/**
 * CENTRAL EMAIL FORMATTER
 * 
 * This is the primary and only email formatting utility to be used.
 * All email formatting should go through here to ensure consistent 
 * handling of text direction and HTML sanitization.
 * 
 * IMPORTANT: This formatter is configured for English-only content
 * and enforces left-to-right text direction.
 */

import DOMPurify from 'isomorphic-dompurify';

// Reset any existing hooks to start clean
DOMPurify.removeAllHooks();

// Configure DOMPurify for English-only content (always LTR)
DOMPurify.addHook('afterSanitizeAttributes', function(node) {
  // Force LTR direction on all elements that can have a dir attribute
  if (node instanceof HTMLElement) {
    node.setAttribute('dir', 'ltr');
    
    // Handle style attribute
    if (node.hasAttribute('style')) {
      let style = node.getAttribute('style') || '';
      
      // Remove any RTL-related styles
      style = style.replace(/direction\s*:\s*rtl\s*;?/gi, '');
      style = style.replace(/text-align\s*:\s*right\s*;?/gi, '');
      style = style.replace(/unicode-bidi\s*:[^;]*;?/gi, '');
      
      // Add explicit LTR styles
      style = style.trim();
      if (style && !style.endsWith(';')) style += ';';
      style += ' direction: ltr; text-align: left;';
      
      node.setAttribute('style', style);
    } else {
      // If no style exists, add default LTR styles
      node.setAttribute('style', 'direction: ltr; text-align: left;');
    }
  }
});

// Configure DOMPurify to add certain attributes and forbid others
DOMPurify.setConfig({
  ADD_ATTR: ['dir'],
  FORBID_ATTR: ['lang', 'bidi']
});

// Interface definitions
export interface EmailAddress {
  name: string;
  address: string;
}

export interface EmailMessage {
  id: string;
  messageId?: string;
  subject: string;
  from: EmailAddress[];
  to: EmailAddress[];
  cc?: EmailAddress[];
  bcc?: EmailAddress[];
  date: Date | string;
  flags?: {
    seen: boolean;
    flagged: boolean;
    answered: boolean;
    deleted: boolean;
    draft: boolean;
  };
  preview?: string;
  content?: string;
  html?: string;
  text?: string;
  hasAttachments?: boolean;
  attachments?: any[];
  folder?: string;
  size?: number;
  contentFetched?: boolean;
}

/**
 * Format email addresses for display
 */
export function formatEmailAddresses(addresses: EmailAddress[]): string {
  if (!addresses || addresses.length === 0) return '';
  
  return addresses.map(addr => 
    addr.name && addr.name !== addr.address 
      ? `${addr.name} <${addr.address}>`
      : addr.address
  ).join(', ');
}

/**
 * Format date for display
 */
export function formatEmailDate(date: Date | string | undefined): string {
  if (!date) return '';
  
  try {
    const dateObj = typeof date === 'string' ? new Date(date) : date;
    return dateObj.toLocaleString('en-US', {
      weekday: 'short',
      year: 'numeric',
      month: 'short',
      day: 'numeric',
      hour: '2-digit',
      minute: '2-digit'
    });
  } catch (e) {
    return typeof date === 'string' ? date : date.toString();
  }
}

/**
 * Sanitize HTML content before processing or displaying
 * This ensures the content is properly formatted for LTR display
 * @param content HTML content to sanitize
 * @returns Sanitized HTML with LTR formatting
 */
export function sanitizeHtml(content: string): string {
  if (!content) return '';
  
  // Sanitize the HTML using our configured DOMPurify with LTR enforced
  return DOMPurify.sanitize(content);
}

/**
 * Format an email for forwarding - CENTRAL IMPLEMENTATION
 * All other formatting functions should be deprecated in favor of this one
 */
export function formatForwardedEmail(email: EmailMessage): {
  subject: string;
  content: string;
} {
  // Format subject with Fwd: prefix if needed
  const subjectBase = email.subject || '(No subject)';
  const subject = subjectBase.match(/^(Fwd|FW|Forward):/i) 
    ? subjectBase 
    : `Fwd: ${subjectBase}`;
  
  // Get sender and recipient information
  const fromString = formatEmailAddresses(email.from || []);
  const toString = formatEmailAddresses(email.to || []);
  const dateString = formatEmailDate(email.date);
  
  // Get and sanitize original content (sanitization enforces LTR)
  const originalContent = sanitizeHtml(email.content || email.html || email.text || '');
  
  // Check if the content already has a forwarded message header
  const hasExistingHeader = originalContent.includes('---------- Forwarded message ---------');
  
  // If there's already a forwarded message header, don't add another one
  if (hasExistingHeader) {
    // Just wrap the content without additional formatting
    const content = `
      <div style="min-height: 20px;"></div>
      <div class="email-original-content">
        ${originalContent}
      </div>
    `;
    return { subject, content };
  }
  
  // Create formatted content for forwarded email
  const content = `
    <div style="min-height: 20px;"></div>
    <div style="border-top: 1px solid #ccc; margin-top: 10px; padding-top: 10px;">
      <div style="font-family: Arial, sans-serif; color: #333;">
        <div style="margin-bottom: 15px;">
          <div>---------- Forwarded message ---------</div>
          <div><b>From:</b> ${fromString}</div>
          <div><b>Date:</b> ${dateString}</div>
          <div><b>Subject:</b> ${email.subject || ''}</div>
          <div><b>To:</b> ${toString}</div>
        </div>
        <div class="email-original-content">
          ${originalContent}
        </div>
      </div>
    </div>
  `;
  
  return { subject, content };
}

/**
 * Format an email for reply or reply-all - CENTRAL IMPLEMENTATION
 * All other formatting functions should be deprecated in favor of this one
 */
export function formatReplyEmail(email: EmailMessage, type: 'reply' | 'reply-all'): {
  to: string;
  cc?: string;
  subject: string;
  content: string;
} {
  // Format subject with Re: prefix if needed
  const subjectBase = email.subject || '(No subject)';
  const subject = subjectBase.match(/^Re:/i) 
    ? subjectBase 
    : `Re: ${subjectBase}`;
  
  // Get sender information for quote header
  const sender = email.from[0];
  const fromText = sender?.name 
    ? `${sender.name} <${sender.address}>`
    : sender?.address || 'Unknown sender';
  
  // Format date for quote header
  const date = typeof email.date === 'string' ? new Date(email.date) : email.date;
  const formattedDate = date.toLocaleString('en-US', {
    weekday: 'short',
    year: 'numeric',
    month: 'short',
    day: 'numeric',
    hour: '2-digit', 
    minute: '2-digit'
  });
  
  // Create quote header
  const quoteHeader = `<div style="font-weight: 500;">On ${formattedDate}, ${fromText} wrote:</div>`;
  
  // Get and sanitize original content (sanitization enforces LTR)
  const quotedContent = sanitizeHtml(email.html || email.content || email.text || '');
  
  // Format recipients
  let to = formatEmailAddresses(email.from || []);
  let cc = '';
  
  if (type === 'reply-all') {
    // For reply-all, add all original recipients to CC
    const allRecipients = [
      ...(email.to || []),
      ...(email.cc || [])
    ];
    
    cc = formatEmailAddresses(allRecipients);
  }
  
  // Format content for reply
  const content = `
    <div style="min-height: 20px;"></div>
    <div class="reply-body">
      <div class="quote-header" style="color: #555; font-size: 13px; margin: 20px 0 10px 0;">${quoteHeader}</div>
      <blockquote style="margin: 0; padding: 10px 0 10px 15px; border-left: 3px solid #ddd; color: #555; background-color: #f8f8f8; border-radius: 4px;">
        <div class="quoted-content" style="font-size: 13px;">
          ${quotedContent}
        </div>
      </blockquote>
    </div>
  `;
  
  return {
    to,
    cc: cc || undefined,
    subject,
    content
  };
}

/**
 * COMPATIBILITY LAYER: For backward compatibility with the old email-formatter.ts
 * These functions map to our new implementation but preserve the old interface
 */
export function formatEmailForReplyOrForward(
  email: EmailMessage, 
  type: 'reply' | 'reply-all' | 'forward'
): {
  to: string;
  cc?: string;
  subject: string;
  body: string;
} {
  if (type === 'forward') {
    const { subject, content } = formatForwardedEmail(email);
    return {
      to: '',
      subject,
      body: content
    };
  } else {
    const { to, cc, subject, content } = formatReplyEmail(email, type as 'reply' | 'reply-all');
    return {
      to,
      cc,
      subject,
      body: content
    };
  }
}

/**
 * Decode compose content from MIME format to HTML and text
 */
export async function decodeComposeContent(content: string): Promise<{
  html: string | null;
  text: string | null;
}> {
  if (!content.trim()) {
    return { html: null, text: null };
  }

  try {
    const response = await fetch('/api/parse-email', {
      method: 'POST',
      headers: {
        'Content-Type': 'application/json',
      },
      body: JSON.stringify({ email: content }),
    });

    if (!response.ok) {
      throw new Error('Failed to parse email');
    }

    const parsed = await response.json();
    
    // Apply LTR sanitization to the parsed content
    return {
      html: parsed.html ? sanitizeHtml(parsed.html) : null,
      text: parsed.text || null
    };
  } catch (error) {
    console.error('Error parsing email content:', error);
    // Fallback to basic content handling with sanitization
    return {
      html: sanitizeHtml(content),
      text: content
    };
  }
}

/**
 * Encode compose content to MIME format for sending
 */
export function encodeComposeContent(content: string): string {
  if (!content.trim()) {
    throw new Error('Email content is empty');
  }

  // Create MIME headers
  const mimeHeaders = {
    'MIME-Version': '1.0',
    'Content-Type': 'text/html; charset="utf-8"',
    'Content-Transfer-Encoding': 'quoted-printable'
  };

  // Combine headers and content
  return Object.entries(mimeHeaders)
    .map(([key, value]) => `${key}: ${value}`)
    .join('\n') + '\n\n' + content;
}