#!/usr/bin/env python3

# Render image to Oscilloscope XY vector audio
#
# https://pypi.org/project/svgpathtools/
# https://dood.al/oscilloscope/
#
# ----------------------------------------------------------------------------
# Copyright (c) 2024 Thomas Buck (thomas@xythobuz.de)
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# See <http://www.gnu.org/licenses/>.
# ----------------------------------------------------------------------------

import sys
import wave
from svgpathtools import svg2paths

samplerate = 44100 #192000
volume_percent = 70
path_steps = 10
default_duration = 5.0
default_outfile = "out.wav"

def read_image(filename):
    paths, attributes = svg2paths(filename)
    path = paths[0]
    if len(paths) > 1:
        print("WARNING: multiple paths in file. will just draw first one.")

    print("paths={} segments={}".format(len(paths), len(path)))

    points = [[path[0].start.real, path[0].start.imag]]
    p_min = [points[0][0], points[0][1]]
    p_max = [points[0][0], points[0][1]]
    for segment in path:
        p = [segment.end.real, segment.end.imag]
        for i in range(0, 2):
            if p[i] < p_min[i]:
                p_min[i] = p[i]
            if p[i] > p_max[i]:
                p_max[i] = p[i]
        points.append(p)
    print("min={} max={}".format(p_min, p_max))

    data = bytearray()

    def add_point(p):
        for i in range(0, 2):
            v = p[i]
            v -= p_min[i]
            v /= p_max[i] - p_min[i]
            if i == 1:
                v = 1 - v
            c = int((v * 2 - 1) * (32767 / 100 * volume_percent))
            data.extend(c.to_bytes(2, byteorder="little", signed=True))

    def interpolate(p1, p2, step):
        p = []
        for i in range(0, 2):
            diff = p2[i] - p1[i]
            v = p1[i] + diff * step
            p.append(v)
        return p

    for n in range(0, len(points) - 1):
        p1 = points[n]
        p2 = points[n + 1]
        for step in range(0, path_steps):
            p = interpolate(p1, p2, step / path_steps)
            add_point(p)
    add_point(points[len(points) - 1])
    return data

def write_waveform(data, filename):
    with wave.open(filename, "w") as f:
        f.setnchannels(2)
        f.setsampwidth(2)
        f.setframerate(samplerate)
        f.writeframes(data)

def main():
    if len(sys.argv) <= 1:
        print("Usage:")
        print("\t" + sys.argv[0] + " image.png [out.wav] [seconds]")
        sys.exit(1)

    if len(sys.argv) == 3:
        duration = float(sys.argv[2])
        outfile = default_outfile
    if len(sys.argv) >= 4:
        duration = float(sys.argv[2])
        outfile = sys.argv[3]
    else:
        duration = default_duration
        outfile = default_outfile

    wave = read_image(sys.argv[1])

    samplecount = int(len(wave) / 2 / 2) # stereo, int16
    drawrate = samplerate / samplecount
    drawcount = drawrate * duration
    print("len={} samples={} drawrate={:.2f} count={:.2f}".format(len(wave), samplecount, drawrate, drawcount))

    data = bytearray()
    for n in range(0, int(drawcount)):
        data.extend(wave)
    print("len={}".format(len(data)))

    write_waveform(bytes(data), outfile)

if __name__ == "__main__":
    main()