require 'childprocess'
require 'tempfile'
require 'shellwords'

require 'aruba/errors'
require 'aruba/processes/basic_process'
require 'aruba/platform'

# Aruba
module Aruba
  # Platforms
  module Processes
    # Spawn a process for command
    #
    # `SpawnProcess` is not meant for direct use - `SpawnProcess.new` - by
    # users. Only it's public methods are part of the public API of aruba, e.g.
    # `#stdin`, `#stdout`.
    #
    # @private
    class SpawnProcess < BasicProcess
      # Use as default launcher
      def self.match?(_mode)
        true
      end

      # Create process
      #
      # @param [String] cmd
      #   Command string
      #
      # @param [Numeric] exit_timeout
      #   The timeout until we expect the command to be finished
      #
      # @param [Numeric] io_wait_timeout
      #   The timeout until we expect the io to be finished
      #
      # @param [String] working_directory
      #   The directory where the command will be executed
      #
      # @param [Hash] environment
      #   Environment variables
      #
      # @param [Class] main_class
      #   E.g. Cli::App::Runner
      #
      # @param [String] stop_signal
      #   Name of signal to send to stop process. E.g. 'HUP'.
      #
      # @param [Numeric] startup_wait_time
      #   The amount of seconds to wait after Aruba has started a command.
      def initialize(cmd, exit_timeout, io_wait_timeout, working_directory,
                     environment = Aruba.platform.environment_variables.hash_from_env,
                     main_class = nil, stop_signal = nil, startup_wait_time = 0)
        super

        @process      = nil
        @stdout_cache = nil
        @stderr_cache = nil
      end

      # Run the command
      #
      # @yield [SpawnProcess]
      #   Run code for process which was started
      #
      # rubocop:disable Metrics/MethodLength
      def start
        # rubocop:disable Metrics/LineLength
        fail CommandAlreadyStartedError, %(Command "#{commandline}" has already been started. Please `#stop` the command first and `#start` it again. Alternatively use `#restart`.\n#{caller.join("\n")}) if started?

        # rubocop:enable Metrics/LineLength

        @started = true

        @process = ChildProcess.build(*command_string.to_a)
        @stdout_file = Tempfile.new('aruba-stdout-')
        @stderr_file = Tempfile.new('aruba-stderr-')

        @stdout_file.sync = true
        @stderr_file.sync = true

        @stdout_file.binmode
        @stderr_file.binmode

        @exit_status = nil
        @duplex      = true

        before_run

        @process.leader    = true
        @process.io.stdout = @stdout_file
        @process.io.stderr = @stderr_file
        @process.duplex    = @duplex
        @process.cwd       = @working_directory

        @process.environment.update(environment)

        begin
          Aruba.platform.with_environment(environment) do
            @process.start
            sleep startup_wait_time
          end
        rescue ChildProcess::LaunchError => e
          raise LaunchError, "It tried to start #{commandline}. " + e.message
        end

        after_run

        yield self if block_given?
      end

      # Access to stdin of process
      def stdin
        return if @process.exited?

        @process.io.stdin
      end

      # Access to stdout of process
      #
      # @param [Hash] opts
      #   Options
      #
      # @option [Integer] wait_for_io
      #   Wait for IO to be finished
      #
      # @return [String]
      #   The content of stdout
      def stdout(opts = {})
        return @stdout_cache if stopped?

        wait_for_io opts.fetch(:wait_for_io, io_wait_timeout) do
          @process.io.stdout.flush
          open(@stdout_file.path).read
        end
      end

      # Access to stderr of process
      #
      # @param [Hash] opts
      #   Options
      #
      # @option [Integer] wait_for_io
      #   Wait for IO to be finished
      #
      # @return [String]
      #   The content of stderr
      def stderr(opts = {})
        return @stderr_cache if stopped?

        wait_for_io opts.fetch(:wait_for_io, io_wait_timeout) do
          @process.io.stderr.flush
          open(@stderr_file.path).read
        end
      end

      def write(input)
        return if stopped?

        @process.io.stdin.write(input)
        @process.io.stdin.flush

        self
      end

      # Close io
      def close_io(name)
        return if stopped?

        @process.io.public_send(name.to_sym).close
      end

      # Stop command
      def stop(*)
        return @exit_status if stopped?

        begin
          @process.poll_for_exit(@exit_timeout)
        rescue ChildProcess::TimeoutError
          @timed_out = true
        end

        terminate
      end

      # Wait for command to finish
      def wait
        @process.wait
      end

      # Terminate command
      def terminate
        return @exit_status if stopped?

        unless @process.exited?
          if @stop_signal
            # send stop signal ...
            send_signal @stop_signal
            # ... and set the exit status
            wait
          else
            @process.stop
          end
        end

        @exit_status  = @process.exit_code

        @stdout_cache = read_temporary_output_file @stdout_file
        @stderr_cache = read_temporary_output_file @stderr_file

        # @stdout_file = nil
        # @stderr_file = nil

        @started = false

        @exit_status
      end

      # Output pid of process
      #
      # This is the PID of the spawned process.
      def pid
        @process.pid
      end

      # Send command a signal
      #
      # @param [String] signal
      #   The signal, i.e. 'TERM'
      def send_signal(signal)
        fail CommandAlreadyStoppedError, %(Command "#{commandline}" with PID "#{pid}" has already stopped.) if @process.exited?

        Process.kill signal, pid
      rescue Errno::ESRCH
        raise CommandAlreadyStoppedError, %(Command "#{commandline}" with PID "#{pid}" has already stopped.)
      end

      # Return file system stats for the given command
      #
      # @return [Aruba::Platforms::FilesystemStatus]
      #   This returns a File::Stat-object
      def filesystem_status
        Aruba.platform.filesystem_status.new(command_path)
      end

      # Content of command
      #
      # @return [String]
      #   The content of the script/command. This might be binary output as
      #   string if your command is a binary executable.
      def content
        File.read command_path
      end

      def interactive?
        true
      end

      private

      def command_string
        fail LaunchError, %(Command "#{command}" not found in PATH-variable "#{environment['PATH']}".) if command_path.nil?

        Aruba.platform.command_string.new(command_path, *arguments)
      end

      def command_path
        @command_path ||= Aruba.platform.which(command, environment['PATH'])
      end

      def wait_for_io(time_to_wait)
        sleep time_to_wait
        yield
      end

      def read_temporary_output_file(file)
        file.flush
        file.rewind
        data = file.read
        file.close

        data.force_encoding('UTF-8')
      end
    end
  end
end