const express = require('express');
const sharp = require('sharp');
const path = require('path');
const log = require('../lib/logger');

const router = express.Router();

function normalizeColor(color) {
  if (!color) return '#cccccc';
  if (/^[0-9A-Fa-f]{6}$/.test(color)) return '#' + color;
  if (/^[0-9A-Fa-f]{3}$/.test(color)) return '#' + color;
  return color.toLowerCase();
}

function escapeXml(str) {
  return str.replace(/&/g, '&amp;').replace(/</g, '&lt;').replace(/>/g, '&gt;').replace(/"/g, '&quot;');
}

async function placeholderHandler(req, res) {
  const { size, bg, fg, text: textFromPath } = req.params;
  const { text: textFromQuery, format = 'png', fontsize } = req.query;
  const text = textFromQuery || textFromPath || '';

  const [w, h] = size.split('x').map(Number);
  const width = Math.min(Math.max(w || 300, 1), 4000);
  const height = Math.min(Math.max(h || 200, 1), 4000);

  const bgColor = normalizeColor(bg);
  const fgColor = normalizeColor(fg);
  const fontSize = fontsize ? parseInt(fontsize, 10) : Math.max(12, Math.floor(Math.min(width, height) / 8));

  const svg = `<svg width="${width}" height="${height}" xmlns="http://www.w3.org/2000/svg">
    <rect width="100%" height="100%" fill="${escapeXml(bgColor)}"/>
    <text x="50%" y="50%" dominant-baseline="central" text-anchor="middle"
          font-family="sans-serif" font-weight="bold" font-size="${fontSize}"
          fill="${escapeXml(fgColor)}">${escapeXml(text)}</text>
  </svg>`;

  try {
    let img = sharp(Buffer.from(svg));
    if (format === 'jpg' || format === 'jpeg') {
      res.type('jpeg').end(await img.jpeg({ quality: 90 }).toBuffer());
    } else if (format === 'webp') {
      res.type('webp').end(await img.webp({ quality: 90 }).toBuffer());
    } else {
      res.type('png').end(await img.png().toBuffer());
    }
  } catch (err) {
    log.error('Placeholder error', { error: err.message });
    res.status(500).json({ error: 'Generation failed' });
  }
}

// Placeholder page
router.get('/', (req, res) => {
  res.sendFile(path.join(__dirname, '..', 'public', 'placeholder.html'));
});

router.get('/:size/:bg/:fg', placeholderHandler);
router.get('/:size/:bg/:fg/:text', placeholderHandler);

module.exports = router;