import os
import glob
import subprocess
import argparse

def restore_dataset(input_path="shards", target_path="samples", sensors_to_extract=None):
    """
    Restores the dataset from shards.
    :param sensors_to_extract: Optional list of strings. 
                               Example: ["LIDAR_TOP", "CAM_FRONT"]
    """
    # Ensure the target directory exists
    if not os.path.exists(target_path):
        os.makedirs(target_path)

    # Find all unique base names (e.g., "LIDAR_TOP.tar" from "LIDAR_TOP.tar.aa")
    all_shards = glob.glob(f"{input_path}/*.tar.*")
    tar_groups = sorted(set(f.split(".tar.")[0] for f in all_shards))

    for base in tar_groups:
        sensor_name = os.path.basename(base)
        
        # 🟢 FILTER LOGIC:
        # If the user provided a list, skip sensors not in that list
        if sensors_to_extract:
            if not any(requested in sensor_name for requested in sensors_to_extract):
                continue

        md5_file = f"{base}.md5"

        # 1. Verify MD5 integrity if the checksum file exists
        if os.path.exists(md5_file):
            print(f"🔍 Verifying integrity for {sensor_name}...")
            try:
                # We use shell=True to handle the redirection in the md5sum command
                subprocess.run(f"md5sum -c {md5_file}", shell=True, check=True)
                print(f"✨ Checksum verified for {sensor_name}.")
            except subprocess.CalledProcessError:
                print(f"⚠️ WARNING: {sensor_name} shards are corrupted! Skipping.")
                continue
        else:
            print(f"ℹ️ No MD5 file found for {sensor_name}, skipping verification.")

        # 2. Reconstruct and extract
        print(f"🔄 Restoring {sensor_name} to {target_path}...")
        
        # Check if the shards are gzipped (ending in .tar.gz.aa) or just tar (.tar.aa)
        # If 'gz' is in the filename, we add the 'z' flag to tar
        is_gz = ".gz" in base
        tar_flags = "-xzf" if is_gz else "-xf"
        
        # Command: concatenate all parts and pipe to tar
        cmd_extract = f"cat {base}.tar.* | tar {tar_flags} - -C {target_path}"
        
        try:
            subprocess.run(cmd_extract, shell=True, check=True)
            print(f"✅ {sensor_name} successfully restored.")
        except subprocess.CalledProcessError as e:
            print(f"❌ Error extracting {sensor_name}: {e}")

if __name__ == "__main__":
    # Example usage:
    # To extract everything: restore_dataset()
    # To extract only LiDAR: restore_dataset(sensors_to_extract=["LIDAR"])
    
    # Optional: Integration with command line arguments
    parser = argparse.ArgumentParser(description="Restore dataset from shards.")
    parser.add_argument("--sensors", nargs="+", help="List of sensors to extract (e.g. LIDAR NARROW)")
    args = parser.parse_args()

    restore_dataset(sensors_to_extract=args.sensors)