#!/usr/bin/env python
#
# Copyright (c) 2017, NORDUnet A/S All rights reserved.
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions are
# met:
# - Redistributions of source code must retain the above copyright notice,
#   this list of conditions and the following disclaimer.
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# - Redistributions in binary form must reproduce the above copyright
#   notice, this list of conditions and the following disclaimer in the
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#   without specific prior written permission.
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# 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
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"""
Console client shim to work with Cryptech Python multiplexer.
"""

import os
import sys
import socket
import atexit
import termios
import logging
import argparse

import tornado.iostream
import tornado.ioloop
import tornado.gen


logger = logging.getLogger("cryptech_console")


class FemtoTerm(object):

    def __init__(self, s):
        self.termios_setup()
        self.stdin_stream  = tornado.iostream.PipeIOStream(sys.stdin.fileno())
        self.stdout_stream = tornado.iostream.PipeIOStream(sys.stdout.fileno())
        self.socket_stream = tornado.iostream.IOStream(s)
        self.closed = False

    def termios_setup(self):
        self.fd = sys.stdin.fileno()
        self.old_tcattr = termios.tcgetattr(self.fd)
        self.new_tcattr = termios.tcgetattr(self.fd)
        atexit.register(self.termios_teardown)
        self.new_tcattr[3] &= ~(termios.ICANON | termios.ECHO) #  | termios.ISIG
        self.new_tcattr[6][termios.VMIN] = 1
        self.new_tcattr[6][termios.VTIME] = 0
        termios.tcsetattr(self.fd, termios.TCSANOW, self.new_tcattr)

    def termios_teardown(self):
        if self.fd is not None:
            termios.tcsetattr(self.fd, termios.TCSAFLUSH, self.old_tcattr)
            self.fd = None

    def close_loops(self):
        self.termios_teardown()
        self.stdin_stream.close()
        self.stdout_stream.close()
        self.socket_stream.close()
        self.closed = True

    @tornado.gen.coroutine
    def stdin_loop(self):
        try:
            while not self.closed:
                buffer = yield self.stdin_stream.read_bytes(1024, partial = True)
                yield self.socket_stream.write(buffer.replace("\n", "\r"))
        except tornado.iostream.StreamClosedError:
            self.close_loops()

    @tornado.gen.coroutine
    def stdout_loop(self):
        try:
            while not self.closed:
                buffer = yield self.socket_stream.read_bytes(1024, partial = True)
                yield self.stdout_stream.write(buffer.replace("\r\n", "\n"))
        except tornado.iostream.StreamClosedError:
            self.close_loops()


@tornado.gen.coroutine
def main():
    parser = argparse.ArgumentParser(formatter_class = argparse.ArgumentDefaultsHelpFormatter)
    parser.add_argument("-v", "--verbose",  action = "store_true",  help = "produce human-readable output")
    parser.add_argument("-d", "--debug",    action = "store_true",  help = "blather about what we're doing")

    parser.add_argument("--cty-socket",            help = "CTY PF_UNIX socket name",
                        default = os.getenv("CRYPTECH_CTY_CLIENT_SOCKET_NAME", "/tmp/.cryptech_muxd.cty"))

    args = parser.parse_args()

    s = socket.socket(socket.AF_UNIX, socket.SOCK_STREAM)
    s.connect(args.cty_socket)

    term = FemtoTerm(s)
    yield [term.stdout_loop(), term.stdin_loop()]

if __name__ == "__main__":
    try:
        #logging.basicConfig(level = logging.DEBUG)
        tornado.ioloop.IOLoop.current().run_sync(main)
    except KeyboardInterrupt:
        pass