import os
import tempfile
import subprocess

from twisted.internet import defer
from twisted.internet.utils import getProcessOutputAndValue


class AudioConversionError(Exception): pass


def _is_exe(fname):
    return os.path.isfile(fname) and os.access(fname, os.X_OK)

def _which(exename):
    for path in os.environ['PATH'].split(os.pathsep):
        fname = os.path.join(path, exename)
        if _is_exe(fname):
            return fname
    return None

def _ffmpeg_or_avconv():
    return _which('ffmpeg') or _which('avconv') or None


def _convert_audio(data, ffmpeg_args):
    fd, tmpname = tempfile.mkstemp()
    os.close(fd)
    try:
        exe = _ffmpeg_or_avconv()
        if exe is None:
            raise AudioConversionError('No ffmpeg of avconv installed')

        args = [exe, '-i', 'pipe:0', '-y' ]
        args.extend(ffmpeg_args)
        args.append(tmpname)
        ffmpeg = subprocess.Popen(args, stdin=subprocess.PIPE, stdout=subprocess.PIPE)
        ffmpeg.communicate(data)

        if ffmpeg.returncode != 0:
            raise AudioConversionError()

        with open(tmpname, 'rb') as f:
            return f.read()
    finally:
        os.unlink(tmpname)


@defer.inlineCallbacks
def _convert_audio_async(data, ffmpeg_args):
    fd, tmpinput = tempfile.mkstemp()
    os.close(fd)
    fd, tmpoutput = tempfile.mkstemp()
    os.close(fd)
    try:
        exe = _ffmpeg_or_avconv()
        if exe is None:
            raise AudioConversionError('No ffmpeg or avconv installed')

        with open(tmpinput, 'wb') as f:
            f.write(data)

        args = ['-i', tmpinput, '-y'] + ffmpeg_args + [tmpoutput]
        out, err, code = yield getProcessOutputAndValue(exe, args)

        if code != 0:
            raise AudioConversionError(err)

        with open(tmpoutput, 'rb') as f:
            return f.read()
    finally:
        os.unlink(tmpinput)
        os.unlink(tmpoutput)


# ADPCM WAV 1ch s16
_adpcm_args = [
    '-f', 'wav',
    '-acodec', 'adpcm_ima_wav',
    '-ac', '1',
    '-ar', '16000',
]

_mp3_args = [
    '-f', 'mp3',
    '-b', '160k',
    '-id3v2_version', '0',
]


def convert_to_adpcm(data):
    """ Takes arbitrary audio data and converts it to  """
    return _convert_audio(data, _adpcm_args)

def convert_to_mp3(data):
    return _convert_audio(data, _mp3_args)

def convert_to_adpcm_async(data):
    return _convert_audio_async(data, _adpcm_args)

def convert_to_mp3_async(data):
    return _convert_audio_async(data, _mp3_args)