// Music Player State
const playerState = {
  isPlaying: false,
  currentTrackIndex: -1,
  volume: 80,
  progress: 0,
  tracks: [],
  draggedElement: null
};

// DOM Elements
const elements = {
  selectFolderBtn: document.getElementById('select-folder-btn'),
  folderInput: document.getElementById('folder-input'),
  tracksList: document.getElementById('tracks-list'),
  playPauseBtn: document.getElementById('play-pause-btn'),
  prevBtn: document.getElementById('prev-btn'),
  nextBtn: document.getElementById('next-btn'),
  progressBar: document.getElementById('progress-bar'),
  volumeSlider: document.getElementById('volume-slider'),
  currentTime: document.getElementById('current-time'),
  totalTime: document.getElementById('total-time'),
  currentTrackTitle: document.getElementById('current-track-title'),
  currentTrackArtist: document.getElementById('current-track-artist'),
  shuffleBtn: document.getElementById('shuffle-btn'),
  repeatBtn: document.getElementById('repeat-btn')
};

// Initialize the application
document.addEventListener('DOMContentLoaded', () => {
  setupEventListeners();
  updatePlayerUI();
});

// Set up event listeners
function setupEventListeners() {
  // Folder selection
  elements.selectFolderBtn.addEventListener('click', () => {
    elements.folderInput.click();
  });
  
  elements.folderInput.addEventListener('change', handleFolderSelection);
  
  // Player controls
  elements.playPauseBtn.addEventListener('click', togglePlayPause);
  elements.prevBtn.addEventListener('click', playPreviousTrack);
  elements.nextBtn.addEventListener('click', playNextTrack);
  elements.progressBar.addEventListener('input', handleProgressChange);
  elements.volumeSlider.addEventListener('input', handleVolumeChange);
  
  // Shuffle and repeat
  elements.shuffleBtn.addEventListener('click', toggleShuffle);
  elements.repeatBtn.addEventListener('click', toggleRepeat);
  
  // Keyboard shortcuts
  document.addEventListener('keydown', handleKeyboardShortcuts);
}

// Handle folder selection
function handleFolderSelection(event) {
  const files = Array.from(event.target.files);
  const audioFiles = files.filter(file => file.type.startsWith('audio/'));
  
  if (audioFiles.length === 0) {
    alert('No audio files found in the selected folder.');
    return;
  }
  
  playerState.tracks = audioFiles.map((file, index) => ({
    id: index,
    title: file.name.replace(/\.[^/.]+$/, ""), // Remove extension
    artist: 'Unknown Artist',
    album: 'Unknown Album',
    duration: '0:00',
    file: file,
    url: URL.createObjectURL(file)
  }));
  
  renderPlaylist();
  updatePlayerUI();
}

// Render playlist
function renderPlaylist() {
  elements.tracksList.innerHTML = '';
  
  playerState.tracks.forEach((track, index) => {
    const trackElement = document.createElement('div');
    trackElement.className = 'track-item grid grid-cols-12 gap-4 p-3 items-center cursor-pointer';
    trackElement.draggable = true;
    trackElement.dataset.index = index;
    
    trackElement.innerHTML = `
      <div class="col-span-1 flex items-center">
        <span class="track-number">${index + 1}</span>
        <button class="play-button hidden ml-2 text-green-500">
          <i data-feather="play"></i>
        </button>
      </div>
      <div class="col-span-5 truncate">${track.title}</div>
      <div class="col-span-3 truncate text-gray-400">${track.album}</div>
      <div class="col-span-2 text-gray-400">${track.duration}</div>
      <div class="col-span-1 flex justify-end">
        <button class="more-button text-gray-400 hover:text-white">
          <i data-feather="more-horizontal"></i>
        </button>
      </div>
    `;
    
    // Add drag and drop events
    trackElement.addEventListener('dragstart', handleDragStart);
    trackElement.addEventListener('dragover', handleDragOver);
    trackElement.addEventListener('dragenter', handleDragEnter);
    trackElement.addEventListener('dragleave', handleDragLeave);
    trackElement.addEventListener('drop', handleDrop);
    trackElement.addEventListener('dragend', handleDragEnd);
    
    // Add click event to play track
    trackElement.addEventListener('click', (e) => {
      if (!e.target.closest('.more-button') && !e.target.closest('.play-button')) {
        playTrack(index);
      }
    });
    
    elements.tracksList.appendChild(trackElement);
  });
  
  feather.replace();
}

// Drag and Drop Functions
function handleDragStart(e) {
  playerState.draggedElement = this;
  setTimeout(() => {
    this.classList.add('dragging');
  }, 0);
}

function handleDragOver(e) {
  e.preventDefault();
}

function handleDragEnter(e) {
  e.preventDefault();
  this.classList.add('drag-over');
}

function handleDragLeave() {
  this.classList.remove('drag-over');
}

function handleDrop(e) {
  e.preventDefault();
  this.classList.remove('drag-over');
  
  if (playerState.draggedElement !== this) {
    const draggedIndex = parseInt(playerState.draggedElement.dataset.index);
    const targetIndex = parseInt(this.dataset.index);
    
    // Reorder tracks array
    const draggedTrack = playerState.tracks[draggedIndex];
    playerState.tracks.splice(draggedIndex, 1);
    playerState.tracks.splice(targetIndex, 0, draggedTrack);
    
    // Update indices
    playerState.tracks.forEach((track, index) => {
      track.id = index;
    });
    
    // Update current track index if needed
    if (playerState.currentTrackIndex === draggedIndex) {
      playerState.currentTrackIndex = targetIndex;
    } else if (playerState.currentTrackIndex === targetIndex) {
      playerState.currentTrackIndex = draggedIndex;
    }
    
    renderPlaylist();
  }
}

function handleDragEnd() {
  this.classList.remove('dragging');
  playerState.draggedElement = null;
  document.querySelectorAll('.track-item').forEach(item => {
    item.classList.remove('drag-over', 'drag-over-after');
  });
}

// Player Control Functions
function togglePlayPause() {
  playerState.isPlaying = !playerState.isPlaying;
  updatePlayPauseButton();
  
  if (playerState.isPlaying && playerState.currentTrackIndex === -1 && playerState.tracks.length > 0) {
    playTrack(0);
  }
}

function playTrack(index) {
  if (index < 0 || index >= playerState.tracks.length) return;
  
  playerState.currentTrackIndex = index;
  playerState.isPlaying = true;
  
  const track = playerState.tracks[index];
  elements.currentTrackTitle.textContent = track.title;
  elements.currentTrackArtist.textContent = track.artist;
  
  updatePlayPauseButton();
  renderPlaylist();
  simulatePlayback();
}

function playNextTrack() {
  if (playerState.tracks.length === 0) return;
  
  let nextIndex = playerState.currentTrackIndex + 1;
  if (nextIndex >= playerState.tracks.length) {
    nextIndex = 0; // Loop to beginning
  }
  
  playTrack(nextIndex);
}

function playPreviousTrack() {
  if (playerState.tracks.length === 0) return;
  
  let prevIndex = playerState.currentTrackIndex - 1;
  if (prevIndex < 0) {
    prevIndex = playerState.tracks.length - 1; // Loop to end
  }
  
  playTrack(prevIndex);
}

function handleProgressChange() {
  playerState.progress = parseInt(elements.progressBar.value);
  updateTimeDisplay();
}

function handleVolumeChange() {
  playerState.volume = parseInt(elements.volumeSlider.value);
  elements.volumeSlider.style.background = `linear-gradient(to right, var(--primary-color) 0%, var(--primary-color) ${playerState.volume}%, rgba(255,255,255,0.3) ${playerState.volume}%, rgba(255,255,255,0.3) 100%)`;
}

function toggleShuffle() {
  elements.shuffleBtn.classList.toggle('text-green-500');
}

function toggleRepeat() {
  elements.repeatBtn.classList.toggle('text-green-500');
}

// Update UI Functions
function updatePlayPauseButton() {
  const icon = elements.playPauseBtn.querySelector('i');
  if (playerState.isPlaying) {
    icon.setAttribute('data-feather', 'pause');
  } else {
    icon.setAttribute('data-feather', 'play');
  }
  feather.replace();
}

function updateTimeDisplay() {
  // In a real app, this would be based on actual track time
  const totalSeconds = 210; // Example: 3:30
  const currentSeconds = Math.floor((playerState.progress / 100) * totalSeconds);
  
  const formatTime = (seconds) => {
    const mins = Math.floor(seconds / 60);
    const secs = seconds % 60;
    return `${mins}:${secs < 10 ? '0' : ''}${secs}`;
  };
  
  elements.currentTime.textContent = formatTime(currentSeconds);
  elements.totalTime.textContent = formatTime(totalSeconds);
}

function updatePlayerUI() {
  // Update volume slider background
  elements.volumeSlider.style.background = `linear-gradient(to right, var(--primary-color) 0%, var(--primary-color) ${playerState.volume}%, rgba(255,255,255,0.3) ${playerState.volume}%, rgba(255,255,255,0.3) 100%)`;
  
  // Update progress bar
  elements.progressBar.value = playerState.progress;
  updateTimeDisplay();
}

// Simulate playback progress
function simulatePlayback() {
  if (!playerState.isPlaying) return;
  
  const interval = setInterval(() => {
    if (!playerState.isPlaying) {
      clearInterval(interval);
      return;
    }
    
    playerState.progress += 0.5;
    if (playerState.progress >= 100) {
      playerState.progress = 0;
      playNextTrack();
    }
    
    updatePlayerUI();
  }, 100);
}

// Keyboard Shortcuts
function handleKeyboardShortcuts(e) {
  // Spacebar to play/pause
  if (e.code === 'Space') {
    e.preventDefault();
    togglePlayPause();
  }
  
  // Left arrow for previous track
  if (e.code === 'ArrowLeft') {
    playPreviousTrack();
  }
  
  // Right arrow for next track
  if (e.code === 'ArrowRight') {
    playNextTrack();
  }
}