/**
 * http://www.openjs.com/scripts/events/keyboard_shortcuts/
 * Version : 2.01.A
 * By Binny V A
 * License : BSD
 */
shortcut = {
  'all_shortcuts': {}, //All the shortcuts are stored in this array
  'add': function(shortcut_combination, callback, opt) {
    //Provide a set of default options
    var default_options = {
      'type': 'keydown',
      'propagate': false,
      'disable_in_input': false,
      'target': document,
      'keycode': false
    }
    if (!opt) opt = default_options;
    else {
      for (var dfo in default_options) {
        if (typeof opt[dfo] == 'undefined') opt[dfo] = default_options[dfo];
      }
    }

    var ele = opt.target
    if (typeof opt.target == 'string') ele = document.getElementById(opt.target);
    var ths = this;
    shortcut_combination = shortcut_combination.toLowerCase();

    //The function to be called at keypress
    var func = function(e) {
      e = e || window.event;

      if (opt['disable_in_input']) { //Don't enable shortcut keys in Input, Textarea fields
        var element;
        if (e.target) element = e.target;
        else if (e.srcElement) element = e.srcElement;
        if (element.nodeType == 3) element = element.parentNode;

        if (element.tagName == 'INPUT' || element.tagName == 'TEXTAREA') return;
      }

      //Find Which key is pressed
      if (e.keyCode) code = e.keyCode;
      else if (e.which) code = e.which;
      var character = String.fromCharCode(code).toLowerCase();

      if (code == 188) character = ","; //If the user presses , when the type is onkeydown
      if (code == 190) character = "."; //If the user presses , when the type is onkeydown

      var keys = shortcut_combination.split("+");
      //Key Pressed - counts the number of valid keypresses - if it is same as the number of keys, the shortcut function is invoked
      var kp = 0;

      //Work around for stupid Shift key bug created by using lowercase - as a result the shift+num combination was broken
      var shift_nums = {
        "`": "~",
        "1": "!",
        "2": "@",
        "3": "#",
        "4": "$",
        "5": "%",
        "6": "^",
        "7": "&",
        "8": "*",
        "9": "(",
        "0": ")",
        "-": "_",
        "=": "+",
        ";": ":",
        "'": "\"",
        ",": "<",
        ".": ">",
        "/": "?",
        "\\": "|"
      }
      //Special Keys - and their codes
      var special_keys = {
        'esc': 27,
        'escape': 27,
        'tab': 9,
        'space': 32,
        'return': 13,
        'enter': 13,
        'backspace': 8,

        'scrolllock': 145,
        'scroll_lock': 145,
        'scroll': 145,
        'capslock': 20,
        'caps_lock': 20,
        'caps': 20,
        'numlock': 144,
        'num_lock': 144,
        'num': 144,

        'pause': 19,
        'break': 19,

        'insert': 45,
        'home': 36,
        'delete': 46,
        'end': 35,

        'pageup': 33,
        'page_up': 33,
        'pu': 33,

        'pagedown': 34,
        'page_down': 34,
        'pd': 34,

        'left': 37,
        'up': 38,
        'right': 39,
        'down': 40,

        'f1': 112,
        'f2': 113,
        'f3': 114,
        'f4': 115,
        'f5': 116,
        'f6': 117,
        'f7': 118,
        'f8': 119,
        'f9': 120,
        'f10': 121,
        'f11': 122,
        'f12': 123
      }

      var modifiers = {
        shift: { wanted: false, pressed: false },
        ctrl: { wanted: false, pressed: false },
        alt: { wanted: false, pressed: false },
        meta: { wanted: false, pressed: false}	//Meta is Mac specific
      };

      if (e.ctrlKey) modifiers.ctrl.pressed = true;
      if (e.shiftKey) modifiers.shift.pressed = true;
      if (e.altKey) modifiers.alt.pressed = true;
      if (e.metaKey) modifiers.meta.pressed = true;

      for (var i = 0; k = keys[i], i < keys.length; i++) {
        //Modifiers
        if (k == 'ctrl' || k == 'control') {
          kp++;
          modifiers.ctrl.wanted = true;

        } else if (k == 'shift') {
          kp++;
          modifiers.shift.wanted = true;

        } else if (k == 'alt') {
          kp++;
          modifiers.alt.wanted = true;
        } else if (k == 'meta') {
          kp++;
          modifiers.meta.wanted = true;
        } else if (k.length > 1) { //If it is a special key
          if (special_keys[k] == code) kp++;

        } else if (opt['keycode']) {
          if (opt['keycode'] == code) kp++;

        } else { //The special keys did not match
          if (character == k) kp++;
          else {
            if (shift_nums[character] && e.shiftKey) { //Stupid Shift key bug created by using lowercase
              character = shift_nums[character];
              if (character == k) kp++;
            }
          }
        }
      }

      if (kp == keys.length &&
						modifiers.ctrl.pressed == modifiers.ctrl.wanted &&
						modifiers.shift.pressed == modifiers.shift.wanted &&
						modifiers.alt.pressed == modifiers.alt.wanted &&
						modifiers.meta.pressed == modifiers.meta.wanted) {
        callback(e);

        if (!opt['propagate']) { //Stop the event
          //e.cancelBubble is supported by IE - this will kill the bubbling process.
          e.cancelBubble = true;
          e.returnValue = false;

          //e.stopPropagation works in Firefox.
          if (e.stopPropagation) {
            e.stopPropagation();
            e.preventDefault();
          }
          return false;
        }
      }
    }
    this.all_shortcuts[shortcut_combination] = {
      'callback': func,
      'target': ele,
      'event': opt['type']
    };
    //Attach the function with the event
    if (ele.addEventListener) ele.addEventListener(opt['type'], func, false);
    else if (ele.attachEvent) ele.attachEvent('on' + opt['type'], func);
    else ele['on' + opt['type']] = func;
  },

  //Remove the shortcut - just specify the shortcut and I will remove the binding
  'remove': function(shortcut_combination) {
    shortcut_combination = shortcut_combination.toLowerCase();
    var binding = this.all_shortcuts[shortcut_combination];
    delete (this.all_shortcuts[shortcut_combination])
    if (!binding) return;
    var type = binding['event'];
    var ele = binding['target'];
    var callback = binding['callback'];

    if (ele.detachEvent) ele.detachEvent('on' + type, callback);
    else if (ele.removeEventListener) ele.removeEventListener(type, callback, false);
    else ele['on' + type] = false;
  }
}