$(document).ready(function () {

    /* Example of hashed params:
     *
     * /Foo/Bar.html#Redirect:Baz
     * /Foo/Bar.html#EditPage
     * /Foo/Bar.html#Redirect:Baz|EditPage
     */

    var cached_rawHash;
    var cached_map;

    /*
    var re_key   = /^[^:|]+$/;
    var re_value = /^[^|]*$/;
     */

    var getRawHash = function () {
        /* Don't use window.location.hash as it isn't portable due to
         * an ambiguous specification.
         */
        var r = window.location.href;
        var i = r.indexOf("#");
        return (i >= 0
                ? r.substr(i + 1)
                : "");
    };

    /*
    var setRawHash = function (hash) {
        var r = window.location.href;
        var i = r.indexOf("#");
        var b = (i >= 0
                 ? r.substr(0, i)
                 : r);
        window.location.href = b + "#" + hash;
    };
     */

    var getHashedParamMap = function () {
        var raw = getRawHash();

        if (cached_rawHash != raw) {
            var src = decodeURIComponent(raw);

            // Split the source by '|' letters.
            cached_map = {};
            $.each(src.split("|"), function () {
                // tuple ::= key ':' value
                //         | key           (value is the same as key)
                var i = this.indexOf(":");
                if (i >= 0) {
                    var key = this.substr(0, i);
                    var val = this.substr(i + 1);
                    cached_map[key] = val;
                }
                else {
                    var key = this;
                    cached_map[key] = key;
                }
            });

            cached_rawHash = raw;
        }

        return cached_map;
    };

    Rakka.getHashedParam = function (key) {
        return getHashedParamMap()[key];
    };

    /*
    var setHashedParamMap = function (map) {
        var tuples = "";

        $.each(map, function(key, val) {
            var tuple = (key == val
                         ? key
                         : key + ":" + val);

            tuples = (tuples == ""
                      ? tuple
                      : tuples + "|" + tuple);
        });

        cached_map = map;
        cached_raw = encodeURIComponent(tuples);

        setRawHash(cached_raw);
    };

    Rakka.setHashedParam = function (key, value) {
        var diff = {};
        diff[key] = value;
        Rakka.setHashedParams(diff);
    };

    Rakka.setHashedParams = function (diff) {
        var orig = getHashedParamMap();
        var next = {};

        // Copy 'orig' to 'next'.
        $.each(orig, function (key, val) {
            next[key] = val;
        });

        // Overwrite the content of 'next' with 'diff'.
        $.each(diff, function (key, val) {

            if (!key.match(re_key)) {
                throw new Error("Invalid key: " + key);
            }
            if (!val.match(re_value)) {
                throw new Error("Invalid value: " + val);
            }

            if (diff[key] == null) {
                delete next[key];
            }
            else {
                next[key] = val;
            }
        });

        setHashedParamMap(next);
    };
     */
});