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 JavascriptHelper

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]
    return nil
  end
  
  # :section: prototype.js

  def live_request(id, options = {})
    __append_script_file__ 'js/behaviour.js'
    __append_script_file__ 'js/prototype.js'
    
    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
    return nil
  end
  alias_method :live, :live_request
  alias_method :async, :live_request
  
  # Denotes an element as toggleable.
  
  def toggleable(id, options = {})
    __append_script_file__ 'js/prototype.js'
    
    behaviour "##{id}", %{
      el.onclick = function() {
        Element.toggle('#{id}');
        return false;
      }
    }
    
    return nil
  end
  
  # :section: script.aculo.us dragdrop.js
  
  # Make the element dragable.
  
  def draggable(id, options = {})
    __append_script_file__ 'js/behaviour.js'
    __append_script_file__ 'js/prototype.js'
    __append_script_file__ 'js/effects.js'
    __append_script_file__ 'js/dragdrop.js'
    
    __append_script__ "\nnew Draggable('#{id}', #{hash_to_js(options)});"
    return nil
  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"

    __append_script_file__ 'js/behaviour.js'
    __append_script_file__ 'js/prototype.js'
    __append_script_file__ 'js/effects.js'
    __append_script_file__ 'js/controls.js'
    
    __append_script__ "\nnew Ajax.Autocompleter('#{id}', '#{update}', '#{url}');"
    
    # Turn off the browser's autocomplete functionality to avoid
    # interference.
    
    behaviour "##{id}", %{
      el.autocomplete = 'off';
    }
    return nil
  end
  
  # :section: styling.
  
  # Style border.
  
  def style_border
  end
  
  # Round element corners using the nifty corners technique.
  
  def round_corners(id, options = {})
    o = {
      :bg => '#fff',
      :fg => '#ccc',
    }.update(options)

    __append_script_file__ 'js/prototype.js'
    __append_script_file__ 'js/round.js'

    __append_script__ %{
      Box.round('#{id}', '#{o[:fg]}', '#{o[:bg]}');
    }

    __append_css__ %{
      .rtop,.rbottom{display:block}
      .rtop *,.rbottom *{display:block;height: 1px;overflow: hidden}
      .r1{margin: 0 5px}
      .r2{margin: 0 3px}
      .r3{margin: 0 2px}
      .r4{margin: 0 1px;height: 2px}
    }
   
    return nil
  end
  
  # Generalized border decoration.
  
  def decorate_borders(options = {})
    o = {
      :bg => '#fff',
      :fg => '#ccc',
      :klass => 'w'
    }.update(options)

    klass = o[:klass]

    __append_script_file__ 'js/prototype.js'
    __append_script_file__ 'js/styler.js'

    __append_script__ %{ 
      decorateBorders('#{klass}');
    }

    __append_css__ %{
      .#{klass}t {
        background: #{o[:bg]};  
        background-image: url(m/#{klass}t.gif);
        background-repeat: repeat-x;
        background-position: top;
      }
      .#{klass}r {
        background-image: url(m/#{klass}r.gif);
        background-repeat: repeat-y;
        background-position: right;
      }
      .#{klass}b {
        background-image: url(m/#{klass}b.gif);
        background-repeat: repeat-x;
        background-position: bottom;
      }
      .#{klass}l {
        background-image: url(m/#{klass}l.gif);
        background-repeat: repeat-y;
        background-position: left;
      }
      .#{klass}tl {
        background-image: url(m/#{klass}tl.gif);
        background-repeat: no-repeat;
        background-position: top left;
      }
      .#{klass}tr {
        background-image: url(m/#{klass}tr.gif);
        background-repeat: no-repeat;
        background-position: top right;
      }
      .#{klass}bl {
        background-image: url(m/#{klass}bl.gif);
        background-repeat: no-repeat;
        background-position: bottom left;
      }
      .#{klass}br {
        background-image: url(m/#{klass}br.gif);
        background-repeat: no-repeat;
        background-position: bottom right;
      }
      .#{klass}c {
        padding: 25px;
      }      
    }
   
    return nil
  end
  
  # -----------------------------------------------------------
  # :section: general javascript helpers.
  
  # Include external javascript file.
  
  def include_script(*files)
    return if @_script_files.nil? and files.empty?
    
    code = ''

    for file in files
      code << %|<script src="#{file}" type="text/javascript">//</script>\n|
    end if files

    for file in @_script_files
      code << %|<script src="#{file}" type="text/javascript">//</script>\n|
    end if @_script_files
    
    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 css.
  
  def emit_css
    return unless @_css
    %{<style>#{@_css.join("\n")}</style>}
  end
  alias_method :helper_css, :emit_css

  # Emits the aggregated helper javascript.
  #--
  # FIXME: refactor this!
  #++
  
  def emit_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 << %|
        #{@_script.join("\n")}
    | if @_script
    code << %|
      </script>
    |
  end
  alias_method :helper_script, :emit_script

  # ...
  
  def js_distance_of_time_in_words(time)
    time = time.utc.strftime("%a, %d %b %Y %H:%M:%S GMT")
    %|<span class="human_time" title="#{time}">#{time}</span>|
  end

  # :section: internal helpers.

  def __append_script_file__(file)
    @_script_files ||= []
    @_script_files << file unless @_script_files.include?(file)
  end

  def __append_script__(script)
    @_script ||= []
    @_script << script unless @_script.include?(script)
  end

  def __append_css__(css)
    @_css ||= []
    @_css << css unless @_css.include?(css)
  end

end

end

# * George Moschovitis <gm@navel.gr>