// ==========================================================================
// Project:   SproutCore - JavaScript Application Framework
// Copyright: ©2006-2009 Sprout Systems, Inc. and contributors.
//            Portions ©2008-2009 Apple Inc. All rights reserved.
// License:   Licensed under MIT license (see license.js)
// ==========================================================================

require('system/platform');

/**
  SC.routes manages the browser location. You can change the hash part of the
  current location. The following code
  
  {{{
    SC.routes.set('location', 'notes/edit/4');
  }}}
  
  will change the location to http://domain.tld/my_app#notes/edit/4. Adding
  routes will register a handler that will be called whenever the location
  changes and matches the route:
  
  {{{
    SC.routes.add(':controller/:action/:id', MyApp, MyApp.route);
  }}}
  
  You can pass additional parameters in the location hash that will be relayed
  to the route handler:
  
  {{{
    SC.routes.set('location', 'notes/show/4?format=xml&language=fr');
  }}}
  
  The syntax for the location hash is described in the location property
  documentation, and the syntax for adding handlers is described in the
  add method documentation.
  
  Browsers keep track of the locations in their history, so when the user
  presses the 'back' or 'forward' button, the location is changed, SC.route
  catches it and calls your handler. Except for Internet Explorer versions 7
  and earlier, which do not modify the history stack when the location hash
  changes.
  
  @since SproutCore 1.1
*/
SC.routes = SC.Object.create({
    
  /** @private
    A boolean value indicating whether or the ping method has been called
    to setup the SC.routes.
  
    @property
    @type {Boolean}
  */
  _didSetup: NO,
  
  
  /** @private
    Internal representation of the current location hash.
  
    @property
    @type {String}
  */
  _location: null,
  
  /** @private
    Routes are stored in a tree structure, this is the root node.
  
    @property
    @type {SC.routes._Route}
  */
  _firstRoute: null,
  
  /** @private
    Internal method used to extract and merge the parameters of a URL.
    
    @returns {Hash}
  */
  _extractParametersAndRoute: function(obj) {
    var params = {},
        route = obj.route || '',
        separator, parts, i, len, crumbs, key;
    
    separator = (route.indexOf('?') < 0 && route.indexOf('&') >= 0) ? '&' : '?';
    parts = route.split(separator);
    route = parts[0];
    if (parts.length === 1) {
      parts = [];
    } else if (parts.length === 2) {
      parts = parts[1].split('&');
    } else if (parts.length > 2) {
      parts.shift();
    }
    
    // extract the parameters from the route string
    len = parts.length;
    for (i = 0; i < len; ++i) {
      crumbs = parts[i].split('=');
      params[crumbs[0]] = crumbs[1];
    }
    
    // overlay any parameter passed in obj
    for (key in obj) {
      if (obj.hasOwnProperty(key) && key !== 'route') {
        params[key] = '' + obj[key];
      }
    }
    
    // build the route
    parts = [];
    for (key in params) {
      parts.push([key, params[key]].join('='));
    }
    params.params = separator + parts.join('&');
    params.route = route;
    
    return params;
  },
  
  /**
    The current location hash. It is the part in the browser's location after
    the '#' mark.
    
    The following code
    
    {{{
      SC.routes.set('location', 'notes/edit/4');
    }}}
    
    will change the location to http://domain.tld/my_app#notes/edit/4 and call
    the correct route handler if it has been registered with the add method.
    
    You can also pass additional parameters. They will be relayed to the route
    handler. For example, the following code
    
    {{{
      SC.routes.add(':controller/:action/:id', MyApp, MyApp.route);
      SC.routes.set('location', 'notes/show/4?format=xml&language=fr');
    }}}
    
    will change the location to 
    http://domain.tld/my_app#notes/show/4?format=xml&language=fr and call the
    MyApp.route method with the following argument:
    
    {{{
      { route: 'notes/show/4',
        params: '?format=xml&language=fr',
        controller: 'notes',
        action: 'show',
        id: '4',
        format: 'xml',
        language: 'fr' }
    }}}
    
    The location can also be set with a hash, the following code
    
    {{{
      SC.routes.set('location',
        { route: 'notes/edit/4', format: 'xml', language: 'fr' });
    }}}
    
    will change the location to
    http://domain.tld/my_app#notes/show/4?format=xml&language=fr.
    
    The 'notes/show/4&format=xml&language=fr' syntax for passing parameters,
    using a '&' instead of a '?', as used in SproutCore 1.0 is still supported.
    
    @property
    @type {String}
  */
  location: function(key, value) {
    var crumbs;
    
    if (value !== undefined) {
      if (value === null) {
        value = '';
      }
      
      if (typeof(value) === 'object') {
        crumbs = this._extractParametersAndRoute(value);
        value = crumbs.route + crumbs.params;
      }
      
      if(!SC.empty(value) || (this._location && this._location !== value)) {
        window.location.hash = encodeURI(value);
      }
      this._location = value;
      
      return this;
    }
    return this._location;
  }.property(),
  
  /**
    You usually don't need to call this method. It is done automatically after
    the application has been initialized.
    
    It registers for the hashchange event if available. If not, it creates a
    timer that looks for location changes every 150ms.
  */
  ping: function() {
    var that;
    
    if (!this._didSetup) {
      this._didSetup = YES;
      
      if (SC.platform.supportsHashChange) {
        this.hashChange();
        SC.Event.add(window, 'hashchange', this, this.hashChange);
      
      } else {
        // we don't use a SC.Timer because we don't want
        // a run loop to be triggered at each ping
        that = this;
        this._invokeHashChange = function() {
          that.hashChange();
          setTimeout(that._invokeHashChange, 100);
        };
        this._invokeHashChange();
      }
    }
  },
  
  /**
    Event handler for the hashchange event. Called automatically by the browser
    if it supports the hashchange event, or by our timer if not.
  */
  hashChange: function(event) {
    var loc = window.location.hash;
    
    loc = (loc && loc.length > 0) ? loc.slice(1, loc.length) : '';
    if (!SC.browser.isMozilla) {
      // because of bug https://bugzilla.mozilla.org/show_bug.cgi?id=483304
      loc = decodeURI(loc);
    }
    
    if (this.get('location') !== loc) {
      SC.RunLoop.begin();
      this.set('location', loc);
      SC.RunLoop.end();
    }
  },
  
  /**
    Adds a route handler. Routes have the following format:
      - 'users/show/5' is a static route and only matches this exact string,
      - ':action/:controller/:id' is a dynamic route and the handler will be
        called with the 'action', 'controller' and 'id' parameters passed in a
        hash,
      - '*url' is a wildcard route, it matches the whole route and the handler
        will be called with the 'url' parameter passed in a hash.
    
    Route types can be combined, the following are valid routes:
      - 'users/:action/:id'
      - ':controller/show/:id'
      - ':controller/ *url' (ignore the space, because of jslint)
    
    @param {String} route the route to be registered
    @param {Object} target the object on which the method will be called, or
      directly the function to be called to handle the route
    @param {Function} method the method to be called on target to handle the
      route, can be a function or a string
  */
  add: function(route, target, method) {
    if (!this._didSetup) {
      this.invokeLast(this.ping);
    }
    
    if (method === undefined && SC.typeOf(target) === SC.T_FUNCTION) {
      method = target;
      target = null;
    } else if (SC.typeOf(method) === SC.T_STRING) {
      method = target[method];
    }
    
    if (!this._firstRoute) this._firstRoute = this._Route.create();
    this._firstRoute.add(route.split('/'), target, method);
    
    return this;
  },
  
  /**
    Observer of the 'location' property that calls the correct route handler
    when the location changes.
  */
  locationDidChange: function() {
    this.trigger();
  }.observes('location'),
  
  /**
    Triggers a route even if already in that route (does change the location, if it
    is not already changed, as well).
    
    If the location is not the same as the supplied location, this simply lets "location"
    handle it (which ends up coming back to here).
  */
  trigger: function() {
    var firstRoute = this._firstRoute,
        location = this.get('location'),
        params, route;
    
    if (firstRoute) {
      params = this._extractParametersAndRoute({ route: location });
      location = params.route;
      delete params.route;
      delete params.params;
      route = firstRoute.routeForParts(location.split('/'), params);
      if (route && route.target && route.method) {
        route.method.call(route.target, params);
      }
    }
  },
  
  /**
    @private
    @class

    SC.routes._Route is a class used internally by SC.routes. The routes defined by your
    application are stored in a tree structure, and this is the class for the
    nodes.
  */
  _Route: SC.Object.extend(
  /** @scope SC.routes._Route.prototype */ {

    target: null,

    method: null,

    staticRoutes: null,

    dynamicRoutes: null,

    wildcardRoutes: null,

    add: function(parts, target, method) {
      var part, nextRoute;

      // clone the parts array because we are going to alter it
      parts = SC.clone(parts);

      if (!parts || parts.length === 0) {
        this.target = target;
        this.method = method;

      } else {
        part = parts.shift();

        // there are 3 types of routes
        switch (part.slice(0, 1)) {

        // 1. dynamic routes
        case ':':
          part = part.slice(1, part.length);
          if (!this.dynamicRoutes) this.dynamicRoutes = {};
          if (!this.dynamicRoutes[part]) this.dynamicRoutes[part] = this.constructor.create();
          nextRoute = this.dynamicRoutes[part];
          break;

        // 2. wildcard routes
        case '*':
          part = part.slice(1, part.length);
          if (!this.wildcardRoutes) this.wildcardRoutes = {};
          nextRoute = this.wildcardRoutes[part] = this.constructor.create();
          break;

        // 3. static routes
        default:
          if (!this.staticRoutes) this.staticRoutes = {};
          if (!this.staticRoutes[part]) this.staticRoutes[part] = this.constructor.create();
          nextRoute = this.staticRoutes[part];
        }

        // recursively add the rest of the route
        if (nextRoute) nextRoute.add(parts, target, method);
      }
    },

    routeForParts: function(parts, params) {
      var part, key, route;

      // clone the parts array because we are going to alter it
      parts = SC.clone(parts);

      // if parts is empty, we are done
      if (!parts || parts.length === 0) {
        return this.method ? this : null;

      } else {
        part = parts.shift();

        // try to match a static route
        if (this.staticRoutes && this.staticRoutes[part]) {
          return this.staticRoutes[part].routeForParts(parts, params);

        } else {

          // else, try to match a dynamic route
          for (key in this.dynamicRoutes) {
            route = this.dynamicRoutes[key].routeForParts(parts, params);
            if (route) {
              params[key] = part;
              return route;
            }
          }

          // else, try to match a wilcard route
          for (key in this.wildcardRoutes) {
            parts.unshift(part);
            params[key] = parts.join('/');
            return this.wildcardRoutes[key].routeForParts(null, params);
          }

          // if nothing was found, it means that there is no match
          return null;
        }
      }
    }

  })
  
});