#!/usr/bin/env node

/**
 * CSS Bundle Builder
 *
 * Combines and minifies CSS files into optimized bundles:
 * - site.min.css: Essential site styles (design system, theme, layout)
 * - app.min.css: Main application styles (UnoCSS, components)
 * - enhancements.min.css: Progressive enhancement styles (highlighting, etc.)
 *
 * Usage:
 *   node scripts/build-css-bundles.js [theme]
 *
 * Examples:
 *   node scripts/build-css-bundles.js         # default theme
 *   node scripts/build-css-bundles.js purple  # purple theme
 */

const fs = require('fs');
const path = require('path');

// Simple CSS minifier
function minifyCss(css) {
  return css
    // Remove comments
    .replace(/\/\*[\s\S]*?\*\//g, '')
    // Remove extra whitespace
    .replace(/\s+/g, ' ')
    // Remove whitespace around specific characters
    .replace(/\s*([{}:;,>+~])\s*/g, '$1')
    // Remove trailing semicolons before }
    .replace(/;}/g, '}')
    // Remove leading/trailing whitespace
    .trim();
}

// Extract critical above-the-fold styles from website.css
function extractSiteStyles(websiteCss) {
  // Extract CSS reset, root variables, and essential layout styles
  // This is a simplified extraction - in a real scenario you might use a more sophisticated approach
  const sitePatterns = [
    // CSS reset and variables
    /\/\* layer: preflights \*\/[\s\S]*?(?=\/\* layer:|$)/g,
    // Root variables
    /:root\s*\{[^}]*\}/g,
    // Essential layout classes (simplified extraction)
    /\.(?:min-h-screen|max-w-|mx-auto|py-|flex|flex-col|flex-grow)[^{]*\{[^}]*\}/g
  ];

  let extracted = '';
  sitePatterns.forEach(pattern => {
    const matches = websiteCss.match(pattern);
    if (matches) {
      extracted += matches.join('\n') + '\n';
    }
  });

  return extracted;
}

async function buildCssBundles() {
  try {
    const assetsStylesDir = path.join(__dirname, '../assets/styles');
    const publicStylesDir = path.join(__dirname, '../public/styles');

    // Get theme from command line argument or default
    const theme = process.argv[2] || 'default';
    const themeFile = `theme-${theme}.css`;

    console.log(`🎨 Building CSS bundles with theme: ${theme}`);

    // Read source files from assets
    const files = {
      designSystem: path.join(assetsStylesDir, 'design-system.css'),
      theme: path.join(assetsStylesDir, themeFile),
      website: path.join(assetsStylesDir, 'website.css'),
      contactOverrides: path.join(assetsStylesDir, 'overrides/contact-tailwind-overrides.css'),
      custom: path.join(assetsStylesDir, 'custom.css'),
      highlight: path.join(publicStylesDir, 'highlight-github-dark.min.css')
    };

    // Check if all required files exist
    const missingFiles = [];
    for (const [name, filePath] of Object.entries(files)) {
      if (!fs.existsSync(filePath)) {
        missingFiles.push(`${name}: ${filePath}`);
      }
    }

    if (missingFiles.length > 0) {
      console.log('⚠️  Some files are missing but continuing with available files:');
      missingFiles.forEach(file => console.log(`   ${file}`));
      console.log('');
    }

    // Read file contents
    const contents = {};
    for (const [name, filePath] of Object.entries(files)) {
      if (fs.existsSync(filePath)) {
        contents[name] = fs.readFileSync(filePath, 'utf8');
      } else {
        contents[name] = '';
      }
    }

    console.log('📂 Source files read:');
    for (const [name, content] of Object.entries(contents)) {
      const size = Math.round(content.length / 1024);
      console.log(`   ${name}: ${size}KB`);
    }
    console.log('');

    // 1. Build site.min.css (essential styles)
    const siteExtracted = extractSiteStyles(contents.website);
    const siteBundle = [
      '/* Site Bundle - Essential Styles */',
      `/* Generated on ${new Date().toISOString()} */`,
      '/* Theme: ' + theme + ' */',
      '',
      '/* Design System Variables */',
      contents.designSystem,
      '',
      '/* Theme Variables */',
      contents.theme,
      '',
      '/* Essential Layout Styles */',
      siteExtracted
    ].join('\n');

    const siteMinified = minifyCss(siteBundle);
    const sitePath = path.join(assetsStylesDir, 'site.min.css');
    fs.writeFileSync(sitePath, siteMinified);

    // 2. Build app.min.css (main application styles)
    const appBundle = [
      '/* App Bundle - Main Application Styles */',
      `/* Generated on ${new Date().toISOString()} */`,
      '',
      '/* Main Website Styles (minus site essentials) */',
      contents.website.replace(siteExtracted, ''), // Remove extracted site styles
      '',
      '/* Custom Styles */',
      contents.custom,
      '',
      '/* Contact Page Overrides */',
      contents.contactOverrides
    ].join('\n');

    const appMinified = minifyCss(appBundle);
    const appPath = path.join(assetsStylesDir, 'app.min.css');
    fs.writeFileSync(appPath, appMinified);

    // 3. Build enhancements.min.css (progressive features)
    const enhancementsBundle = [
      '/* Enhancements Bundle - Progressive Features */',
      `/* Generated on ${new Date().toISOString()} */`,
      '',
      '/* Code Highlighting Styles */',
      contents.highlight
    ].join('\n');

    const enhancementsMinified = minifyCss(enhancementsBundle);
    const enhancementsPath = path.join(assetsStylesDir, 'enhancements.min.css');
    fs.writeFileSync(enhancementsPath, enhancementsMinified);

    // Get final file sizes
    const finalSizes = {
      site: Math.round(fs.statSync(sitePath).size / 1024),
      app: Math.round(fs.statSync(appPath).size / 1024),
      enhancements: Math.round(fs.statSync(enhancementsPath).size / 1024)
    };

    const totalSize = finalSizes.site + finalSizes.app + finalSizes.enhancements;
    const originalTotal = Math.round(Object.values(contents).reduce((sum, content) => sum + content.length, 0) / 1024);
    const savings = Math.round(((originalTotal - totalSize) / originalTotal) * 100);

    console.log('✅ CSS bundles created successfully!');
    console.log('');
    console.log('📊 Bundle Sizes:');
    console.log(`   📁 site.min.css: ${finalSizes.site}KB (design system + theme + essential layout)`);
    console.log(`   📁 app.min.css: ${finalSizes.app}KB (main application styles)`);
    console.log(`   📁 enhancements.min.css: ${finalSizes.enhancements}KB (code highlighting + progressive features)`);
    console.log('');
    console.log(`📈 Total: ${totalSize}KB (${savings}% size reduction from ${originalTotal}KB)`);
    console.log('');
    console.log('🚀 CSS bundles generated in assets/styles/');
    console.log('   📁 assets/styles/site.min.css');
    console.log('   📁 assets/styles/app.min.css');
    console.log('   📁 assets/styles/enhancements.min.css');
    console.log('');
    console.log('💡 Run copy script to deploy to public/styles/');

  } catch (error) {
    console.error('❌ Error building CSS bundles:', error.message);
    process.exit(1);
  }
}

buildCssBundles();