module Streams
  module Overlay
    class Refresh
      class Error < StandardError; end

      def self.call(session)
        new(session).call
      end

      def initialize(session)
        @session = session.reload
      end

      def call
        return false if @session.terminal?

        dir = Streams::Overlay.overlay_dir(@session.id)
        FileUtils.mkdir_p(dir)
        badge = BadgeLabel.for(@session)
        svg = SvgBuilder.new(@session, badge: badge).to_svg
        svg_path = dir.join("overlay.svg")
        png_path = Streams::Overlay.overlay_png_path(@session)
        atomic_write(svg_path, svg)
        render_png!(svg_path, png_path)
        true
      rescue StandardError => e
        Rails.logger.warn("[Overlay::Refresh] session=#{@session.id} #{e.class}: #{e.message}")
        false
      end

      private

      def atomic_write(path, content)
        tmp = "#{path}.tmp"
        File.write(tmp, content)
        File.rename(tmp, path)
      end

      def render_png!(svg_path, png_path)
        unless system("rsvg-convert", "-w", "1280", "-h", "720", "-o", png_path.to_s, svg_path.to_s, out: File::NULL, err: File::NULL)
          raise Error, "rsvg-convert fallito per session #{@session.id}"
        end

        FileUtils.touch(png_path)
      end
    end
  end
end