// keymaster.js // © 2011-2013 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
  },
  code = function(x){
    return _MAP[x] || x.toUpperCase().charCodeAt(0);
  },
  _downKeys = [];

for(k=1;k<20;k++) _MAP['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;
}

// for comparing mods before unassignment
function compareArray(a1, a2) {
  if (a1.length != a2.length) return false;
  for (var i = 0; i < a1.length; i++) {
      if (a1[i] !== a2[i]) return false;
  }
  return true;
}

var modifierMap = {
    16:'shiftKey',
    18:'altKey',
    17:'ctrlKey',
    91:'metaKey'
};
function updateModifierKey(event) {
    for(k in _mods) _mods[k] = event[modifierMap[k]];
};

// handle keydown event
function dispatch(event) {
  var key, handler, k, i, modifiersMatch, scope;
  key = event.keyCode;

  if (index(_downKeys, key) == -1) {
      _downKeys.push(key);
  }

  // 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;
  }
  updateModifierKey(event);

  // see if we need to ignore the keypress (filter() 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;

  scope = getScope();

  // 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,
      i = index(_downKeys, key);

  // remove key from _downKeys
  if (i >= 0) {
      _downKeys.splice(i, 1);
  }

  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;
  keys = getKeys(key);
  if (method === undefined) {
    method = scope;
    scope = 'all';
  }

  // for each shortcut
  for (var i = 0; i < keys.length; i++) {
    // set modifier keys if any
    mods = [];
    key = keys[i].split('+');
    if (key.length > 1){
      mods = getMods(key);
      key = [key[key.length-1]];
    }
    // convert to keycode and...
    key = key[0]
    key = code(key);
    // ...store handler
    if (!(key in _handlers)) _handlers[key] = [];
    _handlers[key].push({ shortcut: keys[i], scope: scope, method: method, key: keys[i], mods: mods });
  }
};

// unbind all handlers for given key in current scope
function unbindKey(key, scope) {
  var multipleKeys, keys,
    mods = [],
    i, j, obj;

  multipleKeys = getKeys(key);

  for (j = 0; j < multipleKeys.length; j++) {
    keys = multipleKeys[j].split('+');

    if (keys.length > 1) {
      mods = getMods(keys);
    }

    key = keys[keys.length - 1];
    key = code(key);

    if (scope === undefined) {
      scope = getScope();
    }
    if (!_handlers[key]) {
      return;
    }
    for (i = 0; i < _handlers[key].length; i++) {
      obj = _handlers[key][i];
      // only clear handlers if correct scope and mods match
      if (obj.scope === scope && compareArray(obj.mods, mods)) {
        _handlers[key][i] = {};
      }
    }
  }
};

// Returns true if the key with code 'keyCode' is currently down
// Converts strings into key codes.
function isPressed(keyCode) {
    if (typeof(keyCode)=='string') {
      keyCode = code(keyCode);
    }
    return index(_downKeys, keyCode) != -1;
}

function getPressedKeyCodes() {
    return _downKeys.slice(0);
}

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++;
    }
  }
};

// abstract key logic for assign and unassign
function getKeys(key) {
  var keys;
  key = key.replace(/\s/g, '');
  keys = key.split(',');
  if ((keys[keys.length - 1]) == '') {
    keys[keys.length - 2] += ',';
  }
  return keys;
}

// abstract mods logic for assign and unassign
function getMods(key) {
  var mods = key.slice(0, key.length - 1);
  for (var mi = 0; mi < mods.length; mi++)
  mods[mi] = _MODIFIERS[mods[mi]];
  return mods;
}

// 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', function(event) { dispatch(event) }); // Passing _scope to a callback to ensure it remains the same by execution. Fixes #48
addEvent(document, 'keyup', clearModifier);

// reset modifiers to false whenever the window is (re)focused.
addEvent(window, 'focus', resetModifiers);

// store previously defined key
var previousKey = global.key;

// restore previously defined key and return reference to our key object
function noConflict() {
  var k = global.key;
  global.key = previousKey;
  return k;
}

// 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;
global.key.isPressed = isPressed;
global.key.getPressedKeyCodes = getPressedKeyCodes;
global.key.noConflict = noConflict;
global.key.unbind = unbindKey;

if(typeof module !== 'undefined') module.exports = assignKey;

})(this);