module Merb
  
  class Dispatcher
    class << self
      
      attr_accessor :path_prefix
      
      def use_mutex=(val)
        @@use_mutex = val
      end
      
      @@mutex = Mutex.new
      @@use_mutex = ::Merb::Server.use_mutex
      # This is where we grab the incoming request REQUEST_URI
      # and use that in the merb routematcher to determine
      # which controller and method to run. 
      # returns a 2 element tuple of:
      # [controller, action]
      def handle(request, response)
        request_uri = request.params[Mongrel::Const::REQUEST_URI]
        request_uri.sub!(path_prefix, '') if path_prefix
        route = route_path(request_uri)
      
        allowed = route.delete(:allowed)
        rest = route.delete(:rest)
      
        controller = instantiate_controller(route[:controller], request.body, request.params, route, response)
      
        if rest
          method = controller.request.method
          if allowed.keys.include?(method) && action = allowed[method]
            controller.params[:action] = action
          else
            raise Merb::RestfulMethodNotAllowed.new(method, allowed)
          end  
        else  
          action = route[:action]
        end
        if @@use_mutex
          @@mutex.synchronize {
            controller.dispatch(action)
          }
        else
          controller.dispatch(action)
        end
        [controller, action]
      end
      
      def route_path(path)
        path = path.sub(/\/+/, '/').sub(/\?.*$/, '')
        path = path[0..-2] if (path[-1] == ?/) && path.size > 1
        Merb::Router.match(path)
      end
      
      # take a controller class name string and reload or require
      # the right controller file then CamelCase it and turn it 
      # into a new object passing in the request and response.
      # this is where your Merb::Controller is instantiated.
      def instantiate_controller(controller_name, req, env, params, res) 
        if !File.exist?(DIST_ROOT+"/app/controllers/#{controller_name.snake_case}.rb")
          raise "Bad controller! #{controller_name.snake_case}"
        end unless $TESTING
        begin
          unless MERB_ENV == 'production'
            Object.send(:remove_const, controller_name.camel_case.intern) rescue nil
            load(controller_name.snake_case + '.rb')
          end
          return Object.const_get( controller_name.camel_case ).new(req, env, params, res)
        rescue RuntimeError
          warn "Error getting instance of '#{controller_name.camel_case}': #{$!}"
          raise $!
        end
      end

    end # end class << self
      
  end
  
end