import argparse
import os
import subprocess
import sys
from pyroute2 import IPRoute, NetNS

class NetworkNamespaceManager:
    """
    Provides functionalities to manage network namespaces.

    Network namespaces partition network resources such as network links,
    IP addresses, and port numbers into disjoint sets.
    """

    @staticmethod
    def list_netns():
        """
        List all available network namespaces.

        Scans the '/var/run/netns' directory and prints out all 
        the network namespace files present. If no namespaces are found, it 
        prints a message indicating that.
        """
        netns_dir = "/var/run/netns"
        try:
            netns_files = os.listdir(netns_dir)
            if netns_files:
                print("List of available network namespaces:")
                for netns_file in netns_files:
                    print(f"- {netns_file}")
            else:
                print("No network namespaces found.")
        except OSError as e:
            print(f"Error listing network namespaces: {e}")

class ContainerNetnsExposer:
    """
    Responsible for exposing network namespaces of containers.

    Supports Docker, LXC, LXD, and Incus containers, allowing the user to interact 
    with their network namespaces.
    """

    def __init__(self):
        """
        Initializes the ContainerNetnsExposer instance.
        """
        self.netns_pid = None
        self.netns_path = None

    def expose_container_netns(self, container_id_or_name, container_type='docker'):
        """
        Expose the network namespace of a specified container.

        Parameters:
            container_id_or_name (str): The identifier or name of the container.
            container_type (str): The type of the container ('docker', 'lxc', 'lxd', or 'incus').

        Returns:
            str: The PID of the container as a string.

        Raises:
            SystemExit: If the container type is unsupported or if there is an error 
            in retrieving the container's PID.
        """
        if container_type == 'docker':
            self.get_docker_container_pid(container_id_or_name)
        elif container_type in ('lxc', 'lxd', 'incus'):
            self.get_lxc_container_pid(container_id_or_name, container_type)
        else:
            print("Unsupported container type. Only 'docker', 'lxc', 'lxd', and 'incus' are supported.")
            sys.exit(1)

        self.create_netns_directory()
        self.create_or_remove_netns_symlink()
        return str(self.netns_pid)

    def get_docker_container_pid(self, container_id_or_name):
        """
        Retrieve the PID of a Docker container.

        Parameters:
            container_id_or_name (str): The identifier or name of the Docker container.

        Raises:
            SystemExit: If there is an error in retrieving the Docker container's PID.
        """
        try:
            self.netns_pid = subprocess.check_output(
                ["sudo", "docker", "inspect", "-f", "{{.State.Pid}}", container_id_or_name],
                universal_newlines=True
            ).strip()
        except subprocess.CalledProcessError:
            print("Error retrieving Docker container PID. Make sure the container exists and is running.")
            sys.exit(1)

    def get_lxc_container_pid(self, container_name, container_type='lxc'):
        """
        Retrieve the PID of an LXC, LXD, or Incus container.

        Parameters:
            container_name (str): The name of the container.
            container_type (str): The type of the container ('lxc', 'lxd', or 'incus').

        Raises:
            SystemExit: If there is an error in retrieving the container's PID.
        """
        try:
            if container_type == 'lxc':
                output = subprocess.check_output(
                    ["lxc-info", "-n", container_name, "-p"],
                    universal_newlines=True
                )
                self.netns_pid = output.strip().split()[-1]
            elif container_type == 'lxd':
                output = subprocess.check_output(
                    ["sudo", "lxc", "info", container_name],
                    universal_newlines=True
                )
                for line in output.splitlines():
                    if line.strip().startswith("PID:"):
                        self.netns_pid = line.split(':')[1].strip()
                        break
                else:
                    print(f"PID not found in 'lxc info' output for container '{container_name}'.")
                    sys.exit(1)
            elif container_type == 'incus':
                output = subprocess.check_output(
                    ["sudo", "incus", "info", container_name],
                    universal_newlines=True
                )
                for line in output.splitlines():
                    if line.strip().startswith("PID:"):
                        self.netns_pid = line.split(':')[1].strip()
                        break
                else:
                    print(f"PID not found in 'incus info' output for container '{container_name}'.")
                    sys.exit(1)
        except subprocess.CalledProcessError as e:
            print(f"Error retrieving {container_type.upper()} container PID for '{container_name}'. Error: {e}")
            sys.exit(1)

    def create_netns_directory(self):
        """
        Create the network namespace directory if it does not exist.

        Ensures that the directory '/var/run/netns' exists, which is used
        to store network namespace symlinks.
        """
        try:
            subprocess.run(["sudo", "mkdir", "-p", "/var/run/netns"], check=True)
        except subprocess.CalledProcessError as e:
            print(f"Error creating network namespace directory: {e.stderr.strip()}")
            sys.exit(1)

    def create_or_remove_netns_symlink(self):
        """
        Create or remove a symlink to the network namespace of a container.

        Sets up a symlink in '/var/run/netns', pointing to the network namespace 
        of the container identified by its PID. If a symlink with the same name 
        already exists, it is removed before creating a new one.
        """
        self.netns_path = f"/var/run/netns/{self.netns_pid}"

        try:
            if os.path.exists(self.netns_path):
                subprocess.run(["sudo", "rm", "-rf", self.netns_path], check=True)
            subprocess.run(["sudo", "ln", "-s", f"/proc/{self.netns_pid}/ns/net", self.netns_path], check=True)
        except subprocess.CalledProcessError as e:
            print(f"Error creating or removing symlink: {e}")
            sys.exit(1)

class IfaceManager:
    """
    Manages network interfaces, including creation, deletion, and configuration
    of veth pairs, VLANs, and bridges.
    """

    def delete(self, iface_name, namespace=None):
        """
        Delete a network interface.

        Parameters:
            iface_name (str): The name of the interface to delete.
            namespace (str, optional): The network namespace where the interface exists.

        Raises:
            Exception: If the interface cannot be deleted.
        """
        try:
            if namespace:
                context_manager = NetNS(namespace)
            else:
                context_manager = IPRoute()

            with context_manager as ns:
                iface_idx_list = ns.link_lookup(ifname=iface_name)
                if not iface_idx_list:
                    raise ValueError(f"Interface {iface_name} not found.")
                iface_idx = iface_idx_list[0]
                ns.link('del', index=iface_idx)
        except Exception as e:
            print(f"Error deleting interface {iface_name} in namespace {namespace}: {e}")

    def create_veth(self, iface1, iface2, namespace=None):
        """
        Create a veth pair.

        Parameters:
            iface1 (str): The name of the first interface.
            iface2 (str): The name of the second interface.
            namespace (str, optional): The network namespace where to create the veth pair.

        Raises:
            Exception: If the veth pair cannot be created.
        """
        try:
            if namespace:
                context_manager = NetNS(namespace)
            else:
                context_manager = IPRoute()

            with context_manager as ns:
                ns.link('add', ifname=iface1, peer={'ifname': iface2}, kind='veth')
        except Exception as e:
            print(f"Error creating veth pair {iface1} and {iface2}: {e}")

    def create_vlan(self, base_iface, vlan_id, namespace=None):
        """
        Create a VLAN interface.

        Parameters:
            base_iface (str): The base interface name.
            vlan_id (int): The VLAN ID.
            namespace (str, optional): The network namespace where to create the VLAN interface.

        Raises:
            Exception: If the VLAN interface cannot be created.
        """
        try:
            if namespace:
                context_manager = NetNS(namespace)
            else:
                context_manager = IPRoute()

            with context_manager as ns:
                base_iface_idx_list = ns.link_lookup(ifname=base_iface)
                if not base_iface_idx_list:
                    raise ValueError(f"Base interface {base_iface} not found.")
                base_iface_idx = base_iface_idx_list[0]

                vlan_iface = f"{base_iface}.{vlan_id}"
                ns.link('add', ifname=vlan_iface, link=base_iface_idx, kind='vlan', vlan_info={'id': vlan_id})
        except Exception as e:
            print(f"Error creating VLAN on interface {base_iface}: {e}")

    def create_bridge(self, bridge_name, namespace=None):
        """
        Create a bridge interface.

        Parameters:
            bridge_name (str): The name of the bridge.
            namespace (str, optional): The network namespace where to create the bridge.

        Raises:
            Exception: If the bridge cannot be created.
        """
        try:
            if namespace:
                context_manager = NetNS(namespace)
            else:
                context_manager = IPRoute()

            with context_manager as ns:
                ns.link('add', ifname=bridge_name, kind='bridge')
        except Exception as e:
            print(f"Error creating bridge {bridge_name}: {e}")

    def move(self, iface, namespace):
        """
        Move a network interface to another namespace.

        Parameters:
            iface (str): The interface name to move.
            namespace (str): The target network namespace.

        Raises:
            Exception: If the interface cannot be moved.
        """
        try:
            ipr = IPRoute()
            idx_list = ipr.link_lookup(ifname=iface)
            if not idx_list:
                raise ValueError(f"Interface {iface} not found.")
            idx = idx_list[0]
            ipr.link('set', index=idx, net_ns_fd=namespace)
        except Exception as e:
            print(f"Error moving interface {iface} to namespace {namespace}: {e}")

    def set_interface_up(self, iface_name, namespace=None):
        """
        Set a network interface up.

        Parameters:
            iface_name (str): The name of the interface.
            namespace (str, optional): The network namespace where the interface exists.

        Raises:
            Exception: If the interface cannot be set up.
        """
        try:
            if namespace:
                context_manager = NetNS(namespace)
            else:
                context_manager = IPRoute()

            with context_manager as ns:
                iface_idx_list = ns.link_lookup(ifname=iface_name)
                if not iface_idx_list:
                    raise ValueError(f"Interface {iface_name} not found.")
                iface_idx = iface_idx_list[0]
                ns.link("set", index=iface_idx, state="up")
        except Exception as e:
            print(f"Error setting up interface {iface_name} in namespace {namespace}: {e}")

    def attach_to_bridge(self, iface_name, bridge_name, namespace=None):
        """
        Attach an interface to a bridge.

        Parameters:
            iface_name (str): The name of the interface.
            bridge_name (str): The name of the bridge.
            namespace (str, optional): The network namespace where the interface and bridge exist.

        Raises:
            Exception: If the interface cannot be attached to the bridge.
        """
        try:
            if namespace:
                context_manager = NetNS(namespace)
            else:
                context_manager = IPRoute()

            with context_manager as ns:
                iface_idx_list = ns.link_lookup(ifname=iface_name)
                if not iface_idx_list:
                    raise ValueError(f"Interface {iface_name} not found.")
                iface_idx = iface_idx_list[0]

                bridge_idx_list = ns.link_lookup(ifname=bridge_name)
                if not bridge_idx_list:
                    raise ValueError(f"Bridge {bridge_name} not found.")
                bridge_idx = bridge_idx_list[0]

                ns.link("set", index=iface_idx, master=bridge_idx)
        except Exception as e:
            print(f"Error attaching interface {iface_name} to bridge {bridge_name} in namespace {namespace}: {e}")

def interpret_namespace(namespace_arg):
    """
    Interpret the namespace argument.

    If the argument is '1', converts it to None (representing the default namespace),
    otherwise returns the argument as is.

    Parameters:
        namespace_arg (str): The namespace argument.

    Returns:
        str or None: The interpreted namespace.
    """
    return None if namespace_arg == '1' else namespace_arg

def main():
    parser = argparse.ArgumentParser(description="Create veth pairs between containers with optional bridge attachment.")
    parser.add_argument("-ns1", "--namespace1", default=None, help="Name of the first namespace or container, or '1' for the default namespace.")
    parser.add_argument("-ns2", "--namespace2", default=None, help="Name of the second namespace or container, or '1' for the default namespace.")
    parser.add_argument("-n1", "--name1", required=True, help="Name of the first veth interface.")
    parser.add_argument("-n2", "--name2", required=True, help="Name of the second veth interface.")
    parser.add_argument("-b1", "--bridge1", default=None, help="Name of the network bridge for ns1.")
    parser.add_argument("-b2", "--bridge2", default=None, help="Name of the network bridge for ns2.")
    parser.add_argument("-t1", "--type1", default=None, help="Container type for ns1 ('docker', 'lxc', 'lxd', 'incus', or 'None' for the default namespace).")
    parser.add_argument("-t2", "--type2", default=None, help="Container type for ns2 ('docker', 'lxc', 'lxd', 'incus', or 'None' for the default namespace).")

    args = parser.parse_args()

    # Processing namespace arguments and container types
    ns1, type1 = interpret_namespace(args.namespace1), args.type1
    ns2, type2 = interpret_namespace(args.namespace2), args.type2

    # Instantiate management classes
    iface_manager = IfaceManager()
    container_exposer = ContainerNetnsExposer()

    # Expose container network namespaces if applicable
    if type1 and ns1:
        ns1_pid = container_exposer.expose_container_netns(ns1, type1)
        ns1 = ns1_pid
    if type2 and ns2:
        ns2_pid = container_exposer.expose_container_netns(ns2, type2)
        ns2 = ns2_pid

    # Create veth pair
    iface_manager.create_veth(args.name1, args.name2)

    # Move ends of the veth pair to appropriate namespaces if required
    if ns1:
        iface_manager.move(args.name1, ns1)
    if ns2:
        iface_manager.move(args.name2, ns2)

    # Optional: Attach to network bridge and bring interfaces up
    if args.bridge1 and args.name1:
        iface_manager.attach_to_bridge(args.name1, args.bridge1, ns1)
        iface_manager.set_interface_up(args.name1, ns1)
    if args.bridge2 and args.name2:
        iface_manager.attach_to_bridge(args.name2, args.bridge2, ns2)
        iface_manager.set_interface_up(args.name2, ns2)

    # Bring up interfaces if not already up
    if not args.bridge1 and args.name1:
        iface_manager.set_interface_up(args.name1, ns1)
    if not args.bridge2 and args.name2:
        iface_manager.set_interface_up(args.name2, ns2)

if __name__ == "__main__":
    main()