#!/usr/bin/env python3

# Builtin libraries
import argparse
import collections
import errno
import hashlib
import os
import re
import shutil
import signal
import struct
import subprocess
import sys
import tempfile
import urllib.error
import urllib.parse
import urllib.request

# External libraries
try:
    import mutagen
except ImportError:
    mutagen = None

audio_ext = (".mp3", ".m4a", ".m4b", ".m4p", ".aa", ".wav", ".flac")
list_ext = (".pls", ".m3u")


def make_dir_if_absent(path):
    try:
        os.makedirs(path)
    except OSError as exc:
        if exc.errno != errno.EEXIST:
            raise


def raises_unicode_error(str):
    try:
        str.encode("latin-1")
        return False
    except (UnicodeEncodeError, UnicodeDecodeError):
        return True


def hash_error_unicode(item):
    item_bytes = item.encode("utf-8")
    return "".join(
        [
            "{0:02X}".format(ord(x))
            for x in reversed(hashlib.md5(item_bytes).hexdigest()[:8])
        ]
    )


def validate_unicode(path):
    path_list = path.split("/")
    last_raise = False
    for i in range(len(path_list)):
        if raises_unicode_error(path_list[i]):
            path_list[i] = hash_error_unicode(path_list[i])
            last_raise = True
        else:
            last_raise = False
    extension = os.path.splitext(path)[1].lower()
    return "/".join(path_list) + (
        extension if last_raise and extension in audio_ext else ""
    )


def exec_exists_in_path(command):
    with open(os.devnull, "w") as FNULL:
        try:
            with open(os.devnull, "r") as RFNULL:
                subprocess.call(
                    [command], stdout=FNULL, stderr=subprocess.STDOUT, stdin=RFNULL
                )
                return True
        except OSError as e:
            return False


def splitpath(path):
    return path.split(os.sep)


def get_relpath(path, basepath):
    commonprefix = os.sep.join(
        os.path.commonprefix(list(map(splitpath, [path, basepath])))
    )
    return os.path.relpath(path, commonprefix)


def is_path_prefix(prefix, path):
    return prefix == os.sep.join(
        os.path.commonprefix(list(map(splitpath, [prefix, path])))
    )


def group_tracks_by_id3_template(tracks, template):
    grouped_tracks_dict = {}
    template_vars = set(re.findall(r"{.*?}", template))
    for track in tracks:
        try:
            id3_dict = mutagen.File(track, easy=True)
        except:
            id3_dict = {}

        key = template
        single_var_present = False
        for var in template_vars:
            val = id3_dict.get(var[1:-1], [""])[0]
            if len(val) > 0:
                single_var_present = True
            key = key.replace(var, val)

        if single_var_present:
            if key not in grouped_tracks_dict:
                grouped_tracks_dict[key] = []
            grouped_tracks_dict[key].append(track)

    return sorted(grouped_tracks_dict.items())


class Text2Speech(object):
    valid_tts = {"pico2wave": True, "RHVoice": True, "espeak": True, "say": True}

    @staticmethod
    def check_support():
        voiceoverAvailable = False

        # Check for macOS say voiceover
        if not exec_exists_in_path("say"):
            Text2Speech.valid_tts["say"] = False
            print("Warning: macOS say not found, voicever won't be generated using it.")
        else:
            voiceoverAvailable = True

        # Check for pico2wave voiceover
        if not exec_exists_in_path("pico2wave"):
            Text2Speech.valid_tts["pico2wave"] = False
            print("Warning: pico2wave not found, voicever won't be generated using it.")
        else:
            voiceoverAvailable = True

        # Check for espeak voiceover
        if not exec_exists_in_path("espeak"):
            Text2Speech.valid_tts["espeak"] = False
            print("Warning: espeak not found, voicever won't be generated using it.")
        else:
            voiceoverAvailable = True

        # Check for Russian RHVoice voiceover
        if not exec_exists_in_path("RHVoice"):
            Text2Speech.valid_tts["RHVoice"] = False
            print("Warning: RHVoice not found, Russian voicever won't be generated.")
        else:
            voiceoverAvailable = True

        # Return if we at least found one voiceover program.
        # Otherwise this will result in silent voiceover for tracks and "Playlist N" for playlists.
        return voiceoverAvailable

    @staticmethod
    def text2speech(out_wav_path, text):
        # Skip voiceover generation if a track with the same name is used.
        # This might happen with "Track001" or "01. Intro" names for example.
        if os.path.isfile(out_wav_path):
            verboseprint("Using existing", out_wav_path)
            return True

        # ensure we deal with unicode later
        if not isinstance(text, str):
            text = str(text, "utf-8")
        lang = Text2Speech.guess_lang(text)
        if lang == "ru-RU":
            return Text2Speech.rhvoice(out_wav_path, text)
        else:
            if Text2Speech.pico2wave(out_wav_path, text):
                return True
            elif Text2Speech.espeak(out_wav_path, text):
                return True
            elif Text2Speech.say(out_wav_path, text):
                return True
            else:
                return False

    # guess-language seems like an overkill for now
    @staticmethod
    def guess_lang(unicodetext):
        lang = "en-GB"
        if re.search("[А-Яа-я]", unicodetext) is not None:
            lang = "ru-RU"
        return lang

    @staticmethod
    def pico2wave(out_wav_path, unicodetext):
        if not Text2Speech.valid_tts["pico2wave"]:
            return False
        subprocess.call(
            ["pico2wave", "-l", "en-GB", "-w", out_wav_path, "--", unicodetext]
        )
        return True

    @staticmethod
    def say(out_wav_path, unicodetext):
        if not Text2Speech.valid_tts["say"]:
            return False
        subprocess.call(
            [
                "say",
                "-o",
                out_wav_path,
                "--data-format=LEI16",
                "--file-format=WAVE",
                "--",
                unicodetext,
            ]
        )
        return True

    @staticmethod
    def espeak(out_wav_path, unicodetext):
        if not Text2Speech.valid_tts["espeak"]:
            return False
        subprocess.call(
            [
                "espeak",
                "-v",
                "english_rp",
                "-s",
                "150",
                "-w",
                out_wav_path,
                "--",
                unicodetext,
            ]
        )
        return True

    @staticmethod
    def rhvoice(out_wav_path, unicodetext):
        if not Text2Speech.valid_tts["RHVoice"]:
            return False

        tmp_file = tempfile.NamedTemporaryFile(suffix=".wav", delete=False)
        tmp_file.close()

        proc = subprocess.Popen(
            [
                "RHVoice",
                "--voice=Elena",
                "--variant=Russian",
                "--volume=100",
                "-o",
                tmp_file.name,
            ],
            stdin=subprocess.PIPE,
        )
        proc.communicate(input=unicodetext.encode("utf-8"))
        # make a little bit louder to be comparable with pico2wave
        subprocess.call(["sox", tmp_file.name, out_wav_path, "norm"])

        os.remove(tmp_file.name)
        return True


class Record(object):
    def __init__(self, parent):
        self.parent = parent
        self._struct = collections.OrderedDict([])
        self._fields = {}
        self.track_voiceover = parent.track_voiceover
        self.playlist_voiceover = parent.playlist_voiceover
        self.rename = parent.rename
        self.trackgain = parent.trackgain

    def __getitem__(self, item):
        if item not in list(self._struct.keys()):
            raise KeyError
        return self._fields.get(item, self._struct[item][1])

    def __setitem__(self, item, value):
        self._fields[item] = value

    def construct(self):
        output = bytes()
        for i in list(self._struct.keys()):
            (fmt, default) = self._struct[i]
            output += struct.pack("<" + fmt, self._fields.get(i, default))
        return output

    def text_to_speech(self, text, dbid, playlist=False):
        if (
            self.track_voiceover
            and not playlist
            or self.playlist_voiceover
            and playlist
        ):
            # Create the voiceover wav file
            fn = "".join(format(x, "02x") for x in reversed(dbid))
            path = os.path.join(
                self.base,
                "iPod_Control",
                "Speakable",
                "Tracks" if not playlist else "Playlists",
                fn + ".wav",
            )
            return Text2Speech.text2speech(path, text)
        return False

    def path_to_ipod(self, filename):
        if os.path.commonprefix([os.path.abspath(filename), self.base]) != self.base:
            raise IOError(
                "Cannot get Ipod filename, since file is outside the IPOD path"
            )
        baselen = len(self.base)
        if self.base.endswith(os.path.sep):
            baselen -= 1
        ipodname = "/".join(os.path.abspath(filename)[baselen:].split(os.path.sep))
        return ipodname

    def ipod_to_path(self, ipodname):
        return os.path.abspath(
            os.path.join(self.base, os.path.sep.join(ipodname.split("/")))
        )

    @property
    def shuffledb(self):
        parent = self.parent
        while parent.__class__ != Shuffler:
            parent = parent.parent
        return parent

    @property
    def base(self):
        return self.shuffledb.path

    @property
    def tracks(self):
        return self.shuffledb.tracks

    @property
    def albums(self):
        return self.shuffledb.albums

    @property
    def artists(self):
        return self.shuffledb.artists

    @property
    def lists(self):
        return self.shuffledb.lists


class TunesSD(Record):
    def __init__(self, parent):
        Record.__init__(self, parent)
        self.track_header = TrackHeader(self)
        self.play_header = PlaylistHeader(self)
        self._struct = collections.OrderedDict(
            [
                ("header_id", ("4s", b"bdhs")),  # shdb
                ("unknown1", ("I", 0x02000003)),
                ("total_length", ("I", 64)),
                ("total_number_of_tracks", ("I", 0)),
                ("total_number_of_playlists", ("I", 0)),
                ("unknown2", ("Q", 0)),
                ("max_volume", ("B", 0)),
                ("voiceover_enabled", ("B", int(self.track_voiceover))),
                ("unknown3", ("H", 0)),
                ("total_tracks_without_podcasts", ("I", 0)),
                ("track_header_offset", ("I", 64)),
                ("playlist_header_offset", ("I", 0)),
                ("unknown4", ("20s", b"\x00" * 20)),
            ]
        )

    def construct(self):
        # The header is a fixed length, so no need to calculate it
        self.track_header.base_offset = 64
        track_header = self.track_header.construct()

        # The playlist offset will depend on the number of tracks
        self.play_header.base_offset = self.track_header.base_offset + len(track_header)
        play_header = self.play_header.construct(self.track_header.tracks)
        self["playlist_header_offset"] = self.play_header.base_offset

        self["total_number_of_tracks"] = self.track_header["number_of_tracks"]
        self["total_tracks_without_podcasts"] = self.track_header["number_of_tracks"]
        self["total_number_of_playlists"] = self.play_header["number_of_playlists"]

        output = Record.construct(self)
        return output + track_header + play_header


class TrackHeader(Record):
    def __init__(self, parent):
        self.base_offset = 0
        Record.__init__(self, parent)
        self._struct = collections.OrderedDict(
            [
                ("header_id", ("4s", b"hths")),  # shth
                ("total_length", ("I", 0)),
                ("number_of_tracks", ("I", 0)),
                ("unknown1", ("Q", 0)),
            ]
        )

    def construct(self):
        self["number_of_tracks"] = len(self.tracks)
        self["total_length"] = 20 + (len(self.tracks) * 4)
        output = Record.construct(self)

        # Construct the underlying tracks
        track_chunk = bytes()
        for i in self.tracks:
            track = Track(self)
            verboseprint("[*] Adding track", i)
            track.populate(i)
            output += struct.pack(
                "I", self.base_offset + self["total_length"] + len(track_chunk)
            )
            track_chunk += track.construct()
        return output + track_chunk


class Track(Record):
    def __init__(self, parent):
        Record.__init__(self, parent)
        self._struct = collections.OrderedDict(
            [
                ("header_id", ("4s", b"rths")),  # shtr
                ("header_length", ("I", 0x174)),
                ("start_at_pos_ms", ("I", 0)),
                ("stop_at_pos_ms", ("I", 0)),
                ("volume_gain", ("I", int(self.trackgain))),
                ("filetype", ("I", 1)),
                ("filename", ("256s", b"\x00" * 256)),
                ("bookmark", ("I", 0)),
                ("dontskip", ("B", 1)),
                ("remember", ("B", 0)),
                ("unintalbum", ("B", 0)),
                ("unknown", ("B", 0)),
                ("pregap", ("I", 0x200)),
                ("postgap", ("I", 0x200)),
                ("numsamples", ("I", 0)),
                ("unknown2", ("I", 0)),
                ("gapless", ("I", 0)),
                ("unknown3", ("I", 0)),
                ("albumid", ("I", 0)),
                ("track", ("H", 1)),
                ("disc", ("H", 0)),
                ("unknown4", ("Q", 0)),
                ("dbid", ("8s", 0)),
                ("artistid", ("I", 0)),
                ("unknown5", ("32s", b"\x00" * 32)),
            ]
        )

    def populate(self, filename):
        self["filename"] = self.path_to_ipod(filename).encode("utf-8")

        if os.path.splitext(filename)[1].lower() in (".m4a", ".m4b", ".m4p", ".aa"):
            self["filetype"] = 2

        text = os.path.splitext(os.path.basename(filename))[0]

        # Try to get album and artist information with mutagen
        if mutagen:
            audio = None
            try:
                audio = mutagen.File(filename, easy=True)
            except:
                print(
                    "Error calling mutagen. Possible invalid filename/ID3Tags (hyphen in filename?)"
                )
            if audio:
                # Note: Rythmbox IPod plugin sets this value always 0.
                self["stop_at_pos_ms"] = int(audio.info.length * 1000)

                artist = audio.get("artist", ["Unknown"])[0]
                if artist in self.artists:
                    self["artistid"] = self.artists.index(artist)
                else:
                    self["artistid"] = len(self.artists)
                    self.artists.append(artist)

                album = audio.get("album", ["Unknown"])[0]
                if album in self.albums:
                    self["albumid"] = self.albums.index(album)
                else:
                    self["albumid"] = len(self.albums)
                    self.albums.append(album)

                if audio.get("title", "") and audio.get("artist", ""):
                    text = " - ".join(audio.get("title", "") + audio.get("artist", ""))

        # Handle the VoiceOverData
        if isinstance(text, str):
            text = text.encode("utf-8", "ignore")
        self["dbid"] = hashlib.md5(text).digest()[:8]
        self.text_to_speech(text, self["dbid"])


class PlaylistHeader(Record):
    def __init__(self, parent):
        self.base_offset = 0
        Record.__init__(self, parent)
        self._struct = collections.OrderedDict(
            [
                ("header_id", ("4s", b"hphs")),  # shph
                ("total_length", ("I", 0)),
                ("number_of_playlists", ("I", 0)),
                ("number_of_non_podcast_lists", ("2s", b"\xff\xff")),
                ("number_of_master_lists", ("2s", b"\x01\x00")),
                ("number_of_non_audiobook_lists", ("2s", b"\xff\xff")),
                ("unknown2", ("2s", b"\x00" * 2)),
            ]
        )

    def construct(self, tracks):
        # Build the master list
        masterlist = Playlist(self)
        verboseprint("[+] Adding master playlist")
        masterlist.set_master(tracks)
        chunks = [masterlist.construct(tracks)]

        # Build all the remaining playlists
        playlistcount = 1
        for i in self.lists:
            playlist = Playlist(self)
            verboseprint("[+] Adding playlist", (i[0] if type(i) == type(()) else i))
            playlist.populate(i)
            construction = playlist.construct(tracks)
            if playlist["number_of_songs"] > 0:
                playlistcount += 1
                chunks += [construction]
            else:
                print(
                    "Error: Playlist does not contain a single track. Skipping playlist."
                )

        self["number_of_playlists"] = playlistcount
        self["total_length"] = 0x14 + (self["number_of_playlists"] * 4)
        # Start the header

        output = Record.construct(self)
        offset = self.base_offset + self["total_length"]

        for i in range(len(chunks)):
            output += struct.pack("I", offset)
            offset += len(chunks[i])

        return output + b"".join(chunks)


class Playlist(Record):
    def __init__(self, parent):
        self.listtracks = []
        Record.__init__(self, parent)
        self._struct = collections.OrderedDict(
            [
                ("header_id", ("4s", b"lphs")),  # shpl
                ("total_length", ("I", 0)),
                ("number_of_songs", ("I", 0)),
                ("number_of_nonaudio", ("I", 0)),
                ("dbid", ("8s", b"\x00" * 8)),
                ("listtype", ("I", 2)),
                ("unknown1", ("16s", b"\x00" * 16)),
            ]
        )

    def set_master(self, tracks):
        # By default use "All Songs" builtin voiceover (dbid all zero)
        # Else generate alternative "All Songs" to fit the speaker voice of other playlists
        if self.playlist_voiceover and (
            Text2Speech.valid_tts["pico2wave"]
            or Text2Speech.valid_tts["espeak"]
            or Text2Speech.valid_tts["say"]
        ):
            self["dbid"] = hashlib.md5(b"masterlist").digest()[:8]
            self.text_to_speech("All songs", self["dbid"], True)
        self["listtype"] = 1
        self.listtracks = tracks

    def populate_m3u(self, data):
        listtracks = []
        for i in data:
            if not i.startswith("#"):
                path = i.strip()
                if self.rename:
                    path = validate_unicode(path)
                listtracks.append(path)
        return listtracks

    def populate_pls(self, data):
        sorttracks = []
        for i in data:
            dataarr = i.strip().split("=", 1)
            if dataarr[0].lower().startswith("file"):
                num = int(dataarr[0][4:])
                filename = urllib.parse.unquote(dataarr[1]).strip()
                if filename.lower().startswith("file://"):
                    filename = filename[7:]
                if self.rename:
                    filename = validate_unicode(filename)
                sorttracks.append((num, filename))
        listtracks = [x for (_, x) in sorted(sorttracks)]
        return listtracks

    def populate_directory(self, playlistpath, recursive=True):
        # Add all tracks inside the folder and its subfolders recursively.
        # Folders containing no music and only a single Album
        # would generate duplicated playlists. That is intended and "wont fix".
        # Empty folders (inside the music path) will generate an error -> "wont fix".
        listtracks = []
        for dirpath, dirnames, filenames in os.walk(playlistpath):
            dirnames.sort()

            # Ignore any hidden directories
            if "/." not in dirpath:
                for filename in sorted(filenames, key=lambda x: x.lower()):
                    # Only add valid music files to playlist
                    if os.path.splitext(filename)[1].lower() in (
                        ".mp3",
                        ".m4a",
                        ".m4b",
                        ".m4p",
                        ".aa",
                        ".wav",
                        ".flac",
                    ):
                        fullPath = os.path.abspath(os.path.join(dirpath, filename))
                        listtracks.append(fullPath)
            if not recursive:
                break
        return listtracks

    def remove_relatives(self, relative, filename):
        base = os.path.dirname(os.path.abspath(filename))
        if not os.path.exists(relative):
            relative = os.path.join(base, relative)
        fullPath = relative
        return fullPath

    def populate(self, obj):
        # Create a playlist of the folder and all subfolders
        if type(obj) == type(()):
            self.listtracks = obj[1]
            text = obj[0]
        else:
            filename = obj
            if os.path.isdir(filename):
                self.listtracks = self.populate_directory(filename)
                text = os.path.splitext(os.path.basename(filename))[0]
            else:
                # Read the playlist file
                with open(filename, "r", errors="replace") as f:
                    data = f.readlines()

                extension = os.path.splitext(filename)[1].lower()
                if extension == ".pls":
                    self.listtracks = self.populate_pls(data)
                elif extension == ".m3u":
                    self.listtracks = self.populate_m3u(data)
                else:
                    raise

                # Ensure all paths are not relative to the playlist file
                for i in range(len(self.listtracks)):
                    self.listtracks[i] = self.remove_relatives(
                        self.listtracks[i], filename
                    )
                text = os.path.splitext(os.path.basename(filename))[0]

        # Handle the VoiceOverData
        self["dbid"] = hashlib.md5(text.encode("utf-8")).digest()[:8]
        self.text_to_speech(text, self["dbid"], True)

    def construct(self, tracks):
        self["total_length"] = 44 + (4 * len(self.listtracks))
        self["number_of_songs"] = 0

        chunks = bytes()
        for i in self.listtracks:
            path = self.ipod_to_path(i)
            position = -1
            try:
                position = tracks.index(path)
            except:
                # Print an error if no track was found.
                # Empty playlists are handeled in the PlaylistHeader class.
                print('Error: Could not find track "' + path + '".')
                print(
                    "Maybe its an invalid FAT filesystem name. Please fix your playlist. Skipping track."
                )
            if position > -1:
                chunks += struct.pack("I", position)
                self["number_of_songs"] += 1
        self["number_of_nonaudio"] = self["number_of_songs"]

        output = Record.construct(self)
        return output + chunks


class Shuffler(object):
    def __init__(
        self,
        path,
        track_voiceover=False,
        playlist_voiceover=False,
        rename=False,
        trackgain=0,
        auto_dir_playlists=None,
        auto_id3_playlists=None,
    ):
        self.path = os.path.abspath(path)
        self.tracks = []
        self.albums = []
        self.artists = []
        self.lists = []
        self.tunessd = None
        self.track_voiceover = track_voiceover
        self.playlist_voiceover = playlist_voiceover
        self.rename = rename
        self.trackgain = trackgain
        self.auto_dir_playlists = auto_dir_playlists
        self.auto_id3_playlists = auto_id3_playlists

    def initialize(self):
        # remove existing voiceover files (they are either useless or will be overwritten anyway)
        for dirname in (
            "iPod_Control/Speakable/Playlists",
            "iPod_Control/Speakable/Tracks",
        ):
            shutil.rmtree(os.path.join(self.path, dirname), ignore_errors=True)
        for dirname in (
            "iPod_Control/iTunes",
            "iPod_Control/Music",
            "iPod_Control/Speakable/Playlists",
            "iPod_Control/Speakable/Tracks",
        ):
            make_dir_if_absent(os.path.join(self.path, dirname))

    def dump_state(self):
        print("Shuffle DB state")
        print("Tracks", self.tracks)
        print("Albums", self.albums)
        print("Artists", self.artists)
        print("Playlists", self.lists)

    def populate(self):
        self.tunessd = TunesSD(self)
        for dirpath, dirnames, filenames in os.walk(self.path):
            dirnames.sort()
            relpath = get_relpath(dirpath, self.path)
            # Ignore the speakable directory and any hidden directories
            if (
                not is_path_prefix("iPod_Control/Speakable", relpath)
                and "/." not in dirpath
            ):
                for filename in sorted(filenames, key=lambda x: x.lower()):
                    # Ignore hidden files
                    if not filename.startswith("."):
                        fullPath = os.path.abspath(os.path.join(dirpath, filename))
                        if os.path.splitext(filename)[1].lower() in (
                            ".mp3",
                            ".m4a",
                            ".m4b",
                            ".m4p",
                            ".aa",
                            ".wav",
                            ".flac",
                        ):
                            self.tracks.append(fullPath)
                        if os.path.splitext(filename)[1].lower() in (".pls", ".m3u"):
                            self.lists.append(fullPath)

            # Create automatic playlists in music directory.
            # Ignore the (music) root and any hidden directories.
            if (
                self.auto_dir_playlists
                and "iPod_Control/Music/" in dirpath
                and "/." not in dirpath
            ):
                # Only go to a specific depth. -1 is unlimted, 0 is ignored as there is already a master playlist.
                depth = (
                    dirpath[len(self.path) + len(os.path.sep) :].count(os.path.sep) - 1
                )
                if self.auto_dir_playlists < 0 or depth <= self.auto_dir_playlists:
                    self.lists.append(os.path.abspath(dirpath))

        if self.auto_id3_playlists != None:
            if mutagen:
                for grouped_list in group_tracks_by_id3_template(
                    self.tracks, self.auto_id3_playlists
                ):
                    self.lists.append(grouped_list)
            else:
                print("Error: No mutagen found. Cannot generate auto-id3-playlists.")
                sys.exit(1)

    def write_database(self):
        print("Writing database. This may take a while...")
        with open(
            os.path.join(self.path, "iPod_Control", "iTunes", "iTunesSD"), "wb"
        ) as f:
            try:
                f.write(self.tunessd.construct())
            except IOError as e:
                print("I/O error({0}): {1}".format(e.errno, e.strerror))
                print("Error: Writing iPod database failed.")
                sys.exit(1)

        print("Database written successfully:")
        print("Tracks", len(self.tracks))
        print("Albums", len(self.albums))
        print("Artists", len(self.artists))
        print("Playlists", len(self.lists))


#
# Read all files from the directory
# Construct the appropriate iTunesDB file
# Construct the appropriate iTunesSD file
#   http://shuffle3db.wikispaces.com/iTunesSD3gen
# Use SVOX pico2wave and RHVoice to produce voiceover data
#


def check_unicode(path):
    ret_flag = False  # True if there is a recognizable file within this level
    for item in os.listdir(path):
        if os.path.isfile(os.path.join(path, item)):
            if os.path.splitext(item)[1].lower() in audio_ext + list_ext:
                ret_flag = True
                if raises_unicode_error(item):
                    src = os.path.join(path, item)
                    dest = (
                        os.path.join(path, hash_error_unicode(item))
                        + os.path.splitext(item)[1].lower()
                    )
                    print("Renaming %s -> %s" % (src, dest))
                    os.rename(src, dest)
        else:
            ret_flag = check_unicode(os.path.join(path, item)) or ret_flag
            if ret_flag and raises_unicode_error(item):
                src = os.path.join(path, item)
                new_name = hash_error_unicode(item)
                dest = os.path.join(path, new_name)
                print("Renaming %s -> %s" % (src, dest))
                os.rename(src, dest)
    return ret_flag


def nonnegative_int(string):
    try:
        intval = int(string)
    except ValueError:
        raise argparse.ArgumentTypeError("Track gain value should be a number")

    if intval < 0 or intval > 99:
        raise argparse.ArgumentTypeError("Track gain value should be in range 0-99")
    return intval


def transcode_to_aac(input_file, output_file):
    """Convert audio file to AAC 256kbps using FFmpeg"""
    if not exec_exists_in_path("ffmpeg"):
        print("Error: FFmpeg not found. Cannot transcode files.")
        return False

    try:
        cmd = [
            "ffmpeg",
            "-i",
            input_file,
            "-vn",  # No video
            "-c:a",
            "aac",
            "-b:a",
            "256k",
            "-ac",
            "2",  # Force stereo output
            "-ar",
            "44100",  # Standard sample rate
            "-map_metadata",
            "0",
            "-avoid_negative_ts",
            "make_zero",
            "-f",
            "ipod",  # iPod-compatible format
            "-movflags",
            "+faststart",  # Optimize for streaming
            "-y",
            output_file,
        ]
        # Capture stderr to show FFmpeg errors
        result = subprocess.run(
            cmd, stdout=subprocess.DEVNULL, stderr=subprocess.PIPE, text=True
        )
        if result.returncode != 0:
            print(f"FFmpeg error for '{os.path.basename(input_file)}':")
            # Filter stderr to show only relevant error messages
            stderr_lines = result.stderr.split("\n")
            error_lines = []
            for line in stderr_lines:
                # Skip version info, configuration, and library info
                if any(
                    skip in line
                    for skip in [
                        "ffmpeg version",
                        "built with",
                        "configuration:",
                        "libav",
                    ]
                ):
                    continue
                # Include error messages and important warnings
                if any(
                    keyword in line.lower()
                    for keyword in ["error", "failed", "invalid", "could not", "cannot"]
                ):
                    error_lines.append(line.strip())
                # Include the final conversion status
                elif (
                    "conversion failed" in line.lower()
                    or "nothing was written" in line.lower()
                ):
                    error_lines.append(line.strip())

            if error_lines:
                for error_line in error_lines[-5:]:  # Show last 5 relevant error lines
                    if error_line:
                        print(f"  {error_line}")
            else:
                print("  Unknown FFmpeg error occurred")
            return False
        return True
    except Exception as e:
        print(f"Error transcoding {input_file}: {e}")
        return False


def process_audio_files(ipod_path):
    """Find .wav and .flac files, convert to AAC, and remove originals"""
    print("Scanning for .wav and .flac files to transcode...")

    converted_count = 0

    for dirpath, dirnames, filenames in os.walk(ipod_path):
        # Skip hidden directories and iPod voiceover files
        if "/." in dirpath or "iPod_Control/Speakable" in dirpath:
            continue

        for filename in filenames:
            if filename.startswith("."):
                continue

            file_path = os.path.join(dirpath, filename)
            file_ext = os.path.splitext(filename)[1].lower()

            if file_ext in (".wav", ".flac"):
                # Generate output filename with .m4a extension
                base_name = os.path.splitext(filename)[0]
                output_file = os.path.join(dirpath, base_name + ".m4a")

                print(f"Converting {filename} to AAC...")

                if transcode_to_aac(file_path, output_file):
                    # Remove original file only if conversion was successful
                    try:
                        os.remove(file_path)
                        print(f"Converted and removed: {filename}")
                        converted_count += 1
                    except OSError as e:
                        print(f"Error removing original file {filename}: {e}")
                else:
                    print(f"Failed to convert {filename}")

    print(f"Transcoding complete. Converted {converted_count} files.")


def checkPathValidity(path):
    if not os.path.isdir(result.path):
        print("Error finding IPod directory. Maybe it is not connected or mounted?")
        sys.exit(1)

    if not os.access(result.path, os.W_OK):
        print("Unable to get write permissions in the IPod directory")
        sys.exit(1)


def handle_interrupt(signal, frame):
    print("Interrupt detected, exiting...")
    sys.exit(1)


if __name__ == "__main__":
    signal.signal(signal.SIGINT, handle_interrupt)

    parser = argparse.ArgumentParser(
        description="Python script for building the Track and Playlist database "
        "for the newer gen IPod Shuffle. Version 1.5"
    )

    parser.add_argument(
        "-t",
        "--track-voiceover",
        action="store_true",
        help="Enable track voiceover feature",
    )

    parser.add_argument(
        "-p",
        "--playlist-voiceover",
        action="store_true",
        help="Enable playlist voiceover feature",
    )

    parser.add_argument(
        "-u",
        "--rename-unicode",
        action="store_true",
        help="Rename files causing unicode errors, will do minimal required renaming",
    )

    parser.add_argument(
        "-g",
        "--track-gain",
        type=nonnegative_int,
        default="0",
        help="Specify volume gain (0-99) for all tracks; "
        "0 (default) means no gain and is usually fine; "
        "e.g. 60 is very loud even on minimal player volume",
    )

    parser.add_argument(
        "-d",
        "--auto-dir-playlists",
        type=int,
        default=None,
        const=-1,
        nargs="?",
        help="Generate automatic playlists for each folder recursively inside "
        '"IPod_Control/Music/". You can optionally limit the depth: '
        "0=root, 1=artist, 2=album, n=subfoldername, default=-1 (No Limit).",
    )

    parser.add_argument(
        "-i",
        "--auto-id3-playlists",
        type=str,
        default=None,
        metavar="ID3_TEMPLATE",
        const="{artist}",
        nargs="?",
        help="Generate automatic playlists based on the id3 tags of any music "
        "added to the iPod. You can optionally specify a template string "
        "based on which id3 tags are used to generate playlists. For eg. "
        "'{artist} - {album}' will use the pair of artist and album to group "
        "tracks under one playlist. Similarly '{genre}' will group tracks based "
        "on their genre tag. Default template used is '{artist}'",
    )

    parser.add_argument(
        "-v",
        "--verbose",
        action="store_true",
        help="Show verbose output of database generation.",
    )

    parser.add_argument(
        "--transcode",
        action="store_true",
        help="Transcode .wav and .flac files to AAC 256kbps and remove originals",
    )

    parser.add_argument("path", help="Path to the IPod's root directory")

    result = parser.parse_args()

    # Enable verbose printing if desired
    verboseprint = print if result.verbose else lambda *a, **k: None

    checkPathValidity(result.path)

    if result.transcode:
        process_audio_files(result.path)
        # If only transcoding, don't recreate database to preserve existing setup
        print(
            "Transcoding complete. Use without --transcode to rebuild database if needed."
        )
        sys.exit(0)

    if result.rename_unicode:
        check_unicode(result.path)

    if not mutagen:
        print(
            "Warning: No mutagen found. Database will not contain any album nor artist information."
        )

    verboseprint("Playlist voiceover requested:", result.playlist_voiceover)
    verboseprint("Track voiceover requested:", result.track_voiceover)
    if result.track_voiceover or result.playlist_voiceover:
        if not Text2Speech.check_support():
            print("Error: Did not find any voiceover program. Voiceover disabled.")
            result.track_voiceover = False
            result.playlist_voiceover = False
        else:
            verboseprint("Voiceover available.")

    shuffle = Shuffler(
        result.path,
        track_voiceover=result.track_voiceover,
        playlist_voiceover=result.playlist_voiceover,
        rename=result.rename_unicode,
        trackgain=result.track_gain,
        auto_dir_playlists=result.auto_dir_playlists,
        auto_id3_playlists=result.auto_id3_playlists,
    )
    shuffle.initialize()
    shuffle.populate()
    shuffle.write_database()