from scipy.io import wavfile
from pydub import AudioSegment
from collections import OrderedDict

DEBUG = False

def get_direction(prev, next_):
    if prev > next_:
        direction = 'down'
    elif prev < next_:
        direction = 'up'
    else:
        direction = 'continue'

    return direction

def quantize(samples, samplerate, thresholds):
    buf = []
    prev = 0
    prev_direction = ''
    continue_count = 0

    for sample in samples:
        if prev_direction != '':
            direction = get_direction(prev, sample)
        else:
            prev_direction = 'continue'
            direction = 'continue'

        if direction == 'continue':
            continue_count += 1
        else:
            continue_count = 0

        if (continue_count == (samplerate / 10) - 1):
            buf += [thresholds[str(int(sample))]]
            continue_count = 0

        prev = sample
        prev_direction = direction

    return buf

def group_by_octal(data):
    tmp = ''
    j = 0
    buf = OrderedDict()

    for i in range(len(data)):
        if len(buf) <= j:
            buf[j] = ''

        tmp += data[i]

        current = '{}{}'.format(buf[j], tmp)
        shift = int(current) > 199

        if (len(tmp) - 1) % 3 == 2 or shift:
            if shift:
                buf[j+1] = current[-1]
                tmp = current[:-1]

            buf[j] = tmp
            tmp = ''
            j += 1

        i += 1

    return buf

# Read WAV file
audio_file = 'audible.wav'
samplerate, samples = wavfile.read(audio_file)

# Signal quantization (3-bit)
thresholds = OrderedDict([
    ('-32000', '0'),
    ('-24000', '1'),
    ('-16200', '2'),
     ('-8100', '3'),
      ('8100', '4'),
     ('16200', '5'),
     ('24000', '6'),
     ('32000', '7')
])
buf = quantize(samples, samplerate, thresholds)
if DEBUG: print(buf)

# Get octal values from quantized data
buf = group_by_octal(buf)
if DEBUG: print(buf)

# Convert octal values to chars
flag = ''
for i in range(len(buf)):
    flag += chr(int(buf[i], 8))

# Print flag
print(flag)