class ApplicationController < ActionController::Base
  session :session_key => '_barleysodas_session_id'
  append_before_filter :block_prefetching_links
  append_before_filter :authorized?
  helper_method :logged_in?
  
  ##
  # Ensures that the request was made using an Ajax request.
  #
  def ensure_xhr
    return false unless request.xhr?
    true
  end
  
  ##
  # Determines if the user is logged in.
  #
  def logged_in?
    return !session[:people_title].nil?
  end
  
  ##
  # Saves the request uri in the session for later redirect after a login.
  #
  def save_request_url
    session[:request_url] = request.request_uri
  end
  
  ##
  # Checks to see if the currently requested uri is the same as the uri saved
  # in the session.
  #
  def already_saved_request_url
    return true if session[:request_url] and
      session[:request_url] == request.request_uri
    false
  end
  
  ##
  # Determines if a user can access an action.
  #
  def authorized?
    return true if has_permission_for_action?
    respond_to do |format|
      format.html {
        # prevent double-redirects to the login page if for some reason it is
        # not allowed
        unless logged_in? and !already_saved_request_url
          save_request_url
          redirect_to new_session_path
          return
        end
        @content_title = 'Forbidden'
        @secondary_title = ''
        @hide_sidebar = true
        render :template => 'shared/unauthorized'
      }
      format.xml { render :nothing => true, :status => 403 }
    end
  end
  
  ##
  # Sane error and missing document messages.
  #
  def rescue_action_in_public(exception)
    logger.debug("#{exception.class.name}: #{exception.to_s}")
    exception.backtrace.each { |bt| logger.debug "! #{bt}" }
    case exception
      when ::ActiveRecord::RecordNotFound,
           ::ActionController::UnknownController,
           ::ActionController::UnknownAction,
           ::ActionController::RoutingError
        render :file => File.join(RAILS_ROOT, 'public/404.html'),
          :status => '404 Not Found'
      else
        render :file => File.join(RAILS_ROOT, 'public/500.html'),
          :status => '500 Error'
    end
  end
  
  ##
  # Sets the <tt>@page</tt> variable to allow discussions. This should probably
  # have some kind of permission availability check later on.
  #
  def allow_page_discussions
    @page.allow_discussions = true
  end
  
  private
  
  ##
  # Stops all prefetching by the Google web accelerator by returning a 403
  # forbidden error.
  #
  # Original Copyright:
  # Copyright (c) 2005 David Heinemeier Hansson
  #
  # Permission is hereby granted, free of charge, to any person obtaining
  # a copy of this software and associated documentation files (the
  # "Software"), to deal in the Software without restriction, including
  # without limitation the rights to use, copy, modify, merge, publish,
  # distribute, sublicense, and/or sell copies of the Software, and to
  # permit persons to whom the Software is furnished to do so, subject to
  # the following conditions:
  #
  # The above copyright notice and this permission notice shall be
  # included in all copies or substantial portions of the Software.
  #
  # THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  # EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  # MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  # NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
  # LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
  # OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  # WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  #
  def block_prefetching_links
    if request.env["HTTP_X_MOZ"] == "prefetch"
      render :nothing => true, :status => "403 Forbidden"
      return false
    end
  end
  
  ##
  # Finds a People Permission models and determines if the People has access
  # to a particular aspect of the system. Also finds the Guest user and checks
  # for the Guest Role.
  #
  def has_permission_for_action?
    role = nil
    if logged_in?
      role = People.find_by_title(session[:people_title]).role rescue nil
    end
    logger.debug("role is #{role.inspect}")
    role ||= Role.base_role
    while role
      return true if role.permissions.detect do |p|
        p.controller.to_s == params[:controller].to_s and
          p.action.to_s == params[:action].to_s
      end
      role = role.parent
    end
    false
  end
end