/* ASCII Art Generator - Frontend */

const dropZone = document.getElementById('dropZone');
const fileInput = document.getElementById('fileInput');
const fileInfo = document.getElementById('fileInfo');
const thumbPreview = document.getElementById('thumbPreview');
const fileName = document.getElementById('fileName');
const clearFile = document.getElementById('clearFile');
const generateBtn = document.getElementById('generateBtn');
const previewArea = document.getElementById('previewArea');
const spinner = document.getElementById('spinner');
const copyBtn = document.getElementById('copyBtn');
const downloadBtn = document.getElementById('downloadBtn');
const gifIndicator = document.getElementById('gifIndicator');
const widthSlider = document.getElementById('width');
const widthVal = document.getElementById('widthVal');

let currentFile = null;
let animationInterval = null;
let lastRenderedHtml = '';
let zoomScale = 1.0;

const zoomIn = document.getElementById('zoomIn');
const zoomOut = document.getElementById('zoomOut');
const zoomFit = document.getElementById('zoomFit');
const zoomLevel = document.getElementById('zoomLevel');
const fullscreenBtn = document.getElementById('fullscreenBtn');
const previewContainer = document.querySelector('.preview-container');
const compareBox = document.getElementById('compareBox');
const compareImg = document.getElementById('compareImg');
const compareToggle = document.getElementById('compareToggle');

// ── File Handling ──────────────────────────────

dropZone.addEventListener('click', () => fileInput.click());

dropZone.addEventListener('dragover', e => {
  e.preventDefault();
  dropZone.classList.add('dragover');
});

dropZone.addEventListener('dragleave', () => {
  dropZone.classList.remove('dragover');
});

dropZone.addEventListener('drop', e => {
  e.preventDefault();
  dropZone.classList.remove('dragover');
  if (e.dataTransfer.files.length) setFile(e.dataTransfer.files[0]);
});

fileInput.addEventListener('change', () => {
  if (fileInput.files.length) setFile(fileInput.files[0]);
});

clearFile.addEventListener('click', () => {
  currentFile = null;
  fileInput.value = '';
  fileInfo.style.display = 'none';
  dropZone.style.display = '';
  generateBtn.disabled = true;
});

function setFile(file) {
  const allowed = ['image/png', 'image/jpeg', 'image/gif', 'image/webp'];
  if (!allowed.includes(file.type)) {
    alert('Please upload a PNG, JPG, GIF, or WebP image.');
    return;
  }
  if (file.size > 10 * 1024 * 1024) {
    alert('File too large (max 10MB).');
    return;
  }

  currentFile = file;
  fileName.textContent = file.name;
  thumbPreview.src = URL.createObjectURL(file);
  dropZone.style.display = 'none';
  fileInfo.style.display = 'flex';
  generateBtn.disabled = false;
}

// ── Width Slider ──────────────────────────────

widthSlider.addEventListener('input', () => {
  widthVal.textContent = widthSlider.value;
});

// ── Generate ──────────────────────────────

generateBtn.addEventListener('click', generate);

async function generate() {
  if (!currentFile) return;

  stopAnimation();
  previewArea.innerHTML = '';
  spinner.style.display = 'flex';
  generateBtn.disabled = true;
  copyBtn.style.display = 'none';
  downloadBtn.style.display = 'none';
  gifIndicator.style.display = 'none';

  const formData = new FormData();
  formData.append('file', currentFile);
  formData.append('width', widthSlider.value);
  formData.append('palette', document.getElementById('palette').value);
  formData.append('bg', document.getElementById('bg').value);
  formData.append('dither', document.getElementById('dither').checked);
  formData.append('double_width', document.getElementById('doubleWidth').checked);
  formData.append('output_format', 'html');

  try {
    const resp = await fetch('/api/render', { method: 'POST', body: formData });
    if (!resp.ok) {
      const err = await resp.json().catch(() => ({ error: 'Request failed' }));
      throw new Error(err.error || `HTTP ${resp.status}`);
    }

    const html = await resp.text();
    lastRenderedHtml = html;
    spinner.style.display = 'none';
    previewArea.innerHTML = html;

    // Check if animated (multiple frames)
    const frames = previewArea.querySelectorAll('.art-frame');
    if (frames.length > 1) {
      gifIndicator.style.display = '';
      startAnimation(frames);
    }

    copyBtn.style.display = '';
    downloadBtn.style.display = '';

    // Show original image for comparison
    compareImg.src = URL.createObjectURL(currentFile);
    compareBox.style.display = '';
    compareBox.classList.remove('minimized');
    compareToggle.innerHTML = '▼';

    // Auto-fit to preview area
    requestAnimationFrame(() => {
      const containerWidth = previewArea.clientWidth - 24;
      const artWidth = previewArea.scrollWidth;
      if (artWidth > containerWidth) {
        setZoom(containerWidth / artWidth);
      }
    });
  } catch (err) {
    spinner.style.display = 'none';
    previewArea.innerHTML = `<p class="placeholder" style="color:#ff453a">${err.message}</p>`;
  }

  generateBtn.disabled = false;
}

// ── GIF Animation ──────────────────────────────

function startAnimation(frames) {
  let current = 0;
  frames[0].style.display = 'block';

  function nextFrame() {
    frames[current].style.display = 'none';
    current = (current + 1) % frames.length;
    frames[current].style.display = 'block';
    const duration = parseInt(frames[current].dataset.duration) || 100;
    animationInterval = setTimeout(nextFrame, duration);
  }

  const duration = parseInt(frames[0].dataset.duration) || 100;
  animationInterval = setTimeout(nextFrame, duration);
}

function stopAnimation() {
  if (animationInterval) {
    clearTimeout(animationInterval);
    animationInterval = null;
  }
}

// ── Copy & Download ──────────────────────────────

copyBtn.addEventListener('click', async () => {
  // Re-render as plain text for clipboard
  if (!currentFile) return;

  const formData = new FormData();
  formData.append('file', currentFile);
  formData.append('width', widthSlider.value);
  formData.append('palette', document.getElementById('palette').value);
  formData.append('bg', document.getElementById('bg').value);
  formData.append('dither', document.getElementById('dither').checked);
  formData.append('double_width', document.getElementById('doubleWidth').checked);
  formData.append('output_format', 'plain');

  try {
    const resp = await fetch('/api/render', { method: 'POST', body: formData });
    const text = await resp.text();
    await navigator.clipboard.writeText(text);
    copyBtn.textContent = 'Copied!';
    setTimeout(() => { copyBtn.textContent = 'Copy'; }, 1500);
  } catch {
    copyBtn.textContent = 'Failed';
    setTimeout(() => { copyBtn.textContent = 'Copy'; }, 1500);
  }
});

downloadBtn.addEventListener('click', () => {
  const wrapper = `<!DOCTYPE html>
<html><head><meta charset="UTF-8"><style>
body{background:#0d1117;margin:20px;display:flex;justify-content:center}
pre{font-family:'JetBrains Mono',monospace;font-size:11px;line-height:1.15;letter-spacing:0.5px}
</style></head><body><pre>${lastRenderedHtml}</pre></body></html>`;

  const blob = new Blob([wrapper], { type: 'text/html' });
  const url = URL.createObjectURL(blob);
  const a = document.createElement('a');
  a.href = url;
  a.download = 'ascii-art.html';
  a.click();
  URL.revokeObjectURL(url);
});

// ── Compare Box ──────────────────────────────

compareToggle.addEventListener('click', e => {
  e.stopPropagation();
  compareBox.classList.toggle('minimized');
  compareToggle.innerHTML = compareBox.classList.contains('minimized') ? '&#x25B2;' : '&#x25BC;';
});

document.querySelector('.compare-header').addEventListener('click', () => {
  compareBox.classList.toggle('minimized');
  compareToggle.innerHTML = compareBox.classList.contains('minimized') ? '&#x25B2;' : '&#x25BC;';
});

// ── Zoom ──────────────────────────────

function setZoom(scale) {
  zoomScale = Math.max(0.25, Math.min(5.0, scale));
  previewArea.style.fontSize = (8 * zoomScale) + 'px';
  zoomLevel.textContent = Math.round(zoomScale * 100) + '%';
}

zoomIn.addEventListener('click', () => setZoom(zoomScale + 0.15));
zoomOut.addEventListener('click', () => setZoom(zoomScale - 0.15));

zoomFit.addEventListener('click', () => {
  // Measure art content width vs container width
  const containerWidth = previewArea.clientWidth - 32; // padding
  // Temporarily reset to measure natural width
  previewArea.style.fontSize = '8px';
  const artWidth = previewArea.scrollWidth;
  if (artWidth > 0) {
    const fitScale = containerWidth / artWidth;
    setZoom(Math.min(fitScale, 2.0)); // cap at 200%
  } else {
    setZoom(1.0);
  }
});

// Ctrl+scroll to zoom
previewArea.addEventListener('wheel', e => {
  if (e.ctrlKey || e.metaKey) {
    e.preventDefault();
    const delta = e.deltaY > 0 ? -0.1 : 0.1;
    setZoom(zoomScale + delta);
  }
}, { passive: false });

// ── Fullscreen ──────────────────────────────

fullscreenBtn.addEventListener('click', toggleFullscreen);

function toggleFullscreen() {
  previewContainer.classList.toggle('fullscreen');
  if (previewContainer.classList.contains('fullscreen')) {
    fullscreenBtn.textContent = '\u2716'; // ✖
    fullscreenBtn.title = 'Exit fullscreen (Esc)';
  } else {
    fullscreenBtn.textContent = '\u26F6'; // ⛶
    fullscreenBtn.title = 'Fullscreen (F)';
  }
}

// ── Keyboard Shortcuts ──────────────────────────────

document.addEventListener('keydown', e => {
  // Don't capture when typing in inputs
  if (e.target.tagName === 'INPUT' || e.target.tagName === 'SELECT') return;

  if (e.key === '+' || e.key === '=') { setZoom(zoomScale + 0.15); e.preventDefault(); }
  if (e.key === '-') { setZoom(zoomScale - 0.15); e.preventDefault(); }
  if (e.key === '0') { setZoom(1.0); e.preventDefault(); }
  if (e.key === 'f' || e.key === 'F') { toggleFullscreen(); e.preventDefault(); }
  if (e.key === 'Escape' && previewContainer.classList.contains('fullscreen')) {
    toggleFullscreen();
    e.preventDefault();
  }
});