'use client';

import DOMPurify from 'dompurify';

/**
 * Client-side utilities for formatting email content
 * This file contains functions for formatting email content in the browser
 * without any server dependencies.
 */

export interface EmailAddress {
  address: string;
  name?: string;
}

export interface FormattedEmail {
  subject: string;
  to?: EmailAddress[];
  cc?: EmailAddress[];
  bcc?: EmailAddress[];
  body: string;
}

export interface EmailMessageForFormatting {
  subject?: string;
  from?: EmailAddress | EmailAddress[];
  to?: EmailAddress | EmailAddress[];
  date?: Date | string;
  html?: string;
  text?: string;
  cc?: EmailAddress | EmailAddress[];
  bcc?: EmailAddress | EmailAddress[];
}

/**
 * Format an email for replying or forwarding
 * Client-side friendly version that doesn't depend on server modules
 */
export function formatEmailForReply(
  originalEmail: EmailMessageForFormatting, 
  type: 'reply' | 'replyAll' | 'forward' = 'reply'
): FormattedEmail {
  // Format the subject with Re: or Fwd: prefix
  const subject = formatSubject(originalEmail.subject || '', type);
  
  // Initialize recipients based on reply type
  let to: EmailAddress[] = [];
  let cc: EmailAddress[] = [];
  
  if (type === 'reply' && originalEmail.from) {
    to = Array.isArray(originalEmail.from) ? originalEmail.from : [originalEmail.from];
  } else if (type === 'replyAll') {
    // To: original sender
    if (originalEmail.from) {
      to = Array.isArray(originalEmail.from) ? originalEmail.from : [originalEmail.from];
    }
    
    // CC: all other recipients
    if (originalEmail.to) {
      cc = Array.isArray(originalEmail.to) ? originalEmail.to : [originalEmail.to];
    }
    
    if (originalEmail.cc) {
      const existingCc = Array.isArray(originalEmail.cc) ? originalEmail.cc : [originalEmail.cc];
      cc = [...cc, ...existingCc];
    }
    
    // Remove duplicates and self from CC (would need user's email here)
    // This is simplified - in a real app you'd filter out the current user
    cc = cc.filter((value, index, self) => 
      index === self.findIndex((t) => t.address === value.address)
    );
  }
  
  // Create the quoted content with header
  const quoteHeader = createQuoteHeader(originalEmail);
  
  // Get the original content, preferring HTML over plain text
  let originalContent = '';
  if (originalEmail.html) {
    // Sanitize any potentially unsafe HTML
    originalContent = DOMPurify.sanitize(originalEmail.html);
  } else if (originalEmail.text) {
    // Convert text to HTML by replacing newlines with br tags
    originalContent = originalEmail.text.replace(/\n/g, '<br>');
  }
  
  // Combine the header with the original content
  const body = `
    <div>
      <br>
      <blockquote style="margin: 0 0 0 0.8ex; border-left: 1px solid #ccc; padding-left: 1ex;">
        ${quoteHeader}
        <div>${originalContent || 'No content available'}</div>
      </blockquote>
    </div>
  `;
  
  return {
    subject,
    to,
    cc,
    body
  };
}

/**
 * Format email subject with appropriate prefix
 */
export function formatSubject(
  originalSubject: string, 
  type: 'reply' | 'replyAll' | 'forward'
): string {
  // Trim whitespace
  let subject = originalSubject.trim();
  
  // Remove existing prefixes to avoid duplication
  subject = subject.replace(/^(Re|Fwd):\s*/gi, '');
  
  // Add appropriate prefix based on action type
  if (type === 'forward') {
    return `Fwd: ${subject}`;
  } else {
    return `Re: ${subject}`;
  }
}

/**
 * Create a formatted quote header with sender and date information
 */
export function createQuoteHeader(email: EmailMessageForFormatting): string {
  let fromName = 'Unknown Sender';
  let fromEmail = '';
  
  // Extract sender information
  if (email.from) {
    if (Array.isArray(email.from)) {
      fromName = email.from[0].name || email.from[0].address;
      fromEmail = email.from[0].address;
    } else {
      fromName = email.from.name || email.from.address;
      fromEmail = email.from.address;
    }
  }
  
  // Format the date
  let dateFormatted = '';
  if (email.date) {
    const date = typeof email.date === 'string' ? new Date(email.date) : email.date;
    
    // Check if the date is valid
    if (!isNaN(date.getTime())) {
      dateFormatted = date.toLocaleString('en-US', {
        weekday: 'short',
        year: 'numeric',
        month: 'short',
        day: 'numeric',
        hour: '2-digit',
        minute: '2-digit'
      });
    }
  }
  
  // Generate recipients string
  let recipients = '';
  if (email.to) {
    if (Array.isArray(email.to)) {
      recipients = email.to.map(r => r.name || r.address).join(', ');
    } else {
      recipients = email.to.name || email.to.address;
    }
  }
  
  // Create the header HTML
  return `
    <div style="margin-bottom: 10px; color: #555; font-size: 0.9em;">
      <div><strong>From:</strong> ${fromName} &lt;${fromEmail}&gt;</div>
      ${dateFormatted ? `<div><strong>Date:</strong> ${dateFormatted}</div>` : ''}
      <div><strong>Subject:</strong> ${email.subject || 'No Subject'}</div>
      <div><strong>To:</strong> ${recipients || 'No Recipients'}</div>
      ${email.cc ? `<div><strong>Cc:</strong> ${Array.isArray(email.cc) ? 
        email.cc.map(r => r.name || r.address).join(', ') : 
        (email.cc.name || email.cc.address)}</div>` : ''}
    </div>
    <hr style="border: none; border-top: 1px solid #ddd; margin: 10px 0;">
  `;
}

/**
 * Format an email for forwarding
 */
export function formatEmailForForward(email: EmailMessageForFormatting): FormattedEmail {
  // Format the subject with Fwd: prefix
  const subject = formatSubject(email.subject || '', 'forward');
  
  // Create the forward header
  const forwardHeader = createQuoteHeader(email);
  
  // Get the original content, preferring HTML over plain text
  let originalContent = '';
  if (email.html) {
    // Sanitize any potentially unsafe HTML
    originalContent = DOMPurify.sanitize(email.html);
  } else if (email.text) {
    // Convert text to HTML by replacing newlines with br tags
    originalContent = email.text.replace(/\n/g, '<br>');
  }
  
  // Combine the header with the original content
  const body = `
    <div>
      <br>
      <div style="border-left: 1px solid #ccc; padding-left: 1ex; margin-left: 0.8ex;">
        <div style="font-weight: bold; margin-bottom: 10px;">---------- Forwarded message ---------</div>
        ${forwardHeader}
        <div>${originalContent || '<div style="padding: 10px; text-align: center; background-color: #f8f8f8; border: 1px dashed #ccc; margin: 10px 0;">No content available</div>'}</div>
      </div>
    </div>
  `;
  
  return {
    subject,
    body
  };
}