// ---------- Glowing cursor effect ----------
const glowingEffect = document.createElement('div');
glowingEffect.classList.add('glowing-effect', 'js-generated');
document.body.appendChild(glowingEffect);

// Update CSS custom properties for the glow position (mouse + touch)
function updateGlow(x, y) {
  glowingEffect.style.setProperty('--x', `${x}px`);
  glowingEffect.style.setProperty('--y', `${y}px`);
}

document.addEventListener('mousemove', (e) => updateGlow(e.clientX, e.clientY));
document.addEventListener('touchmove', (e) => {
  if (e.touches && e.touches[0]) {
    updateGlow(e.touches[0].clientX, e.touches[0].clientY);
  }
}, { passive: true });

// ---------- Helper utilities ----------
const qs = (id) => document.getElementById(id);
const showOutput = (html) => {
  const outputDiv = qs('output') || (() => {
    const d = document.createElement('div');
    d.id = 'output';
    document.body.appendChild(d);
    return d;
  })();
  outputDiv.innerHTML = html;
};
const createDownloadLink = (url, label = 'Download') => {
  const a = document.createElement('a');
  a.href = url;
  a.textContent = label;
  a.download = '';
  a.className = 'download-link';
  return a;
};
const createImgPreview = (src, alt = 'preview') => {
  const img = document.createElement('img');
  img.src = src;
  img.alt = alt;
  img.style.maxWidth = '320px';
  img.style.height = 'auto';
  img.style.display = 'block';
  img.style.marginTop = '12px';
  img.style.borderRadius = '8px';
  return img;
};

// ---------- Elements (gracefully handle missing elements) ----------
const imageInput = qs('image') || qs('image-input');          // caption image
const foregroundInput = qs('foreground');                     // foreground for change bg / remove bg
const backgroundInput = qs('background');                     // background for change bg (optional)
const generateCaptionBtn = qs('generate-caption-btn');
const removeBackgroundBtn = qs('remove-background-btn');
const changeBackgroundBtn = qs('change-background-btn');

// ---------- Core request functions using FormData ----------
async function postFormData(url, formData) {
  const res = await fetch(url, {
    method: 'POST',
    body: formData, // do NOT set Content-Type; browser will add the correct boundary
  });
  if (!res.ok) {
    const text = await res.text().catch(() => '');
    throw new Error(`Server responded ${res.status}: ${text}`);
  }
  return res.json().catch(() => { throw new Error('Invalid JSON response'); });
}

// ---------- Generate Caption ----------
if (generateCaptionBtn) {
  generateCaptionBtn.addEventListener('click', async (e) => {
    e.preventDefault();
    try {
      const fileInput = imageInput;
      if (!fileInput || !fileInput.files || fileInput.files.length === 0) {
        showOutput('<span style="color:#b00">Please choose an image to generate caption.</span>');
        return;
      }

      showOutput('Generating caption…');

      const fd = new FormData();
      fd.append('image', fileInput.files[0]);

      const data = await postFormData('/generate_caption', fd);
      // Expecting JSON like: { caption: "...", image_url: "..." } but handle flexibly
      const caption = data.caption || data.text || '';
      const imageUrl = data.image_url || data.result_url || data.output_url || null;

      let html = `<strong>Generated Caption:</strong><div style="margin-top:8px">${caption || '<em>(no caption returned)</em>'}</div>`;
      if (imageUrl) {
        const img = createImgPreview(imageUrl, 'Generated caption preview');
        html += '<div></div>'; // separator
        // we will set outputDiv innerHTML, then append image node and download link
      }
      showOutput(html);

      if (imageUrl) {
        const outDiv = qs('output');
        outDiv.appendChild(createImgPreview(imageUrl, 'Generated caption preview'));
        outDiv.appendChild(createDownloadLink(imageUrl, 'Download Result Image'));
        // Optional: add "Copy caption" button
        if (caption) {
          const copyBtn = document.createElement('button');
          copyBtn.textContent = 'Copy Caption';
          copyBtn.style.marginLeft = '8px';
          copyBtn.addEventListener('click', () => {
            navigator.clipboard?.writeText(caption).then(() => {
              copyBtn.textContent = 'Copied!';
              setTimeout(() => copyBtn.textContent = 'Copy Caption', 1500);
            }).catch(() => {
              copyBtn.textContent = 'Copy failed';
            });
          });
          outDiv.appendChild(copyBtn);
        }
      }
    } catch (err) {
      console.error(err);
      showOutput(`<span style="color:#b00">Error generating caption: ${err.message}</span>`);
    }
  });
}

// ---------- Remove Background ----------
if (removeBackgroundBtn) {
  removeBackgroundBtn.addEventListener('click', async (e) => {
    e.preventDefault();
    try {
      // Prefer explicit foreground input; fallback to generic image input
      const fileInput = foregroundInput || imageInput;
      if (!fileInput || !fileInput.files || fileInput.files.length === 0) {
        showOutput('<span style="color:#b00">Please choose an image to remove background.</span>');
        return;
      }

      showOutput('Removing background…');

      const fd = new FormData();
      fd.append('image', fileInput.files[0]);

      const data = await postFormData('/remove_background', fd);
      // Expect JSON like: { output_url: "..." } or { output_path: "..." }
      const outUrl = data.output_url || data.output_path || data.result_url || null;

      if (outUrl) {
        const outHtml = '<strong>Removed Background:</strong>';
        showOutput(outHtml);
        const outDiv = qs('output');
        outDiv.appendChild(createImgPreview(outUrl, 'Result - background removed'));
        outDiv.appendChild(createDownloadLink(outUrl, 'Download Result Image'));
      } else {
        showOutput('<span style="color:#b00">Background removed but server did not return a URL.</span>');
      }
    } catch (err) {
      console.error(err);
      showOutput(`<span style="color:#b00">Error removing background: ${err.message}</span>`);
    }
  });
}

// ---------- Change Background ----------
if (changeBackgroundBtn) {
  changeBackgroundBtn.addEventListener('click', async (e) => {
    e.preventDefault();
    try {
      const fgInput = foregroundInput || imageInput;
      if (!fgInput || !fgInput.files || fgInput.files.length === 0) {
        showOutput('<span style="color:#b00">Please choose a foreground image.</span>');
        return;
      }

      // Option A: use a second file input for background if available
      // Option B: fallback to a hard-coded URL (if your server supports that)
      const bgFile = (backgroundInput && backgroundInput.files && backgroundInput.files[0]) || null;
      const FALLBACK_BACKGROUND_URL = null; // set a URL string here only if your server supports background URLs

      if (!bgFile && !FALLBACK_BACKGROUND_URL) {
        showOutput('<span style="color:#b00">Please choose a background image (or configure FALLBACK_BACKGROUND_URL in the script).</span>');
        return;
      }

      showOutput('Changing background…');

      const fd = new FormData();
      fd.append('foreground', fgInput.files[0]);
      if (bgFile) {
        fd.append('background', bgFile);
      } else {
        fd.append('background_url', FALLBACK_BACKGROUND_URL);
      }

      const data = await postFormData('/change_background', fd);
      const outUrl = data.output_url || data.output_path || data.result_url || null;

      if (outUrl) {
        showOutput('<strong>Changed Background:</strong>');
        const outDiv = qs('output');
        outDiv.appendChild(createImgPreview(outUrl, 'Result - background changed'));
        outDiv.appendChild(createDownloadLink(outUrl, 'Download Result Image'));
      } else {
        showOutput('<span style="color:#b00">Background changed but server did not return a URL.</span>');
      }
    } catch (err) {
      console.error(err);
      showOutput(`<span style="color:#b00">Error changing background: ${err.message}</span>`);
    }
  });
}

// ---------- Accessibility: enable Enter key on focused file inputs when needed ----------
document.addEventListener('keydown', (e) => {
  if (e.key === 'Enter') {
    // try to trigger caption generation if that button exists and is visible
    const active = document.activeElement;
    if (active && (active.tagName === 'INPUT' && active.type === 'file')) {
      // don't auto-submit; just do nothing (files require user action)
      return;
    }
  }
});

// ---------- Optional: add minimal CSS for the glowing effect if not already in CSS ----------
(function ensureGlowCss() {
  const id = 'glow-css';
  if (document.getElementById(id)) return;
  const style = document.createElement('style');
  style.id = id;
  style.textContent = `
    .glowing-effect {
      position: fixed;
      left: 0;
      top: 0;
      width: 240px;
      height: 240px;
      pointer-events: none;
      transform: translate(calc(var(--x, 0) - 50%), calc(var(--y, 0) - 50%));
      mix-blend-mode: screen;
      filter: blur(40px);
      z-index: 9999;
      transition: transform 0.04s linear;
      background: radial-gradient(circle at center, rgba(0,150,255,0.18) 0%, rgba(0,150,255,0.06) 40%, transparent 70%);
    }
    .glowing-effect.js-generated { opacity: 0.95; }
    #output { margin: 14px auto; max-width: 720px; text-align: left; }
    .download-link { display:inline-block; margin-top:8px; padding:8px 12px; background:#007bff; color:#fff; border-radius:6px; text-decoration:none; }
    .download-link:hover { background:#0056b3; }
  `;
  document.head.appendChild(style);
})();