# RozK

import errno

from . import libav
from .frame import Frame

class Decoder:
    __slots__ = '_ref'

    def __init__(self, codec):
        self._ref = libav.codec_alloc_context(codec)
        if not self._ref:
            raise MemoryError
        errcode = libav.codec_open(self._ref, codec)
        if errcode < 0:
            libav.codec_free_context(self._ref)
            raise Exception("Failed to open codec context")

    def __del__(self):
        if self._ref:
            libav.codec_free_context(self._ref)

    def _recieve(self, frames):
        while True:
            frame = Frame()
            errcode = libav.codec_receive_frame(self._ref, frame)
            if errcode == 0:
                frames.append(frame)
            elif errcode == errno.EAGAIN:
                break
            else:
                raise Exception(f"Failed to receive frame: {errcode}")

    def decode(self, packet):
        if not self._ref:
            return None
        frames = []
        while True:
            errcode = libav.codec_send_packet(self._ref, packet)
            if errcode != 0 and errcode != errno.EAGAIN:
                raise Exception(f"Failed to send packet: {errcode}")
            self._recieve(frames)
            if errcode == 0:
                break
        return frames