import argparse
import json
import os
import pickle
from collections import Counter, defaultdict
from concurrent.futures import ProcessPoolExecutor, as_completed
from pathlib import Path

from tqdm import tqdm


def inspect_cameras(image_data):
    """
    Record the frame count of every camera entry.

    A camera is valid only when:
        frame_count > 0
    """
    camera_frame_counts = {}

    if not isinstance(image_data, dict):
        return camera_frame_counts, []

    for camera_name, camera_data in image_data.items():
        if not isinstance(camera_data, dict):
            continue

        if "image" not in camera_data:
            continue

        frames = camera_data["image"]

        if frames is None:
            frame_count = 0
        else:
            try:
                frame_count = len(frames)
            except TypeError:
                frame_count = 0

        camera_frame_counts[str(camera_name)] = int(frame_count)

    valid_cameras = sorted(
        camera_name
        for camera_name, frame_count in camera_frame_counts.items()
        if frame_count > 0
    )

    return camera_frame_counts, valid_cameras


def process_one_image_pkl(image_pkl_path_str, source_root_str):
    """
    Worker function executed in a separate process.

    Only returns camera statistics. The loaded image data remains inside
    the worker and is released after this function finishes.
    """
    image_pkl_path = Path(image_pkl_path_str)
    source_root = Path(source_root_str)
    episode_dir = image_pkl_path.parent

    try:
        relative_folder = str(episode_dir.relative_to(source_root))

        with open(image_pkl_path, "rb") as f:
            image_data = pickle.load(f)

        camera_frame_counts, valid_cameras = inspect_cameras(image_data)

        empty_cameras = sorted(
            camera_name
            for camera_name, frame_count in camera_frame_counts.items()
            if frame_count == 0
        )

        return {
            "success": True,
            "folder": relative_folder,
            "num_cameras_in_pkl": len(camera_frame_counts),
            "num_valid_cameras": len(valid_cameras),
            "camera_frame_counts": camera_frame_counts,
            "valid_cameras": valid_cameras,
            "empty_cameras": empty_cameras,
        }

    except Exception as e:
        try:
            relative_folder = str(episode_dir.relative_to(source_root))
        except Exception:
            relative_folder = str(episode_dir)

        return {
            "success": False,
            "folder": relative_folder,
            "image_pkl": str(image_pkl_path),
            "error": repr(e),
        }


def main():
    parser = argparse.ArgumentParser(
        description=(
            "Count non-empty cameras in every image.pkl using "
            "parallel worker processes."
        )
    )
    parser.add_argument(
        "--source_root",
        type=str,
        required=True,
        help="Root directory containing episode folders.",
    )
    parser.add_argument(
        "--output",
        type=str,
        default="camera_count_summary.json",
        help="Output JSON path.",
    )
    parser.add_argument(
        "--workers",
        type=int,
        default=min(8, os.cpu_count() or 1),
        help="Number of worker processes. Start with 8 for large image.pkl files.",
    )
    args = parser.parse_args()

    source_root = Path(args.source_root).resolve()
    output_path = Path(args.output).resolve()

    image_pkl_paths = sorted(source_root.rglob("image.pkl"))

    print(f"Source root: {source_root}")
    print(f"Found {len(image_pkl_paths)} image.pkl files")
    print(f"Using {args.workers} worker processes")

    valid_camera_count_distribution = Counter()
    folders_by_valid_camera_count = defaultdict(list)

    episode_details = []
    failed_folders = []

    with ProcessPoolExecutor(max_workers=args.workers) as executor:
        futures = [
            executor.submit(
                process_one_image_pkl,
                str(image_pkl_path),
                str(source_root),
            )
            for image_pkl_path in image_pkl_paths
        ]

        for future in tqdm(
            as_completed(futures),
            total=len(futures),
            desc="Inspecting episodes",
        ):
            result = future.result()

            if result["success"]:
                result.pop("success")

                num_valid_cameras = result["num_valid_cameras"]
                folder = result["folder"]

                valid_camera_count_distribution[num_valid_cameras] += 1
                folders_by_valid_camera_count[num_valid_cameras].append(folder)
                episode_details.append(result)

            else:
                result.pop("success")
                failed_folders.append(result)

    # Parallel workers finish in arbitrary order, so sort the results.
    episode_details.sort(key=lambda item: item["folder"])
    failed_folders.sort(key=lambda item: item["folder"])

    for folders in folders_by_valid_camera_count.values():
        folders.sort()

    output = {
        "source_root": str(source_root),
        "workers": args.workers,
        "total_folders_with_image_pkl": len(image_pkl_paths),
        "successfully_processed_folders": len(episode_details),
        "failed_folders_count": len(failed_folders),
        "valid_camera_count_distribution": {
            str(num_cameras): folder_count
            for num_cameras, folder_count in sorted(
                valid_camera_count_distribution.items()
            )
        },
        "folders_by_valid_camera_count": {
            str(num_cameras): folders
            for num_cameras, folders in sorted(
                folders_by_valid_camera_count.items()
            )
        },
        "episode_details": episode_details,
        "failed_folders": failed_folders,
    }

    output_path.parent.mkdir(parents=True, exist_ok=True)

    with open(output_path, "w", encoding="utf-8") as f:
        json.dump(output, f, indent=2, ensure_ascii=False)

    print("\nValid camera count distribution:")

    for num_cameras, folder_count in sorted(
        valid_camera_count_distribution.items()
    ):
        print(
            f"  {num_cameras} non-empty camera(s): "
            f"{folder_count} folder(s)"
        )

    print(f"\nSuccessfully processed: {len(episode_details)}")
    print(f"Failed: {len(failed_folders)}")
    print(f"Output saved to: {output_path}")


if __name__ == "__main__":
    main()