// minify.js
const { minify } = require('html-minifier');
const cheerio = require('cheerio');

function sanitizeHtml(html) {
  try {
    // Remove conditional comments
    html = html.replace(/<!--\[if.*?<!\[endif\]-->/gs, '');
    
    // Fix incomplete URLs
    html = html.replace(/src="https?:\/\/[^"]*\.{3}"/g, '');
    
    // Remove problematic script tags
    html = html.replace(/<script\b[^<]*(?:(?!<\/script>)<[^<]*)*<\/script>/gi, '');
    
    return html;
  } catch (err) {
    console.warn('HTML sanitization failed:', err);
    return html;
  }
}

function validateHtml(html) {
  try {
    const $ = cheerio.load(html, {
      xmlMode: false,
      decodeEntities: false
    });
    
    const issues = [];
    
    if ($('html').length === 0) issues.push('Missing html tag');
    if ($('head').length === 0) issues.push('Missing head tag');
    if ($('body').length === 0) issues.push('Missing body tag');
    
    return issues;
  } catch (err) {
    console.warn('HTML validation failed:', err);
    return ['Validation error: ' + err.message];
  }
}

function safeMinify(html, options = {}) {
  const defaultOptions = {
    removeComments: true,
    collapseWhitespace: true,
    minifyCSS: true,
    minifyJS: true,
    conservativeCollapse: true,
    keepClosingSlash: true,
    removeAttributeQuotes: false,
    removeEmptyAttributes: true,
    removeRedundantAttributes: true,
    removeScriptTypeAttributes: false,
    removeStyleLinkTypeAttributes: false,
    sortAttributes: true,
    sortClassName: true
  };

  const minifyOptions = { ...defaultOptions, ...options };

  try {
    // Try full minification first
    return minify(html, minifyOptions);
  } catch (err) {
    console.warn('Full minification failed, trying conservative mode:', err);
    
    try {
      // Fall back to conservative minification
      return minify(html, {
        removeComments: true,
        collapseWhitespace: true,
        conservativeCollapse: true,
        keepClosingSlash: true,
        removeAttributeQuotes: false,
        removeEmptyAttributes: false,
        removeRedundantAttributes: false
      });
    } catch (err2) {
      console.error('Conservative minification also failed:', err2);
      return html;
    }
  }
}

function minifyHtml(html, options = {}) {
  const result = {
    originalSize: html.length,
    minifiedHtml: '',
    success: false,
    issues: [],
    stats: {},
    error: null
  };

  try {
    // Step 1: Validate HTML
    const validationIssues = validateHtml(html);
    result.issues = validationIssues;

    // Step 2: Sanitize HTML
    const sanitized = sanitizeHtml(html);

    // Step 3: Minify HTML
    const minified = safeMinify(sanitized, options);
    result.minifiedHtml = minified;
    result.success = true;

    // Step 4: Calculate stats
    result.stats = {
      originalSize: html.length,
      minifiedSize: minified.length,
      reduction: ((html.length - minified.length) / html.length * 100).toFixed(2) + '%',
      validationIssues: validationIssues.length,
      timestamp: new Date().toISOString()
    };

  } catch (err) {
    result.error = {
      message: err.message,
      stack: err.stack
    };
    result.minifiedHtml = html; // Return original HTML if processing fails
  }

  return result;
}

module.exports = {
  minifyHtml,
  validateHtml,
  sanitizeHtml
};