import wave
import numpy as np
import math

# Nombre d’octets par échantillon
samp_width = 2

# Valeur maximale d’un échantillon
max_val = 2 ** (8 * samp_width - 1) - 1

# Fréquence d’échantillonnage (Hertz)
samp_rate = 44100


def add_signal(dest, start, source):
    dest[int(samp_rate * start):int(samp_rate * start) + len(source)] += source


def silence(dur):
    return np.zeros((int(samp_rate * dur),))


def sine(dur, freq, value=1):
    x = np.arange(int(samp_rate * dur))
    return value * max_val * np.sin(2 * np.pi * freq * x / samp_rate)


def envelope(attack, decay, release, signal):
    total = len(signal)
    attack = int(attack * total)
    decay = int(decay * total)
    release = int(release * total)
    sustain = total - attack - decay - release

    return signal * np.concatenate((
        np.linspace(start=0, stop=1, num=attack, endpoint=False),
        np.linspace(start=1, stop=2/3, num=decay, endpoint=False),
        np.linspace(start=2/3, stop=2/3, num=sustain, endpoint=False),
        np.linspace(start=2/3, stop=0, num=release, endpoint=True),
    ))

notes = {
    'do': 0, 'si#': 0,
    'do#': 1, 'reb': 1,
    're': 2,
    're#': 3, 'mib': 3,
    'mi': 4, 'fab': 4,
    'fa': 5, 'mi#': 5,
    'fa#': 6, 'solb': 6,
    'sol': 7,
    'sol#': 8, 'lab': 8,
    'la': 9,
    'la#': 10, 'sib': 10,
    'si': 11, 'dob': 11,
}


def note_freq(note, octave):
    return (440
        * (2 ** (octave - 3))
        * math.pow(2, (notes[note] - 9) / 12))


def note_freqs(notes):
    return list(map(lambda info: note_freq(*info), notes))


def chord(instr, dur, freqs, value=1):
    signal = np.zeros((int(samp_rate * dur),))

    for freq in freqs:
        signal += instr(dur, freq, value / len(freqs))

    return signal


def save_signal(out_name, signal):
    with wave.open(out_name, 'w') as file:
        file.setnchannels(1)
        file.setsampwidth(samp_width)
        file.setframerate(samp_rate)
        file.writeframesraw(signal.astype('<h').tostring())


def load_signal(in_name):
    with wave.open(in_name, 'r') as file:
        assert file.getnchannels() == 1
        assert file.getsampwidth() == samp_width
        assert file.getframerate() == samp_rate
        size = file.getnframes()
        return np.ndarray((size,), '<h', file.readframes(size))