"""
Basic Idea taken from http://stackoverflow.com/a/8111621/6420372
"""

import os
import socket
import subprocess
from select import select
import time
import contextlib
import settings

try:
    import winreg
except ImportError:
    import _winreg as winreg


def _get_vlc_path():
    views = [(winreg.HKEY_CURRENT_USER, 0),
             (winreg.HKEY_LOCAL_MACHINE, winreg.KEY_WOW64_64KEY),
             (winreg.HKEY_LOCAL_MACHINE, winreg.KEY_WOW64_32KEY)]
    subkey = r'Software\VideoLAN\VLC'
    access = winreg.KEY_QUERY_VALUE
    for hroot, flag in views:
        try:
            with winreg.OpenKey(hroot, subkey, 0, access | flag) as hkey:
                value, type_id = winreg.QueryValueEx(hkey, None)
                if type_id == winreg.REG_SZ:
                    return value
        except WindowsError:
            pass
    raise SystemExit("Error: VLC not found.")


def send_command(sock, cmd, get_result=False):
    try:
        cmd = (cmd + '\n').encode('ascii')
    except AttributeError:
        cmd += b'\n'
    sent = total = sock.send(cmd)
    while total < len(cmd):
        sent = sock.send(cmd[total:])
        if sent == 0:
            raise socket.error('Socket connection broken.')
        total += sent
    if get_result:
        return receive_result(sock)


def receive_result(sock):
    data = bytearray()
    sock.setblocking(0)
    while select([sock], [], [], 1.0)[0]:
        chunk = sock.recv(1024)
        if chunk == b'':
            raise socket.error('Socket connection broken.')
        data.extend(chunk)
    sock.setblocking(1)
    return data.decode('utf-8')


def _outfile(id_):
    return os.path.join(settings.DATA_DIR,
                        'recording_{}_.mp4'.format(id_))


def _sout_options(id_):
    """
    somehow passing them as single options doesn't work
    :param id_:
    :return:
    """
    return "--sout=#transcode{" \
           "vcodec=h264,vb=1024,fps=" + \
           str(settings.CAM_FRAME_RATE) + ",width=640" \
           "}:standard{access=file,mux=ts," \
           "dst=" + "\"{}\"".format(_outfile(id_)) + "}"


def _stream_options():
    return ['--dshow-size={}x{}'.format(*settings.CAM_RES),
            '--dshow-adev=None',
            '--dshow-fps={}'.format(settings.CAM_FRAME_RATE),
            '--dshow-vdev=USB_Camera']


@contextlib.contextmanager
def vlc(address, port, id_):
    rc_host = '{0}:{1}'.format(address, port)
    vlc = subprocess.Popen([_get_vlc_path(), '-I', 'rc', '--rc-host', rc_host,
                            '--rc-quiet', 'dshow://'] + _stream_options() +
                           [_sout_options(id_),'--qt-start-minimized'])

    sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
    try:
        sock.connect((address, port))
        yield sock
        send_command(sock, 'stop')
        send_command(sock, 'quit')
    except socket.error as e:
        exit("Error: " + e.args[0])
    finally:
        sock.close()
        # give vlc some time to finish transcoding the stream?
        time.sleep(5)
        if vlc.poll() is None:
            vlc.terminate()


if __name__ == '__main__':
    with vlc('localhost', 12345, 42) as sock:
        time.sleep(10)