#!/usr/bin/python

# Audio Tools, a module and set of tools for manipulating audio data
# Copyright (C) 2007-2015  Brian Langenberger

# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.

# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.

# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA


import sys
import os
import os.path
import select
from operator import concat
import audiotools
import audiotools.ui
import audiotools.text as _
import termios


MAX_CPUS = audiotools.MAX_JOBS


def convert(progress,
            source_audiofile,
            destination_filename,
            destination_class,
            compression,
            metadata,
            replay_gain,
            sample_rate,
            channels,
            bits_per_sample):
    try:
        if (((sample_rate is None) and
             (channels is None) and
             (bits_per_sample is None))):
            destination_audiofile = source_audiofile.convert(
                destination_filename,
                destination_class,
                compression,
                progress)
        else:
            pcmreader = source_audiofile.to_pcm()
            destination_audiofile = destination_class.from_pcm(
                destination_filename,
                audiotools.PCMConverter(
                    audiotools.PCMReaderProgress(
                        pcmreader,
                        source_audiofile.total_frames(),
                        progress),
                    sample_rate if
                    (sample_rate is not None) else
                    pcmreader.sample_rate,
                    channels if
                    (channels is not None) else
                    pcmreader.channels,
                    0 if
                    (channels is not None) else
                    pcmreader.channel_mask,
                    bits_per_sample if (bits_per_sample is not None) else
                    pcmreader.bits_per_sample),
                compression,
                source_audiofile.total_frames() if
                (source_audiofile.lossless() and (sample_rate is None))
                else None)

        if metadata is not None:
            destination_audiofile.set_metadata(metadata)

        if replay_gain is not None:
            destination_audiofile.set_replay_gain(replay_gain)

        existing_cuesheet = source_audiofile.get_cuesheet()
        if existing_cuesheet is not None:
            destination_audiofile.set_cuesheet(existing_cuesheet)
    except KeyboardInterrupt:
        # delete partially-encoded file
        try:
            os.unlink(destination_filename)
        except OSError:
            pass

    return destination_filename


def __add_replay_gain__(tracks, progress=None):
    """a wrapper around add_replay_gain that catches KeyboardInterrupt"""

    try:
        audiotools.add_replay_gain(tracks=tracks, progress=progress)
    except KeyboardInterrupt:
        pass


if audiotools.ui.AVAILABLE:
    urwid = audiotools.ui.urwid

    class MultiOutputFiller(audiotools.ui.OutputFiller):
        def __init__(self,
                     track_labels,
                     metadata_choices,
                     input_filenames,
                     output_directory,
                     format_string,
                     output_class,
                     quality,
                     completion_label=u"Apply"):
            """track_labels[a][t]
            is a unicode string per album "a", per track "t"

            metadata_choices[a][c][t]
            is a MetaData object per album "a", per choice "c", per track "t"
            must have same album count as track_labels
            and each album's choice must have the same number of tracks
            (but may have different number of choices)

            input_filenames[a][t]
            is a Filename object per album "a", per track "t"

            output_directory is a string of the default output dir

            format_string is a UTF-8 encoded format string

            output_class is the default AudioFile-compatible class

            quality is a string of the default output quality to use
            """

            from functools import reduce

            self.__cancelled__ = True

            # ensure there's at least one album
            assert(len(track_labels) > 0)

            # ensure album count is consistent
            assert(len(track_labels) ==
                   len(metadata_choices) ==
                   len(input_filenames))

            # ensure track count is consistent
            for (labels, filenames) in zip(track_labels, input_filenames):
                assert(len(labels) == len(filenames))

            # ensure there's at least one track
            assert(len(track_labels[0]) > 0)

            # ensure there's at least one set of choices per album
            # and all have the same number of tracks
            for (a, choice_labels) in zip(metadata_choices, track_labels):
                assert(len(a) > 0)
                for c in a:
                    assert(len(c) == len(choice_labels))

            # ensure all input filenames are Filename objects
            for a in input_filenames:
                for f in a:
                    assert(isinstance(f, audiotools.Filename))

            # setup status bars for output messages
            self.metadatas_status = [urwid.Text(u"") for m in track_labels]
            self.options_status = urwid.Text(u"")

            # setup widgets for populated metadata fields
            self.metadatas = [
                audiotools.ui.MetaDataFiller(labels, choices, status)
                for (labels, choices, status) in zip(track_labels,
                                                     metadata_choices,
                                                     self.metadatas_status)]

            # setup a widget for populating output parameters
            self.options = audiotools.ui.OutputOptions(
                output_dir=output_directory,
                format_string=format_string,
                audio_class=output_class,
                quality=quality,
                input_filenames=reduce(concat, input_filenames),
                metadatas=[None for f in reduce(concat, input_filenames)])

            # finish initialization
            from audiotools.text import LAB_CANCEL_BUTTON

            self.wizard = audiotools.ui.Wizard(
                self.metadatas + [self.options],
                urwid.Button(LAB_CANCEL_BUTTON, on_press=self.exit),
                urwid.Button(completion_label, on_press=self.complete),
                self.page_changed)

            self.__current_page__ = self.metadatas[0]

            urwid.Frame.__init__(self,
                                 body=self.wizard,
                                 footer=self.metadatas_status[0])

        def page_changed(self, new_page):
            self.__current_page__ = new_page
            if hasattr(new_page, "status"):
                # one of the metadata pages is selected
                self.set_footer(new_page.status)
            else:
                from functools import reduce

                # the final options page is selected
                self.options.set_metadatas(
                    reduce(concat, [list(m.populated_metadata())
                                    for m in self.metadatas]))
                self.set_footer(self.options_status)

        def handle_text(self, i):
            if ((i == "f1") and hasattr(self.__current_page__,
                                        "select_previous_item")):
                self.__current_page__.select_previous_item()
            elif ((i == "f2") and (hasattr(self.__current_page__,
                                           "select_next_item"))):
                self.__current_page__.select_next_item()

        def output_albums(self):
            """for each album
               yields (output_class,
                       output_filename,
                       output_quality,
                       output_metadata) tuple for each input audio file

            as a nested iterator

            output_metadata is a newly created MetaData object"""

            (audiofile_class,
             quality,
             output_filenames) = self.options.selected_options()

            for widget in self.metadatas:
                album = []
                for metadata in widget.populated_metadata():
                    album.append((audiofile_class,
                                  output_filenames.pop(0),
                                  quality,
                                  metadata))
                yield album


if (__name__ == '__main__'):
    import argparse

    parser = argparse.ArgumentParser(description=_.DESCRIPTION_TRACK2TRACK)

    parser.add_argument("--version",
                        action="version",
                        version="Python Audio Tools %s" % (audiotools.VERSION))

    parser.add_argument("-I", "--interactive",
                        action="store_true",
                        default=False,
                        dest="interactive",
                        help=_.OPT_INTERACTIVE_OPTIONS)

    parser.add_argument("-V", "--verbose",
                        dest="verbosity",
                        choices=audiotools.VERBOSITY_LEVELS,
                        default=audiotools.DEFAULT_VERBOSITY,
                        help=_.OPT_VERBOSE)

    conversion = parser.add_argument_group(_.OPT_CAT_CONVERSION)

    conversion.add_argument(
        "-t", "--type",
        dest="type",
        choices=sorted(list(t.NAME for t in audiotools.AVAILABLE_TYPES
                            if t.supports_from_pcm()) + ["help"]),
        help=_.OPT_TYPE)

    conversion.add_argument("-q", "--quality",
                            dest="quality",
                            help=_.OPT_QUALITY)

    conversion.add_argument("-d", "--dir",
                            dest="dir",
                            default=".",
                            help=_.OPT_DIR)

    conversion.add_argument("--format",
                            default=None,
                            dest="format",
                            help=_.OPT_FORMAT)

    conversion.add_argument("-o", "--output",
                            dest="output",
                            help=_.OPT_OUTPUT_TRACK2TRACK)

    conversion.add_argument("-j", "--joint",
                            type=int,
                            default=MAX_CPUS,
                            dest="max_processes",
                            help=_.OPT_JOINT)

    format = parser.add_argument_group(_.OPT_CAT_OUTPUT_FORMAT)

    format.add_argument("--sample-rate",
                        type=int,
                        dest="sample_rate",
                        metavar="RATE",
                        help=_.OPT_SAMPLE_RATE)

    format.add_argument("--channels",
                        type=int,
                        dest="channels",
                        help=_.OPT_CHANNELS)

    format.add_argument("--bits-per-sample",
                        type=int,
                        dest="bits_per_sample",
                        metavar="BITS",
                        help=_.OPT_BPS)

    lookup = parser.add_argument_group(_.OPT_CAT_CD_LOOKUP)

    lookup.add_argument("-M", "--metadata-lookup",
                        action="store_true",
                        default=False,
                        dest="metadata_lookup",
                        help=_.OPT_METADATA_LOOKUP)

    lookup.add_argument("--musicbrainz-server",
                        dest="musicbrainz_server",
                        default=audiotools.MUSICBRAINZ_SERVER,
                        metavar="HOSTNAME")

    lookup.add_argument("--musicbrainz-port",
                        type=int,
                        dest="musicbrainz_port",
                        default=audiotools.MUSICBRAINZ_PORT,
                        metavar="PORT")

    lookup.add_argument("--no-musicbrainz",
                        action="store_false",
                        dest="use_musicbrainz",
                        default=audiotools.MUSICBRAINZ_SERVICE,
                        help=_.OPT_NO_MUSICBRAINZ)

    lookup.add_argument("--freedb-server",
                        dest="freedb_server",
                        default=audiotools.FREEDB_SERVER,
                        metavar="HOSTNAME")

    lookup.add_argument("--freedb-port",
                        type=int,
                        dest="freedb_port",
                        default=audiotools.FREEDB_PORT,
                        metavar="PORT")

    lookup.add_argument("--no-freedb",
                        action="store_false",
                        dest="use_freedb",
                        default=audiotools.FREEDB_SERVICE,
                        help=_.OPT_NO_FREEDB)

    lookup.add_argument("-D", "--default",
                        dest="use_default",
                        action="store_true",
                        default=False,
                        help=_.OPT_DEFAULT)

    metadata = parser.add_argument_group(_.OPT_CAT_METADATA)

    metadata.add_argument("--replay-gain",
                          action="store_true",
                          default=None,
                          dest="add_replay_gain",
                          help=_.OPT_REPLAY_GAIN)

    metadata.add_argument("--no-replay-gain",
                          action="store_false",
                          default=None,
                          dest="add_replay_gain",
                          help=_.OPT_NO_REPLAY_GAIN)

    parser.add_argument("filenames",
                        metavar="FILENAME",
                        nargs="+",
                        help=_.OPT_INPUT_FILENAME)

    options = parser.parse_args()

    msg = audiotools.Messenger(options.verbosity == "quiet")

    # ensure interactive mode is available, if selected
    if options.interactive and (not audiotools.ui.AVAILABLE):
        audiotools.ui.not_available_message(msg)
        sys.exit(1)

    # if one specifies incompatible output options,
    # complain about it right away
    if options.output is not None:
        if options.dir != ".":
            msg.error(_.ERR_TRACK2TRACK_O_AND_D)
            msg.info(_.ERR_TRACK2TRACK_O_AND_D_SUGGESTION)
            sys.exit(1)

        if options.format is not None:
            msg.warning(_.ERR_TRACK2TRACK_O_AND_FORMAT)

    # get the AudioFile class we are converted to
    if options.type == 'help':
        audiotools.ui.show_available_formats(msg)
        sys.exit(0)
    elif options.output is None:
        if options.type is not None:
            AudioType = audiotools.TYPE_MAP[options.type]
        else:
            AudioType = audiotools.TYPE_MAP[audiotools.DEFAULT_TYPE]
    else:
        if options.type is not None:
            AudioType = audiotools.TYPE_MAP[options.type]
        else:
            try:
                AudioType = audiotools.filename_to_type(options.output)
            except audiotools.UnknownAudioType as exp:
                exp.error_msg(msg)
                sys.exit(1)

    if not AudioType.supports_from_pcm():
        msg.error(_.ERR_UNSUPPORTED_FROM_PCM % {"type": AudioType.NAME})
        sys.exit(1)

    # whether to add ReplayGain to newly converted files
    if AudioType.supports_replay_gain():
        add_replay_gain = ((options.add_replay_gain if
                            (options.add_replay_gain is not None) else
                           audiotools.ADD_REPLAYGAIN))
    else:
        add_replay_gain = False

    # ensure the selected compression is compatible with that class
    if options.quality == 'help':
        audiotools.ui.show_available_qualities(msg, AudioType)
        sys.exit(0)
    elif options.quality is None:
        options.quality = audiotools.__default_quality__(AudioType.NAME)
    elif options.quality not in AudioType.COMPRESSION_MODES:
        msg.error(_.ERR_UNSUPPORTED_COMPRESSION_MODE %
                  {"quality": options.quality,
                   "type": AudioType.NAME})
        sys.exit(1)

    # grab the list of AudioFile objects we are converting from
    audiofiles = []
    input_filenames = set()
    for filename in map(audiotools.Filename, options.filenames):
        if filename not in input_filenames:
            input_filenames.add(filename)
        else:
            msg.error(_.ERR_DUPLICATE_FILE % (filename,))
            sys.exit(1)

        try:
            audiofile = audiotools.open(str(filename))
            if audiofile.__class__.supports_to_pcm():
                audiofiles.append(audiofile)
            else:
                msg.warning(_.ERR_UNSUPPORTED_TO_PCM %
                            {"filename": filename, "type": audiofile.NAME})
        except audiotools.UnsupportedFile:
            msg.warning(_.ERR_UNSUPPORTED_FILE % (filename,))
        except audiotools.InvalidFile as err:
            msg.warning(str(err))
        except IOError:
            msg.warning(_.ERR_OPEN_IOERROR % (filename,))

    if len(audiofiles) < 1:
        msg.error(_.ERR_FILES_REQUIRED)
        sys.exit(1)

    if (options.sample_rate is not None) and (options.sample_rate < 1):
        msg.error(_.ERR_INVALID_SAMPLE_RATE)
        sys.exit(1)

    if (options.channels is not None) and (options.channels < 1):
        msg.error(_.ERR_INVALID_CHANNEL_COUNT)
        sys.exit(1)

    if (((options.bits_per_sample is not None) and
         (options.bits_per_sample < 1))):
        msg.error(_.ERR_INVALID_BITS_PER_SAMPLE)
        sys.exit(1)

    if options.max_processes < 1:
        msg.error(_.ERR_INVALID_JOINT)
        sys.exit(1)

    if (options.output is not None) and (len(audiofiles) != 1):
        msg.error(_.ERR_TRACK2TRACK_O_AND_MULTIPLE)
        sys.exit(1)

    if options.output is None:
        # the default encoding method, without an output file

        queue = audiotools.ExecProgressQueue(msg)

        # split tracks by album
        albums_iter = audiotools.group_tracks(audiofiles)

        # input_tracks[a][t] is an AudioFile object
        # per album "a", per track "t"
        input_tracks = []

        # input_metadatas[a][t] is a MetaData object (or None)
        # per album "a", per track "t"
        input_metadatas = []

        # track_labels[a][t] is a unicode string per album "a", per track "t"
        track_labels = []

        # metadata_choices[a][c][t] is a MetaData object
        # per album "a", per choice "c", per track "t"
        metadata_choices = []

        # input_filenames[a][t] is a Filename object
        # per album "a", per track "t"
        input_filenames = []

        for album_tracks in albums_iter:
            input_tracks.append(album_tracks)

            track_metadatas = [f.get_metadata() for f in album_tracks]
            input_metadatas.append(track_metadatas)

            filenames = [audiotools.Filename(f.filename)
                         for f in album_tracks]
            track_labels.append([f.basename().__unicode__()
                                 for f in filenames])
            input_filenames.append(filenames)

            if not options.metadata_lookup:
                # pull metadata from existing files, if any
                metadata_choices.append([[f.get_metadata() for f in
                                          album_tracks]])
            else:
                # perform CD lookup for existing files
                try:
                    metadata_choices.append(audiotools.track_metadata_lookup(
                        audiofiles=album_tracks,
                        musicbrainz_server=options.musicbrainz_server,
                        musicbrainz_port=options.musicbrainz_port,
                        freedb_server=options.freedb_server,
                        freedb_port=options.freedb_port,
                        use_musicbrainz=options.use_musicbrainz,
                        use_freedb=options.use_freedb))
                except KeyboardInterrupt:
                    msg.ansi_clearline()
                    msg.error(_.ERR_CANCELLED)
                    sys.exit(1)

                # and prepend metadata from existing files as an option, if any
                if track_metadatas != [None] * len(track_metadatas):
                    metadata_choices[-1].insert(
                        0,
                        [(m if m is not None else audiotools.MetaData())
                         for m in track_metadatas])

                # avoid performing too many lookups in a row too quickly
                from time import sleep
                sleep(1)

        # a list of (audiofile,
        #            output_class,
        #            output_filename,
        #            output_quality,
        #            output_metadata,
        #            output_replay_gain) tuples to be executed
        conversion_jobs = []

        # a list of [audiofile, audiofile, ...] lists
        # each containing an album of tracks to add ReplayGain to
        # once conversion is finished
        replaygain_jobs = []

        if options.interactive:
            # pick options using interactive widget

            output_widget = MultiOutputFiller(
                track_labels=track_labels,
                metadata_choices=metadata_choices,
                input_filenames=input_filenames,
                output_directory=options.dir,
                format_string=(options.format if
                               (options.format is not None) else
                               audiotools.FILENAME_FORMAT),
                output_class=AudioType,
                quality=options.quality,
                completion_label=(_.LAB_TRACK2TRACK_APPLY if
                                  (sum(map(len, input_tracks)) != 1)
                                  else _.LAB_TRACK2TRACK_APPLY_1))

            loop = audiotools.ui.urwid.MainLoop(
                output_widget,
                audiotools.ui.style(),
                screen=audiotools.ui.Screen(),
                unhandled_input=output_widget.handle_text,
                pop_ups=True)
            try:
                loop.run()
                msg.ansi_clearscreen()
            except (termios.error, IOError):
                msg.error(_.ERR_TERMIOS_ERROR)
                msg.info(_.ERR_TERMIOS_SUGGESTION)
                msg.info(audiotools.ui.xargs_suggestion(sys.argv))
                sys.exit(1)

            if output_widget.cancelled():
                sys.exit(0)

            for (album_tracks,
                 album_metadatas,
                 album_output) in zip(input_tracks,
                                      input_metadatas,
                                      output_widget.output_albums()):

                # use existing ReplayGain values if we're to add it
                # and *all* input tracks have it
                if add_replay_gain:
                    album_track_gains = [t.get_replay_gain() for t in
                                         album_tracks]
                    if None in album_track_gains:
                        album_track_gains = [None for t in album_tracks]
                        replaygain_jobs.append(
                            [str(o[1]) for o in album_output])
                else:
                    album_track_gains = [None for t in album_tracks]

                for (input_track,
                     current_metadata,
                     (output_class,
                      output_filename,
                      output_quality,
                      output_metadata),
                     output_replay_gain) in zip(album_tracks,
                                                album_metadatas,
                                                album_output,
                                                album_track_gains):
                    # merge current track metadata (if any)
                    # with metadata returned from widget
                    if current_metadata is not None:
                        for attr in audiotools.MetaData.FIELDS:
                            original_value = getattr(current_metadata, attr)
                            updated_value = getattr(output_metadata, attr)
                            if original_value != updated_value:
                                setattr(current_metadata, attr, updated_value)
                        # and queue up conversion job to be executed
                        conversion_jobs.append((input_track,
                                                output_class,
                                                output_filename,
                                                output_quality,
                                                current_metadata,
                                                output_replay_gain))
                    else:
                        # or simply queue up conversion job to be executed
                        # using only new metadata
                        conversion_jobs.append((input_track,
                                                output_class,
                                                output_filename,
                                                output_quality,
                                                output_metadata,
                                                output_replay_gain))

        else:
            # pick options without using GUI
            for (album_tracks,
                 album_metadata_choices,
                 album_filenames) in zip(input_tracks,
                                         metadata_choices,
                                         input_filenames):
                try:
                    output_tracks = list(audiotools.ui.process_output_options(
                        metadata_choices=album_metadata_choices,
                        input_filenames=album_filenames,
                        output_directory=options.dir,
                        format_string=options.format,
                        output_class=AudioType,
                        quality=options.quality,
                        msg=msg,
                        use_default=options.use_default))

                    # use existing ReplayGain values if we're to add it
                    # and *all* input tracks have it
                    if add_replay_gain:
                        album_track_gains = [t.get_replay_gain() for t in
                                             album_tracks]
                        if None in album_track_gains:
                            album_track_gains = [None for t in album_tracks]
                            replaygain_jobs.append(
                                [str(o[1]) for o in output_tracks])
                    else:
                        album_track_gains = [None for t in album_tracks]

                    # queue jobs to be executed
                    for (album_track,
                         (output_class,
                          output_filename,
                          output_quality,
                          output_metadata),
                         output_replay_gain) in zip(album_tracks,
                                                    output_tracks,
                                                    album_track_gains):
                        conversion_jobs.append((album_track,
                                                output_class,
                                                output_filename,
                                                output_quality,
                                                output_metadata,
                                                output_replay_gain))
                except audiotools.UnsupportedTracknameField as err:
                    err.error_msg(msg)
                    sys.exit(1)
                except (audiotools.InvalidFilenameFormat,
                        audiotools.OutputFileIsInput,
                        audiotools.DuplicateOutputFile) as err:
                    msg.error(err)
                    sys.exit(1)

        # re-check that the same output file doesn't occur more than once
        # (although process_output_options also performs that check,
        #  it's possible processing multiple albums at once
        #  may result in the same output file occurring across the whole
        #  job, but not in any individual album)
        output_filenames = set()
        for job in conversion_jobs:
            output_filename = job[2]
            if output_filename not in output_filenames:
                output_filenames.add(output_filename)
            else:
                msg.error(_.ERR_DUPLICATE_OUTPUT_FILE % (output_filename,))
                sys.exit(1)

        # queue conversion jobs to ProgressQueue
        for (audiofile,
             output_class,
             output_filename,
             output_quality,
             output_metadata,
             output_replay_gain) in conversion_jobs:
            # try to create subdirectories in advance
            # so to bail out early if there's an error creating one
            try:
                audiotools.make_dirs(str(output_filename))
            except OSError:
                msg.error(_.ERR_ENCODING_ERROR % (output_filename,))
                sys.exit(1)

            queue.execute(
                function=convert,
                progress_text=output_filename.__unicode__(),
                completion_output=(_.LAB_ENCODE % {
                    "source": audiotools.Filename(audiofile.filename),
                    "destination": output_filename}),
                source_audiofile=audiofile,
                destination_filename=str(output_filename),
                destination_class=output_class,
                compression=output_quality,
                metadata=output_metadata,
                replay_gain=output_replay_gain,
                sample_rate=options.sample_rate,
                channels=options.channels,
                bits_per_sample=options.bits_per_sample)

        # perform actual track conversion
        try:
            output_files = map(audiotools.open,
                               queue.run(options.max_processes))
        except audiotools.EncodingError as err:
            msg.error(err)
            sys.exit(1)
        except KeyboardInterrupt:
            msg.error(_.ERR_CANCELLED)
            sys.exit(1)

        # add ReplayGain to converted files, if necessary

        # separate encoded files by album_name and album_number
        for album in [[audiotools.open(f) for f in fs]
                      for fs in replaygain_jobs]:
            # add ReplayGain to groups of files
            # belonging to the same album

            album_number = {(m.album_number if m is not None else None)
                            for m in
                            [f.get_metadata() for f in album]}.pop()

            if album_number is None:
                progress_text = _.RG_ADDING_REPLAYGAIN
                completion_output = _.RG_REPLAYGAIN_ADDED
            else:
                progress_text = _.RG_ADDING_REPLAYGAIN_TO_ALBUM % \
                    (album_number)
                completion_output = _.RG_REPLAYGAIN_ADDED_TO_ALBUM % \
                    (album_number)

            queue.execute(function=__add_replay_gain__,
                          progress_text=progress_text,
                          completion_output=completion_output,
                          tracks=album)

        try:
            queue.run(options.max_processes)
        except ValueError as err:
            msg.error(err)
            sys.exit(1)
        except KeyboardInterrupt:
            msg.error(_.ERR_CANCELLED)
            sys.exit(1)
    else:
        # encoding only a single file
        audiofile = audiofiles[0]
        input_filename = audiotools.Filename(audiofile.filename)

        if options.interactive:
            track_metadata = audiofile.get_metadata()

            output_widget = audiotools.ui.SingleOutputFiller(
                track_label=input_filename.__unicode__(),
                metadata_choices=[track_metadata if track_metadata is not None
                                  else audiotools.MetaData()],
                input_filenames=[input_filename],
                output_file=options.output,
                output_class=AudioType,
                quality=options.quality,
                completion_label=_.LAB_TRACK2TRACK_APPLY_1)
            loop = audiotools.ui.urwid.MainLoop(
                output_widget,
                audiotools.ui.style(),
                screen=audiotools.ui.Screen(),
                unhandled_input=output_widget.handle_text,
                pop_ups=True)
            loop.run()
            msg.ansi_clearscreen()

            if not output_widget.cancelled():
                (destination_class,
                 output_filename,
                 compression,
                 track_metadata) = output_widget.output_track()
            else:
                sys.exit(0)
        else:
            output_filename = audiotools.Filename(options.output)
            destination_class = AudioType
            compression = options.quality
            track_metadata = audiofile.get_metadata()

            if input_filename == output_filename:
                msg.error(_.ERR_OUTPUT_IS_INPUT %
                          (output_filename,))
                sys.exit(1)

        progress = audiotools.SingleProgressDisplay(
            messenger=msg,
            progress_text=output_filename.__unicode__())
        try:
            convert(progress=progress.update,
                    source_audiofile=audiofile,
                    destination_filename=str(output_filename),
                    destination_class=destination_class,
                    compression=compression,
                    metadata=track_metadata,
                    replay_gain=(audiofile.get_replay_gain() if
                                 add_replay_gain else None),
                    sample_rate=options.sample_rate,
                    channels=options.channels,
                    bits_per_sample=options.bits_per_sample)
            progress.clear_rows()

            msg.output(_.LAB_ENCODE % {"source": input_filename,
                                       "destination": output_filename})
        except audiotools.EncodingError as err:
            progress.clear_rows()
            msg.error(err)
            sys.exit(1)
        except KeyboardInterrupt:
            progress.clear_rows()
            try:
                os.unlink(str(output_filename))
            except OSError:
                pass
            msg.error(_.ERR_CANCELLED)
            sys.exit(1)