#!/usr/bin/env python3
# Cuts the night sounds in public/assets/sounds/ out of their source
# recordings: trims them, cleans up the owls, makes the fire and wind loop
# seamlessly, and encodes them as Ogg Opus (gapless when looped).
#
#   python3 tools/sounds/build-sounds.py SOURCE_DIR public/assets/sounds
#
# SOURCE_DIR holds the downloads under these names. BigSoundBank files are
# https://bigsoundbank.com/UPLOAD/bwf-en/<number>.wav (CC0, Joseph Sardin).
#   0988.wav   "Big branching fire #2"      bigsoundbank.com/big-branching-fire-2-s0988.html
#   0904.wav   "Wind in the Trees"          bigsoundbank.com/wind-in-the-trees-s0904.html
#   1299.wav   "Broken twigs #1"            bigsoundbank.com/broken-twigs-1-s1299.html
#   1301.wav   "Steps on the Twigs"         bigsoundbank.com/steps-on-the-twigs-s1301.html
#   0137.wav   "Feet in Leaves #1"          bigsoundbank.com/feet-in-leaves-1-s0137.html
#   1588.wav   "Gavel, 1 blow"              bigsoundbank.com/gavel-1-blow-s1588.html
#   0581.wav   "Two dice on wooden table"   bigsoundbank.com/two-dice-on-wooden-table-s0581.html
#   gho.mp3    "Bubo virginianus - Great Horned Owl XC450919.mp3" by Michael &
#              Katie LaTour (xeno-canto), CC BY-SA 4.0, on Wikimedia Commons
#   bdow.oga   "Barred Owl, Yellowstone National Park.oga", National Park
#              Service, public domain, on Wikimedia Commons
#
# Needs ffmpeg (with libopus) and numpy.
import os
import subprocess
import sys

import numpy as np

RATE = 48000


def load(path, start=0.0, length=None, filters=None, channels=1):
    cmd = ['ffmpeg', '-v', 'error', '-ss', str(start)]
    if length:
        cmd += ['-t', str(length)]
    cmd += ['-i', path, '-ac', str(channels), '-ar', str(RATE)]
    if filters:
        cmd += ['-af', filters]
    raw = subprocess.run(cmd + ['-f', 'f32le', '-'], capture_output=True, check=True).stdout
    return np.frombuffer(raw, np.float32).reshape(-1, channels).copy()


def save(audio, path, bitrate='64k'):
    audio = audio / np.abs(audio).max() * 0.89  # peak -1 dB; loudness is set in ambience.js
    channels = audio.shape[1]
    subprocess.run(
        ['ffmpeg', '-v', 'error', '-y', '-f', 'f32le', '-ar', str(RATE), '-ac', str(channels), '-i', '-',
         '-c:a', 'libopus', '-b:a', bitrate, path],
        input=audio.astype(np.float32).tobytes(), check=True)
    print(f'{os.path.basename(path)}: {len(audio) / RATE:.1f} s, {os.path.getsize(path) // 1024} KB')


def fade(audio, fade_in=0.05, fade_out=0.3):
    n_in, n_out = int(fade_in * RATE), int(fade_out * RATE)
    audio[:n_in] *= np.linspace(0, 1, n_in)[:, None]
    audio[-n_out:] *= np.linspace(1, 0, n_out)[:, None]
    return audio


def loop(audio, overlap):
    """Folds the last `overlap` seconds over the start with an equal-power crossfade."""
    n = int(overlap * RATE)
    body = audio[:-n].copy()
    t = np.linspace(0, 1, n)[:, None]
    body[:n] = body[:n] * np.sqrt(t) + audio[-n:] * np.sqrt(1 - t)
    return body


def main(src, dst):
    os.makedirs(dst, exist_ok=True)
    s = lambda name: os.path.join(src, name)
    d = lambda name: os.path.join(dst, name)

    # Fire: 40 s of an outdoor branch fire, looped, without the rumble under it
    # (around 20 Hz: the microphone or distant traffic, not the fire).
    save(loop(load(s('0988.wav'), 4, 42, 'highpass=f=70:poles=2,highpass=f=70:poles=2'), 2.0), d('fire.ogg'))

    # Wind in the trees: stereo, looped. Under the rustling there's a steady roar
    # of distant traffic or planes (it doesn't follow the gusts), so only the
    # leaves are kept. (From 33 s: earlier there's a bump, later a few birds.)
    save(loop(load(s('0904.wav'), 33, 63, 'highpass=f=500:poles=2,highpass=f=500:poles=2', channels=2), 3.0),
         d('wind.ogg'), '80k')

    # Owls: two phrases of the great horned owl, with the low hum under them taken out.
    owl = 'highpass=f=250:poles=2,highpass=f=250:poles=2,lowpass=f=1400'
    save(fade(load(s('gho.mp3'), 2.0, 3.6, owl), 0.15, 0.4), d('owl-great-horned-1.ogg'), '48k')
    save(fade(load(s('gho.mp3'), 10.0, 3.6, owl), 0.15, 0.4), d('owl-great-horned-2.ogg'), '48k')
    save(fade(load(s('bdow.oga'), 0, None, 'highpass=f=200:poles=2,highpass=f=200:poles=2'), 0.05, 0.4), d('owl-barred.ogg'), '48k')

    # Something out in the dark: twigs snapping, and footsteps on twigs and in
    # leaves. The footsteps were recorded close up and thud (mostly below 40 Hz),
    # which something small walking past 20 m away wouldn't.
    light = 'highpass=f=150:poles=2,highpass=f=150:poles=2'
    save(fade(load(s('1299.wav'), 3.55, 0.75, light)), d('twig-1.ogg'))
    save(fade(load(s('1299.wav'), 0.0, 2.3, light)), d('twig-2.ogg'))
    save(fade(load(s('1301.wav'), 0.0, 6.4, light), 0.05, 0.5), d('steps-twigs.ogg'))
    save(fade(load(s('0137.wav'), 0.0, 7.8, light), 0.05, 0.6), d('steps-leaves.ogg'))

    # A chess piece set down (chess.js): a light gavel tap, and the first knock of
    # dice landing on a wooden table, cut before they bounce.
    save(fade(load(s('1588.wav'), 0.02, 0.25, light), 0.003, 0.15), d('chess-1.ogg'), '48k')
    save(fade(load(s('0581.wav'), 4.095, 0.17, light), 0.003, 0.08), d('chess-2.ogg'), '48k')
    save(fade(load(s('0581.wav'), 12.825, 0.13, light), 0.003, 0.06), d('chess-3.ogg'), '48k')


if __name__ == '__main__':
    main(sys.argv[1], sys.argv[2])