require 'glue/builder/xml'

module Nitro
module FormHelper

  # A specialized Builder for dynamically building of forms.
  # Provides extra support for forms backed by managed objects
  # (entities).
  #--
  # TODO: allow multiple objects per form.
  # TODO: use more generalized controls.
  #++
  
  class FormXmlBuilder < ::Glue::XmlBuilder
  
    def initialize buffer = '', options = {}
      super
      @obj = options[:object]
    end
    
    # Render a control+label for the given property of the form
    # object.
    
    def property sym, options = {}
      if prop = @obj.class.properties[sym]
        control = Form::Control.fetch(@obj, prop, options).render
        print element(prop, control)
      else
        raise "Undefined property '#{sym}' for class '#{@obj.class}'."
      end
    end

    # Render controls+labels for all relations of the form object.
    
    def all_properties options = {}
      for prop in @obj.class.properties.values
        property prop.symbol, options
      end
    end
    alias_method :properties, :all_properties

    #--
    # IMPLEMENT ME
    #++
    
    def relation sym, options = {}
    end

    #--
    # IMPLEMENT ME
    #++
        
    def all_relations options = {}
    end    

    # Renders a control to select a file for upload.
    
    def select_file name, options = {}
      print %|<input type="file" name="#{name}" />|
    end

  private
  
    # Emit a label. Override this method to customize the
    # rendering for your application needs.
          
    def label prop
      %{<label for="#{prop.name}">#{prop[:title] || prop.name.to_s.humanize}</label>}
    end
    
    # Emit a form element. Override this method to customize the
    # rendering for your application needs.
    
    def element prop, html
      %{
        <p class="form_#{prop.symbol}">
          <div>#{label(prop)}</div>
          #{html}
        </p>
      }        
    end
  
  end

  # A sophisticated form generation helper method.
  #
  # === Options
  #
  # * :object, :entity, :class = The object that acts as model
  #   for this form. If you pass a class an empty object is 
  #   instantiated.
  #
  # === Example
  #   
  # #{form(:object => @owner, :action => :save_profile) do |f|
  #   f.property :name, :editable => false
  #   f.property :password
  #   f.br
  #   f.submit 'Update'
  # end}
  
  def form options = {}, &block
    obj = (options[:object] ||= options[:entity] || options[:class])
    
    # If the passed obj is a Class instantiate an empty object
    # of this class.
    
    if obj.is_a? Class
      obj = options[:object] = obj.allocate
    end

    # Convert virtual :multipart method to method="post",
    # enctype="multipart/form-data"
    
    if options[:method] == :multipart
      options[:method] = :post
      options[:enctype] = 'multipart/form-data'
    end    
        
    b = FormXmlBuilder.new('', options)

    b << '<form'
    b << %| action="#{options[:action]}"| if options[:action]
    b << %| method="#{options[:method]}"| if options[:method]
    b << %| enctype="#{options[:enctype]}"| if options[:enctype]
    b << '>'
    
    b.hidden(:name => 'oid', :value => obj.oid) if obj and obj.saved?
     
    yield b
    
    b << '</form>'
    
    return b
  end
  
end
end

# * George Moschovitis <gm@navel.gr>