gc-alexandria/src/lib/utils/advancedMarkdownParser.ts

import { parseBasicMarkdown } from './basicMarkdownParser';
import hljs from 'highlight.js';
import 'highlight.js/lib/common';  // Import common languages
import 'highlight.js/styles/github-dark.css';  // Dark theme only

// Register common languages
hljs.configure({
  ignoreUnescapedHTML: true
});

// Regular expressions for advanced markdown elements
const HEADING_REGEX = /^(#{1,6})\s+(.+)$/gm;
const ALTERNATE_HEADING_REGEX = /^([^\n]+)\n(=+|-+)\n/gm;
const INLINE_CODE_REGEX = /`([^`\n]+)`/g;
const HORIZONTAL_RULE_REGEX = /^(?:[-*_]\s*){3,}$/gm;
const FOOTNOTE_REFERENCE_REGEX = /\[\^([^\]]+)\]/g;
const FOOTNOTE_DEFINITION_REGEX = /^\[\^([^\]]+)\]:\s*(.+)$/gm;

/**
 * Process headings (both styles)
 */
function processHeadings(content: string): string {
  // Process ATX-style headings (# Heading)
  let processedContent = content.replace(HEADING_REGEX, (_, level, text) => {
    const headingLevel = level.length;
    return `<h${headingLevel} class="text-2xl font-bold mt-6 mb-4">${text.trim()}</h${headingLevel}>`;
  });

  // Process Setext-style headings (Heading\n====)
  processedContent = processedContent.replace(ALTERNATE_HEADING_REGEX, (_, text, level) => {
    const headingLevel = level[0] === '=' ? 1 : 2;
    return `<h${headingLevel} class="text-2xl font-bold mt-6 mb-4">${text.trim()}</h${headingLevel}>`;
  });

  return processedContent;
}

/**
 * Process tables
 */
function processTables(content: string): string {
  try {
    if (!content) return '';
    
    return content.replace(/^\|(.*(?:\n\|.*)*)/gm, (match) => {
      try {
        // Split into rows and clean up
        const rows = match.split('\n').filter(row => row.trim());
        if (rows.length < 1) return match;

        // Helper to process a row into cells
        const processCells = (row: string): string[] => {
          return row
            .split('|')
            .slice(1, -1) // Remove empty cells from start/end
            .map(cell => cell.trim());
        };

        // Check if second row is a delimiter row (only hyphens)
        const hasHeader = rows.length > 1 && rows[1].trim().match(/^\|[-\s|]+\|$/);
        
        // Extract header and body rows
        let headerCells: string[] = [];
        let bodyRows: string[] = [];
        
        if (hasHeader) {
          // If we have a header, first row is header, skip delimiter, rest is body
          headerCells = processCells(rows[0]);
          bodyRows = rows.slice(2);
        } else {
          // No header, all rows are body
          bodyRows = rows;
        }

        // Build table HTML
        let html = '<div class="overflow-x-auto my-4">\n';
        html += '<table class="min-w-full border-collapse">\n';

        // Add header if exists
        if (hasHeader) {
          html += '<thead>\n<tr>\n';
          headerCells.forEach(cell => {
            html += `<th class="py-2 px-4 text-left border-b-2 border-gray-200 dark:border-gray-700 font-semibold">${cell}</th>\n`;
          });
          html += '</tr>\n</thead>\n';
        }

        // Add body
        html += '<tbody>\n';
        bodyRows.forEach(row => {
          const cells = processCells(row);
          html += '<tr>\n';
          cells.forEach(cell => {
            html += `<td class="py-2 px-4 text-left border-b border-gray-200 dark:border-gray-700">${cell}</td>\n`;
          });
          html += '</tr>\n';
        });

        html += '</tbody>\n</table>\n</div>';
        return html;
      } catch (error) {
        console.error('Error processing table row:', error);
        return match;
      }
    });
  } catch (error) {
    console.error('Error in processTables:', error);
    return content;
  }
}

/**
 * Process horizontal rules
 */
function processHorizontalRules(content: string): string {
  return content.replace(HORIZONTAL_RULE_REGEX,
    '<hr class="my-8 h-px border-0 bg-gray-200 dark:bg-gray-700">'
  );
}

/**
 * Process footnotes
 */
function processFootnotes(content: string): string {
  try {
    if (!content) return '';

    // First collect all footnote references and definitions
    const footnotes = new Map<string, string>();
    const references = new Map<string, number>();
    const referenceLocations = new Set<string>();
    let nextNumber = 1;

    // First pass: collect all references to establish order
    let processedContent = content.replace(FOOTNOTE_REFERENCE_REGEX, (match, id) => {
      if (!referenceLocations.has(id) && !references.has(id)) {
        references.set(id, nextNumber++);
      }
      referenceLocations.add(id);
      return match;  // Keep the reference for now
    });

    // Second pass: collect all definitions
    processedContent = processedContent.replace(FOOTNOTE_DEFINITION_REGEX, (match, id, text) => {
      footnotes.set(id, text.trim());
      return '';  // Remove the definition
    });

    // Third pass: process references with collected information
    processedContent = processedContent.replace(FOOTNOTE_REFERENCE_REGEX, (match, id) => {
      if (!footnotes.has(id)) {
        console.warn(`Footnote reference [^${id}] found but no definition exists`);
        return match;
      }
      
      const num = references.get(id)!;
      return `<sup><a href="#fn-${id}" id="fnref-${id}" class="text-primary-600 hover:underline">[${num}]</a></sup>`;
    });

    // Add footnotes section if we have any
    if (references.size > 0) {
      processedContent += '\n\n<h2 class="text-xl font-bold mt-8 mb-4">Footnotes</h2>\n<ol class="list-decimal list-inside">\n';
      
      // Sort footnotes by their reference number
      const sortedFootnotes = Array.from(references.entries())
        .sort((a, b) => a[1] - b[1])
        .filter(([id]) => footnotes.has(id));  // Only include footnotes that have definitions

      // Add each footnote in order
      for (const [id, num] of sortedFootnotes) {
        const text = footnotes.get(id) || '';
        processedContent += `<li id="fn-${id}" value="${num}"><span class="marker">${text}</span> <a href="#fnref-${id}" class="text-primary-600 hover:underline">↩</a></li>\n`;
      }
      processedContent += '</ol>';
    }

    return processedContent;
  } catch (error) {
    console.error('Error processing footnotes:', error);
    return content;
  }
}

/**
 * Process blockquotes
 */
function processBlockquotes(content: string): string {
  // Match blockquotes that might span multiple lines
  const blockquoteRegex = /^>[ \t]?(.+(?:\n>[ \t]?.+)*)/gm;
  
  return content.replace(blockquoteRegex, (match) => {
    // Remove the '>' prefix from each line and preserve line breaks
    const text = match
      .split('\n')
      .map(line => line.replace(/^>[ \t]?/, ''))
      .join('\n')
      .trim();
      
    return `<blockquote class="pl-4 border-l-4 border-gray-300 dark:border-gray-600 my-4 whitespace-pre-wrap">${text}</blockquote>`;
  });
}

/**
 * Process code blocks by finding consecutive code lines and preserving their content
 */
function processCodeBlocks(text: string): { text: string; blocks: Map<string, string> } {
  const lines = text.split('\n');
  const processedLines: string[] = [];
  const blocks = new Map<string, string>();
  let inCodeBlock = false;
  let currentCode: string[] = [];
  let currentLanguage = '';
  let blockCount = 0;
  let lastWasCodeBlock = false;

  for (let i = 0; i < lines.length; i++) {
    const line = lines[i];
    const codeBlockStart = line.match(/^```(\w*)$/);
    
    if (codeBlockStart) {
      if (!inCodeBlock) {
        // Starting a new code block
        inCodeBlock = true;
        currentLanguage = codeBlockStart[1];
        currentCode = [];
        lastWasCodeBlock = true;
      } else {
        // Ending current code block
        blockCount++;
        const id = `CODE_BLOCK_${blockCount}`;
        const code = currentCode.join('\n');
        
        // Try to format JSON if specified
        let formattedCode = code;
        if (currentLanguage.toLowerCase() === 'json') {
          try {
            formattedCode = JSON.stringify(JSON.parse(code), null, 2);
          } catch (e) {
            formattedCode = code;
          }
        }
        
        blocks.set(id, JSON.stringify({
          code: formattedCode,
          language: currentLanguage,
          raw: true
        }));
        
        processedLines.push('');  // Add spacing before code block
        processedLines.push(id);
        processedLines.push('');  // Add spacing after code block
        inCodeBlock = false;
        currentCode = [];
        currentLanguage = '';
      }
    } else if (inCodeBlock) {
      currentCode.push(line);
    } else {
      if (lastWasCodeBlock && line.trim()) {
        processedLines.push('');
        lastWasCodeBlock = false;
      }
      processedLines.push(line);
    }
  }

  // Handle unclosed code block
  if (inCodeBlock && currentCode.length > 0) {
    blockCount++;
    const id = `CODE_BLOCK_${blockCount}`;
    const code = currentCode.join('\n');
    
    // Try to format JSON if specified
    let formattedCode = code;
    if (currentLanguage.toLowerCase() === 'json') {
      try {
        formattedCode = JSON.stringify(JSON.parse(code), null, 2);
      } catch (e) {
        formattedCode = code;
      }
    }
    
    blocks.set(id, JSON.stringify({
      code: formattedCode,
      language: currentLanguage,
      raw: true
    }));
    processedLines.push('');
    processedLines.push(id);
    processedLines.push('');
  }

  return {
    text: processedLines.join('\n'),
    blocks
  };
}

/**
 * Restore code blocks with proper formatting
 */
function restoreCodeBlocks(text: string, blocks: Map<string, string>): string {
  let result = text;
  
  for (const [id, blockData] of blocks) {
    try {
      const { code, language } = JSON.parse(blockData);
      
      let html;
      if (language && hljs.getLanguage(language)) {
        try {
          const highlighted = hljs.highlight(code, {
            language,
            ignoreIllegals: true
          }).value;
          html = `<pre class="code-block"><code class="hljs language-${language}">${highlighted}</code></pre>`;
        } catch (e) {
          console.warn('Failed to highlight code block:', e);
          html = `<pre class="code-block"><code class="hljs ${language ? `language-${language}` : ''}">${code}</code></pre>`;
        }
      } else {
        html = `<pre class="code-block"><code class="hljs">${code}</code></pre>`;
      }

      result = result.replace(id, html);
    } catch (error) {
      console.error('Error restoring code block:', error);
      result = result.replace(id, '<pre class="code-block"><code class="hljs">Error processing code block</code></pre>');
    }
  }

  return result;
}

/**
 * Parse markdown text with advanced formatting
 */
export async function parseAdvancedMarkdown(text: string): Promise<string> {
  if (!text) return '';
  
  try {
    // Step 1: Extract and save code blocks first
    const { text: withoutCode, blocks } = processCodeBlocks(text);
    let processedText = withoutCode;

    // Step 2: Process block-level elements
    processedText = processTables(processedText);
    processedText = processBlockquotes(processedText);
    processedText = processHeadings(processedText);
    processedText = processHorizontalRules(processedText);

    // Process inline elements
    processedText = processedText.replace(INLINE_CODE_REGEX, (_, code) => {
      const escapedCode = code
        .trim()
        .replace(/&/g, '&amp;')
        .replace(/</g, '&lt;')
        .replace(/>/g, '&gt;')
        .replace(/"/g, '&quot;')
        .replace(/'/g, '&#039;');
      return `<code class="px-1.5 py-0.5 bg-white dark:bg-gray-900 border border-gray-200 dark:border-gray-700 rounded text-sm font-mono">${escapedCode}</code>`;
    });

    // Process footnotes
    processedText = processFootnotes(processedText);

    // Process basic markdown (which will also handle Nostr identifiers)
    processedText = await parseBasicMarkdown(processedText);

    // Step 3: Restore code blocks
    processedText = restoreCodeBlocks(processedText, blocks);

    return processedText;
  } catch (error) {
    console.error('Error in parseAdvancedMarkdown:', error);
    return `<div class="text-red-500">Error processing markdown: ${error instanceof Error ? error.message : 'Unknown error'}</div>`;
  }
}