/**
 * Text Direction Utilities
 * 
 * Centralized utilities for handling text direction (RTL/LTR)
 * to ensure consistent behavior across the application.
 */

/**
 * Detects if text contains RTL characters and should be displayed right-to-left
 * Uses a comprehensive regex pattern that covers Arabic, Hebrew, and other RTL scripts
 * 
 * @param text Text to analyze for direction
 * @returns 'rtl' if RTL characters are detected, otherwise 'ltr'
 */
export function detectTextDirection(text: string | undefined | null): 'ltr' | 'rtl' {
  if (!text) return 'ltr';
  
  // Comprehensive pattern for RTL languages:
  // - Arabic (0600-06FF, FB50-FDFF, FE70-FEFF)
  // - Hebrew (0590-05FF, FB1D-FB4F)
  // - RTL marks and controls (200F, 202B, 202E)
  const rtlPattern = /[\u0591-\u07FF\u200F\u202B\u202E\uFB1D-\uFDFD\uFE70-\uFEFC]/;
  
  return rtlPattern.test(text) ? 'rtl' : 'ltr';
}

/**
 * Adds appropriate direction attribute to HTML content based on content analysis
 * 
 * @param htmlContent HTML content to analyze and enhance with direction
 * @param textContent Plain text version for direction analysis (optional)
 * @returns HTML with appropriate direction attribute
 */
export function applyTextDirection(htmlContent: string, textContent?: string): string {
  if (!htmlContent) return '';
  
  // If text content is provided, use it for direction detection
  // Otherwise extract text from HTML for direction detection
  const textForAnalysis = textContent || 
    htmlContent.replace(/<[^>]*>/g, '')
               .replace(/&nbsp;/g, ' ')
               .replace(/&lt;/g, '<')
               .replace(/&gt;/g, '>')
               .replace(/&amp;/g, '&');
               
  const direction = detectTextDirection(textForAnalysis);
  
  // If the HTML already has a dir attribute, don't override it
  if (htmlContent.includes('dir="rtl"') || htmlContent.includes('dir="ltr"')) {
    return htmlContent;
  }
  
  // Check if we already have an email-content wrapper
  if (htmlContent.startsWith('<div class="email-content')) {
    // Replace opening div with one that includes direction
    return htmlContent.replace(
      /<div class="email-content([^"]*)"/,
      `<div class="email-content$1" dir="${direction}"`
    );
  }
  
  // Otherwise, wrap the content with a direction-aware container
  return `<div class="email-content" dir="${direction}">${htmlContent}</div>`;
}