# -*- coding: utf-8 -*-

# Copyright (C) 2018 Vadim Yanitskiy <axilirator@gmail.com>
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 2 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 General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.
#

import select
import struct
import socket
import os

from typing import Optional

from pySim.transport import LinkBase
from pySim.exceptions import *
from pySim.utils import h2b, b2h, Hexstr, ResTuple


class L1CTLMessage:

    # Every (encoded) L1CTL message has the following structure:
    #  - msg_length (2 bytes, net order)
    #  - l1ctl_hdr (packed structure)
    #    - msg_type
    #    - flags
    #    - padding (2 spare bytes)
    #  - ... payload ...

    def __init__(self, msg_type, flags=0x00):
        # Init L1CTL message header
        self.data = struct.pack("BBxx", msg_type, flags)

    def gen_msg(self):
        return struct.pack("!H", len(self.data)) + self.data


class L1CTLMessageReset(L1CTLMessage):

    # L1CTL message types
    L1CTL_RESET_REQ = 0x0d
    L1CTL_RESET_IND = 0x07
    L1CTL_RESET_CONF = 0x0e

    # Reset types
    L1CTL_RES_T_BOOT = 0x00
    L1CTL_RES_T_FULL = 0x01
    L1CTL_RES_T_SCHED = 0x02

    def __init__(self, type=L1CTL_RES_T_FULL):
        super(L1CTLMessageReset, self).__init__(self.L1CTL_RESET_REQ)
        self.data += struct.pack("Bxxx", type)


class L1CTLMessageSIM(L1CTLMessage):

    # SIM related message types
    L1CTL_SIM_REQ = 0x16
    L1CTL_SIM_CONF = 0x17

    def __init__(self, pdu):
        super(L1CTLMessageSIM, self).__init__(self.L1CTL_SIM_REQ)
        self.data += pdu


class CalypsoSimLink(LinkBase):
    """Transport Link for Calypso based phones."""

    def __init__(self, sock_path: str = "/tmp/osmocom_l2", **kwargs):
        super().__init__(**kwargs)
        # Make sure that a given socket path exists
        if not os.path.exists(sock_path):
            raise ReaderError(
                "There is no such ('%s') UNIX socket" % sock_path)

        print("Connecting to osmocon at '%s'..." % sock_path)

        # Establish a client connection
        self.sock = socket.socket(socket.AF_UNIX, socket.SOCK_STREAM)
        self.sock.connect(sock_path)

    def __del__(self):
        self.sock.close()

    def wait_for_rsp(self, exp_len: int = 128):
        # Wait for incoming data (timeout is 3 seconds)
        s, _, _ = select.select([self.sock], [], [], 3.0)
        if not s:
            raise ReaderError("Timeout waiting for card response")

        # Receive expected amount of bytes from osmocon
        rsp = self.sock.recv(exp_len)
        return rsp

    def reset_card(self):
        # Request FULL reset
        req_msg = L1CTLMessageReset()
        self.sock.send(req_msg.gen_msg())

        # Wait for confirmation
        rsp = self.wait_for_rsp()
        rsp_msg = struct.unpack_from("!HB", rsp)
        if rsp_msg[1] != L1CTLMessageReset.L1CTL_RESET_CONF:
            raise ReaderError("Failed to reset Calypso PHY")

    def connect(self):
        self.reset_card()

    def disconnect(self):
        pass  # Nothing to do really ...

    def wait_for_card(self, timeout: Optional[int] = None, newcardonly: bool = False):
        pass  # Nothing to do really ...

    def _send_apdu_raw(self, pdu: Hexstr) -> ResTuple:

        # Request FULL reset
        req_msg = L1CTLMessageSIM(h2b(pdu))
        self.sock.send(req_msg.gen_msg())

        # Read message length first
        rsp = self.wait_for_rsp(struct.calcsize("!H"))
        msg_len = struct.unpack_from("!H", rsp)[0]
        if msg_len < struct.calcsize("BBxx"):
            raise ReaderError("Missing L1CTL header for L1CTL_SIM_CONF")

        # Read the whole message then
        rsp = self.sock.recv(msg_len)

        # Verify L1CTL header
        hdr = struct.unpack_from("BBxx", rsp)
        if hdr[0] != L1CTLMessageSIM.L1CTL_SIM_CONF:
            raise ReaderError("Unexpected L1CTL message received")

        # Verify the payload length
        offset = struct.calcsize("BBxx")
        if len(rsp) <= offset:
            raise ProtocolError("Empty response from SIM?!?")

        # Omit L1CTL header
        rsp = rsp[offset:]

        # Unpack data and SW
        data = rsp[:-2]
        sw = rsp[-2:]

        return b2h(data), b2h(sw)