"""dmxusbpro.py

Class to manage a connection to a serial-connected Enttec DMXUSB Pro
interface.  Requires pySerial and numpy.
"""

import logging
import os.path
import numpy as np

# This requires a pySerial installation.
#  Package details: https://pypi.python.org/pypi/pyserial
#  Documentation:   http://pythonhosted.org/pyserial/
import serial

# initialize logging for this module
log = logging.getLogger(__name__)

#================================================================
class DMXUSBPro:
    """Class to manage a connection to a serial-connected Enttec DMXUSB Pro
    interface. This only supports output.

    :param port: the name of the serial port device
    :param verbose: flag to increase console output
    :param debug: flag to print raw inputs on sconsole
    :param kwargs: collect any unused keyword arguments
    """

    def __init__(self, port=None, verbose=False, debug=False, universe_size=25, **kwargs ):

        # Initialize a default universe.  This publicly readable and writable.
        # The Enttec requires a minimum universe size of 25.
        self.universe = np.zeros((universe_size), dtype=np.uint8)

        # Initialize internal state.
        self.verbose  = verbose
        self.debug     = debug
        self.portname  = port
        self.port      = None
        self.output    = None
        self.input     = None

        return

    def is_connected(self):
        """Return true if the serial port device is open."""
        return self.port is not None

    def set_serial_port_name(self, name):
        """Set the name of the serial port device."""
        self.portname = name
        return

    def open_serial_port(self):
        """Open the serial connection to the controller."""

        if not os.path.exists(self.portname):
            log.warning("Serial port %s not available, running offline.", self.portname)
            return

        # open the serial port

        self.port = serial.Serial( self.portname, 115200 )
        if self.verbose:
            log.info("Opened serial port named %s", self.port.name)

        # save separate copies of the file object; this will ease simulation using other sources
        self.output = self.port
        self.input  = self.port
        return

    def flush_serial_input(self):
        """Clear the input buffer."""
        if self.input is not None:
            self.input.flushInput()

    def close_serial_port(self):
        """Shut down the serial connection, after which this object may no longer be used."""
        if self.port is not None:
            if self.verbose:
                log.info("Closing port.")
            self.port.close()
            self.port = None
        return

    def send_universe(self):
        """Issue a DMX universe update."""
        if self.output is None:
            if self.verbose:
                log.debug("DMX port not open: would send %s", self.universe)
        else:
            message = np.ndarray((6 + self.universe.size), dtype=np.uint8)
            message[0:2] = [126, 6] # Send DMX Packet header
            message[2]   = (self.universe.size+1) % 256   # data length LSB
            message[3]   = (self.universe.size+1) >> 8    # data length MSB
            message[4]   = 0                              # zero 'start code' in first universe position
            message[5:5+self.universe.size] = self.universe
            message[-1]  = 231 # end of message delimiter

            if self.verbose:
                log.debug("Sending: '%s'", message)

            self.output.write(message.tobytes())
        return