class Bell202:
    import numpy
    import pyaudio

    def __init__(self, markFreq=1200, spaceFreq=2200, sampleRate=48000,
                 baud=1200, format=pyaudio.paFloat32):
        self.markFreq = float(markFreq)
        self.spaceFreq = float(spaceFreq)
        self.sampleRate = float(sampleRate)
        self.baud = float(baud)
        self.format = format
        
        # bitLengthSamples is the length of a single bit measured in samples.
        self.bitLengthSamples = self.sampleRate / self.baud
        # bitLengthTime is the length of a single bit measured in seconds.
        self.bitLengthTime = 1.0 / self.baud
        # sampleLengthTime is the length of a single sample in seconds.
        self.sampleLengthTime = 1.0 / self.sampleRate
        self.currentPhase = self.numpy.pi / 2.0
        
    def play(self, audioData):
        try:
            p = self.pyaudio.PyAudio()
            stream = p.open(format=self.format,
                            channels=1,
                            rate=int(self.sampleRate),
                            output=1)
            audio = self.numpy.concatenate(audioData)
            stream.write(audio.astype(self.numpy.float32).tostring())
            stream.close()
            p.terminate()
        except IOError as e:
            print 'failed: %s' % e
            
    def send(self, binaryData):
        self.currentPhase = self.numpy.pi / 2.0
        audio = [self.createSine(self.markFreq, phase=self.currentPhase) if bit == '1'
                 else self.createSine(self.spaceFreq, phase=self.currentPhase)
                 for bit in binaryData]
        self.play(audio)
    
    def createSine(self, frequency, amplitude=1.0, bits=1, phase=0.0):
        w = 2.0 * self.numpy.pi * frequency
        t = self.numpy.arange(bits * self.bitLengthSamples) / self.sampleRate
        audioData = self.numpy.sin(w * t + phase)
        self.currentPhase += w * bits * self.bitLengthSamples / self.sampleRate
        return audioData

def fcs(data):
    fcs = 0xffff
    for bit in data:
        shiftBit = fcs & 0x01
        fcs = fcs >> 1
        if str(shiftBit) != bit:
            fcs = fcs ^ 0x8408
    fcs = fcs ^ 0xffff
    return bin(fcs)[2:].zfill(16)[::-1] # Send FCS low-byte and LSB first

def stuffBits(data):
    from re import sub
    return sub('11111', '111110', data) # Add a 0 after any five 1s

def nrzi(data):
    # Encodes the data in NRZI where 0s in the original data indicate
    # a change in tone and 1s indicate staying on the same tone
    currentState = '0'
    bits = ''
    for bit in data:
        if bit == '0':
            if currentState == '0':
                currentState = '1'
            else:
                currentState = '0'
        bits += currentState
    return bits

def sendCoordinates(source, latitude, longitude,
                    destination = 'APRS', digis = ['WIDE1 1','WIDE2 1'],
                    control = 0x03, protocol = 0xf0):
    for address in [source, destination] + digis:
        if len(address) > 7:
            print('Your address %s is greater than 7 characters.\n' +
                  'The maximum length for an address is 7 characters.' % address)
            return False
    SOURCE = source.ljust(7) # 7 characters total (pad with spaces at the end)
    DESTINATION = destination.ljust(7) # Also 7 characters
    DIGIS = ''
    for d in digis:
        DIGIS += d.ljust(7)
    CONTROL = control
    PROTOCOL = protocol

    print((latitude,longitude))
    
    from datetime import datetime
    now = datetime.utcnow()
    INFORMATION = '/%02d%02d%02dz%s/%s>Testing new software TNC' % (
            now.day, now.hour, now.minute, latitude, longitude)
    
    data = bytearray()
    data.extend(DESTINATION)
    data.extend(SOURCE)
    data.extend(DIGIS)
    data.append(CONTROL)
    data.append(PROTOCOL)
    data.extend(INFORMATION)

    for i in range(len(SOURCE) + len(DESTINATION) + len(DIGIS)):
        data[i] = data[i] << 1 # Addresses' bytes are shifted left
    # The last address should end with high bit to indicate end of addresses
    data[len(SOURCE) + len(DESTINATION) + len(DIGIS) - 1] += 1
    
    binaryData = ''
    for byte in data:
        binaryData += bin(byte)[2:].zfill(8)[::-1] # Send each byte LSB first
    
    binaryData += fcs(binaryData)
    binaryData = stuffBits(binaryData)
    everything = '01111110' * 75 + binaryData + '01111110'
    everything = nrzi(everything)

    b = Bell202()
    b.send(everything)