module POI
  class Area
    def initialize reference
      @ref = reference
    end
    
    def in workbook
      if single_cell_reference?
        ref = area.all_referenced_cells.first
        return [workbook.single_cell ref]
      end
      
      begin
        by_column = {}
        # refs = area.all_referenced_cells
        # slices = refs.enum_slice(refs.length/15)
        # slices.collect do |cell_refs|
        #   Thread.start do
        #     cell_refs.each do |cell_ref|
        #       first = workbook.worksheets[cell_ref.sheet_name].first_row
        #       last  = workbook.worksheets[cell_ref.sheet_name].last_row
        #       next unless cell_ref.row >= first && cell_ref.row <= last
        # 
        #       # ref = POI::CELL_REF.new(c.format_as_string)
        #       cell = workbook.single_cell cell_ref
        #       (by_column[cell_ref.cell_ref_parts.collect.last] ||= []) << cell
        #     end
        #   end
        # end.each {|t| t.join}

        area.all_referenced_cells.each do |cell_ref|
          first = workbook.worksheets[cell_ref.sheet_name].first_row
          last  = workbook.worksheets[cell_ref.sheet_name].last_row
          next unless cell_ref.row >= first && cell_ref.row <= last
        
          # ref = POI::CELL_REF.new(c.format_as_string)
          cell = workbook.single_cell cell_ref
          (by_column[cell_ref.cell_ref_parts.collect.last] ||= []) << cell
        end
                
        by_column.each do |key, cells|
          by_column[key] = cells.compact
        end
        
        if by_column.length == 1
          by_column.values.flatten
        else
          by_column
        end
      rescue
        []
      end
    end
    
    def single_cell_reference?
      area.single_cell? #@ref == getFirstCell.formatAsString rescue false
    end
    
    private
      def area
        @area ||= new_area_reference
      end
      
      def new_area_reference
        begin
          return POI::AREA_REF.new(@ref)
        rescue
          # not a valid reference, so proceed through to see if it's a column-based reference
        end
        sheet_parts = @ref.split('!')
        area_parts  = sheet_parts.last.split(':')
        area_start  = "#{sheet_parts.first}!#{area_parts.first}"
        area_end    = area_parts.last
        begin
          POI::AREA_REF.getWholeColumn(area_start, area_end)
        rescue
          raise "could not determine area reference for #{@ref}: #{$!.message}"
        end
      end
  end
end