Project-M/Assets/_Project/Scripts/Client/Presentation/AmbientAudioSystem.cs

using ProjectM.Simulation;
using Unity.Entities;
using Unity.NetCode;
using UnityEngine;

namespace ProjectM.Client
{
    /// <summary>
    /// Client-only AMBIENT audio bed + run cues. A managed presentation <see cref="SystemBase"/>
    /// (<see cref="PresentationSystemGroup"/>, main thread, no Burst) that plays a low, seamless-looping
    /// procedural drone (asset-free, <c>AudioClip.Create</c> like <c>CombatFeedbackSystem.MakeClip</c>) plus
    /// launch-countdown beeps and the boss-arrival roar — replicated-state observations only. Lives only in the
    /// client world, so the server never creates audio and nothing here affects determinism. Volumes are
    /// deliberately conservative. (The cycle-phase stingers + Core alarm retired with the siege loop — LANTERN purge.)
    /// </summary>
    [WorldSystemFilter(WorldSystemFilterFlags.ClientSimulation)]
    [UpdateInGroup(typeof(PresentationSystemGroup))]
    public partial class AmbientAudioSystem : SystemBase
    {
        AudioSource _ambient;
        AudioClip _ambientClip;
        GameObject _root;

        AudioClip _stingBeep, _stingRoar;
        int _lastCountdownSec = -1;
        bool _bossRoared;

        // 07-16 underwater re-voice: the bed volume + groan cadence live on FeelConfig (live-tunable).
        AudioSource _groanSrc;
        AudioClip _groanClip;
        float _nextGroanIn = 12f; // first distant groan ~12s into a session

        protected override void OnCreate()
        {
            _ambientClip = MakeDrone();
            _groanClip = MakeGroan();
            _stingBeep = MakeSting(880f, 880f, 0.09f, 0.30f);       // countdown tick
            _stingRoar = MakeSting(90f, 38f, 0.90f, 0.60f);         // boss-arrival roar (low falling growl)
        }

        protected override void OnStartRunning()
        {
            if (_root != null) return;
            _root = new GameObject("~AmbientAudio");
            _ambient = _root.AddComponent<AudioSource>();
            _ambient.clip = _ambientClip;
            _ambient.loop = true;
            _ambient.playOnAwake = false;
            _ambient.spatialBlend = 0f; // 2D bed
            _ambient.volume = FeelConfig.AmbienceVolume * GameVolume.Music;
            _ambient.Play();
            _groanSrc = _root.AddComponent<AudioSource>();
            _groanSrc.playOnAwake = false;
            _groanSrc.spatialBlend = 0f; // distant, directionless
            _groanSrc.loop = false;
        }

        protected override void OnDestroy()
        {
            if (_root != null) Object.Destroy(_root);
        }

        protected override void OnUpdate()
        {
            if (_ambient == null) return;

            float dt = SystemAPI.Time.DeltaTime;
            _ambient.volume = Mathf.MoveTowards(_ambient.volume, FeelConfig.AmbienceVolume * GameVolume.Music, dt * 0.25f);

            // Distant groans (07-16 gap-list): a slow low sweep with a soft attack, jittered interval + pitch —
            // the murk answering back. Presentation-only wall-clock randomness is fine here.
            if (_groanSrc != null && FeelConfig.GroanIntervalSec > 0f)
            {
                _nextGroanIn -= dt;
                if (_nextGroanIn <= 0f)
                {
                    _nextGroanIn = FeelConfig.GroanIntervalSec * (0.6f + Random.value * 0.8f);
                    _groanSrc.pitch = 0.85f + Random.value * 0.3f;
                    _groanSrc.PlayOneShot(_groanClip, FeelConfig.GroanVolume * GameVolume.Music);
                }
            }

            // 2026-08-07 audit purge: the 3-2-1 launch countdown beeps and the boss-arrival roar keyed off
            // RunInfo.Lifecycle / RoomTypeId. Both went with the run FSM and the boss.
        }

        // ---- Procedural audio (asset-free; mirrors CombatFeedbackSystem.MakeClip) ----

        // A low, seamless-looping pad: each partial completes an integer number of cycles over the buffer
        // (freq snapped to k/duration) so the loop point has no click. A slow tremolo adds motion.
        // A low, seamless-looping UNDERWATER pressure bed (07-16 re-voice): sub-heavy partials + a pair of
        // detuned subs whose beat completes exactly once per loop (Snap keeps every partial click-free at the
        // loop point) — reads as slow water-column pressure swell rather than a musical pad.
        static AudioClip MakeDrone()
        {
            const int rate = 44100;
            const float dur = 8f;
            int len = (int)(dur * rate);
            var clip = AudioClip.Create("underwater_bed", len, 1, rate, false);
            var data = new float[len];
            float f0 = Snap(38f, dur);          // deep sub
            float f0b = f0 + 1f / dur;          // detuned sub: beats exactly once per loop (seamless)
            float f1 = Snap(55f, dur);
            float f2 = Snap(82.4f, dur);        // faint upper body
            float swell = Snap(0.25f, dur);     // very slow amplitude swell
            for (int i = 0; i < len; i++)
            {
                float t = i / (float)rate;
                float s = 0.46f * Mathf.Sin(2f * Mathf.PI * f0 * t)
                        + 0.34f * Mathf.Sin(2f * Mathf.PI * f0b * t)
                        + 0.22f * Mathf.Sin(2f * Mathf.PI * f1 * t)
                        + 0.07f * Mathf.Sin(2f * Mathf.PI * f2 * t);
                float amp = 0.7f + 0.3f * Mathf.Sin(2f * Mathf.PI * swell * t);
                data[i] = s * amp * 0.5f;
            }
            clip.SetData(data, 0);
            return clip;
        }

        // A distant whale-adjacent groan: slow 58->34Hz sweep with a soft sin^2 attack/decay window and a
        // subtle wobble — never a jump-scare, just the deep being large somewhere off-screen.
        static AudioClip MakeGroan()
        {
            const int rate = 44100;
            const float dur = 3.4f;
            int len = (int)(dur * rate);
            var clip = AudioClip.Create("distant_groan", len, 1, rate, false);
            var data = new float[len];
            float phase = 0f;
            for (int i = 0; i < len; i++)
            {
                float t01 = i / (float)len;
                float t = i / (float)rate;
                float freq = Mathf.Lerp(58f, 34f, t01) * (1f + 0.03f * Mathf.Sin(2f * Mathf.PI * 1.7f * t));
                phase += 2f * Mathf.PI * freq / rate;
                float window = Mathf.Sin(Mathf.PI * t01);
                float env = window * window; // soft attack AND release
                data[i] = (0.8f * Mathf.Sin(phase) + 0.2f * Mathf.Sin(2f * phase)) * env * 0.55f;
            }
            clip.SetData(data, 0);
            return clip;
        }

        // freq snapped so freq*dur is an integer -> the waveform closes seamlessly at the loop point.
        static float Snap(float freq, float dur)
        {
            float cycles = Mathf.Max(1f, Mathf.Round(freq * dur));
            return cycles / dur;
        }

        // Short one-shot tone sweeping f0->f1 with an exponential decay envelope.
        static AudioClip MakeSting(float f0, float f1, float dur, float vol) => FeedbackFx.MakeClip("sting", f0, f1, dur, vol, decay: 3.5f);
    }
}