Chessistics/Scripts/Presentation/SfxManager.cs

using Godot;
using System;

namespace Chessistics.Scripts.Presentation;

/// <summary>
/// Procedural sound effects via synthesized waveforms.
/// No external audio files needed — everything is generated in code.
/// </summary>
public partial class SfxManager : Node
{
    private const int SampleRate = 22050;
    private const float MasterVolume = 0.15f;

    public static SfxManager? Instance { get; private set; }

    public override void _Ready()
    {
        Instance = this;
    }

    // --- Public API ---

    public void PlayPlace() => PlayTone(523.25f, 0.08f, vol: 0.5f); // C5 short blip
    public void PlayProduce() => PlayTone(130.81f, 0.12f, vol: 0.3f, wave: Wave.Triangle); // C3 warm
    public void PlayTransfer() => PlayNoise(0.12f, vol: 0.15f); // filtered swoosh
    public void PlayDeliver() => PlayChord([523.25f, 659.25f], 0.18f, vol: 0.4f); // C5+E5 ding
    public void PlayMove() => PlayNoise(0.04f, vol: 0.08f); // tiny whoosh
    public void PlayDestroy() => PlaySweep(262f, 65f, 0.18f, vol: 0.4f); // descending crunch
    public void PlayVictory() => PlayArpeggio([262f, 330f, 392f, 523f], 0.12f, vol: 0.35f); // C-E-G-C arp
    public void PlayClick() => PlayTone(880f, 0.02f, vol: 0.2f); // tiny tick

    // --- Synthesis ---

    private enum Wave { Sine, Triangle, Square }

    private void PlayTone(float freq, float duration, float vol = 0.3f, Wave wave = Wave.Sine)
    {
        var samples = GenerateTone(freq, duration, vol, wave);
        PlaySamples(samples);
    }

    private void PlayNoise(float duration, float vol = 0.2f)
    {
        var count = (int)(SampleRate * duration);
        var samples = new float[count];
        var rng = new Random();
        for (int i = 0; i < count; i++)
        {
            float t = (float)i / count;
            float envelope = Envelope(t);
            samples[i] = (float)(rng.NextDouble() * 2 - 1) * vol * envelope * MasterVolume;
        }
        // Simple low-pass: average with previous sample
        for (int i = count - 1; i > 0; i--)
            samples[i] = (samples[i] + samples[i - 1]) * 0.5f;
        PlaySamples(samples);
    }

    private void PlayChord(float[] freqs, float duration, float vol = 0.3f)
    {
        var count = (int)(SampleRate * duration);
        var samples = new float[count];
        foreach (var freq in freqs)
        {
            var tone = GenerateTone(freq, duration, vol / freqs.Length, Wave.Sine);
            for (int i = 0; i < count; i++)
                samples[i] += tone[i];
        }
        PlaySamples(samples);
    }

    private void PlaySweep(float startFreq, float endFreq, float duration, float vol = 0.3f)
    {
        var count = (int)(SampleRate * duration);
        var samples = new float[count];
        for (int i = 0; i < count; i++)
        {
            float t = (float)i / count;
            float freq = Mathf.Lerp(startFreq, endFreq, t);
            float envelope = Envelope(t);
            float phase = 2f * Mathf.Pi * freq * i / SampleRate;
            samples[i] = Mathf.Sin(phase) * vol * envelope * MasterVolume;
        }
        PlaySamples(samples);
    }

    private void PlayArpeggio(float[] notes, float noteLength, float vol = 0.3f)
    {
        float totalDuration = noteLength * notes.Length;
        var totalCount = (int)(SampleRate * totalDuration);
        var samples = new float[totalCount];
        var noteCount = (int)(SampleRate * noteLength);

        for (int n = 0; n < notes.Length; n++)
        {
            int offset = n * noteCount;
            var tone = GenerateTone(notes[n], noteLength, vol, Wave.Sine);
            for (int i = 0; i < tone.Length && offset + i < totalCount; i++)
                samples[offset + i] += tone[i];
        }
        PlaySamples(samples);
    }

    private float[] GenerateTone(float freq, float duration, float vol, Wave wave)
    {
        var count = (int)(SampleRate * duration);
        var samples = new float[count];
        for (int i = 0; i < count; i++)
        {
            float t = (float)i / count;
            float phase = 2f * Mathf.Pi * freq * i / SampleRate;
            float value = wave switch
            {
                Wave.Triangle => 2f * Mathf.Abs(2f * ((freq * i / SampleRate) % 1f) - 1f) - 1f,
                Wave.Square => Mathf.Sin(phase) >= 0 ? 1f : -1f,
                _ => Mathf.Sin(phase)
            };
            float envelope = Envelope(t);
            samples[i] = value * vol * envelope * MasterVolume;
        }
        return samples;
    }

    /// <summary>Simple ADSR-ish envelope: quick attack, sustain, smooth release.</summary>
    private static float Envelope(float t)
    {
        if (t < 0.05f) return t / 0.05f;          // attack
        if (t < 0.3f) return 1f;                    // sustain
        return 1f - (t - 0.3f) / 0.7f;             // release
    }

    private void PlaySamples(float[] samples)
    {
        var stream = new AudioStreamWav
        {
            Format = AudioStreamWav.FormatEnum.Format16Bits,
            MixRate = SampleRate,
            Stereo = false,
            Data = FloatsToWav16(samples)
        };

        var player = new AudioStreamPlayer { Stream = stream, VolumeDb = -6f };
        AddChild(player);
        player.Finished += () => player.QueueFree();
        player.Play();
    }

    private static byte[] FloatsToWav16(float[] samples)
    {
        var bytes = new byte[samples.Length * 2];
        for (int i = 0; i < samples.Length; i++)
        {
            short val = (short)(Mathf.Clamp(samples[i], -1f, 1f) * 32767);
            bytes[i * 2] = (byte)(val & 0xFF);
            bytes[i * 2 + 1] = (byte)((val >> 8) & 0xFF);
        }
        return bytes;
    }
}