# Source code for PDW

    import struct
    import math
    import datetime

    # TODO: Use BitArray module in future versions

    class PDW():

        """

        I store information from a single ppdw data block

        .. automethod:: __init__

        """

        @classmethod
        def from_bytes(cls, byte_string):

            """

            I create an instance of class PDW from data body (8 * 32 bits)

            :param byte_string: a byte string containing a single data body read from a ppdw file
            :type byte_string: byte string

            :return: an instance of class PDW with attributes set according to the data of a data body
            :rtype: PDW

            """

            assert(len(byte_string) == 32)

            parts = struct.unpack('Q4s4s4s4s4s4s', byte_string)
            seconds = (parts[0])
            time_of_arrival = datetime.datetime.utcfromtimestamp(seconds / 1000000000)

            third_entry = bin(int.from_bytes(parts[1], byteorder='little'))
            padding = 32-len(str(third_entry)[2:])
            third_entry_bit_string = "0" * padding + str(third_entry)[2:]
            pdw_format_identifier = int(third_entry_bit_string[0:6], 2)
            center_frequency = int(third_entry_bit_string[5:32], 2)

            fourth_entry = bin(int.from_bytes(parts[2], byteorder='little'))
            padding = 32-len(str(fourth_entry)[2:])
            fourth_entry_bit_string = "0" * padding + str(fourth_entry)[2:]
            is_valid = bool(int(fourth_entry_bit_string[0]))
            is_pulse = bool(int(fourth_entry_bit_string[1]))
            level_unit = int(fourth_entry_bit_string[2])
            signal_start_missing = bool(int(fourth_entry_bit_string[3]))
            signal_end_missing = bool(int(fourth_entry_bit_string[4]))
            pulse_width = int(fourth_entry_bit_string[7:33], 2)

            fifth_entry = bin(int.from_bytes(parts[3], byteorder='little'))
            padding = 32-len(str(fifth_entry)[2:])
            fifth_entry_bit_string = "0" * padding + str(fifth_entry)[2:]
            frequency_shift_or_bandwidth = int(fifth_entry_bit_string[0:20], 2)
            # FIXME: You have to scale me to the range from -200.0 to 200.0 in 0.1 steps
            pulse_level_or_pulse_field_strength = math.ceil(int(fifth_entry_bit_string[20:32], 2)) / 10

            sixth_entry = bin(int.from_bytes(parts[4], byteorder='little'))
            padding = 32-len(str(sixth_entry)[2:])
            sixth_entry_bit_string = "0" * padding + str(sixth_entry)[2:]
            region_of_interest = bool(int(sixth_entry_bit_string[0]))
            # FIXME: You have to scale me to a range from 0.0 to 6.2 in steps of 0.1 - 6.3 means unknown
            azimuth_confidence = math.ceil(int(sixth_entry_bit_string[1:7], 2)) / 10
            modulations = {0: 'Unknown', 1: 'Unmodulated', 2: 'FM', 3: 'LFM', 4: 'PSK-2', 5: 'PSK-3', 6: 'PSK-4',
                           7: 'PSK-m', 8: 'NLFM', 9: 'SFM', 10: 'TFM', 11: 'Pulse too short'}
            modulation = modulations[int(sixth_entry_bit_string[7:12], 2)]
            sector = int(sixth_entry_bit_string[28:32], 2)

            seventh_entry = bin(int.from_bytes(parts[5], byteorder='little'))
            padding = 32-len(str(seventh_entry)[2:])
            seventh_entry_bit_string = "0" * padding + str(seventh_entry)[2:]
            polarities = {0: 'Horizontal/Unknown', 1: 'Vertical', 2: 'Counter clockwise', 3: 'Clockwise'}
            polarity = polarities[int(seventh_entry_bit_string[0:2], 2)]
            df_quality = int(seventh_entry_bit_string[2:9], 2)
            # FIXME: You have to scale me from -90 to 90 in 0.1 degree steps
            elevation = int(seventh_entry_bit_string[9:20], 2)
            # FIXME: You have to check me for a range from 0.0 to 359.9 in steps of 0.1
            azimuth = 0.1 * (int(seventh_entry_bit_string[20:32], 2))

            eighth_entry = bin(int.from_bytes(parts[5], byteorder='little'))
            padding = 32-len(str(eighth_entry)[2:])
            eighth_entry_bit_string = "0" * padding + str(eighth_entry)[2:]
            channel = int(eighth_entry_bit_string[0:4], 2)

            return PDW(time_of_arrival, pdw_format_identifier, center_frequency, is_valid, is_pulse, level_unit,
                       signal_start_missing, signal_end_missing, pulse_width, frequency_shift_or_bandwidth,
                       pulse_level_or_pulse_field_strength, region_of_interest, azimuth_confidence, modulation,
                       sector, polarity, df_quality, elevation, azimuth, channel)

        def __init__(self, time_of_arrival, pdw_format_identifier, center_frequency, is_valid, is_pulse,
                     level_unit, signal_start_missing, signal_end_missing, pulse_width, frequency_shift_or_bandwidth,
                     pulse_level_or_pulse_field_strength, region_of_interest, azimuth_confidence, modulation,
                     sector, polarity, df_quality, elevation, azimuth, channel):

            """

            :param time_of_arrival: nanoseconds since 1970-01-01 00:00:00
            :type time_of_arrival: Integer
            :param pdw_format: format code
            :type pdw_format: Integer
            :param center_frequency: center frequency in KHz
            :type center_frequency: Integer
            :param is_valid: flag to mark if pdw data body is valid
            :type is_valid: Boolean
            :param is_pulse: flag to mark if pdw data body contains a pulse or a continuous wave signal
            :type is_pulse: Boolean
            :param level_unit: 0 means dBµV - 1 means dBµV/m
            :type level_unit: Integer
            :param signal_start_missing: signal started before time of arrival
            :type signal_start_missing: Boolean
            :param signal_end_missing: signal stops after time of arrival
            :type signal_end_missing: Boolean
            :param pulse_width: pulse width in nanoseconds - Zero if no valid pulse detected
            :type pulse_width: Integer
            :param frequency_shift_or_bandwidth: Value in KHz - Value set to 1048575 means Unknown
            :type frequency_shift_or_bandwidth: Integer
            :param pulse_level_or_pulse_field_strength: Pulse level or Pulse Field Strength depending on level_unit \
             (-200.0...200.0) in 0.1 steps / minus 204.8 means no valid level detected
            :type pulse_level_or_pulse_field_strength: Float
            :param region_of_interest: Marks if signal is from region of interest
            :type region_of_interest: Boolean
            :param azimuth_confidence: degree in steps of 0.1 (0.0-6.2) / 6.3 means confidence unknown
            :type azimuth_confidence: Float
            :param modulation: type of modulation (e.g. PSK-2, PSK-4, FM etc.)
            :type modulation: String
            :param sector: reference antenna sector (0-15)
            :type sector: Integer
            :param polarity: Horizontal, Vertical, Clockwise, Counter clockwise
            :type polarity: String
            :param df_quality: Direction finding quality in percent (0-100) - Zero means unknown
            :type df_quality: Integer
            :param elevation: elevation of incoming signal (from -90 to 90 degree) in steps of 0.1 degree \
            minus 102.4 means unknown
            :type elevation: Float
            :param azimuth: azimuth of incoming signal (from 0 to 359.9 degree) in steps of 0.1 degree \
            plus 409.5 means unknown
            :type azimuth: Float
            :param channel: detecting channel (0-16) - Zero means unknown
            :type channel: Integer
            :return: An instance of class PDW with attributes set according to the data of a data body
            :rtype: PDW

            """

            self.time_of_arrival = time_of_arrival
            self.pdw_format_identifier = pdw_format_identifier
            self.center_frequency = center_frequency
            self.is_valid = is_valid
            self.is_pulse = is_pulse
            self.level_unit = level_unit
            self.signal_start_missing = signal_start_missing
            self.signal_end_missing = signal_end_missing
            self.pulse_width = pulse_width
            self.frequency_shift_or_bandwidth = frequency_shift_or_bandwidth
            self.pulse_level_or_pulse_field_strength = pulse_level_or_pulse_field_strength
            self.region_of_interest = region_of_interest
            self.azimuth_confidence = azimuth_confidence
            self.modulation = modulation
            self.sector = sector
            self.polarity = polarity
            self.df_quality = df_quality
            self.elevation = elevation
            self.azimuth = azimuth
            self.channel = channel

        def __str__(self):
            output = ("Time of arrival: " + str(self.time_of_arrival) + "\n" +
                      "PDW Format identifier: " + str(self.pdw_format_identifier) + "\n" +
                      "Center frequency: " + str(self.center_frequency) + " KHz\n")

            if self.is_valid:
                output += "Signal: Valid\n"
            else:
                output += "Signal: Invalid\n"

            if self.is_pulse:
                output += "Signal type: Pulse\n"
            else:
                output += "Signal type: Continuous wave\n"

            if self.level_unit == 1:
                output += "Pulse level: " + str(self.pulse_level_or_pulse_field_strength) + " dbµV\n"
            else:
                output += "Pulse field strength: " + str(self.pulse_level_or_pulse_field_strength) + " dbµV/meter\n"

            output += ("Pulse width: " + str(self.pulse_width) + " nanoseconds\n" +
                       "Frequency shift or bandwidth: " + str(self.frequency_shift_or_bandwidth) + " KHz\n")

            if self.region_of_interest:
                output += "Region of interest: Yes\n"
            else:
                output += "Region of interest: No\n"

            if self.azimuth_confidence == 6.3:
                output += "Azimuth confidence: Invalid\n"
            else:
                output += "Azimuth confidence: " + str(self.azimuth_confidence) + " degree\n"

            output += "Modulation: " + str(self.modulation) + "\n"

            if self.sector == 0:
                output += "Sector: Unknown\n"
            else:
                output += "Sector:" + str(self.sector) + "\n"

            output += "Polarity: " + str(self.polarity) + "\n"

            output += "DF quality: " + str(self.df_quality) + " %\n"

            if self.elevation == 1024:
                output += "Elevation: Unknown\n"
            else:
                output += "Elevation: " + str(self.elevation) + " degree\n"

            if self.azimuth == 409.5:
                output += "Azimuth: Unknown\n"
            else:
                output += "Azimuth: " + str(self.azimuth) + " degree\n"

            output += "Channel: " + str(self.channel) + "\n"

            return output

    if __name__ == '__main__':
        pass