from av.container import InputContainer
from av.subtitles.stream import SubtitleStream
from av.video.reformatter import ColorRange
from fractions import Fraction
from typing import Optional
from .._input import AudioInput, VideoInput
import av
import io
import itertools
import json
import numpy as np
import math
import os
import torch
from .._util import VideoContainer, VideoCodec, VideoComponents
import logging


def container_to_output_format(container_format: str | None) -> str | None:
    """
    A container's `format` may be a comma-separated list of formats.
    E.g., iso container's `format` may be `mov,mp4,m4a,3gp,3g2,mj2`.
    However, writing to a file/stream with `av.open` requires a single format,
    or `None` to auto-detect.
    """
    if not container_format:
        return None  # Auto-detect

    if "," not in container_format:
        return container_format

    formats = container_format.split(",")
    return formats[0]

def get_open_write_kwargs(
    dest: str | io.BytesIO, container_format: str, to_format: str | None
) -> dict:
    """Get kwargs for writing a `VideoFromFile` to a file/stream with `av.open`"""
    open_kwargs = {
        "mode": "w",
        # If isobmff, preserve custom metadata tags (workflow, prompt, extra_pnginfo)
        "options": {"movflags": "use_metadata_tags"},
    }

    is_write_to_buffer = isinstance(dest, io.BytesIO)
    if is_write_to_buffer:
        # Set output format explicitly, since it cannot be inferred from file extension
        if to_format == VideoContainer.AUTO:
            to_format = container_format.lower()
        elif isinstance(to_format, str):
            to_format = to_format.lower()
        open_kwargs["format"] = container_to_output_format(to_format)

    return open_kwargs


def video_stream_bit_depth(stream) -> int:
    if stream is None or stream.format is None or not stream.format.components:
        return 8
    return max(component.bits for component in stream.format.components)


def last_decodable_audio_stream(container: InputContainer):
    """Streams FFmpeg has no decoder for have no codec context, and decoding their
    packets crashes the process (e.g. APAC spatial-audio track in iPhone)."""
    stream = next(
        (s for s in reversed(container.streams.audio) if s.codec_context is not None),
        None,
    )
    if stream is None and len(container.streams.audio):
        logging.warning("No decodable audio stream found in video; ignoring audio.")
    return stream


def probe_audio_params(container: InputContainer, audio_stream, max_packets: int = 200):
    """Containers probed only up to a window (mpegts) leave audio codec parameters unset when
    audio starts beyond it; learn them by decoding ahead. The caller must seek back afterwards.
    Returns (sample_rate, channels), zeros when the stream never yields a decodable frame."""
    for i, packet in enumerate(container.demux(audio_stream)):
        try:
            frames = packet.decode()
        except av.error.FFmpegError:
            frames = ()
        if frames:
            return frames[0].sample_rate, frames[0].layout.nb_channels
        if i >= max_packets:
            break
    return 0, 0


def write_output_metadata(container: InputContainer, output, metadata: dict | None):
    """Copy the source container's metadata, then overlay the caller's tags."""
    for key, value in container.metadata.items():
        if metadata is None or key not in metadata:
            output.metadata[key] = value
    if metadata is not None:
        for key, value in metadata.items():
            output.metadata[key] = value if isinstance(value, str) else json.dumps(value)


def mp4_output_open_kwargs(path: str | io.BytesIO, format: VideoContainer, codec: VideoCodec) -> dict:
    if format != VideoContainer.AUTO and format != VideoContainer.MP4:
        raise ValueError("Only MP4 format is supported for now")
    if codec != VideoCodec.AUTO and codec != VideoCodec.H264:
        raise ValueError("Only H264 codec is supported for now")
    open_kwargs = {"mode": "w", "options": {"movflags": "use_metadata_tags"}}
    if isinstance(format, VideoContainer) and format != VideoContainer.AUTO:
        open_kwargs["format"] = format.value
    elif isinstance(path, io.BytesIO):
        open_kwargs["format"] = "mp4"  # no file extension to infer the format from
    return open_kwargs


class VideoFromFile(VideoInput):
    """
    Class representing video input from a file.
    """

    def __init__(self, file: str | io.BytesIO, *, start_time: float=0, duration: float=0):
        """
        Initialize the VideoFromFile object based off of either a path on disk or a BytesIO object
        containing the file contents.
        """
        self.__file = file
        self.__start_time = start_time
        self.__duration = duration

    def get_stream_source(self) -> str | io.BytesIO:
        """
        Return the underlying file source for efficient streaming.
        This avoids unnecessary memory copies when the source is already a file path.
        """
        if isinstance(self.__file, io.BytesIO):
            self.__file.seek(0)
        return self.__file

    def get_active_trim_window(self) -> tuple[float, float]:
        start_time = self.__start_time
        if start_time < 0:
            start_time = max(self._get_raw_duration() + start_time, 0.0)
        return float(start_time), float(self.__duration)

    def get_dimensions(self) -> tuple[int, int]:
        """
        Returns the dimensions of the video input.

        Returns:
            Tuple of (width, height)
        """
        if isinstance(self.__file, io.BytesIO):
            self.__file.seek(0)  # Reset the BytesIO object to the beginning
        with av.open(self.__file, mode='r') as container:
            for stream in container.streams:
                if stream.type == 'video':
                    assert isinstance(stream, av.VideoStream)
                    return stream.width, stream.height
        raise ValueError(f"No video stream found in file '{self.__file}'")

    def get_bit_depth(self) -> int:
        if isinstance(self.__file, io.BytesIO):
            self.__file.seek(0)  # Reset the BytesIO object to the beginning
        with av.open(self.__file, mode="r") as container:
            video_stream = container.streams.video[0] if len(container.streams.video) > 0 else None
            return video_stream_bit_depth(video_stream)

    def get_duration(self) -> float:
        """
        Returns the duration of the video in seconds.

        Returns:
            Duration in seconds
        """
        raw_duration = self._get_raw_duration()
        if self.__start_time < 0:
            duration_from_start = min(raw_duration, -self.__start_time)
        else:
            duration_from_start = raw_duration - self.__start_time
        if self.__duration:
            return min(self.__duration, duration_from_start)
        return duration_from_start

    def _get_raw_duration(self) -> float:
        if isinstance(self.__file, io.BytesIO):
            self.__file.seek(0)
        with av.open(self.__file, mode="r") as container:
            if container.duration is not None:
                return float(container.duration / av.time_base)

            # Fallback: calculate from frame count and frame rate
            video_stream = next(
                (s for s in container.streams if s.type == "video"), None
            )
            if video_stream and video_stream.frames and video_stream.average_rate:
                return float(video_stream.frames / video_stream.average_rate)

            # Last resort: decode frames to count them
            if video_stream and video_stream.average_rate:
                frame_count = 0
                container.seek(0)
                frame_iterator = (
                    container.decode(video_stream)
                    if video_stream.codec.capabilities & 0x100
                    else container.demux(video_stream)
                )
                for packet in frame_iterator:
                    frame_count += 1
                if frame_count > 0:
                    return float(frame_count / video_stream.average_rate)

        raise ValueError(f"Could not determine duration for file '{self.__file}'")

    def get_frame_count(self) -> int:
        """
        Returns the number of frames in the video without materializing them as
        torch tensors.
        """
        if isinstance(self.__file, io.BytesIO):
            self.__file.seek(0)

        with av.open(self.__file, mode="r") as container:
            video_stream = self._get_first_video_stream(container)
            # 1. Prefer the frames field if available and usable
            if (
                video_stream.frames
                and video_stream.frames > 0
                and not self.__start_time
                and not self.__duration
            ):
                return int(video_stream.frames)

            # 2. Try to estimate from duration and average_rate using only metadata
            if (
                getattr(video_stream, "duration", None) is not None
                and getattr(video_stream, "time_base", None) is not None
                and video_stream.average_rate
            ):
                raw_duration = float(video_stream.duration * video_stream.time_base)
                if self.__start_time < 0:
                    duration_from_start = min(raw_duration, -self.__start_time)
                else:
                    duration_from_start = raw_duration - self.__start_time
                duration_seconds = min(self.__duration, duration_from_start)
                estimated_frames = int(round(duration_seconds * float(video_stream.average_rate)))
                if estimated_frames > 0:
                    return estimated_frames

            # 3. Last resort: decode frames and count them (streaming)
            start_time, duration = self.get_active_trim_window()
            frame_count = 1
            start_pts = int(start_time / video_stream.time_base)
            end_pts = int((start_time + duration) / video_stream.time_base)
            container.seek(start_pts, stream=video_stream)
            frame_iterator = (
                container.decode(video_stream)
                if video_stream.codec.capabilities & 0x100
                else container.demux(video_stream)
            )
            for frame in frame_iterator:
                if frame.pts >= start_pts:
                    break
            else:
                raise ValueError(f"Could not determine frame count for file '{self.__file}'\nNo frames exist for start_time {self.__start_time}")
            for frame in frame_iterator:
                if frame.pts >= end_pts:
                    break
                frame_count += 1
            return frame_count

    def get_frame_rate(self) -> Fraction:
        """
        Returns the average frame rate of the video using container metadata
        without decoding all frames.
        """
        if isinstance(self.__file, io.BytesIO):
            self.__file.seek(0)

        with av.open(self.__file, mode="r") as container:
            video_stream = self._get_first_video_stream(container)
            # Preferred: use PyAV's average_rate (usually already a Fraction-like)
            if video_stream.average_rate:
                return Fraction(video_stream.average_rate)

            # Fallback: estimate from frames + duration if available
            if video_stream.frames and container.duration:
                duration_seconds = float(container.duration / av.time_base)
                if duration_seconds > 0:
                    return Fraction(video_stream.frames / duration_seconds).limit_denominator()

            # Last resort: match get_components_internal default
            return Fraction(1)

    def get_container_format(self) -> str:
        """
        Returns the container format of the video (e.g., 'mp4', 'mov', 'avi').

        Returns:
            Container format as string
        """
        if isinstance(self.__file, io.BytesIO):
            self.__file.seek(0)
        with av.open(self.__file, mode='r') as container:
            return container.format.name

    def get_components_internal(self, container: InputContainer) -> VideoComponents:
        video_stream = self._get_first_video_stream(container)
        start_time, duration = self.get_active_trim_window()

        # Get video frames
        frames = []
        audio_frames = []
        alphas = None
        start_pts = int(start_time / video_stream.time_base)
        end_pts = int((start_time + duration) / video_stream.time_base)

        if start_pts != 0:
            container.seek(start_pts, stream=video_stream)

        image_format = 'gbrpf32le'
        process_image_format = lambda a: a
        align_graph = None
        audio = None

        streams = [video_stream]
        has_first_audio_frame = False
        checked_alpha = False

        # Default to False so we decode until EOF if duration is 0
        video_done = False
        audio_done = True

        audio_stream = last_decodable_audio_stream(container)
        if audio_stream is not None:
            streams += [audio_stream]
            resampler = av.audio.resampler.AudioResampler(format='fltp')
            audio_done = False

        for packet in container.demux(*streams):
            if video_done and audio_done:
                break

            if packet.stream.type == "video":
                if video_done:
                    continue
                try:
                    for frame in packet.decode():
                        if frame.pts < start_pts:
                            continue
                        if duration and frame.pts >= end_pts:
                            video_done = True
                            break

                        if not checked_alpha:
                            alpha_channel = False
                            for comp in frame.format.components:
                                if comp.is_alpha or frame.format.name == "pal8":
                                    alphas = []
                                    alpha_channel = True
                                    break
                            if frame.format.name in ("yuvj420p", "yuvj422p", "yuvj444p", "rgb24", "rgba", "pal8"):
                                process_image_format = lambda a: a.float() / 255.0
                                if alpha_channel:
                                    image_format = 'rgba'
                                else:
                                    image_format = 'rgb24'
                            else:
                                process_image_format = lambda a: a
                                if alpha_channel:
                                    image_format = 'gbrapf32le'
                                else:
                                    image_format = 'gbrpf32le'

                            checked_alpha = True

                        # Fix non-deterministic video decode when the video width is not a multiple of 32
                        # For non-yuvj pixel formats: most H.264/H.265 video and static images (e.g. lossy WebP via LoadImage)
                        # Pad both axes to a multiple of 32 and smear the border so the alignment padding never bleeds into the cropped edges
                        if image_format in ('gbrpf32le', 'gbrapf32le') and frame.width % 32 != 0:
                            if align_graph is None:
                                pad_w = ((frame.width + 31) // 32) * 32
                                pad_h = ((frame.height + 31) // 32) * 32
                                g = av.filter.Graph()
                                g_src = g.add_buffer(width=frame.width, height=frame.height,
                                                     format=frame.format.name, time_base=video_stream.time_base)
                                g_pad = g.add('pad', f'{pad_w}:{pad_h}:0:0')
                                g_fill = g.add('fillborders', f'left=0:right={pad_w - frame.width}:top=0:bottom={pad_h - frame.height}:mode=smear')
                                g_sink = g.add('buffersink')
                                g_src.link_to(g_pad)
                                g_pad.link_to(g_fill)
                                g_fill.link_to(g_sink)
                                g.configure()
                                align_graph = (g, g_src, g_sink)
                            align_graph[1].push(frame)
                            img = np.ascontiguousarray(align_graph[2].pull().to_ndarray(format=image_format)[:frame.height, :frame.width])
                        else:
                            img = frame.to_ndarray(format=image_format)
                        if frame.rotation != 0:
                            k = int(round(frame.rotation // 90))
                            img = np.rot90(img, k=k, axes=(0, 1)).copy()
                        if alphas is None:
                            frames.append(torch.from_numpy(img))
                        else:
                            frames.append(torch.from_numpy(img[..., :-1]))
                            alphas.append(torch.from_numpy(img[..., -1:]))
                except av.error.InvalidDataError:
                    logging.info("pyav decode error")

            elif packet.stream.type == "audio":
                if audio_done:
                    continue

                aframes = itertools.chain.from_iterable(
                    map(resampler.resample, packet.decode())
                )
                for frame in aframes:
                    if duration and frame.time > start_time + duration:
                        audio_done = True
                        break

                    if not has_first_audio_frame:
                        offset_seconds = start_time - frame.pts * audio_stream.time_base
                        to_skip = max(0, int(offset_seconds * audio_stream.sample_rate))
                        if to_skip < frame.samples:
                            has_first_audio_frame = True
                            audio_frames.append(frame.to_ndarray()[..., to_skip:])
                    else:
                        audio_frames.append(frame.to_ndarray())

        images = process_image_format(torch.stack(frames)) if len(frames) > 0 else torch.zeros(0, 0, 0, 3)
        if alphas is not None:
            alphas = process_image_format(torch.stack(alphas)) if len(alphas) > 0 else torch.zeros(0, 0, 0, 1)

        # Get frame rate
        frame_rate = Fraction(video_stream.average_rate) if video_stream.average_rate else Fraction(1)

        if len(audio_frames) > 0:
            audio_data = np.concatenate(audio_frames, axis=1)  # shape: (channels, total_samples)
            if duration:
                audio_data = audio_data[..., :int(duration * audio_stream.sample_rate)]

            audio_tensor = torch.from_numpy(audio_data).unsqueeze(0)  # shape: (1, channels, total_samples)
            audio = AudioInput({
                "waveform": audio_tensor,
                "sample_rate": int(audio_stream.sample_rate) if audio_stream.sample_rate else 1,
            })

        metadata = container.metadata
        return VideoComponents(images=images, alpha=alphas, audio=audio, frame_rate=frame_rate, metadata=metadata)

    def get_components(self) -> VideoComponents:
        if isinstance(self.__file, io.BytesIO):
            self.__file.seek(0)  # Reset the BytesIO object to the beginning
        with av.open(self.__file, mode='r') as container:
            return self.get_components_internal(container)
        raise ValueError(f"No video stream found in file '{self.__file}'")

    def save_to(
        self,
        path: str | io.BytesIO,
        format: VideoContainer = VideoContainer.AUTO,
        codec: VideoCodec = VideoCodec.AUTO,
        metadata: Optional[dict] = None,
        bit_depth: int | None = None,
    ):
        if isinstance(self.__file, io.BytesIO):
            self.__file.seek(0)  # Reset the BytesIO object to the beginning
        with av.open(self.__file, mode='r') as container:
            container_format = container.format.name
            video_stream = container.streams.video[0] if len(container.streams.video) > 0 else None
            video_encoding = video_stream.codec.name if video_stream is not None else None
            source_bit_depth = video_stream_bit_depth(video_stream)
            reuse_streams = True
            if format != VideoContainer.AUTO and format not in container_format.split(","):
                reuse_streams = False
            if codec != VideoCodec.AUTO and codec != video_encoding and video_encoding is not None:
                reuse_streams = False
            if bit_depth is not None and video_encoding is not None and bit_depth != source_bit_depth:
                reuse_streams = False
            if self.__start_time or self.__duration:
                reuse_streams = False

            if not reuse_streams:
                if bit_depth is None:
                    bit_depth = source_bit_depth
                return self._save_transcoded(container, path, format=format, codec=codec, metadata=metadata, bit_depth=bit_depth)

            streams = container.streams

            open_kwargs = get_open_write_kwargs(path, container_format, format)
            with av.open(path, **open_kwargs) as output_container:
                # Add metadata before writing any streams
                write_output_metadata(container, output_container, metadata)

                # Add streams to the new container. Streams with no codec context cannot be used as an output template.
                stream_map = {}
                for stream in streams:
                    if isinstance(stream, (av.VideoStream, av.AudioStream, SubtitleStream)):
                        if stream.codec_context is None:
                            logging.warning("Skipping %s stream %d with unsupported codec", stream.type, stream.index)
                            continue
                        out_stream = output_container.add_stream_from_template(template=stream, opaque=True)
                        stream_map[stream] = out_stream

                # Write packets to the new container
                for packet in container.demux():
                    if packet.stream in stream_map and packet.dts is not None:
                        packet.stream = stream_map[packet.stream]
                        output_container.mux(packet)

    def _save_transcoded(
        self,
        container: InputContainer,
        path: str | io.BytesIO,
        format: VideoContainer,
        codec: VideoCodec,
        metadata: dict | None,
        bit_depth: int,
    ):
        """Re-encode to H.264/AAC one frame at a time; peak memory does not scale with video length."""
        open_kwargs = mp4_output_open_kwargs(path, format, codec)
        video_stream = self._get_first_video_stream(container)
        start_time, duration = self.get_active_trim_window()
        start_pts = int(start_time / video_stream.time_base)
        end_pts = int((start_time + duration) / video_stream.time_base) if duration else None
        stream_end_pts = None
        if video_stream.duration is not None:
            stream_end_pts = (video_stream.start_time or 0) + video_stream.duration
        output_end_pts = end_pts
        if stream_end_pts is not None and (output_end_pts is None or stream_end_pts < output_end_pts):
            output_end_pts = stream_end_pts
        if start_pts != 0:
            container.seek(start_pts, stream=video_stream)

        audio_stream = last_decodable_audio_stream(container)
        pix_fmt = "yuv420p10le" if bit_depth >= 10 else "yuv420p"
        rate = Fraction(video_stream.average_rate) if video_stream.average_rate else Fraction(1)

        resampler = None
        sample_rate = 0
        audio_time_base = None
        duration_cap = None
        if audio_stream is not None:
            sample_rate = audio_stream.codec_context.sample_rate
            channels = audio_stream.codec_context.channels
            if not sample_rate:
                sample_rate, channels = probe_audio_params(container, audio_stream)
                container.seek(start_pts, stream=video_stream)
                if sample_rate:
                    audio_stream.codec_context.flush_buffers()
                else:
                    logging.warning("Audio stream parameters could not be determined; ignoring audio.")
                    audio_stream = None
        if audio_stream is not None:
            audio_time_base = Fraction(1, sample_rate)
            layout = {1: "mono", 2: "stereo", 6: "5.1"}.get(channels, "stereo")
            resampler = av.audio.resampler.AudioResampler(format="fltp", layout=layout, rate=sample_rate)
            if duration:
                duration_cap = math.ceil(duration * sample_rate)

        streams = [video_stream] if audio_stream is None else [video_stream, audio_stream]
        pts_step = max(1, int(round((1 / rate) / video_stream.time_base)))
        video_done = False
        audio_done = audio_stream is None
        video_pts_offset = None
        last_video_pts = None
        last_video_end = None
        # rebased pts -> true display duration: the mp4 muxer pads the last sample with 1/rate otherwise
        video_frame_durations = {}
        source_size = None
        rotation_k = 0
        rotation_filter = None
        audio_started = False
        samples_written = 0
        pending_audio = []
        # The output opens lazily on the first kept frame: it decides the geometry (90/270 rotation swaps dims),
        # and never seeking back keeps webm/mkv leading audio intact.
        output = None
        out_video = None
        out_audio = None

        def audio_frame_from_ndarray(nd_planar):
            frame = av.AudioFrame.from_ndarray(np.ascontiguousarray(nd_planar), format="fltp", layout=layout)
            frame.sample_rate = sample_rate
            return frame

        def drain_audio(final=False):
            # Audio may cover the pts span of the video written so far, capped by the requested duration
            nonlocal samples_written, audio_done
            if last_video_end is None:
                cap = 0
            else:
                cap = math.ceil(last_video_end * video_stream.time_base * sample_rate)
            if duration_cap is not None:
                cap = min(cap, duration_cap)
            while pending_audio and not audio_done:
                frame = pending_audio[0]
                if samples_written + frame.samples <= cap:
                    frame.pts = samples_written
                    frame.time_base = audio_time_base
                    output.mux(out_audio.encode(frame))
                    samples_written += frame.samples
                    pending_audio.pop(0)
                    continue
                if final:
                    keep = frame.to_ndarray()[..., :cap - samples_written]
                    if keep.shape[-1] > 0:
                        tail = audio_frame_from_ndarray(keep)
                        tail.pts = samples_written
                        tail.time_base = audio_time_base
                        output.mux(out_audio.encode(tail))
                        samples_written += keep.shape[-1]
                    pending_audio.clear()
                break
            if duration_cap is not None and samples_written >= duration_cap:
                audio_done = True
            return cap

        try:
            for packet in container.demux(*streams):
                if video_done and audio_done:
                    break

                if packet.stream == video_stream and not video_done:
                    try:
                        frames = packet.decode()
                    except av.error.InvalidDataError:
                        logging.info("pyav decode error")
                        continue
                    for frame in frames:
                        if frame.pts is not None and frame.pts < start_pts:
                            continue
                        if end_pts is not None and frame.pts is not None and frame.pts >= end_pts:
                            video_done = True
                            if last_video_pts is not None:
                                # the source continues past the window: hold the last kept frame to the window end
                                end_offset = video_pts_offset if video_pts_offset is not None else start_pts
                                last_video_end = max(last_video_end, end_pts - end_offset)
                            break
                        # the source's true display duration of this frame; average_rate is not a
                        # frame duration (sparse/VFR sources), so it is only the fallback
                        frame_duration = frame.duration if frame.duration else pts_step
                        if end_pts is not None and frame.pts is not None:
                            frame_duration = min(frame_duration, end_pts - frame.pts)
                        if output is None:
                            rotation_k = int(round(frame.rotation // 90)) % 4 if frame.rotation else 0
                            if rotation_k % 2:
                                out_width, out_height = frame.height, frame.width
                            else:
                                out_width, out_height = frame.width, frame.height
                            if out_width % 2 or out_height % 2:
                                raise ValueError(f"H.264 output requires even dimensions, got {out_width}x{out_height}")
                            source_size = (frame.width, frame.height)
                            output = av.open(path, **open_kwargs)
                            # Add metadata before writing any streams
                            write_output_metadata(container, output, metadata)
                            out_video = output.add_stream("h264", rate=rate)
                            # no B-frames: reordering makes mp4 sample durations follow decode order,
                            # so irregular-VFR spans and trim windows land wrong
                            out_video.codec_context.max_b_frames = 0
                            out_video.width = out_width
                            out_video.height = out_height
                            out_video.pix_fmt = pix_fmt
                            # source pts pass through (rebased to 0), so variable frame rate survives
                            out_video.codec_context.time_base = video_stream.time_base
                            if audio_stream is not None:
                                out_audio = output.add_stream("aac", rate=sample_rate, layout=layout)
                        if (frame.width, frame.height) != source_size:
                            # encoding would silently rescale the new geometry into the old one
                            raise ValueError(
                                f"Video resolution changes mid-stream "
                                f"({source_size[0]}x{source_size[1]} -> {frame.width}x{frame.height}); cannot transcode"
                            )
                        if rotation_k:
                            if rotation_filter is None:
                                g = av.filter.Graph()
                                g_src = g.add_buffer(width=frame.width, height=frame.height,
                                                     format=frame.format.name, time_base=video_stream.time_base)
                                tail = g_src
                                for filter_name, filter_args in {1: [("transpose", "cclock")],
                                                                 2: [("hflip", None), ("vflip", None)],
                                                                 3: [("transpose", "clock")]}[rotation_k]:
                                    step = g.add(filter_name, filter_args)
                                    tail.link_to(step)
                                    tail = step
                                g_sink = g.add("buffersink")
                                tail.link_to(g_sink)
                                g.configure()
                                rotation_filter = (g_src, g_sink)
                            rotation_filter[0].push(frame)
                            frame = rotation_filter[1].pull()
                        if frame.color_range == ColorRange.JPEG:
                            # compress full-range sources (yuvj/MJPEG) to limited range
                            frame = frame.reformat(format=pix_fmt, src_color_range="JPEG", dst_color_range="MPEG")
                        else:
                            frame = frame.reformat(format=pix_fmt)
                        frame_output_end = None
                        if frame.pts is not None:
                            if video_pts_offset is None:
                                video_pts_offset = frame.pts
                            frame.pts -= video_pts_offset
                            if output_end_pts is not None:
                                frame_output_end = output_end_pts - video_pts_offset
                                if frame.pts + frame_duration > frame_output_end:
                                    clamped_pts = frame_output_end - frame_duration
                                    if clamped_pts >= 0 and (last_video_pts is None or clamped_pts > last_video_pts):
                                        frame.pts = min(frame.pts, clamped_pts)
                                    elif frame.pts < frame_output_end:
                                        frame_duration = frame_output_end - frame.pts
                                    else:
                                        continue
                        if frame.pts is None or (last_video_pts is not None and frame.pts <= last_video_pts):
                            # broken sources emit missing/backward timestamps mid-stream, which the
                            # muxer rejects; nudge them forward by one nominal frame interval
                            frame.pts = 0 if last_video_pts is None else last_video_pts + pts_step
                            if frame_output_end is not None and frame.pts + frame_duration > frame_output_end:
                                if frame.pts >= frame_output_end:
                                    continue
                                frame_duration = frame_output_end - frame.pts
                        last_video_pts = frame.pts
                        last_video_end = frame.pts + frame_duration
                        video_frame_durations[frame.pts] = frame_duration
                        # the decoded pict_type would force x264's frame types (intra-only
                        # sources like MJPEG/ProRes would come out all-keyframe)
                        frame.pict_type = 0
                        for out_packet in out_video.encode(frame):
                            out_packet.duration = video_frame_durations.pop(out_packet.pts, 0)
                            output.mux(out_packet)
                        drain_audio()

                elif packet.stream == audio_stream and not audio_done:
                    for resampled in itertools.chain.from_iterable(map(resampler.resample, packet.decode())):
                        frame_start = None
                        if resampled.pts is not None:
                            # passthrough frames keep the source stream's time base
                            tb = resampled.time_base if resampled.time_base else audio_time_base
                            frame_start = float(resampled.pts * tb)
                            if duration and not audio_started and frame_start >= start_time + duration:
                                audio_done = True
                                break
                        if not audio_started:
                            if frame_start is None:
                                frame_start = 0.0
                            to_skip = max(0, int((start_time - frame_start) * sample_rate))
                            if to_skip >= resampled.samples:
                                continue
                            audio_started = True
                            if duration and frame_start > start_time:
                                duration_cap = min(duration_cap, math.ceil((start_time + duration - frame_start) * sample_rate))
                            if to_skip:
                                pending_audio.append(audio_frame_from_ndarray(resampled.to_ndarray()[..., to_skip:]))
                                continue
                        pending_audio.append(resampled)
                        if video_done:
                            # the video window is complete so the cap is final, but containers
                            # that interleave audio behind video (fragmented mp4) still owe most
                            # of it: stop only once the demuxed audio covers the cap
                            cap = drain_audio()
                            if pending_audio or samples_written >= cap:
                                drain_audio(final=True)
                                audio_done = True
                                break

            if output is None:
                raise ValueError(f"No decodable video frames found in file '{self.__file}'")
            if out_audio is not None and not audio_done:
                drain_audio(final=True)
            window_fill = last_video_end - last_video_pts if video_done and last_video_pts is not None else 0
            for out_packet in out_video.encode(None):
                duration = video_frame_durations.pop(out_packet.pts, 0)
                if out_packet.pts == last_video_pts:
                    duration = max(duration, window_fill)
                out_packet.duration = duration
                output.mux(out_packet)
            if out_audio is not None:
                output.mux(out_audio.encode(None))
        except BaseException:
            if output is not None:
                output.close()
                if isinstance(path, (str, os.PathLike)) and os.path.exists(path):
                    os.remove(path)
            raise
        else:
            if output is not None:
                output.close()

    def _get_first_video_stream(self, container: InputContainer):
        if len(container.streams.video):
            return container.streams.video[0]
        raise ValueError(f"No video stream found in file '{self.__file}'")

    def as_trimmed(
        self, start_time: float = 0, duration: float = 0, strict_duration: bool = True
    ) -> VideoInput | None:
        trimmed = VideoFromFile(
            self.get_stream_source(),
            start_time=start_time + self.__start_time,
            duration=duration,
        )
        if trimmed.get_duration() < duration and strict_duration:
            return None
        return trimmed


class VideoFromComponents(VideoInput):
    """
    Class representing video input from tensors.
    """

    def __init__(self, components: VideoComponents, bit_depth: int = 8):
        self.__components = components
        # Tensor components have no inherent bit depth; this is the depth used when encoding.
        self.__bit_depth = bit_depth

    def get_components(self) -> VideoComponents:
        return VideoComponents(
            images=self.__components.images,
            audio=self.__components.audio,
            frame_rate=self.__components.frame_rate,
        )

    def get_bit_depth(self) -> int:
        return self.__bit_depth

    def save_to(
        self,
        path: str,
        format: VideoContainer = VideoContainer.AUTO,
        codec: VideoCodec = VideoCodec.AUTO,
        metadata: Optional[dict] = None,
        bit_depth: int | None = None,
    ):
        """Save the video to a file path or BytesIO buffer."""
        open_kwargs = mp4_output_open_kwargs(path, format, codec)
        # None means "use the depth this video was created with" (CreateVideo's choice).
        if bit_depth is None:
            bit_depth = self.__bit_depth
        is_10bit = bit_depth >= 10
        with av.open(path, **open_kwargs) as output:
            # Add metadata before writing any streams
            if metadata is not None:
                for key, value in metadata.items():
                    output.metadata[key] = json.dumps(value)

            frame_rate = Fraction(round(self.__components.frame_rate * 1000), 1000)
            # Create a video stream
            pix_fmt = "yuv420p10le" if is_10bit else "yuv420p"
            video_stream = output.add_stream('h264', rate=frame_rate)
            video_stream.width = self.__components.images.shape[2]
            video_stream.height = self.__components.images.shape[1]
            video_stream.pix_fmt = pix_fmt

            # Create an audio stream
            audio_sample_rate = 1
            audio_stream: Optional[av.AudioStream] = None
            if self.__components.audio:
                audio_sample_rate = int(self.__components.audio['sample_rate'])
                waveform = self.__components.audio['waveform']
                waveform = waveform[0, :, :math.ceil((audio_sample_rate / frame_rate) * self.__components.images.shape[0])]
                layout = {1: 'mono', 2: 'stereo', 6: '5.1'}.get(waveform.shape[0], 'stereo')
                audio_stream = output.add_stream('aac', rate=audio_sample_rate, layout=layout)

            # Encode video
            for i, frame in enumerate(self.__components.images):
                if is_10bit:
                    # 16-bit RGB keeps float precision through the conversion to 10-bit YUV.
                    img = (frame.float() * 65535).clamp(0, 65535).cpu().numpy().astype(np.uint16)  # shape: (H, W, 3)
                    frame = av.VideoFrame.from_ndarray(img, format="rgb48le")
                else:
                    img = (frame * 255).clamp(0, 255).byte().cpu().numpy() # shape: (H, W, 3)
                    frame = av.VideoFrame.from_ndarray(img, format='rgb24')
                frame = frame.reformat(format=pix_fmt)
                packet = video_stream.encode(frame)
                output.mux(packet)

            # Flush video
            packet = video_stream.encode(None)
            output.mux(packet)

            if audio_stream and self.__components.audio:
                frame = av.AudioFrame.from_ndarray(waveform.float().cpu().contiguous().numpy(), format='fltp', layout=layout)
                frame.sample_rate = audio_sample_rate
                frame.pts = 0
                output.mux(audio_stream.encode(frame))

                # Flush encoder
                output.mux(audio_stream.encode(None))

    def as_trimmed(
        self,
        start_time: float | None = None,
        duration: float | None = None,
        strict_duration: bool = True,
    ) -> VideoInput | None:
        if self.get_duration() < start_time + duration:
            return None
        #TODO Consider tracking duration and trimming at time of save?
        return VideoFromFile(self.get_stream_source(), start_time=start_time, duration=duration)
