {
  
                  world.DestroyBody(walls[0]);
                  world.DestroyBody(walls[1]);
                  world.DestroyBody(walls[2]);
                  world.DestroyBody(walls[3]);
                  
                  walls[0] = null; 
                  walls[1] = null;
                  walls[2] = null;
                  walls[3] = null;
          }
          
          walls[0] = createBox(world, stage[2] / 2, - wall_thickness, stage[2], wall_thickness);
          walls[1] = createBox(world, stage[2] / 2, stage[3] + wall_thickness, stage[2], wall_thickness);
          walls[2] = createBox(world, - wall_thickness, stage[3] / 2, wall_thickness, stage[3]);
          walls[3] = createBox(world, stage[2] + wall_thickness, stage[3] / 2, wall_thickness, stage[3]);        
          
          wallsSetted = true;
  }
  
  // .. UTILS
  
  function getElementsByClass( searchClass ) {
  
          var classElements = new Array();
          var els = document.getElementsByTagName('*');
          var elsLen = els.length
  
          for (i = 0, j = 0; i < elsLen; i++) {
  
                  var classes = els[i].className.split(' ');
                  for (k = 0; k < classes.length; k++)
                          if ( classes[k] == searchClass )
                                  classElements[j++] = els[i];
          }
  
          return classElements;
  }
  
  function findPos(obj) {
  
          var curleft = curtop = 0;
  
          if (obj.offsetParent) {
  
                  do {
  
                          curleft += obj.offsetLeft;
                          curtop += obj.offsetTop;
  
                  } while (obj = obj.offsetParent);
          }
  
          return [curleft,curtop];
  }
  
  function getBrowserDimensions() {
  
          var changed = false;
                  
          if (stage[0] != window.screenX) {
  
                  delta[0] = (window.screenX - stage[0]) * 50;
                  stage[0] = window.screenX;
                  changed = true;
          }
          
          if (stage[1] != window.screenY) {
  
                  delta[1] = (window.screenY - stage[1]) * 50;
                  stage[1] = window.screenY;
                  changed = true;
          }
          
          if (stage[2] != window.innerWidth) {
  
                  stage[2] = window.innerWidth;
                  changed = true;
          }
          
          if (stage[3] != window.innerHeight) {
  
                  stage[3] = window.innerHeight;
                  changed = true;
          }
          
          return changed;
  }