mmpSearch/assets/js/creations/pattern/pattern_audio.js

// js/pattern_audio.js
import { appState } from "../state.js";
import { highlightStep } from "./pattern_ui.js";
import { getTotalSteps } from "../utils.js";
import { initializeAudioContext } from "../audio.js";

const timerDisplay = document.getElementById('timer-display');

function formatTime(milliseconds) {
  const totalSeconds = Math.floor(milliseconds / 1000);
  const minutes = Math.floor(totalSeconds / 60).toString().padStart(2, '0');
  const seconds = (totalSeconds % 60).toString().padStart(2, '0');
  const centiseconds = Math.floor((milliseconds % 1000) / 10).toString().padStart(2, '0');
  return `${minutes}:${seconds}:${centiseconds}`;
}

export function playMetronomeSound(isDownbeat) {
  initializeAudioContext();
  const synth = new Tone.Synth().toDestination();
  const freq = isDownbeat ? 1000 : 800;
  synth.triggerAttackRelease(freq, "8n", Tone.now());
}

// --- FUNÇÃO CORRIGIDA E EFICIENTE ---
export function playSample(filePath, trackId) {
  initializeAudioContext();
  const track = trackId ? appState.pattern.tracks.find((t) => t.id == trackId) : null;

  // Se a faixa existe e tem um player pré-carregado, apenas o dispara.
  if (track && track.player) {
    // Atualiza o volume/pan caso tenham sido alterados
    track.gainNode.gain.value = Tone.gainToDb(track.volume);
    track.pannerNode.pan.value = track.pan;
    
    // Dispara o som imediatamente. Esta operação é instantânea.
    track.player.start(Tone.now());
  } 
  // Fallback para preview de samples no navegador (sem trackId)
  else if (!trackId && filePath) {
      const previewPlayer = new Tone.Player(filePath).toDestination();
      previewPlayer.autostart = true;
  }
}

function tick() {
  if (!appState.global.isPlaying) {
    stopPlayback();
    return;
  }

  const totalSteps = getTotalSteps();
  const lastStepIndex = appState.global.currentStep === 0 ? totalSteps - 1 : appState.global.currentStep - 1;
  highlightStep(lastStepIndex, false);

  const bpm = parseInt(document.getElementById("bpm-input").value, 10) || 120;
  const stepInterval = (60 * 1000) / (bpm * 4);
  const currentTime = appState.global.currentStep * stepInterval;
  if (timerDisplay) {
    timerDisplay.textContent = formatTime(currentTime);
  }

  if (appState.global.metronomeEnabled) {
    const noteValue = parseInt(document.getElementById("compasso-b-input").value, 10) || 4;
    const stepsPerBeat = 16 / noteValue;
    if (appState.global.currentStep % stepsPerBeat === 0) {
      playMetronomeSound(appState.global.currentStep % (stepsPerBeat * 4) === 0);
    }
  }

  appState.pattern.tracks.forEach((track) => {
    if (!track.patterns || track.patterns.length === 0) return;
    
    const activePattern = track.patterns[appState.pattern.activePatternIndex];

    if (activePattern && activePattern.steps[appState.global.currentStep] && track.samplePath) {
      playSample(track.samplePath, track.id);
    }
  });

  highlightStep(appState.global.currentStep, true);
  appState.global.currentStep = (appState.global.currentStep + 1) % totalSteps;
}

export function startPlayback() {
  if (appState.global.isPlaying || appState.pattern.tracks.length === 0) return;
  initializeAudioContext();
  
  if (appState.global.currentStep === 0) {
      rewindPlayback();
  }

  const bpm = parseInt(document.getElementById("bpm-input").value, 10) || 120;
  Tone.Transport.bpm.value = bpm;
  const stepInterval = (60 * 1000) / (bpm * 4);

  if (appState.global.playbackIntervalId) clearInterval(appState.global.playbackIntervalId);

  appState.global.isPlaying = true;
  document.getElementById("play-btn").classList.remove("fa-play");
  document.getElementById("play-btn").classList.add("fa-pause");

  tick();
  appState.global.playbackIntervalId = setInterval(tick, stepInterval);
}

export function stopPlayback() {
  if(appState.global.playbackIntervalId) {
    clearInterval(appState.global.playbackIntervalId);
  }
  appState.global.playbackIntervalId = null;
  appState.global.isPlaying = false;

  document.querySelectorAll('.step.playing').forEach(s => s.classList.remove('playing'));
  appState.global.currentStep = 0;
  if (timerDisplay) timerDisplay.textContent = '00:00:00';

  const playBtn = document.getElementById("play-btn");
  if (playBtn) {
    playBtn.classList.remove("fa-pause");
    playBtn.classList.add("fa-play");
  }
}

export function rewindPlayback() {
  const lastStep = appState.global.currentStep > 0 ? appState.global.currentStep - 1 : getTotalSteps() - 1;
  appState.global.currentStep = 0;
  if (!appState.global.isPlaying) {
    if (timerDisplay) timerDisplay.textContent = '00:00:00';
    highlightStep(lastStep, false);
  }
}

export function togglePlayback() {
  initializeAudioContext();
  if (appState.global.isPlaying) {
    stopPlayback();
  } else {
    appState.global.currentStep = 0;
    startPlayback();
  }
}