var shortcutListener = {

    listen: true,

    shortcut: null,
    combination: '',
    lastKeypress: 0,
    clearTimeout: 2000,

    // Keys we don't listen 
    keys: {
        KEY_BACKSPACE: 8,
        KEY_TAB:       9,
        KEY_SHIFT:    16,
        KEY_CTRL:     17,
        KEY_ALT:      18,
        KEY_ESC:      27,
        KEY_SPACE:    32,
        KEY_LEFT:     37,
        KEY_UP:       38,
        KEY_RIGHT:    39,
        KEY_DOWN:     40,
        KEY_DELETE:   46,
        KEY_HOME:     36,
        KEY_END:      35,
        KEY_PAGEUP:   33,
        KEY_PAGEDOWN: 34
    },

    init: function() {
        if (!window.SHORTCUTS) return false;
        this.createStatusArea();
        this.setObserver();
    },

    isInputTarget: function(e) {
        var target = e.target || e.srcElement;
        if (target && target.nodeName) {
            var targetNodeName = target.nodeName.toLowerCase();
            if (targetNodeName == "textarea" || targetNodeName == "select" ||
                (targetNodeName == "input" && target.type &&
                    (target.type.toLowerCase() == "text" ||
                         target.type.toLowerCase() == "password"))
                             )  {
                return true;
            }
        }
        return false;
    },

    stopEvent: function(event) {
        if (event.preventDefault) {
            event.preventDefault();
            event.stopPropagation();
        } else {
            event.returnValue = false;
            event.cancelBubble = true;
        }
    },


    // shortcut notification/status area
    createStatusArea: function() {
        var area = document.createElement('div');
        area.setAttribute('id', 'shortcut_status');
        area.style.display = 'none';
        document.body.appendChild(area);
    },

    showStatus: function() {
        document.getElementById('shortcut_status').style.display = '';
    },

    hideStatus: function() {
        document.getElementById('shortcut_status').style.display = 'none';
    },

    showCombination: function() {
        var bar = document.getElementById('shortcut_status');
        bar.innerHTML = this.combination;
        this.showStatus();
    },

    // This method creates event observer for the whole document
    // This is the common way of setting event observer that works 
    // in all modern brwosers with "keypress" fix for
    // Konqueror/Safari/KHTML borrowed from Prototype.js
    setObserver: function() {
        var name = 'keypress';
        if (navigator.appVersion.match(/Konqueror|Safari|KHTML/) || document.detachEvent) {
          name = 'keydown';
        }
        if (document.addEventListener) {
            document.addEventListener(name, function(e) {shortcutListener.keyCollector(e)}, false);
        } else if (document.attachEvent) {
            document.attachEvent('on'+name, function(e) {shortcutListener.keyCollector(e)});
        }
    },

    // Key press collector. Collects all keypresses into combination 
    // and checks it we have action for it
    keyCollector: function(e) {
        // do not listen if no shortcuts defined
        if (!window.SHORTCUTS) return false;
        // do not listen if listener was explicitly turned off
        if (!shortcutListener.listen) return false;
        // leave modifiers for browser
        if (e.altKey || e.ctrlKey || e.metaKey) return false;
        var keyCode = e.keyCode;
        // do not listen for Ctrl, Alt, Tab, Space, Esc and others
        for (var key in this.keys) {
            if (e.keyCode == this.keys[key]) return false;
        }
        // do not listen for functional keys
        if (navigator.userAgent.match(/Gecko/)) {
            if (e.keyCode >= 112 && e.keyCode <=123) return false;
        }
        
        // get letter pressed for different browsers
        var code = e.which ? e.which : e.keyCode
        var letter = String.fromCharCode(code).toLowerCase();
        if (e.shiftKey) letter = letter.toUpperCase();
        if (shortcutListener.process(letter)) shortcutListener.stopEvent(e);
    },

    // process keys
    process: function(letter) {
        if (!window.SHORTCUTS) return false;
        if (!shortcutListener.listen) return false;
        // if no combination then start from the begining
        if (!shortcutListener.shortcut) { shortcutListener.shortcut = SHORTCUTS; }
        // if unknown letter then say goodbye
        if (!shortcutListener.shortcut[letter]) return false
        if (typeof(shortcutListener.shortcut[letter]) == "function") {
            shortcutListener.shortcut[letter]();
            shortcutListener.clearCombination();
        } else {
            shortcutListener.shortcut = shortcutListener.shortcut[letter];
            // append combination
            shortcutListener.combination = shortcutListener.combination + letter;
            if (shortcutListener.combination.length > 0) {
                shortcutListener.showCombination();
                // save last keypress timestamp (for autoclear)
                var d = new Date;
                shortcutListener.lastKeypress = d.getTime();
                // autoclear combination in 2 seconds
                setTimeout("shortcutListener.clearCombinationOnTimeout()", shortcutListener.clearTimeout);
            };
        }
        return true;
    },

    // clear combination
    clearCombination: function() {
        shortcutListener.shortcut = null;
        shortcutListener.combination = '';
        this.hideStatus();
    },

    clearCombinationOnTimeout: function() {
        var d = new Date;
        // check if last keypress was earlier than (now - clearTimeout)
        // 100ms here is used just to be sure that this will work in superfast browsers :)
        if ((d.getTime() - shortcutListener.lastKeypress) >= (shortcutListener.clearTimeout - 100)) {
            shortcutListener.clearCombination();
        }
    }
}