#!/usr/bin/env python3
import os
import time
import inspect
import torch
from huggingface_hub import hf_hub_download
from safetensors.torch import load_file

from lerobot.policies.smolvla.modeling_smolvla import SmolVLAPolicy
from lerobot.cameras.opencv.configuration_opencv import OpenCVCameraConfig
from lerobot.policies.utils import build_inference_frame, make_robot_action
from lerobot.robots.so101_follower import SO101FollowerConfig, SO101Follower
from lerobot.processor import PolicyProcessorPipeline
from lerobot.datasets.utils import hw_to_dataset_features

# -------------------------
# CONFIG
# -------------------------
MODEL_ID = "lerobot/smolvla_base"
DEVICE = "cuda" if torch.cuda.is_available() else "cpu"

FOLLOWER_PORT = "/dev/ttyACM3"

TOP_CAM_INDEX = 4
WRIST_CAM_INDEX = 9

TASK = "Pick up the red block."
ROBOT_TYPE = "so101_follower"

FPS = 10
EPISODE_SECONDS = 5.0

BUFFER = "so100"  # or "so100-blue" / "so100-red"
os.environ.setdefault("TOKENIZERS_PARALLELISM", "false")


def hw_to_dataset_features_compat(hw_feats, prefix: str, use_videos: bool = True):
    sig = inspect.signature(hw_to_dataset_features)
    params = sig.parameters

    if "use_videos" in params:
        return hw_to_dataset_features(hw_feats, prefix, use_videos=use_videos)
    if "use_images" in params:
        return hw_to_dataset_features(hw_feats, prefix, use_images=use_videos)
    if len(params) >= 3:
        return hw_to_dataset_features(hw_feats, prefix, use_videos)
    return hw_to_dataset_features(hw_feats, prefix)


# -------------------------
# Load pretrained model
# -------------------------
print("[INFO] Loading SmolVLA...")
policy = SmolVLAPolicy.from_pretrained(MODEL_ID).to(DEVICE)
policy.eval()

# -------------------------
# Load pretrained preprocessor
# -------------------------
print("[INFO] Loading pretrained preprocessor...")
preprocess = PolicyProcessorPipeline.from_pretrained(
    MODEL_ID,
    config_filename="policy_preprocessor.json",
    overrides={"device_processor": {"device": DEVICE}},
)

# -------------------------
# Load pretrained action stats
# -------------------------
print("[INFO] Loading pretrained action stats...")
state_path = hf_hub_download(
    repo_id=MODEL_ID,
    filename="policy_postprocessor_step_0_unnormalizer_processor.safetensors",
)
state = load_file(state_path)

mean = state[f"{BUFFER}.buffer.action.mean"].to(DEVICE)
std = state[f"{BUFFER}.buffer.action.std"].to(DEVICE)

print(f"[INFO] Action dim = {mean.numel()}")


def decode_action(action_norm: torch.Tensor) -> torch.Tensor:
    return action_norm * std + mean


# -------------------------
# Setup cameras
# -------------------------
camera_cfg = {
    "camera1": OpenCVCameraConfig(index_or_path=TOP_CAM_INDEX, width=640, height=480, fps=30),
    "camera2": OpenCVCameraConfig(index_or_path=WRIST_CAM_INDEX, width=640, height=480, fps=30),
}

# -------------------------
# Setup robot
# -------------------------
print("[INFO] Connecting SO101 follower...")
robot_cfg = SO101FollowerConfig(
    port=FOLLOWER_PORT,
    id="so101_follower_arm",
    cameras=camera_cfg,
)
robot = SO101Follower(robot_cfg)
robot.connect()

# -------------------------
# Build ds_features (used by build_inference_frame AND make_robot_action)
# -------------------------
USE_VIDEOS = True
action_features = hw_to_dataset_features_compat(robot.action_features, "action", use_videos=USE_VIDEOS)
obs_features = hw_to_dataset_features_compat(robot.observation_features, "observation", use_videos=USE_VIDEOS)
ds_features = {**obs_features, **action_features}

# Sanity: make_robot_action expects ds_features["action"]["names"]
assert "action" in ds_features and "names" in ds_features["action"], f"ds_features['action'] missing names: {ds_features.get('action')}"

# -------------------------
# Control loop
# -------------------------
dt = 1.0 / FPS
t_end = time.time() + EPISODE_SECONDS

print("[INFO] Starting evaluation...")
policy.reset()

try:
    while time.time() < t_end:
        t0 = time.time()

        obs = robot.get_observation()

        obs_frame = build_inference_frame(
            observation=obs,
            ds_features=ds_features,
            device=DEVICE,
            task=TASK,
            robot_type=ROBOT_TYPE,
        )

        batch = preprocess(obs_frame)

        with torch.no_grad():
            action_norm = policy.select_action(batch)  # (1, A)

        action_real = decode_action(action_norm).squeeze(0)

        # ✅ FIX: pass ds_features, not robot.action_features
        robot_action = make_robot_action(action_real, ds_features)
        robot.send_action(robot_action)

        time.sleep(max(0.0, dt - (time.time() - t0)))

except KeyboardInterrupt:
    print("\n[INFO] Ctrl+C received.")

finally:
    try:
        robot.disconnect()
    except Exception:
        pass
    print("[INFO] Done.")