#!/usr/bin/env python
# -*- coding: utf-8 -*-
#
"""
serial_interface (Serial Interface Module)
==========================================

**Author:**

* Dirk Alders <sudo-dirk@mount-mockery.de>

**Description:**

    This Module supports a common interface for a serial port

**Submodules:**

* :mod:`mmod.module.sub1`
* :class:`mmod.module.sub2`
* :func:`mmod.module.sub2`

**Unittest:**

        See also the :download:`unittest <../../serial_interface/_testresults_/unittest.pdf>` documentation.
"""
__DEPENDENCIES__ = ['stringtools']

import stringtools

import logging
import serial
import time

try:
    from config import APP_NAME as ROOT_LOGGER_NAME
except ImportError:
    ROOT_LOGGER_NAME = 'root'
logger = logging.getLogger(ROOT_LOGGER_NAME).getChild(__name__)


class serial_interface(object):
    """
    Class to send and receive data via a serial port.

    .. note:: All parameters are given to the standard :py:class:`serial.Serial` library
    """
    LOG_PREFIX = 'SER:'

    def __init__(self, *args, **kwargs):
        self._args = args
        self._kwargs = kwargs
        self.com = None
        self.open()

    def open(self):
        """
        This opens the serial port.

        :returns: True if the port has been successfully opened
        :rtype: bool
        """
        if self.com is not None:
            self.close()
        try:
            self.com = serial.Serial(*self._args, **self._kwargs)
        except:
            self.com = None
            logger.warning('%s Unable to open comport (%s)', self.LOG_PREFIX, self._args[0])
            return False
        else:
            logger.debug('%s Opening comport (%s)', self.LOG_PREFIX, self._args[0])
        return True

    def close(self):
        """
        This closes the serial port.
        """
        if self.com is not None:
            logger.debug('%s Closing comport (%s)', self.LOG_PREFIX, self._args[0])
            self.com.close()
            self.com = None

    def bytes_in_queue(self):
        """
        This returns the number of available bytes for receiption.

        :returns: Number of bytes in queue
        :rtype: int
        """
        if self.com is not None:
            return self.com.inWaiting()
        else:
            return 0

    def receive(self, max_length=None):
        """
        This receives data from the serial interface.

        :param int length: An optinal number of bytes to be received. None will return all available bytes.
        :returns: The received data
        :rtype: str
        """
        length = self.bytes_in_queue()
        if max_length is not None:
            length = min(length, max_length)
        if self.com is not None and length > 0:
            data = self.com.read(length)
            self._handle_debug('RX <- ', data)
            return data

    def send(self, data):
        """
        This sends data via the serial interface.

        :param str data: The data to be send
        """
        if self.com is not None:
            self._handle_debug('TX -> ', data)
            self.com.write(data)

    def _handle_debug(self, msg, data):
        logger.debug('%s ' + msg + stringtools.hexlify(data), self.LOG_PREFIX)

    def __del__(self):
        self.close()