module Support
  module Browser
    # Create a docker container on demand.
    class DockerContainer
      def initialize(browser_name, selenium_version = "2.45.0")
        @browser_name = browser_name
        @selenium_version = selenium_version
      end

      def url
        start_up unless started?
        "http://#{ip}:#{port}/wd/hub"
      end

      def start_up
        command = "docker run -d -P selenium/standalone-#{@browser_name}:#{@selenium_version}"
        run = Mixlib::ShellOut.new command
        run.run_command
        run.error! # fails on non-zero exit code

        @uid = run.stdout.strip # strip leading/trailing whitespace and newlines
        initiate_connection
        puts "Started docker container at: #{@uid}"
      end

      def tear_down
        return puts "Container (#{@uid}) appears to have already been removed!" unless started?
        rm = Mixlib::ShellOut.new "docker rm -f #{@uid}"
        rm.run_command
        rm.error!

        puts "Removed docker container: #{@uid}"
      end

      private

      def started?
        return false if @uid.nil?

        inspect = Mixlib::ShellOut.new "docker inspect #{@uid}"
        inspect.run_command
        inspect.error!
        true
      rescue Mixlib::ShellOut::ShellCommandFailed
        false
      end

      # Needed because sometimes container is started, but the port is not available for Watir to connect to
      # e.g. Connection refused - connect(2) for "192.168.99.100" port 32769 (Errno::ECONNREFUSED)
      def initiate_connection
        Retriable.retriable on: [Errno::ECONNREFUSED, Errno::EHOSTUNREACH] do
          TCPSocket.new(ip, port).close
        end
      end

      def ip
        # $DOCKER_HOST is usually only set for docker-machine or other non-native docker installs
        # Otherwise, looks like: "tcp://192.168.99.100:2376"
        docker_host = `echo $DOCKER_HOST`.strip
        return "127.0.0.1" if docker_host.empty? # if env var is not set, assume docker is on localhost
        uri = Addressable::URI.parse(docker_host)
        uri.host
      end

      def port
        # Looks like: "4444/tcp -> 0.0.0.0:4444"
        `docker port #{@uid}`.strip.split(":").last
      end
    end
  end
end