import { useState, useEffect, useCallback, useRef } from 'react';
import { useToast } from './use-toast';
import { EmailMessage, EmailContent } from '@/types/email';
import { detectTextDirection } from '@/lib/utils/text-direction';
import { sanitizeHtml } from '@/lib/utils/email-utils';

interface EmailFetchState {
  email: EmailMessage | null;
  loading: boolean;
  error: string | null;
}

interface UseEmailFetchProps {
  onEmailLoaded?: (email: EmailMessage) => void;
  onError?: (error: string) => void;
}

export function useEmailFetch({ onEmailLoaded, onError }: UseEmailFetchProps = {}) {
  const [state, setState] = useState<EmailFetchState>({
    email: null,
    loading: false,
    error: null
  });
  
  const abortControllerRef = useRef<AbortController | null>(null);
  const { toast } = useToast();

  // Validate email fetch parameters
  const validateFetchParams = (emailId: string, accountId: string, folder: string) => {
    if (!emailId || typeof emailId !== 'string') {
      throw new Error('Invalid email ID');
    }
    
    if (!accountId || typeof accountId !== 'string') {
      throw new Error('Invalid account ID');
    }
    
    if (!folder || typeof folder !== 'string') {
      throw new Error('Invalid folder');
    }
    
    // Validate UID format
    if (!/^\d+$/.test(emailId)) {
      throw new Error('Email ID must be a numeric UID');
    }
  };

  // Fetch email with proper error handling and cancellation
  const fetchEmail = useCallback(async (emailId: string, accountId: string, folder: string) => {
    if (!emailId || !accountId || !folder) {
      console.error('Missing required parameters for fetchEmail');
      return;
    }

    // Abort any previous request
    if (abortControllerRef.current) {
      abortControllerRef.current.abort();
    }
    
    abortControllerRef.current = new AbortController();
    setState(prev => ({ ...prev, loading: true, error: null }));

    try {
      const response = await fetch(
        `/api/courrier/${emailId}?accountId=${encodeURIComponent(accountId)}&folder=${encodeURIComponent(folder)}`,
        {
          signal: abortControllerRef.current?.signal
        }
      );
      
      if (!response.ok) {
        throw new Error(`Failed to fetch email: ${response.statusText}`);
      }

      const data = await response.json();
      
      // Create a valid email message object with required fields
      const processContent = (data: any): EmailContent => {
        // Determine the text content - using all possible paths
        let textContent = '';
        if (typeof data.content === 'string') {
          textContent = data.content;
        } else if (data.content?.text) {
          textContent = data.content.text;
        } else if (data.text) {
          textContent = data.text;
        } else if (data.plainText) {
          textContent = data.plainText;
        }

        // Determine the HTML content - using all possible paths
        let htmlContent = undefined;
        if (data.content?.html) {
          htmlContent = data.content.html;
        } else if (data.html) {
          htmlContent = data.html;
        } else if (typeof data.content === 'string' && data.content.includes('<')) {
          // If the content string appears to be HTML
          htmlContent = data.content;
          // We should still keep the text version, will be extracted if needed
        }
        
        // Clean HTML content if present
        if (htmlContent) {
          htmlContent = sanitizeHtml(htmlContent);
        }
        
        // Determine if content is HTML
        const isHtml = !!htmlContent;
        
        // Detect text direction
        const direction = data.content?.direction || detectTextDirection(textContent);
        
        return {
          text: textContent,
          html: htmlContent,
          isHtml,
          direction
        };
      };

      const transformedEmail: EmailMessage = {
        id: data.id || emailId,
        subject: data.subject || '',
        from: data.from || '',
        to: data.to || '',
        cc: data.cc,
        bcc: data.bcc,
        date: data.date || new Date().toISOString(),
        flags: Array.isArray(data.flags) ? data.flags : [],
        content: processContent(data),
        attachments: data.attachments
      };
      
      console.log('Email processed:', transformedEmail.id, 
                  'HTML:', !!transformedEmail.content.html,
                  'Text length:', transformedEmail.content.text.length);
      
      setState({ email: transformedEmail, loading: false, error: null });
      onEmailLoaded?.(transformedEmail);
      
      // Mark as read if not already
      if (!transformedEmail.flags?.includes('seen')) {
        try {
          await fetch(`/api/courrier/${emailId}/mark-read`, {
            method: 'POST',
            headers: { 'Content-Type': 'application/json' },
            body: JSON.stringify({ action: 'mark-read' })
          });
        } catch (err: any) {
          console.error('Error marking email as read:', err);
        }
      }
    } catch (err: any) {
      // Don't set error if request was aborted
      if (err.name === 'AbortError') {
        return;
      }
      
      console.error('Error fetching email:', err);
      const errorMessage = err instanceof Error ? err.message : 'Failed to load email';
      setState(prev => ({ ...prev, loading: false, error: errorMessage }));
      onError?.(errorMessage);
      
      toast({
        title: 'Error',
        description: errorMessage,
        variant: 'destructive'
      });
    }
  }, [onEmailLoaded, onError, toast]);

  // Cleanup on unmount
  useEffect(() => {
    return () => {
      if (abortControllerRef.current) {
        abortControllerRef.current.abort();
      }
    };
  }, []);

  return {
    ...state,
    fetchEmail
  };
}