# This file is part of the TREZOR project.
#
# Copyright (C) 2012-2016 Marek Palatinus <slush@satoshilabs.com>
# Copyright (C) 2012-2016 Pavol Rusnak <stick@satoshilabs.com>
#
# 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 3 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/>.

'''UDP Socket implementation of Transport.'''

import socket
from select import select
from .transport import TransportV2


class UdpTransport(TransportV2):

    def __init__(self, device, *args, **kwargs):
        if device is None:
            device = ''
        device = device.split(':')
        if len(device) < 2:
            if not device[0]:
                # Default port used by trezor v2
                device = ('127.0.0.1', 21324)
            else:
                device = ('127.0.0.1', int(device[0]))
        else:
            device = (device[0], int(device[1]))

        self.socket = None
        super(UdpTransport, self).__init__(device, *args, **kwargs)

    @classmethod
    def enumerate(cls):
        raise Exception('This transport cannot enumerate devices')

    @classmethod
    def find_by_path(cls, path=None):
        return cls(path)

    def _open(self):
        self.socket = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
        self.socket.connect(self.device)
        self.socket.settimeout(10)

    def _close(self):
        self.socket.close()
        self.socket = None

    def _ready_to_read(self):
        rlist, _, _ = select([self.socket], [], [], 0)
        return len(rlist) > 0

    def _write_chunk(self, chunk):
        if len(chunk) != 64:
            raise Exception("Unexpected data length")

        self.socket.sendall(chunk)

    def _read_chunk(self):
        while True:
            try:
                data = self.socket.recv(64)
                break
            except socket.timeout:
                continue
        if len(data) != 64:
            raise Exception("Unexpected chunk size: %d" % len(data))

        return bytearray(data)