# Copyright (c) 2019 Yubico AB
# Copyright (c) 2019 Oleg Moiseenko
# All rights reserved.
#
#   Redistribution and use in source and binary forms, with or
#   without modification, are permitted provided that the following
#   conditions are met:
#
#    1. Redistributions of source code must retain the above copyright
#       notice, this list of conditions and the following disclaimer.
#    2. Redistributions in binary form must reproduce the above
#       copyright notice, this list of conditions and the following
#       disclaimer in the documentation and/or other materials provided
#       with the distribution.
#
# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
# FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
# COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
# INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
# BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
# LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
# CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
# LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
# ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
# POSSIBILITY OF SUCH DAMAGE.

from __future__ import absolute_import, unicode_literals

from .ctap import CtapDevice, CtapError, STATUS
from .hid import CAPABILITY, CTAPHID
from smartcard import System
from smartcard.pcsc.PCSCExceptions import ListReadersException
from smartcard.pcsc.PCSCContext import PCSCContext

from binascii import b2a_hex
from threading import Event
import struct
import six
import logging


AID_FIDO = b'\xa0\x00\x00\x06\x47\x2f\x00\x01'
SW_SUCCESS = (0x90, 0x00)
SW_UPDATE = (0x91, 0x00)
SW1_MORE_DATA = 0x61


logger = logging.getLogger(__name__)


class CtapPcscDevice(CtapDevice):
    """
    CtapDevice implementation using pyscard (PCSC).

    This class is intended for use with NFC readers.
    """

    def __init__(self, connection, name):
        self._capabilities = 0
        self.use_ext_apdu = False
        self._conn = connection
        self._conn.connect()
        self._name = name
        self._select()

        try:  # Probe for CTAP2 by calling GET_INFO
            self.call(CTAPHID.CBOR, b'\x04')
            self._capabilities |= CAPABILITY.CBOR
        except CtapError:
            if self._capabilities == 0:
                raise ValueError('Unsupported device')

    def __repr__(self):
        return 'CtapPcscDevice(%s)' % self._name

    @property
    def version(self):
        """CTAPHID protocol version.
        :rtype: int
        """
        return 2 if self._capabilities & CAPABILITY.CBOR else 1

    @property
    def capabilities(self):
        """Capabilities supported by the device."""
        return self._capabilities

    def get_atr(self):
        """Get the ATR/ATS of the connected card."""
        return self._conn.getATR()

    def apdu_exchange(self, apdu, protocol=None):
        """Exchange data with smart card.

        :param apdu: byte string. data to exchange with card
        :return: byte string. response from card
        """

        logger.debug('apdu %s', b2a_hex(apdu))
        resp, sw1, sw2 = self._conn.transmit(
            list(six.iterbytes(apdu)),
            protocol
        )
        response = bytes(bytearray(resp))
        logger.debug('response [0x%04X] %s', sw1 << 8 + sw2, b2a_hex(response))

        return response, sw1, sw2

    def control_exchange(self, control_code, control_data=b''):
        """Sends control sequence to reader's driver.

        :param control_code: int. code to send to reader driver.
        :param control_data: byte string. data to send to driver
        :return: byte string. response
        """

        logger.debug('control %s', b2a_hex(control_data))
        response = self._conn.control(
            control_code,
            list(six.iterbytes(control_data))
        )
        response = bytes(bytearray(response))
        logger.debug('response %s', b2a_hex(response))

        return response

    def _select(self):
        apdu = b'\x00\xa4\x04\x00' + struct.pack('!B', len(AID_FIDO)) + AID_FIDO
        resp, sw1, sw2 = self.apdu_exchange(apdu)
        if (sw1, sw2) != SW_SUCCESS:
            raise ValueError('FIDO applet selection failure.')
        if resp == b'U2F_V2':
            self._capabilities |= 0x08

    def _chain_apdus(self, cla, ins, p1, p2, data=b''):
        if self.use_ext_apdu:
            header = struct.pack(
                '!BBBBBH', cla, ins, p1, p2, 0x00, len(data))
            resp, sw1, sw2 = self.apdu_exchange(
                header + data)
            return resp, sw1, sw2
        else:
            while len(data) > 250:
                to_send, data = data[:250], data[250:]
                header = struct.pack('!BBBBB',
                                     0x10 | cla, ins, p1, p2, len(to_send))
                resp, sw1, sw2 = self.apdu_exchange(header + to_send)
                if (sw1, sw2) != SW_SUCCESS:
                    return resp, sw1, sw2
            apdu = struct.pack('!BBBB', cla, ins, p1, p2)
            if data:
                apdu += struct.pack('!B', len(data)) + data
            resp, sw1, sw2 = self.apdu_exchange(apdu + b'\x00')
            while sw1 == SW1_MORE_DATA:
                apdu = b'\x00\xc0\x00\x00' + struct.pack('!B', sw2)  # sw2 == le
                lres, sw1, sw2 = self.apdu_exchange(apdu)
                resp += lres
            return resp, sw1, sw2

    def _call_apdu(self, apdu):
        if len(apdu) >= 7 and six.indexbytes(apdu, 4) == 0:
            # Extended APDU
            data_len = struct.unpack('!H', apdu[5:7])[0]
            data = apdu[7:7+data_len]
        else:
            # Short APDU
            data_len = six.indexbytes(apdu, 4)
            data = apdu[5:5+data_len]
        (cla, ins, p1, p2) = six.iterbytes(apdu[:4])

        resp, sw1, sw2 = self._chain_apdus(cla, ins, p1, p2, data)
        return resp + struct.pack('!BB', sw1, sw2)

    def _call_cbor(self, data=b'', event=None, on_keepalive=None):
        event = event or Event()
        # NFCCTAP_MSG
        resp, sw1, sw2 = self._chain_apdus(0x80, 0x10, 0x80, 0x00, data)
        last_ka = None

        while not event.is_set():
            while (sw1, sw2) == SW_UPDATE:
                ka_status = six.indexbytes(resp, 0)
                if on_keepalive and last_ka != ka_status:
                    try:
                        ka_status = STATUS(ka_status)
                    except ValueError:
                        pass  # Unknown status value
                    last_ka = ka_status
                    on_keepalive(ka_status)

                # NFCCTAP_GETRESPONSE
                resp, sw1, sw2 = self._chain_apdus(0x80, 0x11, 0x00, 0x00)

            if (sw1, sw2) != SW_SUCCESS:
                raise CtapError(CtapError.ERR.OTHER)  # TODO: Map from SW error

            return resp

        raise CtapError(CtapError.ERR.KEEPALIVE_CANCEL)

    def call(self, cmd, data=b'', event=None, on_keepalive=None):
        if cmd == CTAPHID.CBOR:
            return self._call_cbor(data, event, on_keepalive)
        elif cmd == CTAPHID.MSG:
            return self._call_apdu(data)
        else:
            raise CtapError(CtapError.ERR.INVALID_COMMAND)

    def close(self):
        self._conn.disconnect()

    @classmethod
    def list_devices(cls, name=''):
        for reader in _list_readers():
            if name in reader.name:
                try:
                    yield cls(reader.createConnection(), reader.name)
                except Exception as e:
                    logger.debug('Error %r', e)


def _list_readers():
    try:
        return System.readers()
    except ListReadersException:
        # If the PCSC system has restarted the context might be stale, try
        # forcing a new context (This happens on Windows if the last reader is
        # removed):
        PCSCContext.instance = None
        return System.readers()
