#!/usr/bin/python3

# Copyright Security Onion Solutions LLC and/or licensed to Security Onion Solutions LLC under one
# or more contributor license agreements. Licensed under the Elastic License 2.0 as shown at
# https://securityonion.net/license; you may not use this file except in compliance with the
# Elastic License 2.0.

"""
Script to modify hardware parameters of a KVM virtual machine.

Usage:
    python so-kvm-modify-hardware.py -v <vm_name> [-c <cpu_count>] [-m <memory_amount>] [-p <pci_id>] [-s]

Example:
    python so-kvm-modify-hardware.py -v my_vm -c 4 -m 8192 -p 0000:00:1f.2 -s
"""

import argparse
import sys
import libvirt
import logging
import xml.etree.ElementTree as ET
from so_vm_utils import start_vm, stop_vm
from so_logging_utils import setup_logging

def parse_arguments():
    parser = argparse.ArgumentParser(description='Modify hardware parameters of a KVM virtual machine.')
    parser.add_argument('-v', '--vm', required=True, help='Name of the virtual machine to modify.')
    parser.add_argument('-c', '--cpu', type=int, help='Number of virtual CPUs to assign.')
    parser.add_argument('-m', '--memory', type=int, help='Amount of memory to assign in MiB.')
    parser.add_argument('-p', '--pci', help='PCI hardware ID to passthrough to the VM (e.g., 0000:00:1f.2).')
    parser.add_argument('-s', '--start', action='store_true', help='Start the VM after modification.')
    args = parser.parse_args()
    return args

def modify_vm(dom, cpu_count, memory_amount, pci_id, logger):
    try:
        # Get the XML description of the VM
        xml_desc = dom.XMLDesc()
        root = ET.fromstring(xml_desc)

        # Modify CPU count
        if cpu_count is not None:
            vcpu_elem = root.find('./vcpu')
            if vcpu_elem is not None:
                vcpu_elem.text = str(cpu_count)
                logger.info(f"Set CPU count to {cpu_count}.")
            else:
                logger.error("Could not find <vcpu> element in XML.")
                sys.exit(1)

        # Modify memory amount
        if memory_amount is not None:
            memory_elem = root.find('./memory')
            current_memory_elem = root.find('./currentMemory')
            if memory_elem is not None and current_memory_elem is not None:
                memory_elem.text = str(memory_amount * 1024)  # Convert MiB to KiB
                current_memory_elem.text = str(memory_amount * 1024)
                logger.info(f"Set memory to {memory_amount} MiB.")
            else:
                logger.error("Could not find <memory> elements in XML.")
                sys.exit(1)

        # Add PCI device passthrough
        if pci_id is not None:
            devices_elem = root.find('./devices')
            if devices_elem is not None:
                hostdev_elem = ET.SubElement(devices_elem, 'hostdev', attrib={
                    'mode': 'subsystem',
                    'type': 'pci',
                    'managed': 'yes'
                })
                source_elem = ET.SubElement(hostdev_elem, 'source')
                domain_id, bus_slot_func = pci_id.split(':')
                bus_slot, function = bus_slot_func.split('.')
                address_attrs = {
                    'domain': f'0x{domain_id}',
                    'bus': f'0x{bus_slot}',
                    'slot': f'0x{bus_slot}',
                    'function': f'0x{function}'
                }
                ET.SubElement(source_elem, 'address', attrib=address_attrs)
                logger.info(f"Added PCI device passthrough for {pci_id}.")
            else:
                logger.error("Could not find <devices> element in XML.")
                sys.exit(1)

        # Convert XML back to string
        new_xml_desc = ET.tostring(root, encoding='unicode')
        return new_xml_desc
    except Exception as e:
        logger.error(f"Failed to modify VM XML: {e}")
        sys.exit(1)

def redefine_vm(conn, new_xml_desc, logger):
    try:
        conn.defineXML(new_xml_desc)
        logger.info("VM redefined with new hardware parameters.")
    except libvirt.libvirtError as e:
        logger.error(f"Failed to redefine VM: {e}")
        sys.exit(1)

def main():
    # Set up logging using the so_logging_utils library
    logger = setup_logging(
        logger_name='so-kvm-modify-hardware',
        log_file_path='/opt/so/log/hypervisor/so-kvm-modify-hardware.log',
        log_level=logging.INFO,
        format_str='%(asctime)s - %(levelname)s - %(message)s'
    )

    try:
        args = parse_arguments()

        vm_name = args.vm
        cpu_count = args.cpu
        memory_amount = args.memory
        pci_id = args.pci
        start_vm_flag = args.start

        # Connect to libvirt
        try:
            conn = libvirt.open(None)
        except libvirt.libvirtError as e:
            logger.error(f"Failed to open connection to libvirt: {e}")
            sys.exit(1)

        # Stop VM if running
        dom = stop_vm(conn, vm_name, logger)

        # Modify VM XML
        new_xml_desc = modify_vm(dom, cpu_count, memory_amount, pci_id, logger)

        # Redefine VM
        redefine_vm(conn, new_xml_desc, logger)

        # Start VM if -s or --start argument is provided
        if start_vm_flag:
            dom = conn.lookupByName(vm_name)
            start_vm(dom, logger)
        else:
            logger.info("VM start flag not provided; VM will remain stopped.")

        # Close connection
        conn.close()
    except KeyboardInterrupt:
        logger.error("Operation cancelled by user.")
        sys.exit(1)
    except Exception as e:
        logger.error(f"An error occurred: {e}")
        sys.exit(1)

if __name__ == '__main__':
    main()