# Copyright 2023 VyOS maintainers and contributors <maintainers@vyos.io>
#
# This library is free software; you can redistribute it and/or
# modify it under the terms of the GNU Lesser General Public
# License as published by the Free Software Foundation; either
# version 2.1 of the License, or (at your option) any later version.
#
# This library is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
# Lesser General Public License for more details.
#
# You should have received a copy of the GNU Lesser General Public
# License along with this library.  If not, see <http://www.gnu.org/licenses/>.

import os

def get_protocol_by_name(protocol_name):
    """Get protocol number by protocol name

       % get_protocol_by_name('tcp')
       % 6
    """
    import socket
    try:
        protocol_number = socket.getprotobyname(protocol_name)
        return protocol_number
    except socket.error:
        return protocol_name

def interface_exists_in_netns(interface_name, netns):
    from vyos.utils.process import rc_cmd
    rc, out = rc_cmd(f'ip netns exec {netns} ip link show dev {interface_name}')
    if rc == 0:
        return True
    return False

def get_interface_vrf(interface):
    """ Returns VRF of given interface """
    from vyos.utils.dict import dict_search
    from vyos.utils.network import get_interface_config
    tmp = get_interface_config(interface)
    if dict_search('linkinfo.info_slave_kind', tmp) == 'vrf':
        return tmp['master']
    return 'default'

def get_interface_config(interface):
    """ Returns the used encapsulation protocol for given interface.
        If interface does not exist, None is returned.
    """
    if not os.path.exists(f'/sys/class/net/{interface}'):
        return None
    from json import loads
    from vyos.utils.process import cmd
    tmp = loads(cmd(f'ip --detail --json link show dev {interface}'))[0]
    return tmp

def get_interface_address(interface):
    """ Returns the used encapsulation protocol for given interface.
        If interface does not exist, None is returned.
    """
    if not os.path.exists(f'/sys/class/net/{interface}'):
        return None
    from json import loads
    from vyos.utils.process import cmd
    tmp = loads(cmd(f'ip --detail --json addr show dev {interface}'))[0]
    return tmp

def get_interface_namespace(iface):
    """
       Returns wich netns the interface belongs to
    """
    from json import loads
    from vyos.utils.process import cmd
    # Check if netns exist
    tmp = loads(cmd(f'ip --json netns ls'))
    if len(tmp) == 0:
        return None

    for ns in tmp:
        netns = f'{ns["name"]}'
        # Search interface in each netns
        data = loads(cmd(f'ip netns exec {netns} ip --json link show'))
        for tmp in data:
            if iface == tmp["ifname"]:
                return netns


def is_wwan_connected(interface):
    """ Determine if a given WWAN interface, e.g. wwan0 is connected to the
    carrier network or not """
    import json
    from vyos.utils.process import cmd

    if not interface.startswith('wwan'):
        raise ValueError(f'Specified interface "{interface}" is not a WWAN interface')

    # ModemManager is required for connection(s) - if service is not running,
    # there won't be any connection at all!
    if not is_systemd_service_active('ModemManager.service'):
        return False

    modem = interface.lstrip('wwan')

    tmp = cmd(f'mmcli --modem {modem} --output-json')
    tmp = json.loads(tmp)

    # return True/False if interface is in connected state
    return dict_search('modem.generic.state', tmp) == 'connected'

def get_bridge_fdb(interface):
    """ Returns the forwarding database entries for a given interface """
    if not os.path.exists(f'/sys/class/net/{interface}'):
        return None
    from json import loads
    from vyos.utils.process import cmd
    tmp = loads(cmd(f'bridge -j fdb show dev {interface}'))
    return tmp

def get_all_vrfs():
    """ Return a dictionary of all system wide known VRF instances """
    from json import loads
    from vyos.utils.process import cmd
    tmp = loads(cmd('ip --json vrf list'))
    # Result is of type [{"name":"red","table":1000},{"name":"blue","table":2000}]
    # so we will re-arrange it to a more nicer representation:
    # {'red': {'table': 1000}, 'blue': {'table': 2000}}
    data = {}
    for entry in tmp:
        name = entry.pop('name')
        data[name] = entry
    return data

def mac2eui64(mac, prefix=None):
    """
    Convert a MAC address to a EUI64 address or, with prefix provided, a full
    IPv6 address.
    Thankfully copied from https://gist.github.com/wido/f5e32576bb57b5cc6f934e177a37a0d3
    """
    import re
    from ipaddress import ip_network
    # http://tools.ietf.org/html/rfc4291#section-2.5.1
    eui64 = re.sub(r'[.:-]', '', mac).lower()
    eui64 = eui64[0:6] + 'fffe' + eui64[6:]
    eui64 = hex(int(eui64[0:2], 16) ^ 2)[2:].zfill(2) + eui64[2:]

    if prefix is None:
        return ':'.join(re.findall(r'.{4}', eui64))
    else:
        try:
            net = ip_network(prefix, strict=False)
            euil = int('0x{0}'.format(eui64), 16)
            return str(net[euil])
        except:  # pylint: disable=bare-except
            return

def check_port_availability(ipaddress, port, protocol):
    """
    Check if port is available and not used by any service
    Return False if a port is busy or IP address does not exists
    Should be used carefully for services that can start listening
    dynamically, because IP address may be dynamic too
    """
    from socketserver import TCPServer, UDPServer
    from ipaddress import ip_address

    # verify arguments
    try:
        ipaddress = ip_address(ipaddress).compressed
    except:
        raise ValueError(f'The {ipaddress} is not a valid IPv4 or IPv6 address')
    if port not in range(1, 65536):
        raise ValueError(f'The port number {port} is not in the 1-65535 range')
    if protocol not in ['tcp', 'udp']:
        raise ValueError(f'The protocol {protocol} is not supported. Only tcp and udp are allowed')

    # check port availability
    try:
        if protocol == 'tcp':
            server = TCPServer((ipaddress, port), None, bind_and_activate=True)
        if protocol == 'udp':
            server = UDPServer((ipaddress, port), None, bind_and_activate=True)
        server.server_close()
    except Exception as e:
        # errno.h:
        #define EADDRINUSE  98  /* Address already in use */
        if e.errno == 98:
            return False

    return True

def is_listen_port_bind_service(port: int, service: str) -> bool:
    """Check if listen port bound to expected program name
    :param port: Bind port
    :param service: Program name
    :return: bool

    Example:
        % is_listen_port_bind_service(443, 'nginx')
        True
        % is_listen_port_bind_service(443, 'ocserv-main')
        False
    """
    from psutil import net_connections as connections
    from psutil import Process as process
    for connection in connections():
        addr = connection.laddr
        pid = connection.pid
        pid_name = process(pid).name()
        pid_port = addr.port
        if service == pid_name and port == pid_port:
            return True
    return False