evOo-local/apps/web/src/lib/oo-vocals.ts

import { ooAudioBus } from "./oo-audio-bus";
import { readOoSoundEnabled } from "./oo-sound-pref";

export type OoVocalReaction = "ouh" | "mhm" | "aaah" | "mm" | "nod-down" | "nod-up" | "hm";

const COOLDOWN_MIN_MS = 8_000;
const COOLDOWN_MAX_MS = 12_000;

let lastPlayedAt = 0;
let nextCooldownMs = COOLDOWN_MIN_MS;

function prefersReducedMotion(): boolean {
  if (typeof window === "undefined" || !window.matchMedia) return false;
  return window.matchMedia("(prefers-reduced-motion: reduce)").matches;
}

function randomCooldown(): number {
  return COOLDOWN_MIN_MS + Math.random() * (COOLDOWN_MAX_MS - COOLDOWN_MIN_MS);
}

function vocalFormant(
  ctx: AudioContext,
  destination: AudioNode,
  baseHz: number,
  startAt: number,
  duration: number,
  gainPeak: number,
) {
  const osc = ctx.createOscillator();
  const gain = ctx.createGain();
  const filter = ctx.createBiquadFilter();
  filter.type = "bandpass";
  filter.frequency.value = baseHz * 2.4;
  filter.Q.value = 4.5;
  osc.type = "triangle";
  osc.frequency.setValueAtTime(baseHz, startAt);
  gain.gain.setValueAtTime(0.0001, startAt);
  gain.gain.exponentialRampToValueAtTime(gainPeak, startAt + 0.025);
  gain.gain.exponentialRampToValueAtTime(0.0001, startAt + duration);
  osc.connect(filter);
  filter.connect(gain);
  gain.connect(destination);
  osc.start(startAt);
  osc.stop(startAt + duration + 0.02);
}

function playReactionOnContext(ctx: AudioContext, reaction: OoVocalReaction) {
  const master = ooAudioBus.sfxDestination(ctx);
  const t0 = ctx.currentTime + 0.01;

  switch (reaction) {
    case "ouh":
      vocalFormant(ctx, master, 280, t0, 0.14, 0.055);
      vocalFormant(ctx, master, 360, t0 + 0.06, 0.1, 0.04);
      break;
    case "mhm":
      vocalFormant(ctx, master, 180, t0, 0.12, 0.042);
      vocalFormant(ctx, master, 200, t0 + 0.1, 0.08, 0.032);
      break;
    case "aaah":
      vocalFormant(ctx, master, 320, t0, 0.18, 0.048);
      vocalFormant(ctx, master, 400, t0 + 0.08, 0.14, 0.038);
      break;
    case "mm":
      vocalFormant(ctx, master, 160, t0, 0.16, 0.04);
      break;
    case "hm":
      vocalFormant(ctx, master, 175, t0, 0.09, 0.038);
      break;
    case "nod-down":
      vocalFormant(ctx, master, 165, t0, 0.07, 0.036);
      break;
    case "nod-up":
      vocalFormant(ctx, master, 205, t0, 0.1, 0.038);
      vocalFormant(ctx, master, 245, t0 + 0.08, 0.12, 0.032);
      break;
    default:
      break;
  }
}

class OoVocalsEngine {
  /** State-change vocal — respects cooldown and reduced-motion. No loops. */
  react(reaction: OoVocalReaction) {
    if (!readOoSoundEnabled()) return;
    if (prefersReducedMotion()) return;
    if (typeof document !== "undefined" && document.visibilityState === "hidden") return;

    const now = Date.now();
    if (now - lastPlayedAt < nextCooldownMs) return;

    const ctx = ooAudioBus.ensureContext();
    if (!ctx) return;

    const run = () => {
      try {
        playReactionOnContext(ctx, reaction);
        lastPlayedAt = Date.now();
        nextCooldownMs = randomCooldown();
      } catch {
        // Ignore playback failures.
      }
    };

    if (ctx.state === "suspended") {
      void ctx
        .resume()
        .then(run)
        .catch(() => undefined);
      return;
    }
    run();
  }

  /** Nod: mh on down, Mhh on up — single cooldown window. */
  reactNod() {
    if (!readOoSoundEnabled()) return;
    if (prefersReducedMotion()) return;
    if (typeof document !== "undefined" && document.visibilityState === "hidden") return;

    const now = Date.now();
    if (now - lastPlayedAt < nextCooldownMs) return;

    const ctx = ooAudioBus.ensureContext();
    if (!ctx) return;

    const run = () => {
      try {
        const t0 = ctx.currentTime + 0.01;
        const master = ooAudioBus.sfxDestination(ctx);
        vocalFormant(ctx, master, 165, t0, 0.07, 0.036);
        vocalFormant(ctx, master, 205, t0 + 0.09, 0.1, 0.038);
        vocalFormant(ctx, master, 245, t0 + 0.17, 0.12, 0.032);
        lastPlayedAt = Date.now();
        nextCooldownMs = randomCooldown();
      } catch {
        // Ignore playback failures.
      }
    };

    if (ctx.state === "suspended") {
      void ctx
        .resume()
        .then(run)
        .catch(() => undefined);
      return;
    }
    run();
  }

  reactForEvent(kind: "need-you" | "success" | "nod" | "curious") {
    switch (kind) {
      case "need-you":
        this.react("ouh");
        break;
      case "success":
        this.react("hm");
        break;
      case "nod":
        this.reactNod();
        break;
      case "curious":
        this.react("mm");
        break;
      default:
        break;
    }
  }
}

export const ooVocals = new OoVocalsEngine();

export function resetOoVocalsCooldownForTests(): void {
  lastPlayedAt = 0;
  nextCooldownMs = COOLDOWN_MIN_MS;
}