"""Write annotated output videos via GStreamer or OpenCV codecs."""

from __future__ import annotations

from pathlib import Path

import cv2


def make_video_writer(
    path: str,
    frame_size: tuple[int, int],
    fps: float,
    *,
    encoder: str = "auto",
    output_bitrate_kbps: int = 4000,
    codec_preference: list[str] | None = None,
) -> cv2.VideoWriter:
    Path(path).parent.mkdir(parents=True, exist_ok=True)
    width, height = frame_size
    bitrate_bps = max(1, output_bitrate_kbps) * 1000
    codecs = codec_preference or ["avc1", "mp4v", "H264"]

    if encoder in ("auto", "gstreamer"):
        writer = _try_gstreamer_writer(path, width, height, fps, bitrate_bps)
        if writer is not None:
            print(f"[video] opened GStreamer hardware encoder (bitrate={output_bitrate_kbps} kbps)")
            return writer
        if encoder == "gstreamer":
            raise RuntimeError(
                f"GStreamer video writer failed for path: {path}. "
                "Ensure OpenCV was built with GStreamer and Jetson encoder plugins are available."
            )

    writer = _try_opencv_writer(path, frame_size, fps, codecs)
    if writer is not None:
        print(f"[video] opened OpenCV encoder (codecs tried: {codecs})")
        return writer

    raise RuntimeError(
        "Unable to open video writer for path: "
        f"{path}. Tried encoder={encoder}, codecs={codecs}"
    )


def _try_gstreamer_writer(
    path: str,
    width: int,
    height: int,
    fps: float,
    bitrate_bps: int,
) -> cv2.VideoWriter | None:
    fps_int = max(1, int(round(fps)))
    pipeline = (
        f"appsrc ! video/x-raw, format=BGR ! "
        f"video/x-raw,width={width},height={height},framerate={fps_int}/1 ! "
        f"videoconvert ! nvvidconv ! "
        f"video/x-raw(memory:NVMM),format=NV12 ! "
        f"nvv4l2h264enc bitrate={bitrate_bps} insert-sps-pps=true ! "
        f"h264parse ! mp4mux ! filesink location={path}"
    )
    writer = cv2.VideoWriter(pipeline, cv2.CAP_GSTREAMER, 0, fps, (width, height), True)
    if writer.isOpened():
        return writer
    writer.release()
    return None


def _try_opencv_writer(
    path: str,
    frame_size: tuple[int, int],
    fps: float,
    codec_candidates: list[str],
) -> cv2.VideoWriter | None:
    for codec in codec_candidates:
        fourcc = cv2.VideoWriter_fourcc(*codec)
        writer = cv2.VideoWriter(path, fourcc, fps, frame_size)
        if writer.isOpened():
            return writer
        writer.release()
    return None