// js/audio.js
import { appState } from "./state.js";
import { highlightStep } from "./ui.js";
import { getTotalSteps } from "./utils.js";

let audioContext;
let mainGainNode;
let masterPannerNode;

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

export function getAudioContext() {
  return audioContext;
}
export function getMainGainNode() {
  return mainGainNode;
}

export function initializeAudioContext() {
  if (!audioContext) {
    audioContext = new (window.AudioContext || window.webkitAudioContext)();
    mainGainNode = audioContext.createGain();
    masterPannerNode = audioContext.createStereoPanner();

    mainGainNode.connect(masterPannerNode);
    masterPannerNode.connect(audioContext.destination);
  }
  if (audioContext.state === "suspended") {
    audioContext.resume();
  }
}

export function updateMasterVolume(volume) {
  if (mainGainNode) {
    mainGainNode.gain.setValueAtTime(volume, audioContext.currentTime);
  }
}

export function updateMasterPan(pan) {
  if (masterPannerNode) {
    masterPannerNode.pan.setValueAtTime(pan, audioContext.currentTime);
  }
}

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 oscillator = audioContext.createOscillator();
  const gainNode = audioContext.createGain();
  const frequency = isDownbeat ? 1000 : 800;
  oscillator.frequency.setValueAtTime(frequency, audioContext.currentTime);
  oscillator.type = "sine";
  gainNode.gain.setValueAtTime(1, audioContext.currentTime);
  gainNode.gain.exponentialRampToValueAtTime(
    0.00001,
    audioContext.currentTime + 0.05
  );
  oscillator.connect(gainNode);
  gainNode.connect(audioContext.destination);
  oscillator.start(audioContext.currentTime);
  oscillator.stop(audioContext.currentTime + 0.05);
}

export function playSample(filePath, trackId) {
  initializeAudioContext();
  if (!filePath) return;

  const track = trackId ? appState.tracks.find((t) => t.id == trackId) : null;

  if (!track || !track.audioBuffer) {
    // Se não houver buffer (ex: preview do sample browser), toca como um áudio simples
    const audio = new Audio(filePath);
    audio.play();
    return;
  }
  
  const source = audioContext.createBufferSource();
  source.buffer = track.audioBuffer;

  if (track.gainNode) {
    source.connect(track.gainNode);
  } else {
    source.connect(mainGainNode);
  }

  source.start(0);
}

function tick() {
  const totalSteps = getTotalSteps();
  if (totalSteps === 0) {
    stopPlayback();
    return;
  }
  const lastStepIndex =
    appState.currentStep === 0 ? totalSteps - 1 : appState.currentStep - 1;
  highlightStep(lastStepIndex, false);

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

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

  // --- INÍCIO DA CORREÇÃO ---
  appState.tracks.forEach((track) => {
    // 1. Verifica se a faixa tem patterns
    if (!track.patterns || track.patterns.length === 0) return;
    
    // 2. Pega o pattern que está ativo para esta faixa
    const activePattern = track.patterns[track.activePatternIndex];

    // 3. Verifica se o pattern existe e se o step atual está ativo NELE
    if (activePattern && activePattern.steps[appState.currentStep] && track.samplePath) {
      playSample(track.samplePath, track.id);
    }
  });
  // --- FIM DA CORREÇÃO ---

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

export function startPlayback() {
  if (appState.isPlaying || appState.tracks.length === 0) return;
  initializeAudioContext();
  const bpm = parseInt(document.getElementById("bpm-input").value, 10) || 120;
  const stepInterval = (60 * 1000) / (bpm * 4);

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

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

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

export function stopPlayback() {
  if(appState.playbackIntervalId) {
    clearInterval(appState.playbackIntervalId);
  }
  appState.playbackIntervalId = null;
  appState.isPlaying = false;
  highlightStep(appState.currentStep - 1, false);
  highlightStep(appState.currentStep, false); // Garante que o último step "playing" seja limpo
  appState.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 previousStep = appState.currentStep;
  appState.currentStep = 0;
  if (!appState.isPlaying) {
    if (timerDisplay) timerDisplay.textContent = '00:00:00';
    highlightStep(previousStep - 1, false);
    highlightStep(previousStep, false);
  }
}

export function togglePlayback() {
  initializeAudioContext(); // Garante que o contexto de áudio foi iniciado por um gesto do usuário
  if (appState.isPlaying) {
    // Pausa a reprodução, mas não reseta
    clearInterval(appState.playbackIntervalId);
    appState.playbackIntervalId = null;
    appState.isPlaying = false;
    document.getElementById("play-btn").classList.remove("fa-pause");
    document.getElementById("play-btn").classList.add("fa-play");
  } else {
    startPlayback();
  }
}