# Copyright 2021-2022 Google LLC
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#      https://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

# -----------------------------------------------------------------------------
# Imports
# -----------------------------------------------------------------------------
import logging
import asyncio
import itertools
import random

from .hci import *
from .l2cap import *

# -----------------------------------------------------------------------------
# Logging
# -----------------------------------------------------------------------------
logger = logging.getLogger(__name__)


# -----------------------------------------------------------------------------
# Utils
# -----------------------------------------------------------------------------
class DataObject:
    pass


# -----------------------------------------------------------------------------
class Connection:
    def __init__(self, controller, handle, role, peer_address, link):
        self.controller   = controller
        self.handle       = handle
        self.role         = role
        self.peer_address = peer_address
        self.link         = link
        self.assembler    = HCI_AclDataPacketAssembler(self.on_acl_pdu)

    def on_hci_acl_data_packet(self, packet):
        self.assembler.feed_packet(packet)
        self.controller.send_hci_packet(HCI_Number_Of_Completed_Packets_Event([(self.handle, 1)]))

    def on_acl_pdu(self, data):
        if self.link:
            self.link.send_acl_data(self.controller.random_address, self.peer_address, data)


# -----------------------------------------------------------------------------
class Controller:
    def __init__(self, name, host_source = None, host_sink = None, link = None):
        self.name     = name
        self.hci_sink = None
        self.link     = link

        self.central_connections    = {}  # Connections where this controller is the central
        self.peripheral_connections = {}  # Connections where this controller is the peripheral

        self.hci_version                  = HCI_VERSION_BLUETOOTH_CORE_5_0
        self.hci_revision                 = 0
        self.lmp_version                  = HCI_VERSION_BLUETOOTH_CORE_5_0
        self.lmp_subversion               = 0
        self.lmp_features                 = bytes.fromhex('0000000060000000')  # BR/EDR Not Supported, LE Supported (Controller)
        self.manufacturer_name            = 0xFFFF
        self.hc_le_data_packet_length     = 27
        self.hc_total_num_le_data_packets = 64
        self.supported_commands           = bytes.fromhex('2000800000c000000000e40000002822000000000000040000f7ffff7f00000030f0f9ff01008004000000000000000000000000000000000000000000000000')
        self.le_features                  = bytes.fromhex('ff49010000000000')
        self.le_states                    = bytes.fromhex('ffff3fffff030000')
        self.avertising_channel_tx_power  = 0
        self.white_list_size              = 8
        self.resolving_list_size          = 8
        self.supported_max_tx_octets      = 27
        self.supported_max_tx_time        = 10000  # microseconds
        self.supported_max_rx_octets      = 27
        self.supported_max_rx_time        = 10000  # microseconds
        self.suggested_max_tx_octets      = 27
        self.suggested_max_tx_time        = 0x0148  # microseconds
        self.default_phy                  = bytes([0, 0, 0])
        self.le_scan_type                 = 0
        self.le_scan_interval             = 0x10
        self.le_scan_window               = 0x10
        self.le_scan_enable               = 0
        self.le_scan_own_address_type     = Address.RANDOM_DEVICE_ADDRESS
        self.le_scanning_filter_policy    = 0
        self.le_scan_response_data        = None
        self.le_address_resolution        = False
        self.le_rpa_timeout               = 0
        self.sync_flow_control            = False
        self.local_name                   = 'Bumble'

        self.advertising_interval     = 2000  # Fixed for now
        self.advertising_data         = None
        self.advertising_timer_handle = None

        self._random_address = Address('00:00:00:00:00:00')
        self._public_address = None

        # Set the source and sink interfaces
        if host_source:
            host_source.set_packet_sink(self)
        self.host = host_sink

        # Add this controller to the link if specified
        if link:
            link.add_controller(self)

    @property
    def host(self):
        return self.hci_sink

    @host.setter
    def host(self, host):
        '''
        Sets the host (sink) for this controller, and set this controller as the controller (sink) for the host
        '''
        self.set_packet_sink(host)
        if host:
            host.controller = self

    def set_packet_sink(self, sink):
        '''
        Method from the Packet Source interface
        '''
        self.hci_sink = sink

    @property
    def public_address(self):
        return self._public_address

    @public_address.setter
    def public_address(self, address):
        if type(address) is str:
            address = Address(address)
        self._public_address = address

    @property
    def random_address(self):
        return self._random_address

    @random_address.setter
    def random_address(self, address):
        if type(address) is str:
            address = Address(address)
        self._random_address = address
        logger.debug(f'new random address: {address}')

        if self.link:
            self.link.on_address_changed(self)

    # Packet Sink protocol (packets coming from the host via HCI)
    def on_packet(self, packet):
        self.on_hci_packet(HCI_Packet.from_bytes(packet))

    def on_hci_packet(self, packet):
        logger.debug(f'{color("<<<", "blue")} [{self.name}] {color("HOST -> CONTROLLER", "blue")}: {packet}')

        # If the packet is a command, invoke the handler for this packet
        if packet.hci_packet_type == HCI_COMMAND_PACKET:
            self.on_hci_command_packet(packet)
        elif packet.hci_packet_type == HCI_EVENT_PACKET:
            self.on_hci_event_packet(packet)
        elif packet.hci_packet_type == HCI_ACL_DATA_PACKET:
            self.on_hci_acl_data_packet(packet)
        else:
            logger.warning(f'!!! unknown packet type {packet.hci_packet_type}')

    def on_hci_command_packet(self, command):
        handler_name = f'on_{command.name.lower()}'
        handler = getattr(self, handler_name, self.on_hci_command)
        result = handler(command)
        if type(result) is bytes:
            self.send_hci_packet(HCI_Command_Complete_Event(
                num_hci_command_packets = 1,
                command_opcode          = command.op_code,
                return_parameters       = result
            ))

    def on_hci_event_packet(self, event):
        logger.warning('!!! unexpected event packet')

    def on_hci_acl_data_packet(self, packet):
        # Look for the connection to which this data belongs
        connection = self.find_connection_by_handle(packet.connection_handle)
        if connection is None:
            logger.warning(f'!!! no connection for handle 0x{packet.connection_handle:04X}')
            return

        # Pass the packet to the connection
        connection.on_hci_acl_data_packet(packet)

    def send_hci_packet(self, packet):
        logger.debug(f'{color(">>>", "green")} [{self.name}] {color("CONTROLLER -> HOST", "green")}: {packet}')
        if self.host:
            self.host.on_packet(packet.to_bytes())

    # This method allow the controller to emulate the same API as a transport source
    async def wait_for_termination(self):
        # For now, just wait forever
        await asyncio.get_running_loop().create_future()

    ############################################################
    # Link connections
    ############################################################
    def allocate_connection_handle(self):
        handle = 0
        max_handle = 0
        for connection in itertools.chain(
            self.central_connections.values(),
            self.peripheral_connections.values()
        ):
            max_handle = max(max_handle, connection.handle)
            if connection.handle == handle:
                # Already used, continue searching after the current max
                handle = max_handle + 1
        return handle

    def find_connection_by_address(self, address):
        return self.central_connections.get(address) or self.peripheral_connections.get(address)

    def find_connection_by_handle(self, handle):
        for connection in itertools.chain(
            self.central_connections.values(),
            self.peripheral_connections.values()
        ):
            if connection.handle == handle:
                return connection
        return None

    def find_central_connection_by_handle(self, handle):
        for connection in self.central_connections.values():
            if connection.handle == handle:
                return connection
        return None

    def on_link_central_connected(self, central_address):
        '''
        Called when an incoming connection occurs from a central on the link
        '''

        # Allocate (or reuse) a connection handle
        peer_address = central_address
        peer_address_type = central_address.address_type
        connection = self.peripheral_connections.get(peer_address)
        if connection is None:
            connection_handle = self.allocate_connection_handle()
            connection = Connection(self, connection_handle, BT_PERIPHERAL_ROLE, peer_address, self.link)
            self.peripheral_connections[peer_address] = connection
            logger.debug(f'New PERIPHERAL connection handle: 0x{connection_handle:04X}')

        # Then say that the connection has completed
        self.send_hci_packet(HCI_LE_Connection_Complete_Event(
            status                = HCI_SUCCESS,
            connection_handle     = connection.handle,
            role                  = connection.role,
            peer_address_type     = peer_address_type,
            peer_address          = peer_address,
            conn_interval         = 10,  # FIXME
            conn_latency          = 0,   # FIXME
            supervision_timeout   = 10,  # FIXME
            master_clock_accuracy = 7    # FIXME
        ))

    def on_link_central_disconnected(self, peer_address, reason):
        '''
        Called when an active disconnection occurs from a peer
        '''

        # Send a disconnection complete event
        if connection := self.peripheral_connections.get(peer_address):
            self.send_hci_packet(HCI_Disconnection_Complete_Event(
                status            = HCI_SUCCESS,
                connection_handle = connection.handle,
                reason            = reason
            ))

            # Remove the connection
            del self.peripheral_connections[peer_address]
        else:
            logger.warn(f'!!! No peripheral connection found for {peer_address}')

    def on_link_peripheral_connection_complete(self, le_create_connection_command, status):
        '''
        Called by the link when a connection has been made or has failed to be made
        '''

        if status == HCI_SUCCESS:
            # Allocate (or reuse) a connection handle
            peer_address = le_create_connection_command.peer_address
            connection = self.central_connections.get(peer_address)
            if connection is None:
                connection_handle = self.allocate_connection_handle()
                connection = Connection(
                    self,
                    connection_handle,
                    BT_CENTRAL_ROLE,
                    peer_address,
                    self.link
                )
                self.central_connections[peer_address] = connection
                logger.debug(f'New CENTRAL connection handle: 0x{connection_handle:04X}')
        else:
            connection = None

        # Say that the connection has completed
        self.send_hci_packet(HCI_LE_Connection_Complete_Event(
            status                = status,
            connection_handle     = connection.handle if connection else 0,
            role                  = BT_CENTRAL_ROLE,
            peer_address_type     = le_create_connection_command.peer_address_type,
            peer_address          = le_create_connection_command.peer_address,
            conn_interval         = le_create_connection_command.conn_interval_min,
            conn_latency          = le_create_connection_command.conn_latency,
            supervision_timeout   = le_create_connection_command.supervision_timeout,
            master_clock_accuracy = 0
        ))

    def on_link_peripheral_disconnection_complete(self, disconnection_command, status):
        '''
        Called when a disconnection has been completed
        '''

        # Send a disconnection complete event
        self.send_hci_packet(HCI_Disconnection_Complete_Event(
            status            = status,
            connection_handle = disconnection_command.connection_handle,
            reason            = disconnection_command.reason
        ))

        # Remove the connection
        if connection := self.find_central_connection_by_handle(disconnection_command.connection_handle):
            logger.debug(f'CENTRAL Connection removed: {connection}')
            del self.central_connections[connection.peer_address]

    def on_link_peripheral_disconnected(self, peer_address):
        '''
        Called when a connection to a peripheral is broken
        '''

        # Send a disconnection complete event
        if connection := self.central_connections.get(peer_address):
            self.send_hci_packet(HCI_Disconnection_Complete_Event(
                status            = HCI_SUCCESS,
                connection_handle = connection.handle,
                reason            = HCI_CONNECTION_TIMEOUT_ERROR
            ))

            # Remove the connection
            del self.central_connections[peer_address]
        else:
            logger.warn(f'!!! No central connection found for {peer_address}')

    def on_link_encrypted(self, peer_address, rand, ediv, ltk):
        # For now, just setup the encryption without asking the host
        if connection := self.find_connection_by_address(peer_address):
            self.send_hci_packet(
                HCI_Encryption_Change_Event(
                    status             = 0,
                    connection_handle  = connection.handle,
                    encryption_enabled = 1
                )
            )

    def on_link_acl_data(self, sender_address, data):
        # Look for the connection to which this data belongs
        connection = self.find_connection_by_address(sender_address)
        if connection is None:
            logger.warning(f'!!! no connection for {sender_address}')
            return

        # Send the data to the host
        # TODO: should fragment
        acl_packet = HCI_AclDataPacket(connection.handle, 2, 0, len(data), data)
        self.send_hci_packet(acl_packet)

    def on_link_advertising_data(self, sender_address, data):
        # Ignore if we're not scanning
        if self.le_scan_enable == 0:
            return

        # Send a scan report
        report = HCI_Object(
            HCI_LE_Advertising_Report_Event.REPORT_FIELDS,
            event_type   = HCI_LE_Advertising_Report_Event.ADV_IND,
            address_type = sender_address.address_type,
            address      = sender_address,
            data         = data,
            rssi         = -50
        )
        self.send_hci_packet(HCI_LE_Advertising_Report_Event([report]))

        # Simulate a scan response
        report = HCI_Object(
            HCI_LE_Advertising_Report_Event.REPORT_FIELDS,
            event_type   = HCI_LE_Advertising_Report_Event.SCAN_RSP,
            address_type = sender_address.address_type,
            address      = sender_address,
            data         = data,
            rssi         = -50
        )
        self.send_hci_packet(HCI_LE_Advertising_Report_Event([report]))

    ############################################################
    # Advertising support
    ############################################################
    def on_advertising_timer_fired(self):
        self.send_advertising_data()
        self.advertising_timer_handle = asyncio.get_running_loop().call_later(self.advertising_interval / 1000.0, self.on_advertising_timer_fired)

    def start_advertising(self):
        # Stop any ongoing advertising before we start again
        self.stop_advertising()

        # Advertise now
        self.advertising_timer_handle = asyncio.get_running_loop().call_soon(self.on_advertising_timer_fired)

    def stop_advertising(self):
        if self.advertising_timer_handle is not None:
            self.advertising_timer_handle.cancel()
            self.advertising_timer_handle = None

    def send_advertising_data(self):
        if self.link and self.advertising_data:
            self.link.send_advertising_data(self.random_address, self.advertising_data)

    @property
    def is_advertising(self):
        return self.advertising_timer_handle is not None

    ############################################################
    # HCI handlers
    ############################################################
    def on_hci_command(self, command):
        logger.warning(color(f'--- Unsupported command {command}', 'red'))
        return bytes([HCI_UNKNOWN_HCI_COMMAND_ERROR])

    def on_hci_create_connection_command(self, command):
        '''
        See Bluetooth spec Vol 2, Part E - 7.1.5 Create Connection command
        '''

        # TODO: classic mode not supported yet

    def on_hci_disconnect_command(self, command):
        '''
        See Bluetooth spec Vol 2, Part E - 7.1.6 Disconnect Command
        '''
        # First, say that the disconnection is pending
        self.send_hci_packet(HCI_Command_Status_Event(
            status                  = HCI_COMMAND_STATUS_PENDING,
            num_hci_command_packets = 1,
            command_opcode          = command.op_code
        ))

        # Notify the link of the disconnection
        if not (connection := self.find_central_connection_by_handle(command.connection_handle)):
            logger.warn('connection not found')
            return

        if self.link:
            self.link.disconnect(self.random_address, connection.peer_address, command)
        else:
            # Remove the connection
            del self.central_connections[connection.peer_address]

    def on_hci_set_event_mask_command(self, command):
        '''
        See Bluetooth spec Vol 2, Part E - 7.3.1 Set Event Mask Command
        '''
        self.event_mask = command.event_mask
        return bytes([HCI_SUCCESS])

    def on_hci_reset_command(self, command):
        '''
        See Bluetooth spec Vol 2, Part E - 7.3.2 Reset Command
        '''
        # TODO: cleanup what needs to be reset
        return bytes([HCI_SUCCESS])

    def on_hci_write_local_name_command(self, command):
        '''
        See Bluetooth spec Vol 2, Part E - 7.3.11 Write Local Name Command
        '''
        local_name = command.local_name
        if len(local_name):
            try:
                first_null = local_name.find(0)
                if first_null >= 0:
                    local_name = local_name[:first_null]
                self.local_name = str(local_name, 'utf-8')
            except UnicodeDecodeError:
                pass
        return bytes([HCI_SUCCESS])

    def on_hci_read_local_name_command(self, command):
        '''
        See Bluetooth spec Vol 2, Part E - 7.3.12 Read Local Name Command
        '''
        local_name = bytes(self.local_name, 'utf-8')[:248]
        if len(local_name) < 248:
            local_name = local_name + bytes(248 - len(local_name))

        return bytes([HCI_SUCCESS]) + local_name

    def on_hci_read_class_of_device_command(self, command):
        '''
        See Bluetooth spec Vol 2, Part E - 7.3.25 Read Class of Device Command
        '''
        return bytes([HCI_SUCCESS, 0, 0, 0])

    def on_hci_write_class_of_device_command(self, command):
        '''
        See Bluetooth spec Vol 2, Part E - 7.3.26 Write Class of Device Command
        '''
        return bytes([HCI_SUCCESS])

    def on_hci_read_synchronous_flow_control_enable_command(self, command):
        '''
        See Bluetooth spec Vol 2, Part E - 7.3.36 Read Synchronous Flow Control Enable Command
        '''
        if self.sync_flow_control:
            ret = 1
        else:
            ret = 0
        return bytes([HCI_SUCCESS, ret])

    def on_hci_write_synchronous_flow_control_enable_command(self, command):
        '''
        See Bluetooth spec Vol 2, Part E - 7.3.37 Write Synchronous Flow Control Enable Command
        '''
        ret = HCI_SUCCESS
        if command.synchronous_flow_control_enable == 1:
            self.sync_flow_control = True
        elif command.synchronous_flow_control_enable == 0:
            self.sync_flow_control = False
        else:
            ret = HCI_INVALID_HCI_COMMAND_PARAMETERS_ERROR
        return bytes([ret])

    def on_hci_write_simple_pairing_mode_command(self, command):
        '''
        See Bluetooth spec Vol 2, Part E - 7.3.59 Write Simple Pairing Mode Command
        '''
        return bytes([HCI_SUCCESS])

    def on_hci_set_event_mask_page_2_command(self, command):
        '''
        See Bluetooth spec Vol 2, Part E - 7.3.69 Set Event Mask Page 2 Command
        '''
        self.event_mask_page_2 = command.event_mask_page_2
        return bytes([HCI_SUCCESS])

    def on_hci_read_le_host_support_command(self, command):
        '''
        See Bluetooth spec Vol 2, Part E - 7.3.78 Write LE Host Support Command
        '''
        return bytes([HCI_SUCCESS, 1, 0])

    def on_hci_write_le_host_support_command(self, command):
        '''
        See Bluetooth spec Vol 2, Part E - 7.3.79 Write LE Host Support Command
        '''
        # TODO / Just ignore for now
        return bytes([HCI_SUCCESS])

    def on_hci_write_authenticated_payload_timeout_command(self, command):
        '''
        See Bluetooth spec Vol 2, Part E - 7.3.94 Write Authenticated Payload Timeout Command
        '''
        # TODO
        return struct.pack('<BH', HCI_SUCCESS, command.connection_handle)

    def on_hci_read_local_version_information_command(self, command):
        '''
        See Bluetooth spec Vol 2, Part E - 7.4.1 Read Local Version Information Command
        '''
        return struct.pack('<BBHBHH',
                           HCI_SUCCESS,
                           self.hci_version,
                           self.hci_revision,
                           self.lmp_version,
                           self.manufacturer_name,
                           self.lmp_subversion)

    def on_hci_read_local_supported_commands_command(self, command):
        '''
        See Bluetooth spec Vol 2, Part E - 7.4.2 Read Local Supported Commands Command
        '''
        return bytes([HCI_SUCCESS]) + self.supported_commands

    def on_hci_read_local_supported_features_command(self, command):
        '''
        See Bluetooth spec Vol 2, Part E - 7.4.3 Read Local Supported Features Command
        '''
        return bytes([HCI_SUCCESS]) + self.lmp_features

    def on_hci_read_bd_addr_command(self, command):
        '''
        See Bluetooth spec Vol 2, Part E - 7.4.6 Read BD_ADDR Command
        '''
        bd_addr = self._public_address.to_bytes() if self._public_address is not None else bytes(6)
        return bytes([HCI_SUCCESS]) + bd_addr

    def on_hci_le_set_event_mask_command(self, command):
        '''
        See Bluetooth spec Vol 2, Part E - 7.8.1 LE Set Event Mask Command
        '''
        self.le_event_mask = command.le_event_mask
        return bytes([HCI_SUCCESS])

    def on_hci_le_read_buffer_size_command(self, command):
        '''
        See Bluetooth spec Vol 2, Part E - 7.8.2 LE Read Buffer Size Command
        '''
        return struct.pack('<BHB',
                           HCI_SUCCESS,
                           self.hc_le_data_packet_length,
                           self.hc_total_num_le_data_packets)

    def on_hci_le_read_local_supported_features_command(self, command):
        '''
        See Bluetooth spec Vol 2, Part E - 7.8.3 LE Read Local Supported Features Command
        '''
        return bytes([HCI_SUCCESS]) + self.le_features

    def on_hci_le_set_random_address_command(self, command):
        '''
        See Bluetooth spec Vol 2, Part E - 7.8.4 LE Set Random Address Command
        '''
        self.random_address = command.random_address
        return bytes([HCI_SUCCESS])

    def on_hci_le_set_advertising_parameters_command(self, command):
        '''
        See Bluetooth spec Vol 2, Part E - 7.8.5 LE Set Advertising Parameters Command
        '''
        self.advertising_parameters = command
        return bytes([HCI_SUCCESS])

    def on_hci_le_read_advertising_channel_tx_power_command(self, command):
        '''
        See Bluetooth spec Vol 2, Part E - 7.8.6 LE Read Advertising Channel Tx Power Command
        '''
        return bytes([HCI_SUCCESS, self.avertising_channel_tx_power])

    def on_hci_le_set_advertising_data_command(self, command):
        '''
        See Bluetooth spec Vol 2, Part E - 7.8.7 LE Set Advertising Data Command
        '''
        self.advertising_data = command.advertising_data
        return bytes([HCI_SUCCESS])

    def on_hci_le_set_scan_response_data_command(self, command):
        '''
        See Bluetooth spec Vol 2, Part E - 7.8.8 LE Set Scan Response Data Command
        '''
        self.le_scan_response_data = command.scan_response_data
        return bytes([HCI_SUCCESS])

    def on_hci_le_set_advertising_enable_command(self, command):
        '''
        See Bluetooth spec Vol 2, Part E - 7.8.9 LE Set Advertising Enable Command
        '''
        if command.advertising_enable:
            self.start_advertising()
        else:
            self.stop_advertising()

        return bytes([HCI_SUCCESS])

    def on_hci_le_set_scan_parameters_command(self, command):
        '''
        See Bluetooth spec Vol 2, Part E - 7.8.10 LE Set Scan Parameters Command
        '''
        self.le_scan_type              = command.le_scan_type
        self.le_scan_interval          = command.le_scan_interval
        self.le_scan_window            = command.le_scan_window
        self.le_scan_own_address_type  = command.own_address_type
        self.le_scanning_filter_policy = command.scanning_filter_policy
        return bytes([HCI_SUCCESS])

    def on_hci_le_set_scan_enable_command(self, command):
        '''
        See Bluetooth spec Vol 2, Part E - 7.8.11 LE Set Scan Enable Command
        '''
        self.le_scan_enable    = command.le_scan_enable
        self.filter_duplicates = command.filter_duplicates
        return bytes([HCI_SUCCESS])

    def on_hci_le_create_connection_command(self, command):
        '''
        See Bluetooth spec Vol 2, Part E - 7.8.12 LE Create Connection Command
        '''

        if not self.link:
            return

        logger.debug(f'Connection request to {command.peer_address}')

        # Check that we don't already have a pending connection
        if self.link.get_pending_connection():
            self.send_hci_packet(HCI_Command_Status_Event(
                status                  = HCI_COMMAND_DISALLOWED_ERROR,
                num_hci_command_packets = 1,
                command_opcode          = command.op_code
            ))
            return

        # Initiate the connection
        self.link.connect(self.random_address, command)

        # Say that the connection is pending
        self.send_hci_packet(HCI_Command_Status_Event(
            status                  = HCI_COMMAND_STATUS_PENDING,
            num_hci_command_packets = 1,
            command_opcode          = command.op_code
        ))

    def on_hci_le_create_connection_cancel_command(self, command):
        '''
        See Bluetooth spec Vol 2, Part E - 7.8.13 LE Create Connection Cancel Command
        '''
        return bytes([HCI_SUCCESS])

    def on_hci_le_read_white_list_size_command(self, command):
        '''
        See Bluetooth spec Vol 2, Part E - 7.8.14 LE Read White List Size Command
        '''
        return bytes([HCI_SUCCESS, self.white_list_size])

    def on_hci_le_clear_white_list_command(self, command):
        '''
        See Bluetooth spec Vol 2, Part E - 7.8.15 LE Clear White List Command
        '''
        return bytes([HCI_SUCCESS])

    def on_hci_le_add_device_to_white_list_command(self, command):
        '''
        See Bluetooth spec Vol 2, Part E - 7.8.16 LE Add Device To White List Command
        '''
        return bytes([HCI_SUCCESS])

    def on_hci_le_remove_device_from_white_list_command(self, command):
        '''
        See Bluetooth spec Vol 2, Part E - 7.8.17 LE Remove Device From White List Command
        '''
        return bytes([HCI_SUCCESS])

    def on_hci_le_read_remote_features_command(self, command):
        '''
        See Bluetooth spec Vol 2, Part E - 7.8.21 LE Read Remote Features Command
        '''

        # First, say that the command is pending
        self.send_hci_packet(HCI_Command_Status_Event(
            status                  = HCI_COMMAND_STATUS_PENDING,
            num_hci_command_packets = 1,
            command_opcode          = command.op_code
        ))

        # Then send the remote features
        self.send_hci_packet(HCI_LE_Read_Remote_Features_Complete_Event(
            status            = HCI_SUCCESS,
            connection_handle = 0,
            le_features       = bytes.fromhex('dd40000000000000')
        ))

    def on_hci_le_rand_command(self, command):
        '''
        See Bluetooth spec Vol 2, Part E - 7.8.23 LE Rand Command
        '''
        return bytes([HCI_SUCCESS]) + struct.pack('Q', random.randint(0, 1 << 64))

    def on_hci_le_start_encryption_command(self, command):
        '''
        See Bluetooth spec Vol 2, Part E - 7.8.24 LE Start Encryption Command
        '''

        # Check the parameters
        if not (connection := self.find_central_connection_by_handle(command.connection_handle)):
            logger.warn('connection not found')
            return bytes([HCI_INVALID_HCI_COMMAND_PARAMETERS_ERROR])

        # Notify that the connection is now encrypted
        self.link.on_connection_encrypted(
            self.random_address,
            connection.peer_address,
            command.random_number,
            command.encrypted_diversifier,
            command.long_term_key
        )

        self.send_hci_packet(HCI_Command_Status_Event(
            status                  = HCI_COMMAND_STATUS_PENDING,
            num_hci_command_packets = 1,
            command_opcode          = command.op_code
        ))

    def on_hci_le_read_supported_states_command(self, command):
        '''
        See Bluetooth spec Vol 2, Part E - 7.8.27 LE Read Supported States Command
        '''
        return bytes([HCI_SUCCESS]) + self.le_states

    def on_hci_le_read_suggested_default_data_length_command(self, command):
        '''
        See Bluetooth spec Vol 2, Part E - 7.8.34 LE Read Suggested Default Data Length Command
        '''
        return struct.pack('<BHH',
                           HCI_SUCCESS,
                           self.suggested_max_tx_octets,
                           self.suggested_max_tx_time)

    def on_hci_le_write_suggested_default_data_length_command(self, command):
        '''
        See Bluetooth spec Vol 2, Part E - 7.8.35 LE Write Suggested Default Data Length Command
        '''
        self.suggested_max_tx_octets, self.suggested_max_tx_time = struct.unpack('<HH', command.parameters[:4])
        return bytes([HCI_SUCCESS])

    def on_hci_le_read_local_p_256_public_key_command(self, command):
        '''
        See Bluetooth spec Vol 2, Part E - 7.8.36 LE Read P-256 Public Key Command
        '''
        # TODO create key and send HCI_LE_Read_Local_P-256_Public_Key_Complete event
        return bytes([HCI_SUCCESS])

    def on_hci_le_add_device_to_resolving_list_command(self, command):
        '''
        See Bluetooth spec Vol 2, Part E - 7.8.38 LE Add Device To Resolving List Command
        '''
        return bytes([HCI_SUCCESS])

    def on_hci_le_clear_resolving_list_command(self, command):
        '''
        See Bluetooth spec Vol 2, Part E - 7.8.40 LE Clear Resolving List Command
        '''
        return bytes([HCI_SUCCESS])

    def on_hci_le_read_resolving_list_size_command(self, command):
        '''
        See Bluetooth spec Vol 2, Part E - 7.8.41 LE Read Resolving List Size Command
        '''
        return bytes([HCI_SUCCESS, self.resolving_list_size])

    def on_hci_le_set_address_resolution_enable_command(self, command):
        '''
        See Bluetooth spec Vol 2, Part E - 7.8.44 LE Set Address Resolution Enable Command
        '''
        ret = HCI_SUCCESS
        if command.address_resolution == 1:
            self.le_address_resolution = True
        elif command.address_resolution == 0:
            self.le_address_resolution = False
        else:
            ret = HCI_INVALID_HCI_COMMAND_PARAMETERS_ERROR
        return bytes([ret])

    def on_hci_le_set_resolvable_private_address_timeout_command(self, command):
        '''
        See Bluetooth spec Vol 2, Part E - 7.8.45 LE Set Resolvable Private Address Timeout Command
        '''
        self.le_rpa_timeout = command.rpa_timeout
        return bytes([HCI_SUCCESS])

    def on_hci_le_read_maximum_data_length_command(self, command):
        '''
        See Bluetooth spec Vol 2, Part E - 7.8.46 LE Read Maximum Data Length Command
        '''
        return struct.pack('<BHHHH',
                           HCI_SUCCESS,
                           self.supported_max_tx_octets,
                           self.supported_max_tx_time,
                           self.supported_max_rx_octets,
                           self.supported_max_rx_time)

    def on_hci_le_set_default_phy_command(self, command):
        '''
        See Bluetooth spec Vol 2, Part E - 7.8.48 LE Set Default PHY Command
        '''
        self.default_phy = {
            'all_phys': command.all_phys,
            'tx_phys':  command.tx_phys,
            'rx_phys':  command.rx_phys
        }
        return bytes([HCI_SUCCESS])