module L4dServer
  class Launcher
    def self.spawn(server)
      new(server).spawn
    end

    def self.cleanup(server)
      new(server).cleanup
    end

    def initialize(server)
      @server = server
      @template = server.server_template
    end

    def spawn
      setup_directories
      generate_config
      mount_overlayfs
      generate_systemd_unit
      enable_and_start_service
    rescue StandardError => e
      Rails.logger.error("Failed to spawn server: #{e.message}")
      Rails.logger.error(e.backtrace.join("\n"))
      @server.update(status: :failed)
      raise
    end

    def cleanup
      unmount_overlayfs
      cleanup_directories
    end

    private

    def setup_directories
      server_dir = "/opt/l4d2/servers/#{@server.id}"
      FileUtils.mkdir_p("#{server_dir}/upper")
      FileUtils.mkdir_p("#{server_dir}/work")
      FileUtils.mkdir_p("#{server_dir}/merged")
    end

    def generate_config
      ConfigGenerator.generate(@server)
    end

    def mount_overlayfs
      server_dir = "/opt/l4d2/servers/#{@server.id}"
      overlays = @template.template_overlays.ordered.map { |to| "/opt/l4d2/overlays/#{to.overlay.name}" }.join(":")
      lower_dirs = "#{overlays}:/opt/l4d2/installation"

      mount_cmd = "fuse-overlayfs -o lowerdir=#{lower_dirs},upperdir=#{server_dir}/upper,workdir=#{server_dir}/work #{server_dir}/merged"

      success = system(mount_cmd)
      raise "Failed to mount overlayfs" unless success
    end

    def generate_systemd_unit
      SystemdManager.new(@server).create_unit_file
    end

    def enable_and_start_service
      SystemdManager.new(@server).enable_and_start
      @server.update(status: :starting)
    end

    def unmount_overlayfs
      server_dir = "/opt/l4d2/servers/#{@server.id}"
      merged = "#{server_dir}/merged"

      if Dir.exist?(merged)
        system("mountpoint -q #{merged} && umount #{merged}")
      end
    rescue StandardError => e
      Rails.logger.warn("Failed to unmount overlayfs: #{e.message}")
    end

    def cleanup_directories
      server_dir = "/opt/l4d2/servers/#{@server.id}"
      FileUtils.rm_rf(server_dir) if Dir.exist?(server_dir)
    rescue StandardError => e
      Rails.logger.warn("Failed to cleanup directories: #{e.message}")
    end
  end
end