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require 'rexml/document'

require 'SVG/Graph/Graph'

require 'SVG/Graph/BarBase'

module SVG

  module Graph

    # === Create presentation quality SVG bar graphs easily

    #

    # = Synopsis

    #

    #   require 'SVG/Graph/Bar'

    #

    #   fields = %w(Jan Feb Mar);

    #   data_sales_02 = [12, 45, 21]

    #

    #   graph = SVG::Graph::Bar.new(

    #     :height => 500,

    #     :width => 300,

    #     :fields => fields

    #   )

    #

    #   graph.add_data(

    #     :data => data_sales_02,

    #     :title => 'Sales 2002'

    #   )

    #

    #   print "Content-type: image/svg+xml\r\n\r\n"

    #   print graph.burn

    #

    # = Description

    #

    # This object aims to allow you to easily create high quality

    # SVG[http://www.w3c.org/tr/svg bar graphs. You can either use the default

    # style sheet or supply your own. Either way there are many options which

    # can be configured to give you control over how the graph is generated -

    # with or without a key, data elements at each point, title, subtitle etc.

    #

    # = Notes

    #

    # The default stylesheet handles upto 12 data sets, if you

    # use more you must create your own stylesheet and add the

    # additional settings for the extra data sets. You will know

    # if you go over 12 data sets as they will have no style and

    # be in black.

    #

    # = Examples

    #

    # * http://germane-software.com/repositories/public/SVG/test/test.rb

    #

    # = See also

    #

    # * SVG::Graph::Graph

    # * SVG::Graph::BarHorizontal

    # * SVG::Graph::Line

    # * SVG::Graph::Pie

    # * SVG::Graph::Plot

    # * SVG::Graph::TimeSeries

    class Bar < BarBase

      include REXML

      # See Graph::initialize and BarBase::set_defaults

      def set_defaults 

        super

        self.top_align = self.top_font = 1

      end

      protected

      def get_x_labels

        @config[:fields]

      end

      def get_y_labels

        maxvalue = max_value

        minvalue = min_value

        range = maxvalue - minvalue

        top_pad = range == 0 ? 10 : range / 20.0

        scale_range = (maxvalue + top_pad) - minvalue

        scale_division = scale_divisions || (scale_range / 10.0)

        if scale_integers

          scale_division = scale_division < 1 ? 1 : scale_division.round

        end

        rv = []

        maxvalue = maxvalue%scale_division == 0 ? 

          maxvalue : maxvalue + scale_division

        minvalue.step( maxvalue, scale_division ) {|v| rv << v}

        return rv

      end

      def x_label_offset( width )

        width / 2.0

      end

      def draw_data

        minvalue = min_value

        fieldwidth = field_width

        unit_size =  (@graph_height.to_f - font_size*2*top_font) / 

                          (get_y_labels.max - get_y_labels.min)

        bargap = bar_gap ? (fieldwidth < 10 ? fieldwidth / 2 : 10) : 0

        bar_width = fieldwidth - bargap

        bar_width /= @data.length if stack == :side

        x_mod = (@graph_width-bargap)/2 - (stack==:side ? bar_width/2 : 0)

        bottom = @graph_height

        field_count = 0

        @config[:fields].each_index { |i|

          dataset_count = 0

          for dataset in @data

            # cases (assume 0 = +ve):

            #   value  min  length

            #    +ve   +ve  value - min

            #    +ve   -ve  value - 0

            #    -ve   -ve  value.abs - 0

            value = dataset[:data][i]

            left = (fieldwidth * field_count)

            length = (value.abs - (minvalue > 0 ? minvalue : 0)) * unit_size

            # top is 0 if value is negative

            top = bottom - (((value < 0 ? 0 : value) - minvalue) * unit_size)

            left += bar_width * dataset_count if stack == :side

            @graph.add_element( "rect", {

              "x" => left.to_s,

              "y" => top.to_s,

              "width" => bar_width.to_s,

              "height" => length.to_s,

              "class" => "fill#{dataset_count+1}"

            })

            make_datapoint_text(left + bar_width/2.0, top - 6, value.to_s)

            dataset_count += 1

          end

          field_count += 1

        }

      end

    end

  end

end