var cram = (function() {
    function appendDiv(fn) {
        if (!document.createElement)
            return null;
        var body = document.getElementsByTagName('body');
        body = body.length > 0 ? body[0] : null;
        if (!body)
            return null;
        var div = document.createElement('div');
        if (!div)
            return null;
        fn(div);
        body.appendChild(div);
        return div;
    }
    var msieVersion = function() {
        if (navigator.appName == "Microsoft Internet Explorer" && /MSIE ([0-9]+[\.0-9]*)/.test(navigator.userAgent)) {
            return parseFloat(RegExp.$1);
        }
        return 0;
    };
    var backend = function() {
        this.store = {};
        this.get = function(key) {
            return this.store[key];
        }
        this.set = function(key, value) {
            this.store[key] = value;
        }
        this.remove = function(key) {
            delete this.store[key];
        }
    };
    backend.valid = function() {
        return true;
    }
    backend.create = function(valid, init) {
        var k = init || function() {};
        k.valid = valid || backend.valid;
        k.prototype = new backend();
        return k;
    };
    var html5 = backend.create(function() {
        return window.localStorage && window.localStorage.getItem;
    }, function() {
        var store = window.localStorage;
        this.get = function(key) {
            if (store)
                return store.getItem(key);
        }
        this.set = function(k, v) {
            if (store)
                store.setItem(k, v);
        }
        this.remove = function(key) {
            if (store)
                store.removeItem(key);
        }
    });
    var userData = backend.create(function() {
        return !! window.ActiveXObject && msieVersion() >= 7.0;
    }, function() {
        var store = appendDiv(function(div) {
            div.id = '_cram_userData';
            div.style.display = 'none';
            div.addBehavior('#default#userData');
        });
        store.load("_cram");
        this.get = function(k) {
            if (store)
                return store.getAttribute(k);
        };
        this.set = function(k, v) {
            if (store)
                store.setAttribute(k, v);
            store.save("_cram");
        }
        this.remove = function(k) {
            store.removeAttribute(k);
        }
        this.free = function() {
            store = null;
        };
    });
    var flash = backend.create(function() {
        return window.SWFObject;
    }, function() {
        if (document.getElementById('_cram_flash')) {
            return;
        }
        var div = appendDiv(function(div) {
            div.id = '_cram_flash';
            div.style.position = 'absolute';
            div.style.top = '-100px';
            div.style.left = '-100px';
        });
        if (!div)
            return;
        var so = new SWFObject("/cram.swf", "_cram_swf", "1", "1", "9");
        so.addParam("allowScriptAccess", "sameDomain");
        if (so.write("_cram_flash")) {
            var swf = document.getElementById('_cram_swf');
            if (swf) {
                this.get = function(k) {
                    if (swf && swf.get)
                        return swf.get(k);
                };
                this.set = function(k, v) {
                    if (swf && swf.set)
                        swf.set(k, v);
                };
                this.remove = function(k) {
                    if (swf && swf.remove)
                        swf.remove(k);
                };
                this.free = function() {
                    swf = null;
                };
            }
        }
    });
    var methods = {
        html5: html5,
        flash: flash
    };
    var order = ['html5', 'flash'];
    var store = null;
    var self = {
        load: function() {
            for (var i = 0; i < order.length; i++) {
                var method = methods[order[i]];
                if (method.valid()) {
                    store = new method();
                    break;
                }
            }
            document.fire('cram:load');
        },
        methods: methods,
        valid: function() {
            return !! store;
        },
        unload: function() {
            if (store && store.free)
                store.free();
            document.fire('cram:unload');
        },
        setStore: function(manualStore) {
            store = manualStore;
        },
        get: function(key) {
            var r = null;
            if (store) {
                var value = store.get(key) || "null";
                r = unescape(value).evalJSON(true);
            }
            return r;
        },
        set: function(key, value) {
            if (store)
                store.set(key, escape(Object.toJSON(value)));
        },
        remove: function(key) {
            if (store)
                store.remove(key);
        }
    };
    if (Event && Event.observe) {
        Event.observe(window, "load", self.load);
        Event.observe(window, "unload", self.unload);
    }
    return self;
})();