const dropzone   = document.getElementById('dropzone');
const fileInput  = document.getElementById('fileInput');
const scanStage  = document.getElementById('scanStage');
const previewImg = document.getElementById('previewImg');
const scanLabel  = document.getElementById('scanLabel');
const rescanBtn  = document.getElementById('rescanBtn');
const result     = document.getElementById('result');
const errorBox   = document.getElementById('errorBox');

const verdictIcon  = document.getElementById('verdictIcon');
const verdictLabel = document.getElementById('verdictLabel');
const verdictSub   = document.getElementById('verdictSub');
const realPct      = document.getElementById('realPct');
const screenPct    = document.getElementById('screenPct');
const meterFillReal   = document.getElementById('meterFillReal');
const meterFillScreen = document.getElementById('meterFillScreen');

const MIN_SCAN_MS = 1700;
const SCAN_MESSAGES = ['Reading pixels…', 'Checking bezel shadows…', 'Measuring color temperature…', 'Scoring saturation profile…'];

dropzone.addEventListener('click', () => fileInput.click());
dropzone.addEventListener('dragover', (e) => { e.preventDefault(); dropzone.classList.add('drag-over'); });
dropzone.addEventListener('dragleave', () => dropzone.classList.remove('drag-over'));
dropzone.addEventListener('drop', (e) => {
  e.preventDefault();
  dropzone.classList.remove('drag-over');
  if (e.dataTransfer.files.length) handleFile(e.dataTransfer.files[0]);
});
fileInput.addEventListener('change', () => {
  if (fileInput.files.length) handleFile(fileInput.files[0]);
});
rescanBtn.addEventListener('click', resetUI);

function resetUI() {
  fileInput.value = '';
  dropzone.classList.remove('hidden');
  scanStage.classList.add('hidden');
  scanStage.classList.remove('scanning');
  rescanBtn.classList.add('hidden');
  result.classList.add('hidden');
  errorBox.classList.add('hidden');
  meterFillReal.style.width = '0%';
  meterFillScreen.style.width = '0%';
}

function handleFile(file) {
  if (!file.type.startsWith('image/')) {
    showError('That file does not look like an image.');
    return;
  }

  const url = URL.createObjectURL(file);
  previewImg.src = url;

  dropzone.classList.add('hidden');
  scanStage.classList.remove('hidden');
  scanStage.classList.add('scanning');
  rescanBtn.classList.add('hidden');
  result.classList.add('hidden');
  errorBox.classList.add('hidden');

  let msgIdx = 0;
  scanLabel.textContent = SCAN_MESSAGES[0];
  const msgTimer = setInterval(() => {
    msgIdx = (msgIdx + 1) % SCAN_MESSAGES.length;
    scanLabel.textContent = SCAN_MESSAGES[msgIdx];
  }, 600);

  const started = Date.now();
  const formData = new FormData();
  formData.append('file', file);

  fetch('/api/predict', { method: 'POST', body: formData })
    .then(async (res) => {
      const body = await res.json().catch(() => ({}));
      if (!res.ok) throw new Error(body.detail || 'Prediction failed.');
      return body;
    })
    .then((data) => {
      const elapsed = Date.now() - started;
      const wait = Math.max(0, MIN_SCAN_MS - elapsed);
      setTimeout(() => {
        clearInterval(msgTimer);
        finishScan();
        showResult(data);
      }, wait);
    })
    .catch((err) => {
      clearInterval(msgTimer);
      const elapsed = Date.now() - started;
      const wait = Math.max(0, 600 - elapsed);
      setTimeout(() => {
        finishScan();
        showError(err.message || 'Something went wrong while analyzing the image.');
      }, wait);
    });
}

function finishScan() {
  scanStage.classList.remove('scanning');
  rescanBtn.classList.remove('hidden');
}

function showResult(data) {
  result.classList.remove('hidden');
  const isScreen = data.label === 'screen_recapture';

  verdictIcon.className = 'verdict-icon ' + (isScreen ? 'screen' : 'real');
  verdictIcon.textContent = isScreen ? '⚠' : '✓';

  verdictLabel.className = 'verdict-label ' + (isScreen ? 'screen' : 'real');
  verdictLabel.textContent = isScreen ? 'Screen Recapture' : 'Real Photo';
  verdictSub.textContent = `${data.confidence}% confidence`;

  realPct.textContent = `${data.real_pct}%`;
  screenPct.textContent = `${data.screen_pct}%`;

  requestAnimationFrame(() => {
    meterFillReal.style.width = `${data.real_pct}%`;
    meterFillScreen.style.width = `${data.screen_pct}%`;
  });
}

function showError(message) {
  result.classList.remove('hidden');
  errorBox.textContent = message;
  errorBox.classList.remove('hidden');
  verdictIcon.className = 'verdict-icon screen';
  verdictIcon.textContent = '!';
  verdictLabel.className = 'verdict-label screen';
  verdictLabel.textContent = 'Could not analyze image';
  verdictSub.textContent = '';
  realPct.textContent = '0%';
  screenPct.textContent = '0%';
  meterFillReal.style.width = '0%';
  meterFillScreen.style.width = '0%';
}