import math
import sounddevice as sd


# ==================================================
# RTTY PARAMETERS
# ==================================================

Fs = 48000                 # PC sound-card sample rate

baud = 45.45              # RTTY baud rate

mark_freq = 2125          # MARK
space_freq = 2295         # SPACE

text = "HELLO WORLD 123"


# ==================================================
# ITA2 / BAUDOT
# ==================================================

LETTERS = {
    'A': 0b00011,
    'B': 0b11001,
    'C': 0b01110,
    'D': 0b01001,
    'E': 0b00001,
    'F': 0b01101,
    'G': 0b11010,
    'H': 0b10100,
    'I': 0b00110,
    'J': 0b01011,
    'K': 0b01111,
    'L': 0b10010,
    'M': 0b11100,
    'N': 0b01100,
    'O': 0b11000,
    'P': 0b10110,
    'Q': 0b10111,
    'R': 0b01010,
    'S': 0b00101,
    'T': 0b10000,
    'U': 0b00111,
    'V': 0b11110,
    'W': 0b10011,
    'X': 0b11101,
    'Y': 0b10101,
    'Z': 0b10001,
    ' ': 0b00100
}

FIGURES = {
    '1': 0b10111,
    '2': 0b10011,
    '3': 0b00001,
    '4': 0b01010,
    '5': 0b10000,
    '6': 0b10101,
    '7': 0b00111,
    '8': 0b00110,
    '9': 0b11000,
    '0': 0b10110,
}

FIGURES_SHIFT = 0b1101
LETTERS_SHIFT = 0b11111


# ==================================================
# TEXT → BAUDOT
# ==================================================

baudot_bits = []

mode = "LETTERS"

for char in text.upper():

    if char == ' ':
        code = LETTERS[' ']

    elif char in LETTERS:

        if mode != "LETTERS":

            code = LETTERS_SHIFT

            for i in range(5):
                baudot_bits.append((code >> i) & 1)

            mode = "LETTERS"

        code = LETTERS[char]

    elif char in FIGURES:

        if mode != "FIGURES":

            code = FIGURES_SHIFT

            for i in range(5):
                baudot_bits.append((code >> i) & 1)

            mode = "FIGURES"

        code = FIGURES[char]

    else:
        continue

    # LSB first
    for i in range(5):
        baudot_bits.append((code >> i) & 1)


# ==================================================
# ADD RTTY FRAMING
# ==================================================

framed_bits = []

for i in range(0, len(baudot_bits), 5):

    data = baudot_bits[i:i + 5]

    # START = SPACE
    framed_bits.append(0)

    # DATA
    framed_bits.extend(data)

    # STOP = MARK
    framed_bits.append(1)


# ==================================================
# FSK MODULATOR
# ==================================================

phase = 0.0

signal = []

samples_per_bit = Fs / baud

sample_accumulator = 0.0


for bit in framed_bits:

    if bit == 1:
        frequency = mark_freq
    else:
        frequency = space_freq

    # Number of samples for this symbol
    sample_accumulator += samples_per_bit

    samples_this_symbol = int(sample_accumulator)

    sample_accumulator -= samples_this_symbol

    # Generate the symbol
    for _ in range(samples_this_symbol):

        phase += 2 * math.pi * frequency / Fs

        # Keep phase between 0 and 2*pi
        phase %= 2 * math.pi

        sample = math.cos(phase)

        signal.append(sample)


# ==================================================
# PLAY AUDIO
# ==================================================

print("Playing RTTY...")
print()
print("Text:", text)
print("MARK:", mark_freq, "Hz")
print("SPACE:", space_freq, "Hz")
print("Baud:", baud)
print("Duration:", len(signal) / Fs, "seconds")

sd.play(signal, Fs)

sd.wait()

print("Finished.")