Quintus.Input = function(Q) {
    var KEY_NAMES = { LEFT: 37, RIGHT: 39, SPACE: 32,
                      UP: 38, DOWN: 40,
                      Z: 90, X: 88   
                    };
    
    var DEFAULT_KEYS = { LEFT: 'left', RIGHT: 'right',
                         UP: 'up',     DOWN: 'down',
                         SPACE: 'fire',
                         Z: 'fire',
                         X: 'action' };
  
    var DEFAULT_TOUCH_CONTROLS  = [ ['left','<' ],
                              ['right','>' ],
                              [],
                              ['action','b'],
                              ['fire', 'a' ]];
  
    // Clockwise from midnight (a la CSS)
    var DEFAULT_JOYPAD_INPUTS =  [ 'up','right','down','left'];
  
    Q.inputs = {};
    Q.joypad = {};
  
    var hasTouch =  !!('ontouchstart' in window);
  
    Q.InputSystem = Q.Evented.extend({
  
      keys: {},
      keypad: {},
      keyboardEnabled: false,
      touchEnabled: false,
      joypadEnabled: false,
  
      bindKey: function(key,name) {
        Q.input.keys[KEY_NAMES[key] || key] = name;
      },
  
      keyboardControls: function(keys) {
        keys = keys || DEFAULT_KEYS;
        _(keys).each(function(name,key) {
         this.bindKey(key,name);
        },Q.input);
        this.enableKeyboard();
      },
  
      enableKeyboard: function() {
        if(this.keyboardEnabled) return false;
  
        // Make selectable and remove an :focus outline
        Q.el.attr('tabindex',0).css('outline',0);
  
        Q.el.keydown(function(e) {
          if(Q.input.keys[e.keyCode]) {
            var actionName = Q.input.keys[e.keyCode];
            Q.inputs[actionName] = true;
            Q.input.trigger(actionName);
            Q.input.trigger('keydown',e.keyCode);
          }
          e.preventDefault();
        });
  
        Q.el.keyup(function(e) {
          if(Q.input.keys[e.keyCode]) {
            var actionName = Q.input.keys[e.keyCode];
            Q.inputs[actionName] = false;
            Q.input.trigger(actionName + "Up");
            Q.input.trigger('keyup',e.keyCode);
          }
          e.preventDefault();
        });
        this.keyboardEnabled = true;
      },
  
      touchLocation: function(touch) {
        var el = Q.el, 
            pageX = touch.pageX,
            pageY = touch.pageY,
            pos = el.offset(),
            touchX = (el.attr('width')||Q.width) * (pageX - pos.left) / el.width(),
            touchY = (el.attr('height')||Q.height) * (pageY - pos.top) / el.height();
        return { x: touchX, y: touchY };
      },
  
      touchControls: function(opts) {
        if(this.touchEnabled) return false;
        if(!hasTouch) return false;
  
        Q.input.keypad = opts = _({
          left: 0,
          gutter:10,
          controls: DEFAULT_TOUCH_CONTROLS,
          width: Q.el.attr('width') || Q.width,
          bottom: Q.el.attr('height') || Q.height
        }).extend(opts||{});
  
        opts.unit = (opts.width / opts.controls.length);
        opts.size = opts.unit - 2 * opts.gutter;
  
        function getKey(touch) {
          var pos = Q.input.touchLocation(touch);
          for(var i=0,len=opts.controls.length;i<len;i++) {
            if(pos.x < opts.unit * (i+1)) {
              return opts.controls[i][0];
            }
          }
        }
  
        function touchDispatch(event) {
          var elemPos = Q.el.position(),
              wasOn = {},
              i, len, tch, key, actionName;
  
          // Reset all the actions bound to controls
          // but keep track of all the actions that were on
          for(i=0,len = opts.controls.length;i<len;i++) {
            actionName = opts.controls[i][0];
            if(Q.inputs[actionName]) { wasOn[actionName] = true; }
            Q.inputs[actionName] = false;
          }
  
          for(i=0,len=event.touches.length;i<len;i++) {
            tch = event.touches[i];
            key = getKey(tch);
  
            if(key) {
              // Mark this input as on
              Q.inputs[key] = true;
  
              // Either trigger a new action
              // or remove from wasOn list
              if(!wasOn[key]) {
                Q.input.trigger(key);
              } else {
                delete wasOn[key];
              }
            }
          }
  
          // Any remaining were on the last frame
          // and need to trigger an up action
          for(actionName in wasOn) {
            Q.input.trigger(actionName + "Up");
          }
  
          return null;
        }
  
        Q.el.on('touchstart touchend touchmove touchcancel',function(e) {
          touchDispatch(e.originalEvent);
          e.preventDefault();
        });
  
        this.touchEnabled = true;
      },
  
      disableTouchControls: function() {
        Q.el.off('touchstart touchend touchmove touchcancel');
        this.touchEnabled = false;
      },
  
      joypadControls: function(opts) {
        if(this.joypadEnabled) return false;
        //if(!hasTouch) return false;
        var joypad = Q.joypad = _.defaults(opts || {},{
          size: 50,
          trigger: 20,
          center: 25,
          color: "#CCC",
          background: "#000",
          alpha: 0.5,
          zone: (Q.el.attr('width')||Q.width) / 2,
          joypadTouch: null,
          inputs: DEFAULT_JOYPAD_INPUTS,
          triggers: []
        });
  
        Q.el.on('touchstart',function(e) {
          if(joypad.joypadTouch === null) {
            var evt = e.originalEvent,
            touch = evt.changedTouches[0],
            loc = Q.input.touchLocation(touch);
  
            if(loc.x < joypad.zone) {
              joypad.joypadTouch = touch.identifier;
              joypad.centerX = loc.x;
              joypad.centerY = loc.y; 
              joypad.x = null;
              joypad.y = null;
            }
          }
        });
        
        Q.el.on('touchmove',function(e) {
          if(joypad.joypadTouch !== null) {
            var evt = e.originalEvent;
  
            for(var i=0,len=evt.changedTouches.length;i<len;i++) {
              var touch = evt.changedTouches[i];
  
              if(touch.identifier === joypad.joypadTouch) {
                var loc = Q.input.touchLocation(touch),
                    dx = loc.x - joypad.centerX,
                    dy = loc.y - joypad.centerY,
                    dist = Math.sqrt(dx * dx + dy * dy),
                    overage = Math.max(1,dist / joypad.size),
                    ang =  Math.atan2(dx,dy);
  
                if(overage > 1) {
                  dx /= overage;
                  dy /= overage;
                  dist /= overage;
                }
  
                var triggers = [
                  dy < -joypad.trigger,
                  dx > joypad.trigger,
                  dy > joypad.trigger,
                  dx < -joypad.trigger
                ];
  
                for(var k=0;k<triggers.length;k++) {
                  var actionName = joypad.inputs[k];
                  if(triggers[k]) {
                    Q.inputs[actionName] = true;
  
                    if(!joypad.triggers[k]) { 
                      Q.input.trigger(actionName);
                    }
                  } else {
                    Q.inputs[actionName] = false;
                    if(joypad.triggers[k]) { 
                      Q.input.trigger(actionName + "Up");
                    }
                  }
                }
  
                _.extend(joypad, {
                  dx: dx, dy: dy,
                  x: joypad.centerX + dx,
                  y: joypad.centerY + dy,
                  dist: dist,
                  ang: ang,
                  triggers: triggers
                });
  
                break;
              }
            }
          }
          e.preventDefault();
  
        });
  
        Q.el.on('touchend touchcancel',function(e) {
            var evt = e.originalEvent;
  
            if(joypad.joypadTouch !== null) {
              for(var i=0,len=evt.changedTouches.length;i<len;i++) {
                var touch = evt.changedTouches[i];
                if(touch.identifier === joypad.joypadTouch) {
                  for(var k=0;k<joypad.triggers.length;k++) {
                    var actionName = joypad.inputs[k];
                    Q.inputs[actionName] = false;
                  }
                  joypad.joypadTouch = null;
                  break;
                }
              }
            }
            e.preventDefault();
        });
  
        this.joypadEnabled = true;
      },
  
       drawButtons: function() {
        var keypad = Q.input.keypad,
            ctx = Q.ctx;
  
        for(var i=0;i<keypad.controls.length;i++) {
          var control = keypad.controls[i];
  
          if(control[0]) {
  
            if(control[2]) {
              // TODO: Draw an asset instead of squares
            } else {
              ctx.font = "bold " + (keypad.size/2) + "px arial";
              var x = i * keypad.unit + keypad.gutter,
                y = keypad.bottom - keypad.unit,
                key = Q.inputs[control[0]],
                txtSize = ctx.measureText(control[1]);
  
              ctx.fillStyle = keypad.color || "#FFFFFF";
              ctx.globalAlpha = key ? 1.0 : 0.5;
              ctx.fillRect(x,y,keypad.size,keypad.size);
  
              ctx.fillStyle = keypad.text || "#000000";
              ctx.fillText(control[1],
                           x+keypad.size/2-txtSize.width/2, 
                           y+3*keypad.size/4);
            }
          }
        }
      },
  
      drawCircle: function(x,y,color,size) {
        var ctx = Q.ctx,
            joypad = Q.joypad;
  
        ctx.beginPath();
        ctx.globalAlpha=joypad.alpha;
        ctx.fillStyle = color;
        ctx.arc(x, y, size, 0, Math.PI*2, true); 
        ctx.closePath();
        ctx.fill();
      },
  
      drawJoypad: function() {
        var joypad = Q.joypad;
        if(joypad.joypadTouch !== null) {
          Q.input.drawCircle(joypad.centerX,
                             joypad.centerY,
                             joypad.background,
                             joypad.size);
  
          if(joypad.x !== null) {
            Q.input.drawCircle(joypad.x,
                             joypad.y,
                             joypad.color,
                             joypad.center);
          }
        }
  
      },
  
      drawCanvas: function() {
        Q.ctx.save();
  
        if(this.touchEnabled) {
          this.drawButtons();
        }
  
        if(this.joypadEnabled) {
          this.drawJoypad();
        }
  
        Q.ctx.restore();
      }
  
    });
  
    Q.input = new Q.InputSystem();
  
    Q.controls = function(joypad) {
      Q.input.keyboardControls();
  
      if(joypad) {
        Q.input.touchControls({
          controls: [ [],[],[],['action','b'],['fire','a']]
        });
        Q.input.joypadControls();
      } else {
        Q.input.touchControls();
      }
  
      return Q;
    };
  
  };