/**
 * URL State manipulation utility
 * 
 * Usage Example:
 * //urlState.strictMode = (function() { return !this; })();
 * var queryString = urlState.search();
 * queryString.name = 'sujeet';
 * urlState.pathname('/result-page').search(queryString).update();
 */
 (function (win) {
    'use strict';

    var toType = function (val) {
        var type = Object.prototype.toString.call(val);
        return type.replace(/\[(\w+)\s(\w+)\]/, '$2').toLowerCase();
    };

    var parseQstr = function (queryString, coerce) {
        queryString = ('' + queryString).replace(/^\?/, '');
        var re = /([^&=]+)=?([^&]*)/g,
            m,
            params = {},
            coerceTypes = {'true': !0, 'false': !1, 'null': null},
            decode = function (str) {
                return decodeURIComponent(str.replace(/\+/g, '%20'));
            };
        if (queryString) {
            while (m = re.exec(queryString)) {
                var k = decode(m[1]),
                    v = decode(m[2]),
                    curr = params;
                if (coerce) {
                    v = !isNaN(v) ? +v : (v === 'undefined' ? undefined : (coerceTypes[v] ? coerceTypes[v] : v));
                }
                var keys = k.split('][');
                var keysLast = keys.length - 1;
                if (/\[/.test(keys[0]) && /\]$/.test(keys[keysLast])) {
                    keys[keysLast] = keys[keysLast].replace(/\]$/, '');
                    keys = keys.shift().split('[').concat(keys);
                    keysLast = keys.length - 1;
                }
                if (keysLast) {
                    for (var i = 0; i <= keysLast; i++) {
                        k = (keys[i] === '') ? curr.length : keys[i];
                        curr = curr[k] = (i < keysLast) ? curr[k] || (keys[i+1] && isNaN(keys[i+1]) ? {} : []) : v;
                    }
                } else if (params[k]) {
                    if (toType(params[k]) === 'array') {
                        params[k].push(v);
                    } else {
                        params[k] = [params[k], v];
                    }
                } else {
                    params[k] = v;
                }
            }
        }
        return params;
    };

    var createQstr = function (obj) {
        var key, s = [];
        var add = function (k, v) {
            v = typeof v === 'function' ? v() : v;
            v = (v === null || v === undefined) ? '' : v === undefined ? '' : v;
            s[s.length] = encodeURIComponent(k) + '=' + encodeURIComponent(v);
        };
        var buildParams = function (prefix, obj) {
            var i, len, key, objectType = toType(obj);
            if (objectType === 'array') {
                for (i = 0, len = obj.length; i < len; i++) {
                    buildParams(prefix + '[' + (typeof obj[i] === 'object' && obj[i] ? i : '') + ']', obj[i]);
                }
            } else if (objectType === 'object') {
                for (key in obj) {
                    buildParams(prefix + '[' + key + ']', obj[key]);
                }
            } else {
                add(prefix, obj);
            }
        };
        for (key in obj) {
            buildParams(key, obj[key]);
        }
        return s.join('&');
    };

    win.urlState = (function () {
        var init_state = win.history.state,
            init_title = win.document.title,
            init_loc = win.document.createElement('a'),
            wloc = win.document.createElement('a');
        init_loc.href = win.location.href;
        wloc.href = win.location.href;
        return {
            strictMode: true,

            get protocol() { return wloc.protocol; },
            set protocol(value) {
                if (this.strictMode) {
                    throw new TypeError('"protocol" is read-only');
                }
            },

            get host() { return wloc.host; },
            set host(value) {
                if (this.strictMode) {
                    throw new TypeError('"host" is read-only');
                }
            },

            get hostname() { return wloc.hostname; },
            set hostname(value) {
                if (this.strictMode) {
                    throw new TypeError('"hostname" is read-only');
                }
            },

            get port() { return wloc.port; },
            set port(value) {
                if (this.strictMode) {
                    throw new TypeError('"port" is read-only');
                }
            },

            pathname: function (pathname) {
                if (pathname === undefined) {
                    return wloc.pathname;
                } else {
                    wloc.pathname = pathname;
                    return this;
                }
            },
            search: function (search) {
                if (search === undefined) {
                    return parseQstr(wloc.search);
                } else {
                    wloc.search = createQstr(search);
                    return this;
                }
            },
            hash: function (hash) {
                if (hash === undefined) {
                    return wloc.hash;
                } else {
                    wloc.hash = hash;
                    return this;
                }
            },

            update: function (title, replace) {
                win.history[replace?'replaceState':'pushState'](init_state, '', this.toString());
                win.document.title = title || init_title;
                return this;
            },
            reset: function () {
                wloc = init_loc;
                win.history.replaceState(init_state, '', this.toString());
                win.document.title = init_title;
                return this;
            },

            toString: function () {
                return wloc.toString();
            },
        };
    })();
})(this);