/**
 * @ngdoc object
 * @name ui.router.router.$urlRouterProvider
 *
 * @requires ui.router.util.$urlMatcherFactoryProvider
 * @requires $locationProvider
 *
 * @description
 * `$urlRouterProvider` has the responsibility of watching `$location`. 
 * When `$location` changes it runs through a list of rules one by one until a 
 * match is found. `$urlRouterProvider` is used behind the scenes anytime you specify 
 * a url in a state configuration. All urls are compiled into a UrlMatcher object.
 *
 * There are several methods on `$urlRouterProvider` that make it useful to use directly
 * in your module config.
 */
$UrlRouterProvider.$inject = ['$locationProvider', '$urlMatcherFactoryProvider'];
function $UrlRouterProvider(   $locationProvider,   $urlMatcherFactory) {
  var rules = [], otherwise = null, interceptDeferred = false, listener;

  // Returns a string that is a prefix of all strings matching the RegExp
  function regExpPrefix(re) {
    var prefix = /^\^((?:\\[^a-zA-Z0-9]|[^\\\[\]\^$*+?.()|{}]+)*)/.exec(re.source);
    return (prefix != null) ? prefix[1].replace(/\\(.)/g, "$1") : '';
  }

  // Interpolates matched values into a String.replace()-style pattern
  function interpolate(pattern, match) {
    return pattern.replace(/\$(\$|\d{1,2})/, function (m, what) {
      return match[what === '$' ? 0 : Number(what)];
    });
  }

  /**
   * @ngdoc function
   * @name ui.router.router.$urlRouterProvider#rule
   * @methodOf ui.router.router.$urlRouterProvider
   *
   * @description
   * Defines rules that are used by `$urlRouterProvider` to find matches for
   * specific URLs.
   *
   * @example
   * <pre>
   * var app = angular.module('app', ['ui.router.router']);
   *
   * app.env(function ($urlRouterProvider) {
   *   // Here's an example of how you might allow case insensitive urls
   *   $urlRouterProvider.rule(function ($injector, $location) {
   *     var path = $location.path(),
   *         normalized = path.toLowerCase();
   *
   *     if (path !== normalized) {
   *       return normalized;
   *     }
   *   });
   * });
   * </pre>
   *
   * @param {object} rule Handler function that takes `$injector` and `$location`
   * services as arguments. You can use them to return a valid path as a string.
   *
   * @return {object} `$urlRouterProvider` - `$urlRouterProvider` instance
   */
  this.rule = function (rule) {
    if (!isFunction(rule)) throw new Error("'rule' must be a function");
    rules.push(rule);
    return this;
  };

  /**
   * @ngdoc object
   * @name ui.router.router.$urlRouterProvider#otherwise
   * @methodOf ui.router.router.$urlRouterProvider
   *
   * @description
   * Defines a path that is used when an invalid route is requested.
   *
   * @example
   * <pre>
   * var app = angular.module('app', ['ui.router.router']);
   *
   * app.env(function ($urlRouterProvider) {
   *   // if the path doesn't match any of the urls you configured
   *   // otherwise will take care of routing the user to the
   *   // specified url
   *   $urlRouterProvider.otherwise('/index');
   *
   *   // Example of using function rule as param
   *   $urlRouterProvider.otherwise(function ($injector, $location) {
   *     return '/a/valid/url';
   *   });
   * });
   * </pre>
   *
   * @param {string|object} rule The url path you want to redirect to or a function 
   * rule that returns the url path. The function version is passed two params: 
   * `$injector` and `$location` services, and must return a url string.
   *
   * @return {object} `$urlRouterProvider` - `$urlRouterProvider` instance
   */
  this.otherwise = function (rule) {
    if (isString(rule)) {
      var redirect = rule;
      rule = function () { return redirect; };
    }
    else if (!isFunction(rule)) throw new Error("'rule' must be a function");
    otherwise = rule;
    return this;
  };


  function handleIfMatch($injector, handler, match) {
    if (!match) return false;
    var result = $injector.invoke(handler, handler, { $match: match });
    return isDefined(result) ? result : true;
  }

  /**
   * @ngdoc function
   * @name ui.router.router.$urlRouterProvider#when
   * @methodOf ui.router.router.$urlRouterProvider
   *
   * @description
   * Registers a handler for a given url matching. if handle is a string, it is
   * treated as a redirect, and is interpolated according to the syntax of match
   * (i.e. like `String.replace()` for `RegExp`, or like a `UrlMatcher` pattern otherwise).
   *
   * If the handler is a function, it is injectable. It gets invoked if `$location`
   * matches. You have the option of inject the match object as `$match`.
   *
   * The handler can return
   *
   * - **falsy** to indicate that the rule didn't match after all, then `$urlRouter`
   *   will continue trying to find another one that matches.
   * - **string** which is treated as a redirect and passed to `$location.url()`
   * - **void** or any **truthy** value tells `$urlRouter` that the url was handled.
   *
   * @example
   * <pre>
   * var app = angular.module('app', ['ui.router.router']);
   *
   * app.env(function ($urlRouterProvider) {
   *   $urlRouterProvider.when($state.url, function ($match, $stateParams) {
   *     if ($state.$current.navigable !== state ||
   *         !equalForKeys($match, $stateParams) {
   *      $state.transitionTo(state, $match, false);
   *     }
   *   });
   * });
   * </pre>
   *
   * @param {string|object} what The incoming path that you want to redirect.
   * @param {string|object} handler The path you want to redirect your user to.
   */
  this.when = function (what, handler) {
    var redirect, handlerIsString = isString(handler);
    if (isString(what)) what = $urlMatcherFactory.compile(what);

    if (!handlerIsString && !isFunction(handler) && !isArray(handler))
      throw new Error("invalid 'handler' in when()");

    var strategies = {
      matcher: function (what, handler) {
        if (handlerIsString) {
          redirect = $urlMatcherFactory.compile(handler);
          handler = ['$match', function ($match) { return redirect.format($match); }];
        }
        return extend(function ($injector, $location) {
          return handleIfMatch($injector, handler, what.exec($location.path(), $location.search()));
        }, {
          prefix: isString(what.prefix) ? what.prefix : ''
        });
      },
      regex: function (what, handler) {
        if (what.global || what.sticky) throw new Error("when() RegExp must not be global or sticky");

        if (handlerIsString) {
          redirect = handler;
          handler = ['$match', function ($match) { return interpolate(redirect, $match); }];
        }
        return extend(function ($injector, $location) {
          return handleIfMatch($injector, handler, what.exec($location.path()));
        }, {
          prefix: regExpPrefix(what)
        });
      }
    };

    var check = { matcher: $urlMatcherFactory.isMatcher(what), regex: what instanceof RegExp };

    for (var n in check) {
      if (check[n]) return this.rule(strategies[n](what, handler));
    }

    throw new Error("invalid 'what' in when()");
  };

  /**
   * @ngdoc function
   * @name ui.router.router.$urlRouterProvider#deferIntercept
   * @methodOf ui.router.router.$urlRouterProvider
   *
   * @description
   * Disables (or enables) deferring location change interception.
   *
   * If you wish to customize the behavior of syncing the URL (for example, if you wish to
   * defer a transition but maintain the current URL), call this method at configuration time.
   * Then, at run time, call `$urlRouter.listen()` after you have configured your own
   * `$locationChangeSuccess` event handler.
   *
   * @example
   * <pre>
   * var app = angular.module('app', ['ui.router.router']);
   *
   * app.env(function ($urlRouterProvider) {
   *
   *   // Prevent $urlRouter from automatically intercepting URL changes;
   *   // this allows you to configure custom behavior in between
   *   // location changes and route synchronization:
   *   $urlRouterProvider.deferIntercept();
   *
   * }).run(function ($rootScope, $urlRouter, UserService) {
   *
   *   $rootScope.$on('$locationChangeSuccess', function(e) {
   *     // UserService is an example service for managing user state
   *     if (UserService.isLoggedIn()) return;
   *
   *     // Prevent $urlRouter's default handler from firing
   *     e.preventDefault();
   *
   *     UserService.handleLogin().then(function() {
   *       // Once the user has logged in, sync the current URL
   *       // to the router:
   *       $urlRouter.sync();
   *     });
   *   });
   *
   *   // Configures $urlRouter's listener *after* your custom listener
   *   $urlRouter.listen();
   * });
   * </pre>
   *
   * @param {boolean} defer Indicates whether to defer location change interception. Passing
            no parameter is equivalent to `true`.
   */
  this.deferIntercept = function (defer) {
    if (defer === undefined) defer = true;
    interceptDeferred = defer;
  };

  /**
   * @ngdoc object
   * @name ui.router.router.$urlRouter
   *
   * @requires $location
   * @requires $rootScope
   * @requires $injector
   * @requires $browser
   *
   * @description
   *
   */
  this.$get = $get;
  $get.$inject = ['$location', '$rootScope', '$injector', '$browser'];
  function $get(   $location,   $rootScope,   $injector,   $browser) {

    var baseHref = $browser.baseHref(), location = $location.url(), lastPushedUrl;

    function appendBasePath(url, isHtml5, absolute) {
      if (baseHref === '/') return url;
      if (isHtml5) return baseHref.slice(0, -1) + url;
      if (absolute) return baseHref.slice(1) + url;
      return url;
    }

    // TODO: Optimize groups of rules with non-empty prefix into some sort of decision tree
    function update(evt) {
      if (evt && evt.defaultPrevented) return;
      var ignoreUpdate = lastPushedUrl && $location.url() === lastPushedUrl;
      lastPushedUrl = undefined;
      if (ignoreUpdate) return true;

      function check(rule) {
        var handled = rule($injector, $location);

        if (!handled) return false;
        if (isString(handled)) $location.replace().url(handled);
        return true;
      }
      var n = rules.length, i;

      for (i = 0; i < n; i++) {
        if (check(rules[i])) return;
      }
      // always check otherwise last to allow dynamic updates to the set of rules
      if (otherwise) check(otherwise);
    }

    function listen() {
      listener = listener || $rootScope.$on('$locationChangeSuccess', update);
      return listener;
    }

    if (!interceptDeferred) listen();

    return {
      /**
       * @ngdoc function
       * @name ui.router.router.$urlRouter#sync
       * @methodOf ui.router.router.$urlRouter
       *
       * @description
       * Triggers an update; the same update that happens when the address bar url changes, aka `$locationChangeSuccess`.
       * This method is useful when you need to use `preventDefault()` on the `$locationChangeSuccess` event,
       * perform some custom logic (route protection, auth, env, redirection, etc) and then finally proceed
       * with the transition by calling `$urlRouter.sync()`.
       *
       * @example
       * <pre>
       * angular.module('app', ['ui.router'])
       *   .run(function($rootScope, $urlRouter) {
       *     $rootScope.$on('$locationChangeSuccess', function(evt) {
       *       // Halt state change from even starting
       *       evt.preventDefault();
       *       // Perform custom logic
       *       var meetsRequirement = ...
       *       // Continue with the update and state transition if logic allows
       *       if (meetsRequirement) $urlRouter.sync();
       *     });
       * });
       * </pre>
       */
      sync: function() {
        update();
      },

      listen: function() {
        return listen();
      },

      update: function(read) {
        if (read) {
          location = $location.url();
          return;
        }
        if ($location.url() === location) return;

        $location.url(location);
        $location.replace();
      },

      push: function(urlMatcher, params, options) {
        $location.url(urlMatcher.format(params || {}));
        lastPushedUrl = options && options.$$avoidResync ? $location.url() : undefined;
        if (options && options.replace) $location.replace();
      },

      /**
       * @ngdoc function
       * @name ui.router.router.$urlRouter#href
       * @methodOf ui.router.router.$urlRouter
       *
       * @description
       * A URL generation method that returns the compiled URL for a given
       * {@link ui.router.util.type:UrlMatcher `UrlMatcher`}, populated with the provided parameters.
       *
       * @example
       * <pre>
       * $bob = $urlRouter.href(new UrlMatcher("/video/:person"), {
       *   person: "bob"
       * });
       * // $bob == "/video/bob";
       * </pre>
       *
       * @param {UrlMatcher} urlMatcher The `UrlMatcher` object which is used as the template of the URL to generate.
       * @param {object=} params An object of parameter values to fill the matcher's required parameters.
       * @param {object=} options Options object. The options are:
       *
       * - **`absolute`** - {boolean=false},  If true will generate an absolute url, e.g. "http://www.example.com/fullurl".
       *
       * @returns {string} Returns the fully compiled URL, or `null` if `params` fail validation against `urlMatcher`
       */
      href: function(urlMatcher, params, options) {
        if (!urlMatcher.validates(params)) return null;

        var isHtml5 = $locationProvider.html5Mode();
        if (angular.isObject(isHtml5)) {
          isHtml5 = isHtml5.enabled;
        }
        
        var url = urlMatcher.format(params);
        options = options || {};

        if (!isHtml5 && url !== null) {
          url = "#" + $locationProvider.hashPrefix() + url;
        }
        url = appendBasePath(url, isHtml5, options.absolute);

        if (!options.absolute || !url) {
          return url;
        }

        var slash = (!isHtml5 && url ? '/' : ''), port = $location.port();
        port = (port === 80 || port === 443 ? '' : ':' + port);

        return [$location.protocol(), '://', $location.host(), port, slash, url].join('');
      }
    };
  }
}

angular.module('ui.router.router').provider('$urlRouter', $UrlRouterProvider);
