#!/usr/bin/env python3
# -*- coding: utf-8 -*-

import json
import math
import subprocess
from pathlib import Path

from tqdm import tqdm


# =========================
# Parameters
# =========================
DATAMAKER_DIR = Path(__file__).resolve().parent
PROJECT_ROOT = DATAMAKER_DIR.parent

INPUT_DIR = DATAMAKER_DIR / "02_warp"
OUTPUT_DIR = PROJECT_ROOT / "dataset"

VIDEO_IDS = [f"{idx:02d}" for idx in range(1, 15)]
WINDOW_LEN_SECONDS = 5
STRIDE_SECONDS = 5
KEEP_AUDIO = False
TOLERANCE_SECONDS = 0.02
OVERWRITE = True
# =========================


def probe(video_path: Path) -> tuple[float, int]:
    cmd = [
        "ffprobe",
        "-v",
        "error",
        "-count_frames",
        "-select_streams",
        "v:0",
        "-show_entries",
        "stream=nb_read_frames,nb_frames,duration:format=duration",
        "-print_format",
        "json",
        str(video_path),
    ]
    raw = subprocess.check_output(cmd, stderr=subprocess.DEVNULL, text=True)
    info = json.loads(raw)
    stream = info["streams"][0]
    duration = float(stream.get("duration") or info.get("format", {}).get("duration"))
    frames_raw = stream.get("nb_read_frames") or stream.get("nb_frames")
    if frames_raw is None:
        raise RuntimeError(f"Could not read frame count: {video_path}")
    return duration, int(frames_raw)


def segment_count(duration: float) -> int:
    if duration < WINDOW_LEN_SECONDS:
        return 0
    return math.floor((duration - WINDOW_LEN_SECONDS) / STRIDE_SECONDS) + 1


def pad_seconds(seconds: int) -> str:
    return f"{seconds:04d}"


def clip_video(src: Path, dst: Path, start: int, duration: int) -> None:
    dst.parent.mkdir(parents=True, exist_ok=True)
    cmd = ["ffmpeg", "-hide_banner", "-loglevel", "error", "-nostats"]
    cmd.append("-y" if OVERWRITE else "-n")
    cmd += [
        "-ss",
        str(start),
        "-i",
        str(src),
        "-t",
        str(duration),
        "-c:v",
        "copy",
    ]
    cmd += ["-c:a", "copy"] if KEEP_AUDIO else ["-an"]
    cmd.append(str(dst))
    subprocess.run(cmd, stdout=subprocess.DEVNULL, stderr=subprocess.DEVNULL, check=True)


def collect_valid_pairs() -> list[tuple[str, Path, Path, float]]:
    valid_pairs: list[tuple[str, Path, Path, float]] = []
    for video_id in tqdm(VIDEO_IDS, desc="Probe videos", unit="video"):
        ir_path = INPUT_DIR / video_id / "ir.mp4"
        vi_path = INPUT_DIR / video_id / "vi.mp4"
        if not ir_path.exists() or not vi_path.exists():
            raise FileNotFoundError(f"Missing input pair: {ir_path}, {vi_path}")

        ir_duration, ir_frames = probe(ir_path)
        vi_duration, vi_frames = probe(vi_path)
        if abs(ir_duration - vi_duration) >= TOLERANCE_SECONDS:
            raise ValueError(
                f"{video_id}: duration mismatch "
                f"ir={ir_duration:.3f}s vi={vi_duration:.3f}s"
            )
        if ir_frames != vi_frames:
            raise ValueError(
                f"{video_id}: frame mismatch ir={ir_frames} vi={vi_frames}"
            )

        valid_pairs.append((video_id, ir_path, vi_path, ir_duration))
    return valid_pairs


def main() -> None:
    valid_pairs = collect_valid_pairs()
    total_clips = sum(2 * segment_count(duration) for _, _, _, duration in valid_pairs)
    if total_clips == 0:
        tqdm.write("No valid 5-second clips found.")
        return

    (OUTPUT_DIR / "ir").mkdir(parents=True, exist_ok=True)
    (OUTPUT_DIR / "vi").mkdir(parents=True, exist_ok=True)

    with tqdm(
        total=len(valid_pairs),
        desc="Total split",
        unit="video",
        position=0,
    ) as video_progress, tqdm(
        total=total_clips,
        desc="Split clips",
        unit="clip",
        position=1,
        leave=False,
    ) as clip_progress:
        for video_id, ir_path, vi_path, duration in valid_pairs:
            video_progress.set_postfix(video=video_id)
            start = 0
            while start + WINDOW_LEN_SECONDS <= duration:
                end = start + WINDOW_LEN_SECONDS
                name = f"{video_id}_{pad_seconds(start)}_{pad_seconds(end)}.mp4"
                clip_video(ir_path, OUTPUT_DIR / "ir" / name, start, WINDOW_LEN_SECONDS)
                clip_progress.update(1)
                clip_video(vi_path, OUTPUT_DIR / "vi" / name, start, WINDOW_LEN_SECONDS)
                clip_progress.update(1)
                start += STRIDE_SECONDS

            if start < duration:
                skipped = duration - start
                tqdm.write(
                    f"{video_id}: skipped tail {skipped:.2f}s "
                    f"(< {WINDOW_LEN_SECONDS}s)"
                )
            video_progress.update(1)

    tqdm.write(f"Dataset clips written to {OUTPUT_DIR}")


if __name__ == "__main__":
    main()