/**
 * Generate Blog Card Sections
 *
 * Converts blog post content into card-based sections for better UI presentation.
 * Similar to document card sections but optimized for blog posts.
 */

const { getCollection, connect, close } = require('../src/utils/db.util');
const { extractTOC, markdownToHtml } = require('../src/utils/markdown.util');

const SLUG = 'tractatus-research-working-paper-v01';

/**
 * Parse HTML content into sections based on H2 headings
 */
function parseContentIntoSections(htmlContent) {
  const sections = [];

  // Split by H2 headings
  const h2Regex = /<h2[^>]*id="([^"]*)"[^>]*>(.*?)<\/h2>/g;
  const matches = [...htmlContent.matchAll(h2Regex)];

  if (matches.length === 0) {
    // No H2 headings - treat entire content as one section
    return [{
      number: 1,
      title: 'Introduction',
      slug: 'introduction',
      content_html: htmlContent,
      excerpt: extractExcerpt(htmlContent),
      readingTime: calculateReadingTime(htmlContent),
      technicalLevel: 'intermediate',
      category: 'conceptual'
    }];
  }

  // Process each section
  for (let i = 0; i < matches.length; i++) {
    const match = matches[i];
    const slug = match[1];
    const title = stripHtmlTags(match[2]);

    // Find content between this H2 and the next one (or end of document)
    const startIndex = match.index;
    const endIndex = i < matches.length - 1 ? matches[i + 1].index : htmlContent.length;
    const sectionHtml = htmlContent.substring(startIndex, endIndex);

    sections.push({
      number: i + 1,
      title,
      slug,
      content_html: sectionHtml,
      excerpt: extractExcerpt(sectionHtml),
      readingTime: calculateReadingTime(sectionHtml),
      technicalLevel: determineTechnicalLevel(title, sectionHtml),
      category: determineCategory(title, sectionHtml)
    });
  }

  return sections;
}

/**
 * Strip HTML tags from text
 */
function stripHtmlTags(html) {
  return html.replace(/<[^>]*>/g, '').trim();
}

/**
 * Extract excerpt from HTML content
 */
function extractExcerpt(html, maxLength = 200) {
  const text = stripHtmlTags(html);
  if (text.length <= maxLength) return text;

  // Find last complete sentence within maxLength
  const truncated = text.substring(0, maxLength);
  const lastPeriod = truncated.lastIndexOf('.');

  if (lastPeriod > maxLength * 0.7) {
    return truncated.substring(0, lastPeriod + 1);
  }

  return truncated + '...';
}

/**
 * Calculate reading time in minutes
 */
function calculateReadingTime(html) {
  const text = stripHtmlTags(html);
  const wordsPerMinute = 200;
  const words = text.split(/\s+/).length;
  const minutes = Math.ceil(words / wordsPerMinute);
  return Math.max(1, minutes);
}

/**
 * Determine technical level based on content
 */
function determineTechnicalLevel(title, content) {
  const text = (title + ' ' + stripHtmlTags(content)).toLowerCase();

  // Advanced indicators
  if (text.match(/\b(architecture|implementation|validation|methodology|hook|interceptor|database schema)\b/)) {
    return 'advanced';
  }

  // Beginner indicators
  if (text.match(/\b(what this is|introduction|getting started|overview|background)\b/)) {
    return 'beginner';
  }

  return 'intermediate';
}

/**
 * Determine category based on content
 */
function determineCategory(title, content) {
  const text = (title + ' ' + stripHtmlTags(content)).toLowerCase();

  if (text.match(/\b(critical|limitation|warning|cannot claim|disclaimer)\b/)) {
    return 'critical';
  }

  if (text.match(/\b(example|pattern|code|implementation)\b/)) {
    return 'practical';
  }

  if (text.match(/\b(research|study|methodology|validation|citation)\b/)) {
    return 'research';
  }

  return 'conceptual';
}

async function generateBlogCardSections() {
  try {
    console.log('🎨 Generating blog card sections...\n');

    await connect();
    const collection = await getCollection('blog_posts');

    // Find the blog post
    const post = await collection.findOne({ slug: SLUG });
    if (!post) {
      console.error('❌ Blog post not found:', SLUG);
      return;
    }

    console.log('📝 Found blog post:', post.title);
    console.log('   Content type:', post.content.startsWith('<') ? 'HTML' : 'Markdown');
    console.log('   Content length:', post.content.length, 'characters\n');

    // Parse content into sections
    const sections = parseContentIntoSections(post.content);

    console.log(`✅ Generated ${sections.length} card sections:\n`);

    sections.forEach(section => {
      console.log(`   ${section.number}. ${section.title}`);
      console.log(`      Slug: ${section.slug}`);
      console.log(`      Reading time: ${section.readingTime} min`);
      console.log(`      Level: ${section.technicalLevel}`);
      console.log(`      Category: ${section.category}`);
      console.log(`      Excerpt: ${section.excerpt.substring(0, 80)}...`);
      console.log('');
    });

    // Update the blog post with sections
    await collection.updateOne(
      { slug: SLUG },
      { $set: { sections } }
    );

    console.log('✅ Blog post updated with card sections');
    console.log('   Total sections:', sections.length);
    console.log('   Total reading time:', sections.reduce((sum, s) => sum + s.readingTime, 0), 'minutes');
    console.log('');
    console.log('📍 Preview at: http://localhost:9000/blog-post.html?slug=' + SLUG);

  } catch (error) {
    console.error('❌ Error generating blog card sections:', error);
    throw error;
  } finally {
    await close();
  }
}

// Run if called directly
if (require.main === module) {
  generateBlogCardSections()
    .then(() => {
      console.log('\n✨ Card section generation complete');
      process.exit(0);
    })
    .catch(error => {
      console.error('\n💥 Card section generation failed:', error);
      process.exit(1);
    });
}

module.exports = { generateBlogCardSections };