# frozen_string_literal: true

class Runner::Strategy::DockerContainerPool < Runner::Strategy
  attr_reader :container_id, :command, :execution_environment

  def self.config
    # Since the docker configuration file contains code that must be executed, we use ERB templating.
    @config ||= CodeOcean::Config.new(:docker).read(erb: true)
  end

  def self.request_from_management(environment)
    container_id = JSON.parse(Faraday.get("#{config[:pool][:location]}/docker_container_pool/get_container/#{environment.id}").body)['id']
    container_id.presence || raise(Runner::Error::NotAvailable.new("DockerContainerPool didn't return a container id"))
  rescue Faraday::Error => e
    raise Runner::Error::Unknown.new("Faraday request to DockerContainerPool failed: #{e.inspect}")
  rescue JSON::ParserError => e
    raise Runner::Error::Unknown.new("DockerContainerPool returned invalid JSON: #{e.inspect}")
  end

  def initialize(runner_id, _environment)
    super
    @container_id = runner_id
  end

  def copy_files(files)
    FileUtils.mkdir_p(local_workspace_path)
    clean_workspace
    files.each do |file|
      if file.path.present?
        local_directory_path = local_path(file.path)
        FileUtils.mkdir_p(local_directory_path)
      end

      local_file_path = local_path(file.filepath)
      if file.file_type.binary?
        FileUtils.cp(file.native_file.path, local_file_path)
      else
        begin
          File.open(local_file_path, 'w') {|f| f.write(file.content) }
        rescue IOError => e
          # TODO: try catch i/o exception and log failed attempts
          # Does this fix the issue @Sebastian? What exceptions did you have in mind?
          raise Runner::Error::Unknown.new("Could not create workspace file #{file.filepath}: #{e.inspect}")
        end
      end
    end
    FileUtils.chmod_R('+rwX', local_workspace_path)
  end

  def destroy_at_management
    Faraday.get("#{self.class.config[:pool][:location]}/docker_container_pool/destroy_container/#{container.id}")
  rescue Faraday::Error => e
    raise Runner::Error::Unknown.new("Faraday request to DockerContainerPool failed: #{e.inspect}")
  end

  def attach_to_execution(command)
    @command = command
    starting_time = Time.zone.now
    query_params = 'logs=0&stream=1&stderr=1&stdout=1&stdin=1'
    websocket_url = "#{self.class.config[:ws_host]}/v1.27/containers/#{@container_id}/attach/ws?#{query_params}"

    EventMachine.run do
      socket = Connection.new(websocket_url, self)
      EventMachine.add_timer(@execution_environment.permitted_execution_time) do
        socket.status = :timeout
        destroy_at_management
      end
      socket.send(command)
      yield(socket)
    end
    Time.zone.now - starting_time # execution duration in seconds
  end

  private

  def container
    return @container if @container.present?

    @container = Docker::Container.get(@container_id)
    raise Runner::Error::RunnerNotFound unless @container.info['State']['Running']

    @container
  rescue Docker::Error::NotFoundError
    raise Runner::Error::RunnerNotFound
  end

  def local_path(path)
    unclean_path = local_workspace_path.join(path)
    clean_path = File.expand_path(unclean_path)
    unless clean_path.to_s.start_with? local_workspace_path.to_s
      raise Runner::Error::Unknown.new("Local filepath #{clean_path.inspect} not allowed")
    end

    Pathname.new(clean_path)
  end

  def clean_workspace
    FileUtils.rm_r(local_workspace_path.children, secure: true)
  rescue Errno::ENOENT => e
    raise Runner::Error::Unknown.new("The workspace directory does not exist and cannot be deleted: #{e.inspect}")
  rescue Errno::EACCES => e
    # TODO: Why was this rescued before @Sebastian?
    raise Runner::Error::Unknown.new("Not allowed to clean workspace #{local_workspace_path}: #{e.inspect}")
  end

  def local_workspace_path
    @local_workspace_path ||= Pathname.new(container.binds.first.split(':').first)
  end

  class Connection < Runner::Connection
    def initialize(*args)
      @stream = 'stdout'
      super
    end

    def encode(data)
      "#{data}\n"
    end

    def decode(raw_event)
      case raw_event.data
        when /@#{@strategy.container_id[0..11]}/
          # Assume correct termination for now and return exit code 0
          # TODO: Can we use the actual exit code here?
          @exit_code = 0
          @status = :terminated
          @socket.close
        when /#{format(@strategy.execution_environment.test_command, class_name: '.*', filename: '.*', module_name: '.*')}/
          # TODO: Super dirty hack to redirect test output to stderr (remove attr_reader afterwards)
          @stream = 'stderr'
        when /#{@strategy.command}/
        when /bash: cmd:canvasevent: command not found/
        else
          {'type' => @stream, 'data' => raw_event.data}
      end
    end
  end
end