"""Visualize a synced HDF5 dataset (output of sync_image_low_dim.py) as per-demo MP4s.

For each demo, renders selected image observations side-by-side and overlays
selected low-dim observations as text on every frame.

Example:
  python visualize_synced_data.py synced.h5 --out-dir ./vis --fps 10 \
      --image-keys agentview_image oak_image \
      --overlay-keys robot0_eef_pos robot0_gripper_qpos
"""

import argparse
import os

import cv2
import h5py
import numpy as np


def format_value(v) -> str:
    arr = np.asarray(v).reshape(-1)
    if arr.size == 1:
        return f"{float(arr[0]):.3f}"
    return "[" + ", ".join(f"{float(x):.3f}" for x in arr) + "]"


def visualize_demo(
    demo_grp: h5py.Group,
    demo_name: str,
    out_dir: str,
    image_keys: list,
    fps: int,
    overlay_keys: list,
    target_size=(480, 680),
) -> None:
    print(f"Visualizing {demo_name} ({image_keys})...")
    obs = demo_grp["obs"]
    present_keys = [k for k in image_keys if k in obs]
    if not present_keys:
        print(f"  Skipping {demo_name}: none of {image_keys} in obs.")
        return
    image_stacks = [obs[k][:] for k in present_keys]
    n_frames = min(len(s) for s in image_stacks)
    if n_frames == 0:
        print(f"  Skipping {demo_name}: no frames.")
        return

    overlay_data = []
    for key in overlay_keys:
        if key not in obs:
            print(f"  Note: overlay key '{key}' not in obs, skipping.")
            continue
        overlay_data.append((key, obs[key][:]))

    target_h, per_w = target_size
    total_w = per_w * len(present_keys)
    total_h = target_h

    video_path = os.path.join(out_dir, f"{demo_name}.mp4")
    fourcc = cv2.VideoWriter_fourcc(*"mp4v")
    writer = cv2.VideoWriter(video_path, fourcc, fps, (total_w, total_h))

    for i in range(n_frames):
        panels = []
        for key, stack in zip(present_keys, image_stacks):
            frame = stack[i]
            if frame.ndim == 2:
                frame = cv2.cvtColor(frame, cv2.COLOR_GRAY2BGR)
            else:
                frame = cv2.cvtColor(frame, cv2.COLOR_RGB2BGR)
            frame = cv2.resize(frame, (per_w, target_h))
            cv2.putText(frame, key, (10, 30), cv2.FONT_HERSHEY_SIMPLEX, 1, (0, 255, 0), 2)
            panels.append(frame)
        row = np.hstack(panels)

        cv2.putText(row, f"Frame: {i}/{n_frames}", (10, target_h - 20),
                    cv2.FONT_HERSHEY_SIMPLEX, 0.7, (255, 255, 255), 2)

        # Overlay low-dim values as text (top-right, stacked)
        y = 30
        for key, data in overlay_data:
            val = data[i] if i < len(data) else data[-1]
            text = f"{key}: {format_value(val)}"
            (tw, th), _ = cv2.getTextSize(text, cv2.FONT_HERSHEY_SIMPLEX, 0.6, 2)
            x = total_w - tw - 10
            cv2.putText(row, text, (x, y), cv2.FONT_HERSHEY_SIMPLEX, 0.6,
                        (0, 200, 255), 2)
            y += th + 10

        writer.write(row)

    writer.release()
    print(f"  Saved {video_path}")


def _sort_key(name: str):
    parts = name.split("_")
    for p in reversed(parts):
        if p.isdigit():
            return (0, int(p))
    return (1, name)


def main() -> None:
    parser = argparse.ArgumentParser(description="Visualize synced HDF5 dataset as videos.")
    parser.add_argument("file", help="Path to synced HDF5 file")
    parser.add_argument("--out-dir", default="./vis", help="Output directory for videos")
    parser.add_argument("--fps", type=int, default=30)
    parser.add_argument("--image-keys", nargs="+", default=["agentview_image"],
                        help="Image observation keys to render side-by-side")
    parser.add_argument("--overlay-keys", nargs="*", default=[],
                        help="Low-dim obs keys to overlay as text on each frame")
    parser.add_argument("--target-size", type=int, nargs=2, default=[240, 680],
                        metavar=("H", "W"))
    args = parser.parse_args()

    if not os.path.exists(args.file):
        print(f"File not found: {args.file}")
        return
    os.makedirs(args.out_dir, exist_ok=True)

    with h5py.File(args.file, "r") as f:
        if "data" not in f:
            print("Invalid file: no top-level 'data' group.")
            return
        demos = sorted(f["data"].keys(), key=_sort_key)
        print(f"Found {len(demos)} demos.")
        for demo in demos:
            visualize_demo(
                f["data"][demo],
                demo,
                args.out_dir,
                args.image_keys,
                args.fps,
                args.overlay_keys,
                tuple(args.target_size),
            )
    print("Done.")


if __name__ == "__main__":
    main()