# RozK

from . import libav
from .codec import Codec
from .stream import NullStream, Stream
from .packet import Packet

class Context:
    __slots__ = '_ref'

    def __init__(self):
        self._ref = libav.alloc_context()
        if not self._ref:
            raise MemoryError

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

    @property
    def _as_parameter_(self):
        return self._ref

    def open_input(self, url):
        if not self._ref:
            return
        errcode = libav.open_input(self._ref, url)
        if errcode < 0:
            raise Exception(f"Failed to open: {url}")
        errcode = libav.find_stream_info(self._ref)
        if errcode < 0:
            libav.close_input(self._ref)
            raise Exception("Failed to find stream info")

    def close_input(self):
        if self._ref:
            libav.close_input(self._ref)

    def find_stream(self, type):
        if not self._ref:
            return NullStream()
        index, codec_ref = libav.find_best_stream(self._ref, type)
        if index < 0 or not codec_ref:
            return NullStream()
        return Stream(index, Codec(codec_ref))

    def read_packet(self):
        if not self._ref:
            return None
        packet = Packet()
        errcode = libav.read_frame(self._ref, packet)
        if errcode < 0:
            return None
        return packet