module Nitro

# A collection of useful Javascript helpers. This modules
# integrates helpers for the following javascript libraries:
#
# * behaviour.js
# * prototype.js
# * effects.js
# * dragdrop.js
# * controls.js

module JavascriptMixin

private

  unless const_defined? :DEFAULT_JAVASCRIPT_FILES
    DEFAULT_JAVASCRIPT_FILES = [
      'js/behaviour.js', 
      'js/prototype.js', 
      'js/effects.js', 
      'js/dragdrop.js', 
      'js/controls.js'
    ]
  end

  # :section: behaviour.js
  
  def behaviour(id, js)
    @_behaviours ||= []
    @_behaviours << [id, js]
  end
  
  # :section: prototype.js

  def live_request(id, options = {})
    if href = options.delete(:href)
      behaviour "##{id}", %{
        el.onclick = function() {
          new Ajax.Request('#{href}', #{hash_to_js(options)});
          return false;
        }
      }
    else
      behaviour "##{id}", %{
        el.onclick = function() {
          new Ajax.Request(el.href, #{hash_to_js(options)});
          return false;
        }
      }
    end
  end
  alias_method :live, :live_request
  alias_method :async, :live_request
  
  # :section: script.aculo.us dragdrop.js
  
  # Make the element dragable.
  
  def draggable(id, options = {})
    @_javascript ||= ''
    @_javascript << "\nnew Draggable('#{id}', #{hash_to_js(options)});"
  end
  
  # :section: script.aculo.us controls.js
  
  # Add autocomplete functionality to a text field.
  
  def auto_complete(id, options = {})
    update = options[:update] || "#{id}_auto_complete"
    url = options[:url] || "#{id}_auto_complete"
    @_javascript ||= ''
    @_javascript << "\nnew Ajax.Autocompleter('#{id}', '#{update}', '#{url}');"
    
    # Turn off the browser's autocomplete functionality to avoid
    # interference.
    
    behaviour "##{id}", %{
      el.autocomplete = 'off';
    }
  end
  
  # :section: general javascript helpers.
  
  # Include external javascript file.
  
  def include_script(files = DEFAULT_JAVASCRIPT_FILES)
    code = ''
    
    for file in [files].flatten
      code << %|<script src="#{file}" type="text/javascript">//</script>|
    end
    
    return code
  end
  
  # Escape carrier returns and single and double quotes for JavaScript segments.
  
  def escape_javascript(js)
    (js || '').gsub(/\r\n|\n|\r/, "\\n").gsub(/["']/) { |m| "\\#{m}" }
  end

  # Converts a Ruby hash to a Javascript hash.
  
  def hash_to_js(options)
    '{' + options.map {|k, v| "#{k}:#{v}"}.join(', ') + '}'
  end

  # Emits the aggregated helper javascript.
  #--
  # FIXME: refactor this!
  #++
  
  def helper_script
    code = %|<script type="text/javascript">\n|
    unless @_behaviours.empty?
      code << %|var _behaviours = {\n|
      compo = []
      for id, js in @_behaviours
        compo << %|'#{id}': function(el) { #{js} \n }|
      end
      code << compo.join(',')
      code << %|
      }
      Behaviour.register(_behaviours);    
      |
    end
    code << %|
        #@_javascript
      </script>
    |
  end
  
end

end

# * George Moschovitis <gm@navel.gr>