table_builder_helper.rb

module TableBuilderHelper

  def column(options = {}, &block)
    @table ||= TableBuilderHelper::TableBuilder.new(self)
    
    @table.add_column(options, block)
  end
  
  def row_dom_id(&block)
    @table ||= TableBuilderHelper::TableBuilder.new(self)
    
    @table.set_row_dom_id_method(block)
  end
  
  def table(contents = [])
    the_table = @table
    @table = nil
    the_table.generate(contents, @requester)
  end

  #####################
  #                   #
  # == TableColumn == #
  #                   #
  #####################
  
  class TableColumn
    
    include ActionView::Helpers::TagHelper

    attr_reader :options
    
    SORTABLE_CLASS = 'sortable'
    
    def initialize(options, cell_contents_block, view)
      @options = options
      @cell_contents_block = cell_contents_block
      @view = view
    end
    
    def contents_for(item)
      @view.capture(item, &@cell_contents_block)
    end
    
    # Sorting
    
    def order
      in_order  = options[:order]
      unordered = options[:unordered]
      
      if in_order == nil
        [ 2, unordered ]
      elsif in_order >= 0
        [ 1, in_order ]
      else # if in_order < 0
        [ 3, in_order ]
      end
    end
    
    def <=>(other)
      order <=> other.order
    end
    
    ###################
    #                 #
    # Builder Methods #
    #                 #
    ###################
    
    def header_options
      styles = []
      styles << 'display: none'              if options[:hidden]
      
      Hash.new.tap do |opts|
        opts[:style] = styles.join('; ') unless styles.empty?
        
        css_classes = []
        css_classes << options[:css_class] if options[:css_class]
        opts[:class] = css_classes.join(' ') unless css_classes.empty?
      end
    end
    
    def header_cell(html, page_requester)
      html.th(header_options) do
        if options[:sortable]
          href = (options[:sortable] == page_requester.current_order) ? page_requester.for_toggled_ascending : page_requester.for_order( options[:sortable] )
          css_class = SORTABLE_CLASS
          css_class += ' ' + page_requester.current_ascending_css_class if options[:sortable] == page_requester.current_order
          
          html.a :href => href, :class => css_class do
            html << (options[:header] || String.new)
          end
        else
          html << (options[:header] || String.new)
        end
      end
    end

    def cell_options
      Hash.new.tap do |opts|
        opts[:style] = "display: none;"    if options[:hidden]
        opts[:class] = options[:css_class] if options[:css_class]
        opts[:colspan] = options[:colspan] if options[:colspan]
      end
    end
    
    def content_cell(html, item)
      options = cell_options
      
      unless cell_options.fetch(:colspan, 1) == 0
        html.td(cell_options) do
          html << contents_for(item)
        end
      end
    end
    
  end
  
  ######################
  #                    #
  # == TableBuilder == #
  #                    #
  ######################
  
  class TableBuilder
    
    attr_reader :columns
    
    def initialize(view)
      @columns = Array.new
      @view = view
    end
    
    def add_column(options, block)
      columns << TableBuilderHelper::TableColumn.new(options.merge(:unordered => @columns.length), block, @view)
    end
    
    def set_row_dom_id_method(block)
      @row_dom_id = block
    end

    ###################
    #                 #
    # Builder Methods #
    #                 #
    ###################
    
    def header_row(html, page_requester)
      html.tr do
        columns.each do |column|
          column.header_cell(html, page_requester)
        end
      end
    end

    def content_row(html, item)
      row_options = @row_dom_id ? { :id => @row_dom_id[item] } : {}
      
      html.tr row_options do
        columns.each { |column| column.content_cell(html, item) }
      end
    end

    def generate(contents, page_requester)
      columns.sort!

      html = Builder::XmlMarkup.new(:indent => 4, :target => Array.new)

      html.table do
        header_row(html, page_requester)

        contents.each { |item| content_row(html, item) }
      end

      html.target!.join
    end
    
  end
  
end