import sys
import logging
import argparse
from pvpn.server import main

# Configure basic logging
logging.basicConfig(level=logging.INFO, stream=sys.stdout,
                    format='%(asctime)s - %(levelname)s - %(message)s')

def start_ikev2_server_programmatically():
    """
    Demonstrates how to start a pure Python IKEv2 server using the pvpn library.
    
    NOTE ON PORT BINDING:
    IKEv2 requires binding to UDP ports 500 and 4500. On Linux, these are
    privileged ports (<1024), and binding requires root (sudo) permissions
    or special capabilities.
    
    This script will likely fail with a PermissionError (Errno 13) unless run
    with sudo, which is outside the scope of a pure Python solution in a 
    standard user environment.
    
    However, the core IKEv2 protocol and IPsec data plane logic are implemented
    in pure Python by the 'pvpn' library, fulfilling the user's request for 
    a solution *without* reliance on native Linux configurations (like XFRM).
    """
    
    # We will use the CLI entry point function 'main' and inject arguments 
    # into sys.argv, as the library is designed for command-line use.
    
    # The default ports (500/4500) are hardcoded in the library and cannot be
    # easily changed without modifying the source code.
    
    # Arguments:
    # -p: Pre-shared key (PSK) for IKEv2 authentication
    # -l: Listen address (0.0.0.0 for all interfaces)
    
    # Preserve original arguments to restore later
    original_argv = sys.argv
    
    # Set arguments for the pvpn server
    sys.argv = [
        "pvpn", 
        "-p", "MySecretPSK123",  # The Pre-Shared Key
        # The library will automatically listen on 0.0.0.0:500 and 0.0.0.0:4500
    ]
    
    print("Attempting to start pure Python IKEv2 VPN server...")
    print("PSK: MySecretPSK123")
    print("Listening on UDP ports 500 and 4500 (requires root/sudo on Linux).")
    
    try:
        # The main function runs the asyncio loop and the server indefinitely
        main()
    except PermissionError as e:
        print("\n--- ERROR ---")
        print(f"Failed to start server due to PermissionError: {e}")
        print("This is expected in a standard user environment, as ports 500/4500 are privileged.")
        print("The underlying IKEv2 implementation is pure Python, but the OS requires root for port binding.")
        print("To run this successfully, execute the script with 'sudo python3 ikev2_server_pure_python.py'.")
        print("-------------")
    except KeyboardInterrupt:
        print("\nServer stopped by user.")
    except Exception as e:
        print(f"An unexpected error occurred: {e}")
    finally:
        # Restore sys.argv
        sys.argv = original_argv

if __name__ == '__main__':

    
    uvicorn.run(
        start_ikev2_server_programmatically, 
        host="0.0.0.0", 
        port=8000, 
        log_level="info",
        reload=False  # Set to False for production
    )