# 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/>.

from __future__ import absolute_import

import time
import usb1
import os

from .protocol_v1 import ProtocolV1
from .protocol_v2 import ProtocolV2
from .transport import Transport, TransportException

DEV_TREZOR1 = (0x534c, 0x0001)
DEV_TREZOR2 = (0x1209, 0x53c1)
DEV_TREZOR2_BL = (0x1209, 0x53c0)

INTERFACE = 0
ENDPOINT = 1
DEBUG_INTERFACE = 1
DEBUG_ENDPOINT = 2

context = usb1.USBContext()
context.open()

import atexit

def exit_handler():
    context.close()

atexit.register(exit_handler)

class WebUsbHandle(object):

    def __init__(self, device):
        self.device = device
        self.count = 0
        self.handle = None

    def open(self, interface):
        if self.count == 0:
            self.handle = self.device.open()
            if self.handle is None:
                raise Exception('Cannot open device')
            self.handle.claimInterface(interface)
            self.count += 1

    def close(self, interface):
        if self.count == 1:
            self.handle.releaseInterface(interface)
            self.handle.close()
        if self.count > 0:
            self.count -= 1


class WebUsbTransport(Transport):
    '''
    WebUsbTransport implements transport over WebUSB interface.
    '''

    PATH_PREFIX = 'webusb'

    def __init__(self, device, protocol=None, handle=None, debug=False):
        super(WebUsbTransport, self).__init__()

        if handle is None:
            handle = WebUsbHandle(device)

        if protocol is None:
            force_v1 = os.environ.get('TREZOR_TRANSPORT_V1', '0')

            if is_trezor2(device) and not int(force_v1):
                protocol = ProtocolV2()
            else:
                protocol = ProtocolV1()

        self.device = device
        self.protocol = protocol
        self.handle = handle
        self.debug = debug

    def __str__(self):
        return "%s:%s" % (self.PATH_PREFIX, dev_to_str(self.device))

    @staticmethod
    def enumerate():
        devices = []
        for dev in context.getDeviceIterator(skip_on_error=True):
            if not (is_trezor1(dev) or is_trezor2(dev) or is_trezor2_bl(dev)):
                continue
            devices.append(WebUsbTransport(dev))
        return devices

    @classmethod
    def find_by_path(cls, path=None):
        path = path.replace('%s:' % cls.PATH_PREFIX, '') # Remove prefix from __str__()        
        for transport in WebUsbTransport.enumerate():
            if path is None or dev_to_str(transport.device) == path:
                return transport
        raise TransportException('WebUSB device not found')

    def find_debug(self):
        if isinstance(self.protocol, ProtocolV2):
            # TODO test this
            # For v2 protocol, lets use the same WebUSB interface, but with a different session
            protocol = ProtocolV2()
            debug = WebUsbTransport(self.device, protocol, self.handle)
            return debug
        if isinstance(self.protocol, ProtocolV1):
            # For v1 protocol, find debug USB interface for the same serial number
            protocol = ProtocolV1()
            debug = WebUsbTransport(self.device, protocol, None, True)
            return debug
        raise TransportException('Debug WebUSB device not found')

    def open(self):
        interface = DEBUG_INTERFACE if self.debug else INTERFACE
        self.handle.open(interface)
        self.protocol.session_begin(self)

    def close(self):
        interface = DEBUG_INTERFACE if self.debug else INTERFACE
        self.protocol.session_end(self)
        self.handle.close(interface)

    def read(self):
        return self.protocol.read(self)

    def write(self, msg):
        return self.protocol.write(self, msg)

    def write_chunk(self, chunk):
        endpoint = DEBUG_ENDPOINT if self.debug else ENDPOINT
        if len(chunk) != 64:
            raise TransportException('Unexpected chunk size: %d' % len(chunk))
        self.handle.handle.interruptWrite(endpoint, chunk)

    def read_chunk(self):
        endpoint = DEBUG_ENDPOINT if self.debug else ENDPOINT
        endpoint = 0x80 | endpoint
        while True:
            chunk = self.handle.handle.interruptRead(endpoint, 64)
            if chunk:
                break
            else:
                time.sleep(0.001)
        if len(chunk) != 64:
            raise TransportException('Unexpected chunk size: %d' % len(chunk))
        return bytearray(chunk)


def is_trezor1(dev):
    return (dev.getVendorID(), dev.getProductID()) == DEV_TREZOR1


def is_trezor2(dev):
    return (dev.getVendorID(), dev.getProductID()) == DEV_TREZOR2


def is_trezor2_bl(dev):
    return (dev.getVendorID(), dev.getProductID()) == DEV_TREZOR2_BL


def dev_to_str(dev):
    return ':'.join(str(x) for x in ['%03i' % (dev.getBusNumber(), )]  + dev.getPortNumberList())