module NSWTopo::GPS::KML

def collection
  GeoJSON::Collection.new.tap do |collection|
    @xml.elements.each "/kml//Placemark" do |placemark|
      %w[. MultiGeometry].each do |container|
        placemark.elements.each "#{container}/Point/coordinates" do |coordinates|
          coords = coordinates.text.split(',').take(2).map(&:to_f)
          collection.add_point coords, properties(placemark).merge("styles" => {})
        end
        placemark.elements.each "#{container}/LineString/coordinates" do |coordinates|
          coords = coordinates.text.split(' ').map { |triplet| triplet.split(',')[0..1].map(&:to_f) }
          collection.add_linestring coords, properties(placemark).merge("styles" => styles(placemark))
        end
        placemark.elements.each "#{container}/gx:Track[gx:coord]" do |track|
          coords = track.collect("gx:coord") { |coord| coord.text.split(?\s).take(2).map(&:to_f) }
          collection.add_linestring coords, properties(placemark).merge("styles" => styles(placemark))
        end
        placemark.elements.each "#{container}/Polygon[outerBoundaryIs/LinearRing/coordinates]" do |polygon|
          coords = [polygon.elements["outerBoundaryIs/LinearRing/coordinates"].text]
          coords += polygon.elements.collect("innerBoundaryIs/LinearRing/coordinates", &:text)
          coords.map! do |text|
            text.split(' ').map { |triplet| triplet.split(?,).take(2).map(&:to_f) }
          end
          collection.add_polygon coords, properties(placemark).merge("styles" => styles(placemark))
        end
      end
    end
  end
end

def properties(placemark)
  { "name" => placemark.elements["name"]&.text, "folder" => placemark.elements["ancestor::Folder/name"]&.text }
end

def styles(placemark)
  style_url = placemark.elements["styleUrl"]&.text&.delete_prefix(?#)
  return {} unless style_url
  style_element = @xml.elements["/kml/Document/*[@id='%s']" % style_url]
  result = {}
  case style_element&.name
  when "StyleMap"
    style_element = style_element.elements["Pair[key[text()='normal']]"]
    result = styles(style_element) if style_element
  when "Style"
    [%w[LineStyle stroke], %w[PolyStyle fill]].each do |element, attribute|
      /^[0-9a-fA-F]{8}$/.match(style_element.elements["#{element}/color"]&.text) do |match|
        a, b, g, r = match[0].each_char.each_slice(2).map(&:join)
        result["#{attribute}-opacity"] = (Float("0x%s" % a) / 255).round(5)
        result[attribute] = Colour.new("#%s%s%s" % [r, g, b]).to_s
      end
    end
    result["stroke"] ||= "#FFFFFF"
    result["stroke-width"] = ((style_element.elements["LineStyle/width"]&.text || 1).to_f * 25.4 / 96.0).round(5)
    [%w[fill fill], %w[outline stroke]].each do |element, attribute|
      if style_element.elements["PolyStyle/#{element}"]&.text == ?0
        result[attribute] = "none"
        result.delete "#{attribute}-opacity"
        result.delete "#{attribute}-width"
      end
    end
  end
  result
end