#
# This file is part of Plinth.
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU Affero General Public License as
# published by the Free Software Foundation, either version 3 of the
# License, or (at your option) any later version.
#
# This program 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 Affero General Public License for more details.
#
# You should have received a copy of the GNU Affero General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.
#

"""
Helper functions for working with network manager.
"""

import collections
from gi.repository import GLib as glib
from gi.repository import NM as nm
import logging
import socket
import struct
import uuid


logger = logging.getLogger(__name__)

CONNECTION_TYPE_NAMES = collections.OrderedDict([
    ('802-3-ethernet', 'Ethernet'),
    ('802-11-wireless', 'Wi-Fi'),
    ('pppoe', 'PPPoE')
])


class ConnectionNotFound(Exception):
    """Network connection with a given name could not be found."""
    pass


class DeviceNotFound(Exception):
    """Network device for specified operation could not be found."""
    pass


def ipv4_string_to_int(address):
    """Return an integer equivalent of a string contain IPv4 address."""
    return struct.unpack("=I", socket.inet_aton(address))[0]


def _callback(source_object, result, user_data):
    """Called when an operation is completed."""
    del source_object  # Unused
    del result  # Unused
    del user_data  # Unused


def _commit_callback(connection, error, data=None):
    """Called when the connection changes are committed."""
    del connection
    del error
    del data


def get_interface_list(device_type):
    """Get a list of network interface available on the system."""
    interfaces = {}
    for device in nm.Client.new(None).get_devices():
        if device.get_device_type() == device_type:
            interfaces[device.get_iface()] = device.get_hw_address()

    return interfaces


def get_connection_list():
    """Get a list of active and available connections."""
    active_uuids = []
    client = nm.Client.new(None)
    for connection in client.get_active_connections():
        active_uuids.append(connection.get_uuid())

    connections = []
    for connection in client.get_connections():
        # Display a friendly type name if known.
        connection_type = connection.get_connection_type()
        connection_type = CONNECTION_TYPE_NAMES.get(connection_type,
                                                    connection_type)
        connections.append({
            'name': connection.get_id(),
            'uuid': connection.get_uuid(),
            'type': connection_type,
            'is_active': connection.get_uuid() in active_uuids,
        })
    connections.sort(key=lambda connection: connection['is_active'],
                     reverse=True)
    return connections


def get_connection(connection_uuid):
    """Return connection with matching uuid.

    Raise ConnectionNotFound if a connection with that uuid is not
    found.
    """
    client = nm.Client.new(None)
    connection = client.get_connection_by_uuid(connection_uuid)
    if not connection:
        raise ConnectionNotFound(connection_uuid)

    return connection


def get_active_connection(connection_uuid):
    """Return active connection with matching UUID.

    Raise ConnectionNotFound if a connection with that uuid is not
    found.
    """
    connections = nm.Client.new(None).get_active_connections()
    connections = {connection.get_uuid(): connection
                   for connection in connections}
    try:
        return connections[connection_uuid]
    except KeyError:
        raise ConnectionNotFound(connection_uuid)


def _update_common_settings(connection, connection_uuid, name, type_, interface,
                            zone):
    """Create/edit basic settings for network manager connections.

    Return newly created connection object if connection is None.
    """
    if not connection:
        connection = nm.SimpleConnection.new()

    settings = connection.get_setting_connection()
    if not settings:
        settings = nm.SettingConnection.new()
        connection.add_setting(settings)

    settings.set_property(nm.SETTING_CONNECTION_UUID, connection_uuid)
    settings.set_property(nm.SETTING_CONNECTION_ID, name)
    settings.set_property(nm.SETTING_CONNECTION_TYPE, type_)
    settings.set_property(nm.SETTING_CONNECTION_INTERFACE_NAME, interface)
    settings.set_property(nm.SETTING_CONNECTION_ZONE, zone)

    return connection


def _update_ipv4_settings(connection, ipv4_method, ipv4_address):
    """Edit IPv4 settings for network manager connections."""
    settings = connection.get_setting_ip4_config()
    if not settings:
        settings = nm.SettingIP4Config.new()
        connection.add_setting(settings)

    settings.set_property(nm.SETTING_IP_CONFIG_METHOD, ipv4_method)
    if ipv4_method == nm.SETTING_IP4_CONFIG_METHOD_MANUAL and ipv4_address:
        ipv4_address_int = ipv4_string_to_int(ipv4_address)
        ipv4_prefix = nm.utils_ip4_get_default_prefix(ipv4_address_int)

        address = nm.IPAddress.new(socket.AF_INET, ipv4_address, ipv4_prefix)
        settings.add_address(address)

        settings.set_property(nm.SETTING_IP_CONFIG_GATEWAY, '0.0.0.0')
    else:
        settings.clear_addresses()


def _update_ethernet_settings(connection, connection_uuid, name, interface,
                              zone, ipv4_method, ipv4_address):
    """Create/edit ethernet settings for network manager connections."""
    type_ = '802-3-ethernet'

    connection = _update_common_settings(connection, connection_uuid, name,
                                         type_, interface, zone)
    _update_ipv4_settings(connection, ipv4_method, ipv4_address)

    # Ethernet
    settings = connection.get_setting_wired()
    if not settings:
        settings = nm.SettingWired.new()
        connection.add_setting(settings)

    return connection


def _update_pppoe_settings(connection, connection_uuid, name, interface, zone,
                           username, password):
    """Create/edit PPPoE settings for network manager connections."""
    type_ = 'pppoe'

    connection = _update_common_settings(connection, connection_uuid, name,
                                         type_, interface, zone)

    # PPPoE
    settings = connection.get_setting_pppoe()
    if not settings:
        settings = nm.SettingPppoe.new()
        connection.add_setting(settings)

    settings.set_property(nm.SETTING_PPPOE_USERNAME, username)
    settings.set_property(nm.SETTING_PPPOE_PASSWORD, password)

    settings = connection.get_setting_ppp()
    if not settings:
        settings = nm.SettingPpp.new()
        connection.add_setting(settings)

    # TODO: make this configurable? Some PPP peers don't respond to
    # echo requests according to NetworkManager documentation.
    settings.set_property(nm.SETTING_PPP_LCP_ECHO_FAILURE, 5)
    settings.set_property(nm.SETTING_PPP_LCP_ECHO_INTERVAL, 30)

    return connection


def add_pppoe_connection(name, interface, zone, username, password):
    """Add an automatic PPPoE connection in network manager.

    Return the UUID for the connection.
    """
    connection_uuid = str(uuid.uuid4())
    connection = _update_pppoe_settings(
        None, connection_uuid, name, interface, zone, username, password)
    client = nm.Client.new(None)
    client.add_connection_async(connection, True, None, _callback, None)
    return connection_uuid


def edit_pppoe_connection(connection, name, interface, zone, username,
                          password):
    """Edit an existing pppoe connection in network manager."""
    _update_pppoe_settings(
        connection, connection.get_uuid(), name, interface, zone, username,
        password)
    connection.commit_changes(True)


def add_ethernet_connection(name, interface, zone, ipv4_method, ipv4_address):
    """Add an automatic ethernet connection in network manager.

    Return the UUID for the connection.
    """
    connection_uuid = str(uuid.uuid4())
    connection = _update_ethernet_settings(
        None, connection_uuid, name, interface, zone, ipv4_method,
        ipv4_address)
    client = nm.Client.new(None)
    client.add_connection_async(connection, True, None, _callback, None)
    return connection_uuid


def edit_ethernet_connection(connection, name, interface, zone, ipv4_method,
                             ipv4_address):
    """Edit an existing ethernet connection in network manager."""
    _update_ethernet_settings(
        connection, connection.get_uuid(), name, interface, zone, ipv4_method,
        ipv4_address)
    connection.commit_changes(True)


def _update_wifi_settings(connection, connection_uuid, name, interface, zone,
                          ssid, mode, auth_mode, passphrase, ipv4_method,
                          ipv4_address):
    """Create/edit wifi settings for network manager connections."""
    type_ = '802-11-wireless'
    key_mgmt = 'wpa-psk'

    connection = _update_common_settings(connection, connection_uuid, name,
                                         type_, interface, zone)
    _update_ipv4_settings(connection, ipv4_method, ipv4_address)

    # Wireless
    settings = connection.get_setting_wireless()
    if not settings:
        settings = nm.SettingWireless.new()
        connection.add_setting(settings)

    ssid_gbytes = glib.Bytes.new(ssid.encode())
    settings.set_property(nm.SETTING_WIRELESS_SSID, ssid_gbytes)
    settings.set_property(nm.SETTING_WIRELESS_MODE, mode)

    # Wireless Security
    if auth_mode == 'wpa' and passphrase:
        settings = connection.get_setting_wireless_security()
        if not settings:
            settings = nm.SettingWirelessSecurity.new()
            connection.add_setting(settings)

        settings.set_property(nm.SETTING_WIRELESS_SECURITY_KEY_MGMT, key_mgmt)
        settings.set_property(nm.SETTING_WIRELESS_SECURITY_PSK, passphrase)
    else:
        connection.remove_setting(nm.SettingWirelessSecurity)

    return connection


def add_wifi_connection(name, interface, zone, ssid, mode, auth_mode,
                        passphrase, ipv4_method, ipv4_address):
    """Add an automatic Wi-Fi connection in network manager.

    Return the UUID for the connection.
    """
    connection_uuid = str(uuid.uuid4())
    connection = _update_wifi_settings(
        None, connection_uuid, name, interface, zone, ssid, mode, auth_mode,
        passphrase, ipv4_method, ipv4_address)
    client = nm.Client.new(None)
    client.add_connection_async(connection, True, None, _callback, None)
    return connection_uuid


def edit_wifi_connection(connection, name, interface, zone, ssid, mode,
                         auth_mode, passphrase, ipv4_method, ipv4_address):
    """Edit an existing wifi connection in network manager."""
    _update_wifi_settings(
        connection, connection.get_uuid(), name, interface, zone, ssid, mode,
        auth_mode, passphrase, ipv4_method, ipv4_address)
    connection.commit_changes(True)


def activate_connection(connection_uuid):
    """Find and activate a network connection."""
    connection = get_connection(connection_uuid)
    interface = connection.get_interface_name()
    client = nm.Client.new(None)
    for device in client.get_devices():
        if device.get_iface() == interface:
            client.activate_connection_async(
                connection, device, '/', None, _callback, None)
            break
    else:
        raise DeviceNotFound(connection)

    return connection


def deactivate_connection(connection_uuid):
    """Find and de-activate a network connection."""
    active_connection = get_active_connection(connection_uuid)
    nm.Client.new(None).deactivate_connection(active_connection)
    return active_connection


def delete_connection(connection_uuid):
    """Delete an exiting connection from network manager.

    Raise ConnectionNotFound if connection does not exist.
    """
    connection = get_connection(connection_uuid)
    name = connection.get_id()
    connection.delete()
    return name


def wifi_scan():
    """Scan for available access points across all Wi-Fi devices."""
    access_points = []
    for device in nm.Client.new(None).get_devices():
        if device.get_device_type() != nm.DeviceType.WIFI:
            continue

        for access_point in device.get_access_points():
            # Retrieve the bytes in SSID.  Don't convert to utf-8 or
            # escape it in any way as it may contain null bytes.  When
            # this is used in the URL it will be escaped properly and
            # unescaped when taken as view function's argument.
            ssid = access_point.get_ssid()
            ssid_string = ssid.get_data() if ssid else ''
            access_points.append({
                'ssid': ssid_string,
                'strength': access_point.get_strength()})

    return access_points