class VPCDiscoveryMixin:
    """
    Mixin for VPC discovery and management operations.
    """
    def discover_existing_vpcs(self):
        """Discover existing VPCs in the account"""
        # In real implementation, this would query AWS EC2 API
        # For now, return mock data
        return {
            'vpc-default-12345': {
                'vpc_id': 'vpc-default-12345',
                'cidr_block': '172.31.0.0/16',
                'is_default': True,
                'state': 'available'
            }
        }
    
    def get_vpc_details(self, vpc_id: str):
        """Get detailed information about a specific VPC"""
        # Mock implementation
        return {
            'vpc_id': vpc_id,
            'cidr_block': '10.0.0.0/16',
            'state': 'available',
            'is_default': False,
            'instance_tenancy': 'default',
            'dns_support': True,
            'dns_hostnames': True,
            'subnets': [
                {
                    'subnet_id': 'subnet-12345',
                    'cidr_block': '10.0.1.0/24',
                    'availability_zone': 'us-east-1a',
                    'map_public_ip_on_launch': True
                }
            ],
            'internet_gateways': ['igw-12345'],
            'route_tables': ['rtb-12345'],
            'tags': {}
        }
    
    def find_vpc_by_name(self, name: str):
        """Find VPC by name tag"""
        # Mock implementation
        return None
    
    def get_available_azs(self):
        """Get available availability zones in the region"""
        # Mock implementation
        return ['us-east-1a', 'us-east-1b', 'us-east-1c']
    
    def validate_cidr_availability(self, cidr_block: str):
        """Check if CIDR block is available and doesn't conflict"""
        # Mock validation
        import ipaddress
        try:
            network = ipaddress.IPv4Network(cidr_block, strict=False)
            return {
                'available': True,
                'network_address': str(network.network_address),
                'broadcast_address': str(network.broadcast_address),
                'num_addresses': network.num_addresses
            }
        except ValueError as e:
            return {
                'available': False,
                'error': str(e)
            }
    
    def get_vpc_limits(self):
        """Get VPC service limits for the account"""
        return {
            'vpcs_per_region': 5,
            'subnets_per_vpc': 200,
            'route_tables_per_vpc': 200,
            'internet_gateways_per_vpc': 1,
            'nat_gateways_per_az': 5
        }