#!/usr/bin/env python3
"""
make-sounds.py - sintetiza os dois efeitos sonoros do martelo do Neverwell Moor para o fredygames.com.

Os dois originais (mallet_swing.ogg e mallet_whomp.ogg, atribuidos a "Etherian") nao tem licenca
registrada, entao o site nao os usa. Este script gera outros, do zero, com os mesmos nomes de arquivo,
que o jogo carrega sem mudanca: o balanco do martelo (um sopro de ruido filtrado que sobe e desce) e a
pancada (uma batida grave com um estalo). Sao sons simples (senoides, ruido filtrado, envelopes),
criados pelo FredyGames e dedicados ao dominio publico (CC0 1.0). A saida e deterministica (o ruido vem
de um gerador com semente fixa).

  python3 -I make-sounds.py <pasta de saida>      # escreve mallet_swing.wav e mallet_whomp.wav (44,1 kHz, 16 bits, estereo)

O build-neverwell-moor.sh codifica cada .wav em Ogg Vorbis com o wav2ogg (qualidade 0.3).
"""
import math, random, struct, sys, wave, os

RATE = 44100


def n(sec):
    return int(sec * RATE)


def mix(*parts):
    out = [0.0] * max(len(p) for p in parts)
    for p in parts:
        for i, v in enumerate(p):
            out[i] += v
    return out


def delay(sig, sec):
    return [0.0] * n(sec) + sig


def sweep_noise(sec, seed, amp_fn, cutoff_fn):
    """Ruido branco por um passa-baixa de um polo cuja frequencia de corte (0..1) muda no tempo."""
    rng = random.Random(seed)
    out, y = [], 0.0
    for i in range(n(sec)):
        t = i / RATE
        y += cutoff_fn(t) * (rng.uniform(-1, 1) - y)
        out.append(y * amp_fn(t))
    return out


def thump(freq0, freq1, sec, rate, amp=1.0):
    ph, out = 0.0, []
    for i in range(n(sec)):
        t = i / RATE
        ph += 2 * math.pi * (freq1 + (freq0 - freq1) * math.exp(-t * 25)) / RATE
        out.append(math.sin(ph) * amp * math.exp(-rate * t))
    return out


def click(seed, amp, sec):
    rng = random.Random(seed)
    out, y = [], 0.0
    for i in range(n(sec)):
        x = rng.uniform(-1, 1)
        y += 0.6 * (x - y)
        out.append((x - y) * amp * math.exp(-i / RATE * 300))
    return out


def sounds():
    dur = 0.32
    swing = sweep_noise(dur, 21, lambda t: math.sin(math.pi * t / dur) ** 2 * 0.9,
                        lambda t: 0.04 + 0.28 * math.sin(math.pi * t / dur))
    whomp = mix(thump(150, 55, 0.45, 9, 1.0), click(22, 0.5, 0.03),
                sweep_noise(0.2, 23, lambda t: 0.5 * math.exp(-18 * t), lambda t: 0.15))
    return {'mallet_swing': swing, 'mallet_whomp': whomp}


def write(path, sig):
    peak = max(abs(v) for v in sig) or 1.0
    scale = 0.7 / peak
    fade = n(0.005)
    frames = bytearray()
    for i, v in enumerate(sig):
        g = min(1.0, i / fade, (len(sig) - i) / fade)
        x = int(max(-1.0, min(1.0, v * scale * g)) * 32767)
        frames += struct.pack('<hh', x, x)
    with wave.open(path, 'wb') as w:
        w.setnchannels(2)
        w.setsampwidth(2)
        w.setframerate(RATE)
        w.writeframes(bytes(frames))


if __name__ == '__main__':
    out = sys.argv[1]
    os.makedirs(out, exist_ok=True)
    for name, sig in sounds().items():
        write(os.path.join(out, name + '.wav'), sig)