'use client';

import DOMPurify from 'dompurify';

export interface ParsedEmail {
  subject: string | null;
  from: string | null;
  to: string | null;
  cc: string | null;
  bcc: string | null;
  date: Date | null;
  html: string | null;
  text: string | null;
  attachments: Array<{
    filename: string;
    contentType: string;
    size: number;
  }>;
  headers: Record<string, any>;
}

export async function decodeEmail(emailContent: string): Promise<ParsedEmail> {
  try {
    // Ensure the email content is properly formatted
    const formattedContent = emailContent?.trim();
    if (!formattedContent) {
      return {
        subject: null,
        from: null,
        to: null,
        cc: null,
        bcc: null,
        date: null,
        html: null,
        text: 'No content available',
        attachments: [],
        headers: {}
      };
    }

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

    const data = await response.json();

    if (!response.ok) {
      console.error('API Error:', data);
      return {
        subject: null,
        from: null,
        to: null,
        cc: null,
        bcc: null,
        date: null,
        html: null,
        text: data.error || 'Failed to parse email',
        attachments: [],
        headers: {}
      };
    }

    // If we have a successful response but no content
    if (!data.html && !data.text) {
      return {
        ...data,
        date: data.date ? new Date(data.date) : null,
        html: null,
        text: 'No content available',
        attachments: data.attachments || [],
        headers: data.headers || {}
      };
    }

    return {
      ...data,
      date: data.date ? new Date(data.date) : null,
      text: data.text || null,
      html: data.html || null,
      attachments: data.attachments || [],
      headers: data.headers || {}
    };
  } catch (error) {
    console.error('Error parsing email:', error);
    return {
      subject: null,
      from: null,
      to: null,
      cc: null,
      bcc: null,
      date: null,
      html: null,
      text: 'Error parsing email content',
      attachments: [],
      headers: {}
    };
  }
}

/**
 * Cleans HTML content by removing potentially harmful elements while preserving styling.
 * This is the centralized HTML sanitization function to be used across the application.
 * 
 * Key features:
 * - Safely removes scripts, iframes, and other potentially harmful elements
 * - Optionally preserves and scopes CSS styles to prevent them from affecting the rest of the page
 * - Fixes self-closing tags that might break in React or contentEditable contexts
 * - Can add a wrapper div with isolation for additional safety
 * 
 * @param html HTML content to sanitize
 * @param options Configuration options:
 *   - preserveStyles: Whether to keep <style> tags (default: true)
 *   - scopeStyles: Whether to scope CSS to prevent leakage into the rest of the page (default: true)
 *   - addWrapper: Whether to add a container div with CSS isolation (default: true)
 * @returns Sanitized HTML that can be safely inserted into the document
 */
export function cleanHtml(html: string, options: {
  preserveStyles?: boolean;
  scopeStyles?: boolean;
  addWrapper?: boolean;
} = {}): string {
  if (!html) return '';
  
  try {
    const defaultOptions = {
      preserveStyles: true,
      scopeStyles: true,
      addWrapper: true,
      ...options
    };
    
    // Extract style tags if we're preserving them
    const styleTagsContent: string[] = [];
    let processedHtml = html;
    
    if (defaultOptions.preserveStyles) {
      processedHtml = html.replace(/<style[^>]*>([\s\S]*?)<\/style>/gi, (match, styleContent) => {
        styleTagsContent.push(styleContent);
        return ''; // Remove style tags temporarily
      });
    }
    
    // Process the HTML content
    processedHtml = processedHtml
      // Remove potentially harmful elements and attributes
      .replace(/<script\b[^<]*(?:(?!<\/script>)<[^<]*)*<\/script>/gi, '')
      .replace(/<iframe\b[^<]*(?:(?!<\/iframe>)<[^<]*)*<\/iframe>/gi, '')
      .replace(/<object\b[^<]*(?:(?!<\/object>)<[^<]*)*<\/object>/gi, '')
      .replace(/<embed\b[^<]*(?:(?!<\/embed>)<[^<]*)*<\/embed>/gi, '')
      .replace(/<form\b[^<]*(?:(?!<\/form>)<[^<]*)*<\/form>/gi, '')
      .replace(/on\w+="[^"]*"/gi, '') // Remove inline event handlers (onclick, onload, etc.)
      .replace(/on\w+='[^']*'/gi, '')
      // Fix self-closing tags that might break React
      .replace(/<(br|hr|img|input|link|meta|area|base|col|embed|keygen|param|source|track|wbr)([^>]*)>/gi, '<$1$2 />');
    
    // If we're scoping styles, prefix classes
    if (defaultOptions.scopeStyles) {
      processedHtml = processedHtml.replace(/class=["']([^"']*)["']/gi, (match, classContent) => {
        const classes = classContent.split(/\s+/).map((cls: string) => `email-forwarded-${cls}`).join(' ');
        return `class="${classes}"`;
      });
    }
    
    // Add scoped styles if needed
    if (defaultOptions.preserveStyles && styleTagsContent.length > 0 && defaultOptions.scopeStyles) {
      // Create a modified version of the styles that scope them to our container
      const scopedStyles = styleTagsContent.map(style => {
        // Replace CSS selectors to be scoped to our container
        return style
          // Add scope to class selectors
          .replace(/(\.[a-zA-Z0-9_-]+)/g, '.email-forwarded-$1')
          // Add scope to ID selectors
          .replace(/(#[a-zA-Z0-9_-]+)/g, '#email-forwarded-$1')
          // Fix any CSS that might break out
          .replace(/@import/g, '/* @import */')
          .replace(/@media/g, '/* @media */');
      }).join('\n');
      
      // Add the styles back in a scoped way
      if (defaultOptions.addWrapper) {
        return `
          <div class="email-forwarded-content" style="position: relative; overflow: auto; max-width: 100%;">
            <style type="text/css">
              /* Scoped styles for forwarded email */
              .email-forwarded-content {
                /* Base containment */
                font-family: Arial, sans-serif;
                color: #333;
                line-height: 1.5;
              }
              /* Original email styles (scoped) */
              ${scopedStyles}
            </style>
            ${processedHtml}
          </div>
        `;
      } else {
        return `<style type="text/css">${scopedStyles}</style>${processedHtml}`;
      }
    }
    
    // Just wrap the content if needed
    if (defaultOptions.addWrapper) {
      return `<div class="email-forwarded-content" style="position: relative; overflow: auto; max-width: 100%;">${processedHtml}</div>`;
    }
    
    return processedHtml;
  } catch (error) {
    console.error('Error cleaning HTML:', error);
    // Return something safe in case of error
    return `<div style="color: #666; font-style: italic;">Error processing HTML content</div>`;
  }
}