# -*- coding: utf-8 -*-

"""
The MIT License (MIT)

Copyright (c) 2015-2019 Rapptz

Permission is hereby granted, free of charge, to any person obtaining a
copy of this software and associated documentation files (the "Software"),
to deal in the Software without restriction, including without limitation
the rights to use, copy, modify, merge, publish, distribute, sublicense,
and/or sell copies of the Software, and to permit persons to whom the
Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
DEALINGS IN THE SOFTWARE.
"""

import array
import ctypes
import ctypes.util
import logging
import os.path
import sys

from .errors import DiscordException

log = logging.getLogger(__name__)
c_int_ptr = ctypes.POINTER(ctypes.c_int)
c_int16_ptr = ctypes.POINTER(ctypes.c_int16)
c_float_ptr = ctypes.POINTER(ctypes.c_float)

class EncoderStruct(ctypes.Structure):
    pass

EncoderStructPtr = ctypes.POINTER(EncoderStruct)

def _err_lt(result, func, args):
    if result < 0:
        log.info('error has happened in %s', func.__name__)
        raise OpusError(result)
    return result

def _err_ne(result, func, args):
    ret = args[-1]._obj
    if ret.value != 0:
        log.info('error has happened in %s', func.__name__)
        raise OpusError(ret.value)
    return result

# A list of exported functions.
# The first argument is obviously the name.
# The second one are the types of arguments it takes.
# The third is the result type.
# The fourth is the error handler.
exported_functions = [
    ('opus_strerror',
        [ctypes.c_int], ctypes.c_char_p, None),
    ('opus_encoder_get_size',
        [ctypes.c_int], ctypes.c_int, None),
    ('opus_encoder_create',
        [ctypes.c_int, ctypes.c_int, ctypes.c_int, c_int_ptr], EncoderStructPtr, _err_ne),
    ('opus_encode',
        [EncoderStructPtr, c_int16_ptr, ctypes.c_int, ctypes.c_char_p, ctypes.c_int32], ctypes.c_int32, _err_lt),
    ('opus_encoder_ctl',
        None, ctypes.c_int32, _err_lt),
    ('opus_encoder_destroy',
        [EncoderStructPtr], None, None),
]

def libopus_loader(name):
    # create the library...
    lib = ctypes.cdll.LoadLibrary(name)

    # register the functions...
    for item in exported_functions:
        func = getattr(lib, item[0])

        try:
            if item[1]:
                func.argtypes = item[1]

            func.restype = item[2]
        except KeyError:
            pass

        try:
            if item[3]:
                func.errcheck = item[3]
        except KeyError:
            log.exception("Error assigning check function to %s", func)

    return lib

try:
    if sys.platform == 'win32':
        _basedir = os.path.dirname(os.path.abspath(__file__))
        _bitness = 'x64' if sys.maxsize > 2**32 else 'x86'
        _filename = os.path.join(_basedir, 'bin', 'libopus-0.{}.dll'.format(_bitness))
        _lib = libopus_loader(_filename)
    else:
        _lib = libopus_loader(ctypes.util.find_library('opus'))
except Exception:
    _lib = None

def load_opus(name):
    """Loads the libopus shared library for use with voice.

    If this function is not called then the library uses the function
    :func:`ctypes.util.find_library` and then loads that one
    if available.

    Not loading a library leads to voice not working.

    This function propagates the exceptions thrown.

    .. warning::

        The bitness of the library must match the bitness of your python
        interpreter. If the library is 64-bit then your python interpreter
        must be 64-bit as well. Usually if there's a mismatch in bitness then
        the load will throw an exception.

    .. note::

        On Windows, this function should not need to be called as the binaries
        are automatically loaded.

    .. note::

        On Windows, the .dll extension is not necessary. However, on Linux
        the full extension is required to load the library, e.g. ``libopus.so.1``.
        On Linux however, :func:`ctypes.util.find_library` will usually find the library automatically
        without you having to call this.

    Parameters
    ----------
    name: :class:`str`
        The filename of the shared library.
    """
    global _lib
    _lib = libopus_loader(name)

def is_loaded():
    """Function to check if opus lib is successfully loaded either
    via the :func:`ctypes.util.find_library` call of :func:`load_opus`.

    This must return ``True`` for voice to work.

    Returns
    -------
    :class:`bool`
        Indicates if the opus library has been loaded.
    """
    global _lib
    return _lib is not None

class OpusError(DiscordException):
    """An exception that is thrown for libopus related errors.

    Attributes
    ----------
    code: :class:`int`
        The error code returned.
    """

    def __init__(self, code):
        self.code = code
        msg = _lib.opus_strerror(self.code).decode('utf-8')
        log.info('"%s" has happened', msg)
        super().__init__(msg)

class OpusNotLoaded(DiscordException):
    """An exception that is thrown for when libopus is not loaded."""
    pass


# Some constants...
OK = 0
APPLICATION_AUDIO    = 2049
APPLICATION_VOIP     = 2048
APPLICATION_LOWDELAY = 2051
CTL_SET_BITRATE      = 4002
CTL_SET_BANDWIDTH    = 4008
CTL_SET_FEC          = 4012
CTL_SET_PLP          = 4014
CTL_SET_SIGNAL       = 4024

band_ctl = {
    'narrow': 1101,
    'medium': 1102,
    'wide': 1103,
    'superwide': 1104,
    'full': 1105,
}

signal_ctl = {
    'auto': -1000,
    'voice': 3001,
    'music': 3002,
}

class Encoder:
    SAMPLING_RATE = 48000
    CHANNELS = 2
    FRAME_LENGTH = 20
    SAMPLE_SIZE = 4 # (bit_rate / 8) * CHANNELS (bit_rate == 16)
    SAMPLES_PER_FRAME = int(SAMPLING_RATE / 1000 * FRAME_LENGTH)

    FRAME_SIZE = SAMPLES_PER_FRAME * SAMPLE_SIZE

    def __init__(self, application=APPLICATION_AUDIO):
        self.application = application

        if not is_loaded():
            raise OpusNotLoaded()

        self._state = self._create_state()
        self.set_bitrate(128)
        self.set_fec(True)
        self.set_expected_packet_loss_percent(0.15)
        self.set_bandwidth('full')
        self.set_signal_type('auto')

    def __del__(self):
        if hasattr(self, '_state'):
            _lib.opus_encoder_destroy(self._state)
            self._state = None

    def _create_state(self):
        ret = ctypes.c_int()
        return _lib.opus_encoder_create(self.SAMPLING_RATE, self.CHANNELS, self.application, ctypes.byref(ret))

    def set_bitrate(self, kbps):
        kbps = min(512, max(16, int(kbps)))

        _lib.opus_encoder_ctl(self._state, CTL_SET_BITRATE, kbps * 1024)
        return kbps

    def set_bandwidth(self, req):
        if req not in band_ctl:
            raise KeyError('%r is not a valid bandwidth setting. Try one of: %s' % (req, ','.join(band_ctl)))

        k = band_ctl[req]
        _lib.opus_encoder_ctl(self._state, CTL_SET_BANDWIDTH, k)

    def set_signal_type(self, req):
        if req not in signal_ctl:
            raise KeyError('%r is not a valid signal setting. Try one of: %s' % (req, ','.join(signal_ctl)))

        k = signal_ctl[req]
        _lib.opus_encoder_ctl(self._state, CTL_SET_SIGNAL, k)

    def set_fec(self, enabled=True):
        _lib.opus_encoder_ctl(self._state, CTL_SET_FEC, 1 if enabled else 0)

    def set_expected_packet_loss_percent(self, percentage):
        _lib.opus_encoder_ctl(self._state, CTL_SET_PLP, min(100, max(0, int(percentage * 100))))

    def encode(self, pcm, frame_size):
        max_data_bytes = len(pcm)
        pcm = ctypes.cast(pcm, c_int16_ptr)
        data = (ctypes.c_char * max_data_bytes)()

        ret = _lib.opus_encode(self._state, pcm, frame_size, data, max_data_bytes)

        return array.array('b', data[:ret]).tobytes()
