import os
import subprocess
import ffmpeg


def transcode_video(input_path: str, output_dir: str, orig_width: int, orig_height: int):
    os.makedirs(output_dir, exist_ok=True)

    def get_video_bitrate():
        try:
            probe = ffmpeg.probe(input_path)
            for stream in probe["streams"]:
                if stream["codec_type"] == "video":
                    return int(stream.get("bit_rate", "800000"))
        except:
            pass
        return 800000

    def get_audio_bitrate():
        try:
            probe = ffmpeg.probe(input_path)
            for stream in probe["streams"]:
                if stream["codec_type"] == "audio":
                    return int(stream.get("bit_rate", "64000"))
        except:
            pass
        return 64000

    def has_audio():
        try:
            probe = ffmpeg.probe(input_path)
            return any(s["codec_type"] == "audio" for s in probe.get("streams", []))
        except:
            return False

    def get_fps():
        try:
            probe = ffmpeg.probe(input_path)
            v_stream = next(s for s in probe["streams"] if s["codec_type"] == "video")
            return eval(v_stream["r_frame_rate"])
        except:
            return 30

    renditions = [
        {"name": "1080p", "width": 1920, "height": 1080, "crf": "22", "audio_bitrate": 192000},
        {"name": "720p", "width": 1280, "height": 720, "crf": "24", "audio_bitrate": 128000},
        {"name": "480p", "width": 854, "height": 480, "crf": "26", "audio_bitrate": 96000},
        {"name": "360p", "width": 640, "height": 360, "crf": "28", "audio_bitrate": 64000},
    ]
    renditions = [r for r in renditions if r["width"] <= orig_width and r["height"] <= orig_height]

    if not renditions:
        renditions = [{
            "name": "source",
            "width": orig_width,
            "height": orig_height,
            "crf": "28",
            "audio_bitrate": 64000
        }]

    video_bitrate = get_video_bitrate()
    audio_bitrate = get_audio_bitrate()
    audio_exists = has_audio()
    fps = get_fps()
    gop_size = int(fps * 4)

    video_split = f"[0:v]split={len(renditions)}" + "".join([f"[v{i}]" for i in range(len(renditions))])
    scale_filters = [f"[v{i}]scale=w={r['width']}:h={r['height']}[v{i}out]" for i, r in enumerate(renditions)]
    filter_parts = [video_split] + scale_filters

    map_cmds = []
    var_stream_map = []

    for idx, r in enumerate(renditions):
        map_cmds.extend([
            "-map", f"[v{idx}out]",
            f"-c:v:{idx}", "libx264",
            "-crf", str(r["crf"]),
            "-preset", "medium",
            "-g", str(gop_size),
            "-keyint_min", str(gop_size),
            "-sc_threshold", "0"
        ])
        if audio_exists:
            safe_ab = min(audio_bitrate, r["audio_bitrate"])
            map_cmds.extend([
                "-map", "0:a:0",
                f"-c:a:{idx}", "aac",
                f"-b:a:{idx}", str(safe_ab),
                "-ac", "2",
                "-ar", "44100"
            ])
            var_stream_map.append(f"v:{idx},a:{idx}")
        else:
            var_stream_map.append(f"v:{idx}")

    ffmpeg_cmd = [
        "ffmpeg", "-y", "-i", input_path,
        "-filter_complex", ";".join(filter_parts),
        *map_cmds,
        "-f", "hls",
        "-hls_time", "4",
        "-hls_playlist_type", "vod",
        "-hls_flags", "independent_segments+single_file",
        "-hls_segment_type", "mpegts",
        "-hls_segment_filename", os.path.join(output_dir, "stream_%v.ts"),
        "-master_pl_name", "master.m3u8",
        "-var_stream_map", " ".join(var_stream_map),
        "-avoid_negative_ts", "make_zero",
        "-movflags", "+faststart",
        os.path.join(output_dir, "stream_%v.m3u8")
    ]

    print("[FFMPEG FULL CMD]", " ".join(ffmpeg_cmd))
    subprocess.run(ffmpeg_cmd, check=True)