import geopandas
import sys
import os
from pathlib import Path


def convert_shapefile_to_geojson(
    input_shapefile, 
    output_geojson, 
    target_crs=4326 # Convert to WGS 84
):
    """
    Main conversion function
    
    Args:
        input_shapefile: Path to input shapefile
        output_geojson: Path to output GeoJSON file
        target_crs: Target coordinate reference system
    """
    try:
        # Read shapefile
        print(f"Reading shapefile: {input_shapefile}")
        df = geopandas.read_file(input_shapefile)
        print(f"Converting to CRS {target_crs}")
        df = df.to_crs(target_crs)
        exploded = df.explode()
        exploded.to_file(output_geojson, driver='GeoJSON')
    except Exception as e:
        print(f"Error during conversion: {str(e)}")
        sys.exit(1)

def main():
    """
    Main function to handle command line arguments
    """
    import argparse
    
    parser = argparse.ArgumentParser(
        description='Convert shapefile to GeoJSON'
    )
    parser.add_argument(
        'input_shapefile', 
        help='Path to input shapefile'
    )
    parser.add_argument(
        'output_geojson', 
        help='Path to output GeoJSON file'
    )
    parser.add_argument(
        '--target-crs', 
        default='4326',
        help='Target coordinate reference system (default: 4326)'
    )
    
    args = parser.parse_args()
    
    # Validate input file
    if not os.path.exists(args.input_shapefile):
        print(f"Error: Input shapefile '{args.input_shapefile}' not found")
        sys.exit(1)
    
    # Create output directory if it doesn't exist
    output_dir = Path(args.output_geojson).parent
    output_dir.mkdir(parents=True, exist_ok=True)
    
    # Run conversion
    convert_shapefile_to_geojson(
        args.input_shapefile,
        args.output_geojson,
        args.target_crs
    )

if __name__ == "__main__":
    import pandas as pd
    main()