'''
Audio
=====

Load an audio sound and play it with::

    from kivy.core.audio import SoundLoader

    sound = SoundLoader.load('mytest.wav')
    if sound:
        print("Sound found at %s" % sound.source)
        print("Sound is %.3f seconds" % sound.length)
        sound.play()

You should not use the Sound class directly. The class returned by
:func:`SoundLoader.load` will be the best sound provider for that particular
file type, so it might return different Sound classes depending the file type.

Event dispatching and state changes
-----------------------------------

Audio is often processed in parallel to your code. This means you often need to
enter the Kivy :func:`eventloop <kivy.base.EventLoopBase>` in order to allow
events and state changes to be dispatched correctly.

You seldom need to worry about this as Kivy apps typically always
require this event loop for the GUI to remain responsive, but it is good to
keep this in mind when debugging or running in a
`REPL <https://en.wikipedia.org/wiki/Read%E2%80%93eval%E2%80%93print_loop>`_
(Read-eval-print loop).

.. versionchanged:: 1.8.0
    There are now 2 distinct Gstreamer implementations: one using Gi/Gst working
    for both Python 2+3 with Gstreamer 1.0, and one using PyGST working
    only for Python 2 + Gstreamer 0.10.
    If you have issue with GStreamer, have a look at
    :ref:`gstreamer-compatibility`

.. note::

    The core audio library does not support recording audio. If you require
    this functionality, please refer to the
    `audiostream <https://github.com/kivy/audiostream>`_ extension.

'''

__all__ = ('Sound', 'SoundLoader')

from kivy.logger import Logger
from kivy.event import EventDispatcher
from kivy.core import core_register_libs
from kivy.compat import PY2
from kivy.resources import resource_find
from kivy.properties import StringProperty, NumericProperty, OptionProperty, \
    AliasProperty, BooleanProperty
from kivy.utils import platform
from kivy.setupconfig import USE_SDL2


class SoundLoader:
    '''Load a sound, using the best loader for the given file type.
    '''

    _classes = []

    @staticmethod
    def register(classobj):
        '''Register a new class to load the sound.'''
        Logger.debug('Audio: register %s' % classobj.__name__)
        SoundLoader._classes.append(classobj)

    @staticmethod
    def load(filename):
        '''Load a sound, and return a Sound() instance.'''
        rfn = resource_find(filename)
        if rfn is not None:
            filename = rfn
        ext = filename.split('.')[-1].lower()
        if '?' in ext:
            ext = ext.split('?')[0]
        for classobj in SoundLoader._classes:
            if ext in classobj.extensions():
                return classobj(source=filename)
        Logger.warning('Audio: Unable to find a loader for <%s>' %
                       filename)
        return None


class Sound(EventDispatcher):
    '''Represents a sound to play. This class is abstract, and cannot be used
    directly.

    Use SoundLoader to load a sound.

    :Events:
        `on_play` : None
            Fired when the sound is played.
        `on_stop` : None
            Fired when the sound is stopped.
    '''

    source = StringProperty(None)
    '''Filename / source of your audio file.

    .. versionadded:: 1.3.0

    :attr:`source` is a :class:`~kivy.properties.StringProperty` that defaults
    to None and is read-only. Use the :meth:`SoundLoader.load` for loading
    audio.
    '''

    volume = NumericProperty(1.)
    '''Volume, in the range 0-1. 1 means full volume, 0 means mute.

    .. versionadded:: 1.3.0

    :attr:`volume` is a :class:`~kivy.properties.NumericProperty` and defaults
    to 1.
    '''

    state = OptionProperty('stop', options=('stop', 'play'))
    '''State of the sound, one of 'stop' or 'play'.

    .. versionadded:: 1.3.0

    :attr:`state` is a read-only :class:`~kivy.properties.OptionProperty`.'''

    loop = BooleanProperty(False)
    '''Set to True if the sound should automatically loop when it finishes.

    .. versionadded:: 1.8.0

    :attr:`loop` is a :class:`~kivy.properties.BooleanProperty` and defaults to
    False.'''

    #
    # deprecated
    #
    def _get_status(self):
        return self.state
    status = AliasProperty(_get_status, None, bind=('state', ))
    '''
    .. deprecated:: 1.3.0
        Use :attr:`state` instead.
    '''

    def _get_filename(self):
        return self.source
    filename = AliasProperty(_get_filename, None, bind=('source', ))
    '''
    .. deprecated:: 1.3.0
        Use :attr:`source` instead.
    '''

    __events__ = ('on_play', 'on_stop')

    def on_source(self, instance, filename):
        self.unload()
        if filename is None:
            return
        self.load()

    def get_pos(self):
        '''
        Returns the current position of the audio file.
        Returns 0 if not playing.

        .. versionadded:: 1.4.1
        '''
        return 0

    def _get_length(self):
        return 0

    length = property(lambda self: self._get_length(),
                      doc='Get length of the sound (in seconds).')

    def load(self):
        '''Load the file into memory.'''
        pass

    def unload(self):
        '''Unload the file from memory.'''
        pass

    def play(self):
        '''Play the file.'''
        self.state = 'play'
        self.dispatch('on_play')

    def stop(self):
        '''Stop playback.'''
        self.state = 'stop'
        self.dispatch('on_stop')

    def seek(self, position):
        '''Go to the <position> (in seconds).'''
        pass

    def on_play(self):
        pass

    def on_stop(self):
        pass


# Little trick here, don't activate gstreamer on window
# seem to have lot of crackle or something...
audio_libs = []
if platform in ('macosx', 'ios'):
    audio_libs += [('avplayer', 'audio_avplayer')]
# from now on, prefer our gstplayer instead of gi/pygst.
try:
    from kivy.lib.gstplayer import GstPlayer  # NOQA
    audio_libs += [('gstplayer', 'audio_gstplayer')]
except ImportError:
    #audio_libs += [('gi', 'audio_gi')]
    if PY2:
        audio_libs += [('pygst', 'audio_pygst')]
audio_libs += [('ffpyplayer', 'audio_ffpyplayer')]
if USE_SDL2:
    audio_libs += [('sdl2', 'audio_sdl2')]
else:
    audio_libs += [('pygame', 'audio_pygame')]

libs_loaded = core_register_libs('audio', audio_libs)
