import DOMPurify from 'dompurify';

/**
 * Format and standardize email content for display following email industry standards.
 * This function handles various email content formats and ensures proper display
 * including support for HTML emails, plain text emails, RTL languages, and email client quirks.
 */
export function formatEmailContent(email: any): string {
  if (!email) {
    console.log('formatEmailContent: No email provided');
    return '';
  }
  
  try {
    // Get the content in order of preference with proper fallbacks
    let content = '';
    let isHtml = false;
    let textContent = '';
    
    // Extract content based on standardized property hierarchy
    if (email.content && typeof email.content === 'object') {
      isHtml = !!email.content.html;
      content = email.content.html || '';
      textContent = email.content.text || '';
    } else if (typeof email.content === 'string') {
      // Check if the string content is HTML
      isHtml = email.content.trim().startsWith('<') && 
               (email.content.includes('<html') || 
                email.content.includes('<body') || 
                email.content.includes('<div') || 
                email.content.includes('<p>'));
      content = email.content;
      textContent = email.content;
    } else if (email.html) {
      isHtml = true;
      content = email.html;
      textContent = email.text || '';
    } else if (email.text) {
      isHtml = false;
      content = '';
      textContent = email.text;
    } else if (email.formattedContent) {
      // Assume formattedContent is already HTML
      isHtml = true;
      content = email.formattedContent;
      textContent = '';
    }
    
    // If we have HTML content, sanitize and standardize it
    if (isHtml && content) {
      // Sanitize with industry-standard email tags and attributes
      const sanitizedContent = DOMPurify.sanitize(content, {
        ADD_TAGS: [
          'style', 'table', 'thead', 'tbody', 'tfoot', 'tr', 'td', 'th', 
          'caption', 'col', 'colgroup', 'div', 'span', 'img', 'br', 'hr',
          'h1', 'h2', 'h3', 'h4', 'h5', 'h6', 'p', 'blockquote', 'pre',
          'ul', 'ol', 'li', 'dl', 'dt', 'dd', 'a', 'b', 'i', 'u', 'em',
          'strong', 'del', 'ins', 'sub', 'sup', 'small', 'mark', 'q'
        ],
        ADD_ATTR: [
          'class', 'style', 'id', 'href', 'src', 'alt', 'title', 'width', 'height',
          'border', 'cellspacing', 'cellpadding', 'bgcolor', 'color', 'dir', 'lang',
          'align', 'valign', 'span', 'colspan', 'rowspan', 'target', 'rel',
          'background', 'data-*'
        ],
        ALLOW_DATA_ATTR: true,
        WHOLE_DOCUMENT: false,
        RETURN_DOM: false,
        FORBID_TAGS: ['script', 'iframe', 'object', 'embed', 'form', 'input', 'textarea', 'select', 'button'],
        FORBID_ATTR: ['onerror', 'onload', 'onclick', 'onmouseover', 'onmouseout']
      });
      
      // Wrap the content in standard email container with responsive styling
      return `
        <div class="email-content" style="font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Helvetica, Arial, sans-serif; line-height: 1.6; color: #333; max-width: 100%; word-wrap: break-word;">
          ${sanitizedContent}
        </div>
      `;
    } 
    // If we only have text content, format it properly
    else if (textContent) {
      // Format plain text with proper line breaks and paragraphs
      const formattedText = textContent
        .replace(/\r\n|\r|\n/g, '<br>') // Convert all newlines to <br>
        .replace(/((?:<br>){2,})/g, '</p><p>') // Convert multiple newlines to paragraphs
        .replace(/<br><\/p>/g, '</p>') // Fix any <br></p> combinations
        .replace(/<p><br>/g, '<p>'); // Fix any <p><br> combinations
        
      return `
        <div class="email-content plain-text" style="font-family: monospace; white-space: pre-wrap; line-height: 1.5; color: #333; max-width: 100%; word-wrap: break-word;">
          <p>${formattedText}</p>
        </div>
      `;
    }
    
    // Default case: empty or unrecognized content
    return '<div class="email-content-empty">No content available</div>';
  } catch (error) {
    console.error('formatEmailContent: Error formatting email content:', error);
    return '<div class="email-content-error">Error displaying email content</div>';
  }
}