#!/usr/local/bin/ruby
require 'rubygems'
require 'mongrel'

# Add the request handler directory to the load path.
# Files in the 'app/controllers' dir will be mapped against the first segment
# of a URL
$LOAD_PATH.unshift( File.join( File.dirname( __FILE__ ) , 'app/controllers' ) )

PORT = 4000

 # If true, controller source files are 'load'ed rather than 'require'd
# so you can tweak code and reload a page.
ALLOW_RELOADING = true 

class String
  def import
    ALLOW_RELOADING ? load(  self  + '.rb' ) : require(  self )
  end

  def controller_class_name
    self.capitalize
  end
end

class MerberHandler < Mongrel::HttpHandler

  def instantiate_controller(controller_name)
    controller_name.import
    begin
      return Object.const_get( controller_name.controller_class_name ).new
    rescue Exception
      # If life is sad, then print the error and re-raise the exception:
      warn "Error getting instance of '#{controller_name.controller_class_name}': #{$!}"
      raise $!
    end
  end

  # Grab the request URL and break it up to get the parts that map to the 
  # code request.  There's a simple assumption that the first part defines a
  # class holding the desired  code.
  def handle(request)
    path = request.params["PATH_INFO"]
    puts request.inspect
    puts '='*50
    # Might want to consider returning a default object if we have a bare URL.
    return [nil, nil, nil ] if path =~ /^\/$/
    c, m, args = path.to_s.gsub( /^\//, '' ).split( '/' , 3)
    args = args.to_s.strip.empty? ? nil : args.split( '/' )
    # STDERR.puts( "handler_details  returning #{h}, #{m}, #{args.inspect} ")
    # Return an array with our object instance, the method name, and any args.
    [ instantiate_controller(c), m, args ]
  end

  def process(request, response)
    response.start(200) do |head,out|
      head["Content-Type"] = "text/html"
      begin
        # Looks at the URL and breaks it up into 
        # chunks that  map to a class, a method call,
        # and arguments.
        # Basically, 
        #   /foo/bar/baz/baz
        # ends up becoming
        #   Foo.new.bar( baz, baz )
        controller, method, args = handle(request)

        if controller
          # No allowance for default methods.  
          # Worth considering, maybe default to 'index' or 'to_s' 
          out << (  args ?  controller.send( method, *args ) : 
                            controller.send( method ) )
        else
          out << "Error: no merb controller found for this url."
        end
      rescue Exception
        out << "Error! #{$!}"
      end
    end
  end

end

h = Mongrel::HttpServer.new("0.0.0.0", PORT)
h.register("/", MerberHandler.new)
h.register("/", Mongrel::DirHandler.new("assets"))
h.run.join


--merb.rb---
require 'erb'

class Merb
  # Define a class variable to track the default location of the template
  # files.
  @@template_dir = File.expand_path( ( File.dirname( __FILE__ ) + "/../views/merb" ) )


  def hello(*names)
    # Assign the parameter to an instance variable
    @name = names.join(', ')
    template = ERB.new( IO.read( @@template_dir + '/hello.rhtml' ) ) 
    template.result( binding )
  end
end


--hello.rhtml--
 
 
  
 
 
 
Hello, <%= @name %>!