//     keymaster.js
  //     (c) 2011 Thomas Fuchs
  //     keymaster.js may be freely distributed under the MIT license.
  
  ;(function(global){
    var k,
      _handlers = {},
      _mods = { 16: false, 18: false, 17: false, 91: false },
      _scope = 'all',
      // modifier keys
      _MODIFIERS = {
        '⇧': 16, shift: 16,
        '⌥': 18, alt: 18, option: 18,
        '⌃': 17, ctrl: 17, control: 17,
        '⌘': 91, command: 91
      },
      // special keys
      _MAP = {
        backspace: 8, tab: 9, clear: 12,
        enter: 13, 'return': 13,
        esc: 27, escape: 27, space: 32,
        left: 37, up: 38,
        right: 39, down: 40,
        del: 46, 'delete': 46,
        home: 36, end: 35,
        pageup: 33, pagedown: 34,
        ',': 188, '.': 190, '/': 191,
        '`': 192, '-': 189, '=': 187,
        ';': 186, '\'': 222,
        '[': 219, ']': 221, '\\': 220
      };
  
    for(k=1;k<20;k++) _MODIFIERS['f'+k] = 111+k;
  
    // IE doesn't support Array#indexOf, so have a simple replacement
    function index(array, item){
      var i = array.length;
      while(i--) if(array[i]===item) return i;
      return -1;
    }
  
    // handle keydown event
    function dispatch(event){
      var key, handler, k, i, modifiersMatch;
      key = event.keyCode;
  
      // if a modifier key, set the key.<modifierkeyname> property to true and return
      if(key == 93 || key == 224) key = 91; // right command on webkit, command on Gecko
      if(key in _mods) {
        _mods[key] = true;
        // 'assignKey' from inside this closure is exported to window.key
        for(k in _MODIFIERS) if(_MODIFIERS[k] == key) assignKey[k] = true;
        return;
      }
  
      // see if we need to ignore the keypress (ftiler() can can be overridden)
      // by default ignore key presses if a select, textarea, or input is focused
      if(!assignKey.filter.call(this, event)) return;
  
      // abort if no potentially matching shortcuts found
      if (!(key in _handlers)) return;
  
      // for each potential shortcut
      for (i = 0; i < _handlers[key].length; i++) {
        handler = _handlers[key][i];
  
        // see if it's in the current scope
        if(handler.scope == _scope || handler.scope == 'all'){
          // check if modifiers match if any
          modifiersMatch = handler.mods.length > 0;
          for(k in _mods)
            if((!_mods[k] && index(handler.mods, +k) > -1) ||
              (_mods[k] && index(handler.mods, +k) == -1)) modifiersMatch = false;
          // call the handler and stop the event if neccessary
          if((handler.mods.length == 0 && !_mods[16] && !_mods[18] && !_mods[17] && !_mods[91]) || modifiersMatch){
            if(handler.method(event, handler)===false){
              if(event.preventDefault) event.preventDefault();
                else event.returnValue = false;
              if(event.stopPropagation) event.stopPropagation();
              if(event.cancelBubble) event.cancelBubble = true;
            }
          }
        }
  	}
    };
  
    // unset modifier keys on keyup
    function clearModifier(event){
      var key = event.keyCode, k;
      if(key == 93 || key == 224) key = 91;
      if(key in _mods) {
        _mods[key] = false;
        for(k in _MODIFIERS) if(_MODIFIERS[k] == key) assignKey[k] = false;
      }
    };
  
    function resetModifiers() {
      for(k in _mods) _mods[k] = false;
      for(k in _MODIFIERS) assignKey[k] = false;
    }
  
    // parse and assign shortcut
    function assignKey(key, scope, method){
      var keys, mods, i, mi;
      if (method === undefined) {
        method = scope;
        scope = 'all';
      }
      key = key.replace(/\s/g,'');
      keys = key.split(',');
  
      if((keys[keys.length-1])=='')
        keys[keys.length-2] += ',';
      // for each shortcut
      for (i = 0; i < keys.length; i++) {
        // set modifier keys if any
        mods = [];
        key = keys[i].split('+');
        if(key.length > 1){
          mods = key.slice(0,key.length-1);
          for (mi = 0; mi < mods.length; mi++)
            mods[mi] = _MODIFIERS[mods[mi]];
          key = [key[key.length-1]];
        }
        // convert to keycode and...
        key = key[0]
        key = _MAP[key] || key.toUpperCase().charCodeAt(0);
        // ...store handler
        if (!(key in _handlers)) _handlers[key] = [];
        _handlers[key].push({ shortcut: keys[i], scope: scope, method: method, key: keys[i], mods: mods });
      }
    };
  
    function filter(event){
      var tagName = (event.target || event.srcElement).tagName;
      // ignore keypressed in any elements that support keyboard data input
      return !(tagName == 'INPUT' || tagName == 'SELECT' || tagName == 'TEXTAREA');
    }
  
    // initialize key.<modifier> to false
    for(k in _MODIFIERS) assignKey[k] = false;
  
    // set current scope (default 'all')
    function setScope(scope){ _scope = scope || 'all' };
    function getScope(){ return _scope || 'all' };
  
    // delete all handlers for a given scope
    function deleteScope(scope){
      var key, handlers, i;
  
      for (key in _handlers) {
        handlers = _handlers[key];
        for (i = 0; i < handlers.length; ) {
          if (handlers[i].scope === scope) handlers.splice(i, 1);
          else i++;
        }
      }
    };
  
    // cross-browser events
    function addEvent(object, event, method) {
      if (object.addEventListener)
        object.addEventListener(event, method, false);
      else if(object.attachEvent)
        object.attachEvent('on'+event, function(){ method(window.event) });
    };
  
    // set the handlers globally on document
    addEvent(document, 'keydown', dispatch);
    addEvent(document, 'keyup', clearModifier);
  
    // reset modifiers to false whenever the window is (re)focused.
    addEvent(window, 'focus', resetModifiers);
  
    // set window.key and window.key.set/get/deleteScope, and the default filter
    global.key = assignKey;
    global.key.setScope = setScope;
    global.key.getScope = getScope;
    global.key.deleteScope = deleteScope;
    global.key.filter = filter;
  
    if(typeof module !== 'undefined') module.exports = key;
  
  })(this);