text: from __future__ import unicode_literals
  
  import os.path
  import re
  import subprocess
  import sys
  import time
  
  from .common import FileDownloader
  from ..compat import (
      compat_setenv,
      compat_str,
  )
  from ..postprocessor.ffmpeg import FFmpegPostProcessor, EXT_TO_OUT_FORMATS
  from ..utils import (
      cli_option,
      cli_valueless_option,
      cli_bool_option,
      cli_configuration_args,
      encodeFilename,
      encodeArgument,
      handle_youtubedl_headers,
      check_executable,
      is_outdated_version,
  )
  
  
  class ExternalFD(FileDownloader):
      def real_download(self, filename, info_dict):
          self.report_destination(filename)
          tmpfilename = self.temp_name(filename)
  
          try:
              started = time.time()
              retval = self._call_downloader(tmpfilename, info_dict)
          except KeyboardInterrupt:
              if not info_dict.get('is_live'):
                  raise
              # Live stream downloading cancellation should be considered as
              # correct and expected termination thus all postprocessing
              # should take place
              retval = 0
              self.to_screen('[%s] Interrupted by user' % self.get_basename())
  
          if retval == 0:
              status = {
                  'filename': filename,
                  'status': 'finished',
                  'elapsed': time.time() - started,
              }
              if filename != '-':
                  fsize = os.path.getsize(encodeFilename(tmpfilename))
                  self.to_screen('\r[%s] Downloaded %s bytes' % (self.get_basename(), fsize))
                  self.try_rename(tmpfilename, filename)
                  status.update({
                      'downloaded_bytes': fsize,
                      'total_bytes': fsize,
                  })
              self._hook_progress(status)
              return True
          else:
              self.to_stderr('\n')
              self.report_error('%s exited with code %d' % (
                  self.get_basename(), retval))
              return False
  
      @classmethod
      def get_basename(cls):
          return cls.__name__[:-2].lower()
  
      @property
      def exe(self):
          return self.params.get('external_downloader')
  
      @classmethod
      def available(cls):
          return check_executable(cls.get_basename(), [cls.AVAILABLE_OPT])
  
      @classmethod
      def supports(cls, info_dict):
          return info_dict['protocol'] in ('http', 'https', 'ftp', 'ftps')
  
      @classmethod
      def can_download(cls, info_dict):
          return cls.available() and cls.supports(info_dict)
  
      def _option(self, command_option, param):
          return cli_option(self.params, command_option, param)
  
      def _bool_option(self, command_option, param, true_value='true', false_value='false', separator=None):
          return cli_bool_option(self.params, command_option, param, true_value, false_value, separator)
  
      def _valueless_option(self, command_option, param, expected_value=True):
          return cli_valueless_option(self.params, command_option, param, expected_value)
  
      def _configuration_args(self, default=[]):
          return cli_configuration_args(self.params, 'external_downloader_args', default)
  
      def _call_downloader(self, tmpfilename, info_dict):
          """ Either overwrite this or implement _make_cmd """
          cmd = [encodeArgument(a) for a in self._make_cmd(tmpfilename, info_dict)]
  
          self._debug_cmd(cmd)
  
          p = subprocess.Popen(
              cmd, stderr=subprocess.PIPE)
          _, stderr = p.communicate()
          if p.returncode != 0:
              self.to_stderr(stderr.decode('utf-8', 'replace'))
          return p.returncode
  
  
  class CurlFD(ExternalFD):
      AVAILABLE_OPT = '-V'
  
      def _make_cmd(self, tmpfilename, info_dict):
          cmd = [self.exe, '--location', '-o', tmpfilename]
          if info_dict.get('http_headers') is not None:
              for key, val in info_dict['http_headers'].items():
                  cmd += ['--header', '%s: %s' % (key, val)]
  
          cmd += self._bool_option('--continue-at', 'continuedl', '-', '0')
          cmd += self._valueless_option('--silent', 'noprogress')
          cmd += self._valueless_option('--verbose', 'verbose')
          cmd += self._option('--limit-rate', 'ratelimit')
          retry = self._option('--retry', 'retries')
          if len(retry) == 2:
              if retry[1] in ('inf', 'infinite'):
                  retry[1] = '2147483647'
              cmd += retry
          cmd += self._option('--max-filesize', 'max_filesize')
          cmd += self._option('--interface', 'source_address')
          cmd += self._option('--proxy', 'proxy')
          cmd += self._valueless_option('--insecure', 'nocheckcertificate')
          cmd += self._configuration_args()
          cmd += ['--', info_dict['url']]
          return cmd
  
      def _call_downloader(self, tmpfilename, info_dict):
          cmd = [encodeArgument(a) for a in self._make_cmd(tmpfilename, info_dict)]
  
          self._debug_cmd(cmd)
  
          # curl writes the progress to stderr so don't capture it.
          p = subprocess.Popen(cmd)
          p.communicate()
          return p.returncode
  
  
  class AxelFD(ExternalFD):
      AVAILABLE_OPT = '-V'
  
      def _make_cmd(self, tmpfilename, info_dict):
          cmd = [self.exe, '-o', tmpfilename]
          if info_dict.get('http_headers') is not None:
              for key, val in info_dict['http_headers'].items():
                  cmd += ['-H', '%s: %s' % (key, val)]
          cmd += self._configuration_args()
          cmd += ['--', info_dict['url']]
          return cmd
  
  
  class WgetFD(ExternalFD):
      AVAILABLE_OPT = '--version'
  
      def _make_cmd(self, tmpfilename, info_dict):
          cmd = [self.exe, '-O', tmpfilename, '-nv', '--no-cookies']
          if info_dict.get('http_headers') is not None:
              for key, val in info_dict['http_headers'].items():
                  cmd += ['--header', '%s: %s' % (key, val)]
          cmd += self._option('--limit-rate', 'ratelimit')
          retry = self._option('--tries', 'retries')
          if len(retry) == 2:
              if retry[1] in ('inf', 'infinite'):
                  retry[1] = '0'
              cmd += retry
          cmd += self._option('--bind-address', 'source_address')
          cmd += self._option('--proxy', 'proxy')
          cmd += self._valueless_option('--no-check-certificate', 'nocheckcertificate')
          cmd += self._configuration_args()
          cmd += ['--', info_dict['url']]
          return cmd
  
  
  class Aria2cFD(ExternalFD):
      AVAILABLE_OPT = '-v'
  
      def _make_cmd(self, tmpfilename, info_dict):
          cmd = [self.exe, '-c']
          cmd += self._configuration_args([
              '--min-split-size', '1M', '--max-connection-per-server', '4'])
          dn = os.path.dirname(tmpfilename)
          if dn:
              cmd += ['--dir', dn]
          cmd += ['--out', os.path.basename(tmpfilename)]
          if info_dict.get('http_headers') is not None:
              for key, val in info_dict['http_headers'].items():
                  cmd += ['--header', '%s: %s' % (key, val)]
          cmd += self._option('--interface', 'source_address')
          cmd += self._option('--all-proxy', 'proxy')
          cmd += self._bool_option('--check-certificate', 'nocheckcertificate', 'false', 'true', '=')
          cmd += self._bool_option('--remote-time', 'updatetime', 'true', 'false', '=')
          cmd += ['--', info_dict['url']]
          return cmd
  
  
  class HttpieFD(ExternalFD):
      @classmethod
      def available(cls):
          return check_executable('http', ['--version'])
  
      def _make_cmd(self, tmpfilename, info_dict):
          cmd = ['http', '--download', '--output', tmpfilename, info_dict['url']]
  
          if info_dict.get('http_headers') is not None:
              for key, val in info_dict['http_headers'].items():
                  cmd += ['%s:%s' % (key, val)]
          return cmd
  
  
  class FFmpegFD(ExternalFD):
      @classmethod
      def supports(cls, info_dict):
          return info_dict['protocol'] in ('http', 'https', 'ftp', 'ftps', 'm3u8', 'rtsp', 'rtmp', 'mms')
  
      @classmethod
      def available(cls):
          return FFmpegPostProcessor().available
  
      def _call_downloader(self, tmpfilename, info_dict):
          url = info_dict['url']
          ffpp = FFmpegPostProcessor(downloader=self)
          if not ffpp.available:
              self.report_error('m3u8 download detected but ffmpeg or avconv could not be found. Please install one.')
              return False
          ffpp.check_version()
  
          args = [ffpp.executable, '-y']
  
          for log_level in ('quiet', 'verbose'):
              if self.params.get(log_level, False):
                  args += ['-loglevel', log_level]
                  break
  
          seekable = info_dict.get('_seekable')
          if seekable is not None:
              # setting -seekable prevents ffmpeg from guessing if the server
              # supports seeking(by adding the header `Range: bytes=0-`), which
              # can cause problems in some cases
              # https://github.com/ytdl-org/youtube-dl/issues/11800#issuecomment-275037127
              # http://trac.ffmpeg.org/ticket/6125#comment:10
              args += ['-seekable', '1' if seekable else '0']
  
          args += self._configuration_args()
  
          # start_time = info_dict.get('start_time') or 0
          # if start_time:
          #     args += ['-ss', compat_str(start_time)]
          # end_time = info_dict.get('end_time')
          # if end_time:
          #     args += ['-t', compat_str(end_time - start_time)]
  
          if info_dict.get('http_headers') is not None and re.match(r'^https?://', url):
              # Trailing \r\n after each HTTP header is important to prevent warning from ffmpeg/avconv:
              # [http @ 00000000003d2fa0] No trailing CRLF found in HTTP header.
              headers = handle_youtubedl_headers(info_dict['http_headers'])
              args += [
                  '-headers',
                  ''.join('%s: %s\r\n' % (key, val) for key, val in headers.items())]
  
          env = None
          proxy = self.params.get('proxy')
          if proxy:
              if not re.match(r'^[\da-zA-Z]+://', proxy):
                  proxy = 'http://%s' % proxy
  
              if proxy.startswith('socks'):
                  self.report_warning(
                      '%s does not support SOCKS proxies. Downloading is likely to fail. '
                      'Consider adding --hls-prefer-native to your command.' % self.get_basename())
  
              # Since December 2015 ffmpeg supports -http_proxy option (see
              # http://git.videolan.org/?p=ffmpeg.git;a=commit;h=b4eb1f29ebddd60c41a2eb39f5af701e38e0d3fd)
              # We could switch to the following code if we are able to detect version properly
              # args += ['-http_proxy', proxy]
              env = os.environ.copy()
              compat_setenv('HTTP_PROXY', proxy, env=env)
              compat_setenv('http_proxy', proxy, env=env)
  
          protocol = info_dict.get('protocol')
  
          if protocol == 'rtmp':
              player_url = info_dict.get('player_url')
              page_url = info_dict.get('page_url')
              app = info_dict.get('app')
              play_path = info_dict.get('play_path')
              tc_url = info_dict.get('tc_url')
              flash_version = info_dict.get('flash_version')
              live = info_dict.get('rtmp_live', False)
              conn = info_dict.get('rtmp_conn')
              if player_url is not None:
                  args += ['-rtmp_swfverify', player_url]
              if page_url is not None:
                  args += ['-rtmp_pageurl', page_url]
              if app is not None:
                  args += ['-rtmp_app', app]
              if play_path is not None:
                  args += ['-rtmp_playpath', play_path]
              if tc_url is not None:
                  args += ['-rtmp_tcurl', tc_url]
              if flash_version is not None:
                  args += ['-rtmp_flashver', flash_version]
              if live:
                  args += ['-rtmp_live', 'live']
              if isinstance(conn, list):
                  for entry in conn:
                      args += ['-rtmp_conn', entry]
              elif isinstance(conn, compat_str):
                  args += ['-rtmp_conn', conn]
  
          args += ['-i', url, '-c', 'copy']
  
          if self.params.get('test', False):
              args += ['-fs', compat_str(self._TEST_FILE_SIZE)]
  
          if protocol in ('m3u8', 'm3u8_native'):
              if self.params.get('hls_use_mpegts', False) or tmpfilename == '-':
                  args += ['-f', 'mpegts']
              else:
                  args += ['-f', 'mp4']
                  if (ffpp.basename == 'ffmpeg' and is_outdated_version(ffpp._versions['ffmpeg'], '3.2', False)) and (not info_dict.get('acodec') or info_dict['acodec'].split('.')[0] in ('aac', 'mp4a')):
                      args += ['-bsf:a', 'aac_adtstoasc']
          elif protocol == 'rtmp':
              args += ['-f', 'flv']
          else:
              args += ['-f', EXT_TO_OUT_FORMATS.get(info_dict['ext'], info_dict['ext'])]
  
          args = [encodeArgument(opt) for opt in args]
          args.append(encodeFilename(ffpp._ffmpeg_filename_argument(tmpfilename), True))
  
          self._debug_cmd(args)
  
          proc = subprocess.Popen(args, stdin=subprocess.PIPE, env=env)
          try:
              retval = proc.wait()
          except KeyboardInterrupt:
              # subprocces.run would send the SIGKILL signal to ffmpeg and the
              # mp4 file couldn't be played, but if we ask ffmpeg to quit it
              # produces a file that is playable (this is mostly useful for live
              # streams). Note that Windows is not affected and produces playable
              # files (see https://github.com/ytdl-org/youtube-dl/issues/8300).
              if sys.platform != 'win32':
                  proc.communicate(b'q')
              raise
          return retval
  
  
  class AVconvFD(FFmpegFD):
      pass
  
  
  _BY_NAME = dict(
      (klass.get_basename(), klass)
      for name, klass in globals().items()
      if name.endswith('FD') and name != 'ExternalFD'
  )
  
  
  def list_external_downloaders():
      return sorted(_BY_NAME.keys())
  
  
  def get_external_downloader(external_downloader):
      """ Given the name of the executable, see whether we support the given
          downloader . """
      # Drop .exe extension on Windows
      bn = os.path.splitext(os.path.basename(external_downloader))[0]
      return _BY_NAME[bn]
  