import { useReducer, useCallback, useEffect, useRef } from 'react';
import { useSession } from 'next-auth/react';
import { useToast } from './use-toast';
import { 
  emailReducer, 
  initialState, 
  EmailState, 
  EmailAction,
  normalizeFolderAndAccount,
  Account
} from '@/lib/reducers/emailReducer';
import { 
  getCachedEmailsWithTimeout, 
  refreshEmailsInBackground 
} from '@/lib/services/prefetch-service';
import { Email, EmailData } from './use-courrier';
import { formatEmailForReplyOrForward } from '@/lib/utils/email-utils';

// Add a global dispatcher for compatibility with older code
// This is a temporary solution until we fully migrate to the reducer pattern
declare global {
  interface Window {
    dispatchEmailAction?: (action: EmailAction) => void;
    __emailStateDispatch?: (action: EmailAction) => void;
  }
}

export const useEmailState = () => {
  const [state, dispatch] = useReducer(emailReducer, initialState);
  const { data: session } = useSession();
  const { toast } = useToast();

  // Refs to track state
  const updateUnreadTimerRef = useRef<number | null>(null);
  const lastEmailViewedRef = useRef<number | null>(null);
  const failedFetchCountRef = useRef<number>(0);
  const lastFolderRef = useRef<string | null>(null);
  const lastPageLoadedRef = useRef<number>(0);
  const prevFolderRef = useRef<string | null>(null);
  const loadMoreTriggerTimeRef = useRef<number>(0);

  // Expose dispatch function to window for external components
  useEffect(() => {
    // Make dispatch available globally for older code
    window.dispatchEmailAction = dispatch;
    window.__emailStateDispatch = dispatch;
    
    // Clean up on unmount
    return () => {
      window.dispatchEmailAction = undefined;
      window.__emailStateDispatch = undefined;
    };
  }, [dispatch]);

  // Helper function to log operations
  const logEmailOp = useCallback((operation: string, details: string, data?: any) => {
    const timestamp = new Date().toISOString().split('T')[1].substring(0, 12);
    console.log(`[${timestamp}][EMAIL-STATE][${operation}] ${details}`);
    if (data) {
      console.log(`[${timestamp}][EMAIL-STATE][DATA]`, data);
    }
  }, []);

  // Load emails from the server
  const loadEmails = useCallback(async (page: number, perPage: number, isLoadMore: boolean = false) => {
    // CRITICAL FIX: Do important validation before setting loading state
    if (!session?.user?.id) return;
    
    // CRITICAL FIX: Always log the isLoadMore parameter
    console.log(`[DEBUG-LOAD_EMAILS] Called with isLoadMore=${isLoadMore}, page=${page}, currentEmails=${state.emails.length}`);
    
    // Set the current folder and account being loaded to detect changes
    const startFolder = state.currentFolder;
    const startAccount = state.selectedAccount ? state.selectedAccount.id : 'default';
    
    // CRITICAL FIX: Force loading state to true
    dispatch({ type: 'SET_LOADING', payload: true });
    
    try {
      // Get normalized parameters using helper function with proper account ID handling
      const accountId = state.selectedAccount ? state.selectedAccount.id : undefined;
      const { normalizedFolder, effectiveAccountId, prefixedFolder } = 
        normalizeFolderAndAccount(state.currentFolder, accountId);
      
      logEmailOp('LOAD_EMAILS', `Loading emails for ${prefixedFolder} (account: ${effectiveAccountId}, isLoadMore: ${isLoadMore}, page: ${page})`);
      
      // Construct query parameters
      const queryParams = new URLSearchParams({
        folder: normalizedFolder,
        page: page.toString(),
        perPage: perPage.toString(),
        accountId: effectiveAccountId
      });
      
      // Debug log existing emails count
      if (isLoadMore) {
        console.log(`[DEBUG-PAGINATION] Loading more emails. Current page: ${page}, existing emails: ${state.emails.length}`);
      }
      
      // Try to get cached emails first
      logEmailOp('CACHE_CHECK', `Checking cache for ${prefixedFolder}, page: ${page}`);
      const cachedEmails = await getCachedEmailsWithTimeout(
        session.user.id,
        prefixedFolder,
        page,
        perPage,
        100,
        effectiveAccountId
      );
      
      if (cachedEmails) {
        logEmailOp('CACHE_HIT', `Using cached data for ${prefixedFolder}, page: ${page}, emails: ${cachedEmails.emails?.length || 0}, isLoadMore: ${isLoadMore}`);
        
        // Ensure cached data has emails array property
        if (Array.isArray(cachedEmails.emails)) {
          // CRITICAL FIX: Double check we're using the right action type based on isLoadMore param
          console.log(`[DEBUG-CACHE_HIT] Dispatching ${isLoadMore ? 'APPEND_EMAILS' : 'SET_EMAILS'} with ${cachedEmails.emails.length} emails`);
          
          // Dispatch appropriate action based on if we're loading more - DO NOT OVERRIDE isLoadMore!
          dispatch({ 
            type: isLoadMore ? 'APPEND_EMAILS' : 'SET_EMAILS', 
            payload: cachedEmails.emails 
          });
          
          // Set pagination info from cache if available
          if (cachedEmails.totalEmails) {
            dispatch({ type: 'SET_TOTAL_EMAILS', payload: cachedEmails.totalEmails });
          }
          
          if (cachedEmails.totalPages) {
            dispatch({ type: 'SET_TOTAL_PAGES', payload: cachedEmails.totalPages });
          }
          
          // Update available mailboxes if provided
          if (cachedEmails.mailboxes && cachedEmails.mailboxes.length > 0) {
            dispatch({ type: 'SET_MAILBOXES', payload: cachedEmails.mailboxes });
          }
        }
        
        // CRITICAL FIX: If this was a loadMore operation, check the result after the dispatch
        if (isLoadMore) {
          setTimeout(() => {
            console.log(`[DEBUG-CACHE_HIT_APPEND] After ${isLoadMore ? 'APPEND' : 'SET'}, email count is now: ${state.emails.length}`);
          }, 0);
        }
        
        return;
      }
      
      // Fetch emails from API if no cache hit
      logEmailOp('API_FETCH', `Fetching emails from API: ${queryParams.toString()}, isLoadMore: ${isLoadMore}`);
      console.log(`[DEBUG-API_FETCH] Fetching from /api/courrier/emails?${queryParams.toString()}`);
      const response = await fetch(`/api/courrier/emails?${queryParams.toString()}`);
      
      if (!response.ok) {
        // CRITICAL FIX: Try to recover from fetch errors by retrying with different pagination
        if (isLoadMore && page > 1) {
          logEmailOp('ERROR_RECOVERY', `Failed to fetch emails for page ${page}, attempting to recover by decrementing page`);
          console.log(`[DEBUG-ERROR] API returned ${response.status} for page ${page}`);
          // If we're loading more and there's an error, just decrement the page to avoid getting stuck
          dispatch({ type: 'SET_PAGE', payload: page - 1 });
          dispatch({ type: 'SET_LOADING', payload: false });
          // Also reset total pages to try again
          dispatch({ type: 'SET_TOTAL_PAGES', payload: page });
          return;
        }
        
        const errorData = await response.json();
        throw new Error(errorData.error || 'Failed to fetch emails');
      }
      
      const data = await response.json();
      console.log(`[DEBUG-API_RESPONSE] Got response with ${data.emails?.length || 0} emails, totalPages: ${data.totalPages}, totalEmails: ${data.totalEmails}, isLoadMore: ${isLoadMore}`);
      
      // CRITICAL FIX: Enhanced empty results handling
      if (!data.emails || data.emails.length === 0) {
        console.log(`[DEBUG-EMPTY] No emails in response for page ${page}`);
        // If we're at a page > 1 and got no results, the paging is off, so try again with page 1
        if (page > 1 && !isLoadMore) {
          logEmailOp('EMPTY_RESULTS', `No emails returned for page ${page}, resetting to page 1`);
          dispatch({ type: 'SET_PAGE', payload: 1 });
          dispatch({ type: 'SET_LOADING', payload: false });
          return;
        }
        
        // If we're already at page 1, just update the state with no emails
        if (!isLoadMore) {
          logEmailOp('EMPTY_RESULTS', `No emails found in ${state.currentFolder}`);
          dispatch({ type: 'SET_EMAILS', payload: [] });
          dispatch({ type: 'SET_TOTAL_EMAILS', payload: 0 });
          dispatch({ type: 'SET_TOTAL_PAGES', payload: 0 });
        } else {
          // For load more, just set loading to false but keep existing emails
          dispatch({ type: 'SET_LOADING', payload: false });
        }
        return;
      }
      
      // Ensure all emails have proper account ID and folder format
      if (Array.isArray(data.emails)) {
        // Log email dates for debugging
        if (data.emails.length > 0) {
          logEmailOp('EMAIL_DATES', `First few email dates before processing:`, 
            data.emails.slice(0, 5).map((e: any) => ({
              id: e.id.substring(0, 8),
              subject: e.subject?.substring(0, 20),
              date: e.date,
              dateObj: new Date(e.date),
              timestamp: new Date(e.date).getTime()
            }))
          );
        }
        
        data.emails.forEach((email: Email) => {
          // If email doesn't have an accountId, set it to the effective one
          if (!email.accountId) {
            email.accountId = effectiveAccountId;
          }
          
          // Ensure folder has the proper prefix format
          if (email.folder && !email.folder.includes(':')) {
            email.folder = `${email.accountId}:${email.folder}`;
          }
          
          // Ensure date is a valid Date object (handle strings or timestamps)
          if (email.date && !(email.date instanceof Date)) {
            try {
              // Convert to a proper Date object if it's a string or number
              const dateObj = new Date(email.date);
              // Verify it's a valid date
              if (!isNaN(dateObj.getTime())) {
                email.date = dateObj;
              }
            } catch (err) {
              // If conversion fails, log and use current date as fallback
              console.error(`Invalid date format for email ${email.id}: ${email.date}`);
              email.date = new Date();
            }
          }
        });
      }
      
      // CRITICAL FIX: Log what we're about to do
      console.log(`[DEBUG-DISPATCH] About to dispatch ${isLoadMore ? 'APPEND_EMAILS' : 'SET_EMAILS'} with ${data.emails?.length || 0} emails`);
      
      // Update state with fetched data
      dispatch({ 
        type: isLoadMore ? 'APPEND_EMAILS' : 'SET_EMAILS', 
        payload: Array.isArray(data.emails) ? data.emails : [] 
      });
      
      // Double-check that we've updated the email list correctly after dispatch
      setTimeout(() => {
        console.log(`[DEBUG-AFTER-DISPATCH] Email count is now: ${state.emails.length}, should include the ${data.emails?.length || 0} new emails we just loaded`);
      }, 0);
      
      if (data.totalEmails) {
        dispatch({ type: 'SET_TOTAL_EMAILS', payload: data.totalEmails });
      }
      
      if (data.totalPages) {
        dispatch({ type: 'SET_TOTAL_PAGES', payload: data.totalPages });
      }
      
      // Update available mailboxes if provided
      if (data.mailboxes && data.mailboxes.length > 0) {
        dispatch({ type: 'SET_MAILBOXES', payload: data.mailboxes });
      }
    } catch (err) {
      logEmailOp('ERROR', `Failed to load emails: ${err instanceof Error ? err.message : String(err)}`);
      dispatch({ 
        type: 'SET_ERROR', 
        payload: err instanceof Error ? err.message : 'Failed to load emails' 
      });
      toast({
        variant: "destructive",
        title: "Error",
        description: err instanceof Error ? err.message : 'Failed to load emails'
      });
    } finally {
      // CRITICAL FIX: Only clear loading state if the folder/account hasn't changed
      if (startFolder === state.currentFolder && 
          (startAccount === (state.selectedAccount?.id || 'default'))) {
        // Safe to clear loading state
        dispatch({ type: 'SET_LOADING', payload: false });
      } else {
        console.log(`[DEBUG-LOAD_EMAILS] Folder/account changed during load, not clearing loading state`);
      }
    }
  }, [session?.user?.id, state.currentFolder, state.selectedAccount, state.page, state.perPage, state.emails.length, toast, logEmailOp]);

  // Change folder
  const changeFolder = useCallback(async (folder: string, accountId?: string) => {
    logEmailOp('CHANGE_FOLDER', `Changing to folder ${folder} with account ${accountId || 'default'}`);
    
    try {
      // CRITICAL FIX: Reset pagination state immediately
      lastPageLoadedRef.current = 0;
      
      // Reset page to 1 directly to prevent any issues with page effects
      // This will be atomic with the CHANGE_FOLDER action
      dispatch({ type: 'SET_PAGE', payload: 1 });
      
      // Clear existing emails - don't show old emails during load
      dispatch({ type: 'SET_EMAILS', payload: [] });
      
      // Set loading state explicitly - this is critical
      dispatch({ type: 'SET_LOADING', payload: true });
      
      // This will handle folder setting in a single atomic operation
      dispatch({ 
        type: 'CHANGE_FOLDER', 
        payload: { folder, accountId: accountId || 'default' } 
      });
      
      // CRITICAL: The email loading will be triggered by the folder effect
      // We don't need to call loadEmails directly here
    } catch (error) {
      logEmailOp('ERROR', `Failed to change folder: ${error instanceof Error ? error.message : String(error)}`);
      dispatch({ 
        type: 'SET_ERROR', 
        payload: error instanceof Error ? error.message : 'Failed to change folder' 
      });
      
      // Always ensure loading state is cleared on error
      dispatch({ type: 'SET_LOADING', payload: false });
    }
  }, [logEmailOp, dispatch]);

  // Select account
  const selectAccount = useCallback((account: Account) => {
    logEmailOp('SELECT_ACCOUNT', `Selecting account: ${account.email} (${account.id})`);
    
    // Handle the entire account selection in a single atomic operation
    dispatch({ type: 'SELECT_ACCOUNT', payload: account });
    
    // The folder loading will be triggered by the useEffect watching for currentFolder changes
  }, [logEmailOp]);

  // Handle email selection
  const handleEmailSelect = useCallback(async (emailId: string, accountId: string, folder: string) => {
    logEmailOp('SELECT_EMAIL', `Selecting email ${emailId} from account ${accountId} in folder ${folder}`);
    
    if (!emailId) {
      dispatch({ 
        type: 'SELECT_EMAIL', 
        payload: { emailId: '', accountId: '', folder: '', email: null } 
      });
      return;
    }
    
    try {
      // Find the email in the current list
      const existingEmail = state.emails.find(e => e.id === emailId);
      
      if (existingEmail && existingEmail.contentFetched) {
        // Use the existing email if it has content already
        dispatch({ 
          type: 'SELECT_EMAIL',
          payload: { emailId, accountId, folder, email: existingEmail }
        });
        
        // Mark as read if not already
        if (!existingEmail.flags.seen) {
          markEmailAsRead(emailId, true, accountId);
        }
        
        return;
      }
      
      // Need to fetch the email content
      dispatch({ type: 'SET_LOADING', payload: true });
      
      // Extract account ID from folder name if present and none was explicitly provided
      const { normalizedFolder, effectiveAccountId } = normalizeFolderAndAccount(folder, accountId);
      
      // Fetch email content from API
      const response = await fetch(`/api/courrier/${emailId}?folder=${normalizedFolder}&accountId=${effectiveAccountId}`);
      
      if (!response.ok) {
        throw new Error(`Failed to fetch email content: ${response.status}`);
      }
      
      const emailData = await response.json();
      
      // Mark the email as read on the server
      markEmailAsRead(emailId, true, effectiveAccountId);
      
      // Select the email
      dispatch({ 
        type: 'SELECT_EMAIL',
        payload: { emailId, accountId: effectiveAccountId, folder, email: emailData }
      });
    } catch (error) {
      logEmailOp('ERROR', `Failed to select email: ${error instanceof Error ? error.message : String(error)}`);
      dispatch({ 
        type: 'SET_ERROR', 
        payload: error instanceof Error ? error.message : 'Failed to select email' 
      });
    } finally {
      dispatch({ type: 'SET_LOADING', payload: false });
    }
  }, [state.emails, logEmailOp]);

  // Toggle email selection for multi-select
  const toggleEmailSelection = useCallback((emailId: string) => {
    dispatch({ type: 'TOGGLE_EMAIL_SELECTION', payload: emailId });
  }, []);

  // Toggle select all
  const toggleSelectAll = useCallback(() => {
    dispatch({ type: 'TOGGLE_SELECT_ALL' });
  }, []);

  // Mark email as read/unread
  const markEmailAsRead = useCallback(async (emailId: string, isRead: boolean, accountId?: string) => {
    try {
      // Find the email to get its account ID if not provided
      const email = state.emails.find(e => e.id === emailId);
      const effectiveAccountId = accountId || email?.accountId || 'default';
      const folder = email?.folder || state.currentFolder;
      
      // Extract normalized folder
      const { normalizedFolder } = normalizeFolderAndAccount(folder, effectiveAccountId);
      
      logEmailOp('MARK_READ', `Marking email ${emailId} as ${isRead ? 'read' : 'unread'} in ${normalizedFolder}`);
      
      // Update UI state immediately (optimistic update)
      dispatch({
        type: 'MARK_EMAIL_AS_READ',
        payload: { emailId, isRead, accountId: effectiveAccountId }
      });
      
      // NOTE: Don't update unread counts here - that's now handled by the updateUnreadCounts function
      // which is triggered by the email update above via the useEffect
      
      // Make API call to update on server
      const response = await fetch(`/api/courrier/${emailId}/mark-read`, {
        method: 'POST',
        headers: { 'Content-Type': 'application/json' },
        body: JSON.stringify({
          isRead,
          folder: normalizedFolder,
          accountId: effectiveAccountId
        })
      });
      
      if (!response.ok) {
        throw new Error('Failed to mark email as read');
      }
      
      return true;
    } catch (error) {
      logEmailOp('ERROR', `Failed to mark email as read: ${error instanceof Error ? error.message : String(error)}`);
      toast({
        variant: "destructive",
        title: "Error",
        description: 'Failed to update email read status'
      });
      return false;
    }
  }, [state.emails, state.currentFolder, toast, logEmailOp]);

  // Toggle starred status
  const toggleStarred = useCallback(async (emailId: string) => {
    try {
      // Find the email in current list
      const email = state.emails.find(e => e.id === emailId);
      if (!email) {
        throw new Error('Email not found');
      }
      
      const newFlaggedStatus = !email.flags.flagged;
      logEmailOp('TOGGLE_STAR', `Setting starred status to ${newFlaggedStatus} for email ${emailId}`);
      
      // TODO: Implement optimistic update
      
      // Make API call
      const response = await fetch(`/api/courrier/${emailId}/flag`, {
        method: 'POST',
        headers: { 'Content-Type': 'application/json' },
        body: JSON.stringify({
          flagged: newFlaggedStatus,
          folder: email.folder,
          accountId: email.accountId
        })
      });
      
      if (!response.ok) {
        throw new Error('Failed to update star status');
      }
      
      // Reload emails to get updated state
      loadEmails(state.page, state.perPage, true);
      
      return true;
    } catch (error) {
      logEmailOp('ERROR', `Failed to toggle star: ${error instanceof Error ? error.message : String(error)}`);
      toast({
        variant: "destructive",
        title: "Error",
        description: 'Failed to update star status'
      });
      return false;
    }
  }, [state.emails, toast, loadEmails, logEmailOp]);

  // Function to check for new emails without disrupting the user
  const checkForNewEmails = useCallback(async () => {
    if (!session?.user?.id) return;
    
    // Don't check if already loading emails
    if (state.isLoading) return;
    
    try {
      // Get normalized parameters using helper function
      const accountId = state.selectedAccount ? state.selectedAccount.id : undefined;
      const { normalizedFolder, effectiveAccountId, prefixedFolder } = 
        normalizeFolderAndAccount(state.currentFolder, accountId);
      
      logEmailOp('CHECK_NEW_EMAILS', `Checking for new emails in ${prefixedFolder}`);
      
      // Quietly check for new emails with a special parameter
      const queryParams = new URLSearchParams({
        folder: normalizedFolder,
        page: '1',
        perPage: '1', // We only need to check the newest email
        accountId: effectiveAccountId,
        checkOnly: 'true' // Special parameter to indicate this is just a check
      });
      
      const response = await fetch(`/api/courrier/emails?${queryParams.toString()}`, {
        method: 'GET',
        headers: { 'Content-Type': 'application/json' },
        cache: 'no-cache'
      });
      
      if (!response.ok) {
        throw new Error(`Failed to check for new emails: ${response.status}`);
      }
      
      const data = await response.json();
      
      // Store the latest email's ID for easier reference
      const lastKnownEmailId = state.emails.length > 0 ? parseInt(state.emails[0].id) : 0;
      
      // Use newestEmailId from API response (more reliable than checking emails array)
      if (data.newestEmailId && data.newestEmailId > lastKnownEmailId) {
        logEmailOp('NEW_EMAILS', `Found new emails, newest ID: ${data.newestEmailId} (current: ${lastKnownEmailId})`);
        
        // Show a toast notification with the new custom variant
        toast({
          variant: "new-email", // Use our new custom variant
          title: "New emails",
          description: "You have new emails in your inbox",
          duration: 5000
        });
        
        // Full refresh just like the refresh button in sidebar
        // Reset to page 1 to ensure we get the newest emails
        dispatch({ type: 'SET_PAGE', payload: 1 });
        loadEmails(1, state.perPage, false);
        
        // Also update unread counts - this will be handled in the effect
        // The fetchUnreadCounts function will be available when this callback is called
      } else {
        logEmailOp('CHECK_NEW_EMAILS', 'No new emails found');
      }
    } catch (error) {
      console.error('Error checking for new emails:', error);
    }
  }, [session?.user?.id, state.currentFolder, state.isLoading, state.emails, state.perPage, toast, loadEmails, logEmailOp, dispatch]);

  // Delete emails
  const deleteEmails = useCallback(async (emailIds: string[]) => {
    if (emailIds.length === 0) return;
    
    dispatch({ type: 'SET_LOADING', payload: true });
    
    try {
      logEmailOp('DELETE', `Deleting ${emailIds.length} emails`);
      
      // Find the first email to get account ID and folder
      const firstEmail = state.emails.find(e => e.id === emailIds[0]);
      const accountId = firstEmail?.accountId || 'default';
      const folder = firstEmail?.folder || state.currentFolder;
      const { normalizedFolder } = normalizeFolderAndAccount(folder, accountId);
      
      // Make API call to delete emails
      const response = await fetch('/api/courrier/delete', {
        method: 'POST',
        headers: { 'Content-Type': 'application/json' },
        body: JSON.stringify({
          emailIds,
          folder: normalizedFolder,
          accountId
        })
      });
      
      if (!response.ok) {
        throw new Error('Failed to delete emails');
      }
      
      // Clear selections
      dispatch({ type: 'CLEAR_SELECTED_EMAILS' });
      
      // Show toast notification
      toast({
        title: "Emails Deleted",
        description: `${emailIds.length} email(s) moved to trash`
      });
      
      // Full refresh just like the refresh button in sidebar
      // Reset to page 1 to ensure we get the updated email list
      dispatch({ type: 'SET_PAGE', payload: 1 });
      loadEmails(1, state.perPage, false);
      
      // Also update unread counts - this will be handled in the effect
      // The fetchUnreadCounts function will be available when this callback is called
      
      return true;
    } catch (error) {
      logEmailOp('ERROR', `Failed to delete emails: ${error instanceof Error ? error.message : String(error)}`);
      toast({
        variant: "destructive",
        title: "Error",
        description: 'Failed to delete emails'
      });
      return false;
    } finally {
      dispatch({ type: 'SET_LOADING', payload: false });
    }
  }, [state.emails, state.currentFolder, state.perPage, toast, loadEmails, logEmailOp, dispatch]);

  // Send email
  const sendEmail = useCallback(async (emailData: EmailData) => {
    dispatch({ type: 'SET_LOADING', payload: true });
    
    try {
      logEmailOp('SEND', `Sending email to ${emailData.to}`);
      
      // Make API call to send email
      const response = await fetch('/api/courrier/send', {
        method: 'POST',
        headers: { 'Content-Type': 'application/json' },
        body: JSON.stringify(emailData)
      });
      
      if (!response.ok) {
        const errorData = await response.json();
        throw new Error(errorData.error || 'Failed to send email');
      }
      
      const result = await response.json();
      
      toast({
        title: "Email Sent",
        description: "Your message has been sent successfully"
      });
      
      // Wait a moment for the email to be available in the sent folder
      // (emails may need time to be stored on IMAP server)
      setTimeout(() => {
        // Check for new emails and refresh mailbox
        checkForNewEmails();
        
        // Refresh emails to show the sent email in current view
        loadEmails(state.page, state.perPage, false);
      }, 1500);
      
      return { success: true, ...result };
    } catch (error) {
      logEmailOp('ERROR', `Failed to send email: ${error instanceof Error ? error.message : String(error)}`);
      toast({
        variant: "destructive",
        title: "Error",
        description: error instanceof Error ? error.message : 'Failed to send email'
      });
      return { success: false, error: error instanceof Error ? error.message : 'Failed to send email' };
    } finally {
      dispatch({ type: 'SET_LOADING', payload: false });
    }
  }, [toast, loadEmails, logEmailOp, checkForNewEmails]);
  
  // Search emails
  const searchEmails = useCallback(async (query: string) => {
    // Set loading state
    dispatch({ type: 'SET_LOADING', payload: true });
    
    try {
      if (!session?.user?.id) return;
      
      logEmailOp('SEARCH', `Searching for "${query}" in ${state.currentFolder}`);
      
      // Extract account ID from current folder
      const { normalizedFolder, effectiveAccountId } = normalizeFolderAndAccount(state.currentFolder);
      
      // Construct query params for search
      const queryParams = new URLSearchParams({
        folder: normalizedFolder,
        search: query,
        accountId: effectiveAccountId
      });
      
      // Call API for search
      const response = await fetch(`/api/courrier/search?${queryParams.toString()}`);
      
      if (!response.ok) {
        const errorData = await response.json();
        throw new Error(errorData.error || 'Failed to search emails');
      }
      
      const results = await response.json();
      
      // Update emails with search results
      dispatch({ type: 'SET_EMAILS', payload: results.emails || [] });
      
      if (results.totalEmails) {
        dispatch({ type: 'SET_TOTAL_EMAILS', payload: results.totalEmails });
      }
      
      if (results.totalPages) {
        dispatch({ type: 'SET_TOTAL_PAGES', payload: results.totalPages });
      }
    } catch (error) {
      logEmailOp('ERROR', `Search failed: ${error instanceof Error ? error.message : String(error)}`);
      dispatch({ 
        type: 'SET_ERROR', 
        payload: error instanceof Error ? error.message : 'Failed to search emails' 
      });
      toast({
        variant: "destructive",
        title: "Error",
        description: 'Failed to search emails'
      });
    } finally {
      dispatch({ type: 'SET_LOADING', payload: false });
    }
  }, [session?.user?.id, state.currentFolder, toast, logEmailOp]);
  
  // Format email for reply, reply all, or forward
  const formatEmailForAction = useCallback((email: any, type: 'reply' | 'reply-all' | 'forward') => {
    return formatEmailForReplyOrForward(email, type);
  }, []);

  // Update page
  const setPage = useCallback((page: number) => {
    dispatch({ type: 'SET_PAGE', payload: page });
  }, []);

  // Set emails directly
  const setEmails = useCallback((emails: Email[]) => {
    dispatch({ type: 'SET_EMAILS', payload: emails });
  }, []);

  // Handle loading more emails
  const handleLoadMore = useCallback(() => {
    // Don't load more if already loading or if there are no more pages
    if (state.isLoading || state.page >= state.totalPages) {
      console.log(`[LOAD_MORE] Skipping load more - already loading: ${state.isLoading}, page: ${state.page}, totalPages: ${state.totalPages}`);
      return;
    }
    
    // Log the current state
    console.log(`[LOAD_MORE] Loading more emails for ${state.currentFolder}, currentPage: ${state.page}, totalPages: ${state.totalPages}, current email count: ${state.emails.length}`);
    
    // Set loading state immediately to prevent double-loading
    dispatch({
      type: 'SET_LOADING',
      payload: true
    });
    
    // Calculate next page
    const nextPage = state.page + 1;
    
    // Update the page state - fix type issue
    dispatch({
      type: 'SET_PAGE',
      payload: nextPage
    });
    
    // CRITICAL FIX: Update the lastLoadedPage ref to track pagination state
    lastPageLoadedRef.current = nextPage;
    
    // Load the next page
    loadEmails(nextPage, state.perPage, true).then(() => {
      console.log(`[LOAD_MORE] Completed loading more emails for page ${nextPage}`);
    });
  }, [state.isLoading, state.page, state.totalPages, state.currentFolder, state.emails.length, state.perPage, dispatch, loadEmails]);

  // Effect to load emails when folder changes
  useEffect(() => {
    if (session?.user?.id && state.currentFolder) {
      // CRITICAL FIX: REMOVE this check that's causing the problem
      // Instead, detect a real folder change and always load when that happens
      
      // Extract account ID for consistent loading
      const { effectiveAccountId } = normalizeFolderAndAccount(state.currentFolder);
      
      // Track if the folder actually changed
      const folderChanged = prevFolderRef.current !== state.currentFolder;
      
      if (folderChanged) {
        console.log(`[DEBUG-FOLDER_EFFECT] Folder changed from ${prevFolderRef.current} to ${state.currentFolder}`);
        prevFolderRef.current = state.currentFolder;
        
        // CRITICAL FIX: Always reset pagination state when folder actually changes
        console.log(`[DEBUG-FOLDER_EFFECT] Folder changed - resetting pagination state`);
        
        // Reset page to 1 AND reset lastPageLoadedRef to ensure we load
        lastPageLoadedRef.current = 0;
        
        if (state.page !== 1) {
          console.log(`[DEBUG-FOLDER_EFFECT] Resetting page to 1 because folder changed`);
          dispatch({ type: 'SET_PAGE', payload: 1 });
        }
        
        // CRITICAL FIX: Clear emails and set loading when folder changes
        dispatch({ type: 'SET_EMAILS', payload: [] });
        dispatch({ type: 'SET_LOADING', payload: true });
        
        // CRITICAL FIX: Always load emails when folder changes, no matter what
        console.log(`[DEBUG-FOLDER_EFFECT] Loading emails for new folder: ${state.currentFolder}`);
        loadEmails(1, state.perPage, false);
        return; // Exit early after handling folder change
      }
      
      // If no folder change detected, only load if on page 1 and not already loaded
      if (state.page === 1 && lastPageLoadedRef.current === 0) {
        logEmailOp('FOLDER_LOAD', `Loading initial emails for folder ${state.currentFolder}`);
        loadEmails(state.page, state.perPage, false);
      }
    }
  }, [session?.user?.id, state.currentFolder, state.page, state.perPage, loadEmails, logEmailOp, dispatch]);

  // Effect to load more emails when page changes
  useEffect(() => {
    if (!session?.user?.id || !state.currentFolder) return;
    
    // Make sure we're on at least page 1
    if (state.page < 1) {
      dispatch({ type: 'SET_PAGE', payload: 1 });
      return;
    }
    
    console.log(`[DEBUG-PAGE_EFFECT] Page changed to ${state.page}`);
    
    // CRITICAL FIX: Add a special case for page 1 loads - we should never skip loading the first page
    // This ensures that after a folder change, page 1 always loads even if loading state is true
    if (state.page === 1) {
      const currentFolder = state.currentFolder;
      const lastLoadedFolder = prevFolderRef.current;
      
      // Check if this is a fresh folder load (folder changed or first time loading)
      if (currentFolder !== lastLoadedFolder || lastPageLoadedRef.current === 0) {
        // Force loading page 1 for new folders, regardless of loading state
        console.log(`[DEBUG-PAGE_EFFECT] Force loading page 1 for folder: ${currentFolder}`);
        
        // Set the loading state explicitly (might already be true)
        dispatch({ type: 'SET_LOADING', payload: true });
        
        // Update refs to track the current state
        prevFolderRef.current = currentFolder;
        lastPageLoadedRef.current = 1;
        
        // Call loadEmails to load the first page - never skip this!
        loadEmails(1, state.perPage, false);
        return;
      }
    }
    
    // For pages > 1 or already loaded folders, follow normal rules
    
    // Skip if already loading
    if (state.isLoading) {
      console.log(`[DEBUG-PAGE_EFFECT] Skipping effect execution entirely - already loading`);
      return;
    }
    
    // Normalize folder and get account ID
    const { effectiveAccountId } = normalizeFolderAndAccount(state.currentFolder);
    
    // Check if this is a duplicate page load
    if (state.page === lastPageLoadedRef.current) {
      console.log(`[DEBUG-PAGE_EFFECT] Skipping - already loaded page ${state.page}`);
      return;
    }
    
    // Skip loads for zero-based pages
    if (state.page === 0) {
      console.log(`[DEBUG-PAGE_EFFECT] Skipping load for invalid page ${state.page}`);
      return;
    }
    
    // Update our reference to prevent duplicate loads
    lastPageLoadedRef.current = state.page;
    
    // Always use isLoadMore=true when page > 1
    console.log(`[DEBUG-PAGE_EFFECT] Calling loadEmails with isLoadMore=true for page ${state.page}`);
    loadEmails(state.page, state.perPage, true);
    
  // Do NOT include state.emails.length here to prevent infinite loops
  }, [session?.user?.id, state.page, state.currentFolder, state.isLoading, state.perPage, loadEmails, logEmailOp, dispatch]);

  // Fetch unread counts from API
  const fetchUnreadCounts = useCallback(async () => {
    if (!session?.user) return;
    
    // Don't fetch if we're already fetching
    if (state.isLoadingUnreadCounts) return;
    
    // Skip fetching if an email was viewed recently (within last 5 seconds)
    const now = Date.now();
    // Initialize the ref to the current time if it's null
    if (lastEmailViewedRef.current === null) {
      lastEmailViewedRef.current = now;
    }
    
    // Now we can safely use it since we've initialized it
    if (now - lastEmailViewedRef.current < 5000) {
      console.log('Skipping unread count update - email viewed recently');
      return;
    }
    
    // Try to get from sessionStorage first for faster response
    try {
      const storageKey = `unread_counts_${session.user.id}`;
      const storedData = sessionStorage.getItem(storageKey);
      
      if (storedData) {
        const { data, timestamp } = JSON.parse(storedData);
        // Use stored data if it's less than 30 seconds old
        if (now - timestamp < 30000) {
          logEmailOp('FETCH_UNREAD', 'Using sessionStorage data', { age: Math.round((now - timestamp)/1000) + 's' });
          dispatch({ type: 'SET_UNREAD_COUNTS', payload: data });
          return;
        }
      }
    } catch (err) {
      // Ignore storage errors
    }
    
    // Reset failure tracking if it's been more than 1 minute since last failure
    if ((window as any).__unreadCountFailures?.lastFailureTime && 
        now - (window as any).__unreadCountFailures.lastFailureTime > 60000) {
      (window as any).__unreadCountFailures = { count: 0, lastFailureTime: 0 };
    }
    
    // Exponential backoff for failures with proper tracking object
    if (!(window as any).__unreadCountFailures) {
      (window as any).__unreadCountFailures = { count: 0, lastFailureTime: 0 };
    }
    
    if ((window as any).__unreadCountFailures.count > 0) {
      const failures = (window as any).__unreadCountFailures.count;
      const backoffMs = Math.min(30000, 1000 * Math.pow(2, failures - 1));
      if (now - (window as any).__unreadCountFailures.lastFailureTime < backoffMs) {
        logEmailOp('BACKOFF', `Skipping unread fetch, in backoff period (${backoffMs}ms)`);
        return;
      }
    }
    
    try {
      dispatch({ type: 'SET_LOADING_UNREAD_COUNTS', payload: true });
      
      const timeBeforeCall = performance.now();
      logEmailOp('FETCH_UNREAD', 'Fetching unread counts from API');
      
      const response = await fetch('/api/courrier/unread-counts', {
        method: 'GET',
        headers: { 'Content-Type': 'application/json' },
        // Add cache control headers
        cache: 'no-cache',
        next: { revalidate: 0 }
      });
      
      if (!response.ok) {
        // If request failed, track failures properly
        (window as any).__unreadCountFailures.count = 
          Math.min((window as any).__unreadCountFailures.count + 1, 10);
        (window as any).__unreadCountFailures.lastFailureTime = now;
        
        const failures = (window as any).__unreadCountFailures.count;
        
        if (failures > 3) {
          // After 3 failures, slow down requests with exponential backoff
          const backoffTime = Math.min(Math.pow(2, failures - 3) * 1000, 30000); // Max 30 seconds
          logEmailOp('FETCH_UNREAD', `API failure #${failures}, backing off for ${backoffTime}ms`);
          
          // Schedule next attempt with backoff
          if ((window as any).__failureBackoffTimer) {
            clearTimeout((window as any).__failureBackoffTimer);
          }
          
          (window as any).__failureBackoffTimer = setTimeout(() => {
            fetchUnreadCounts();
          }, backoffTime);
          
          throw new Error(`Failed to fetch unread counts: ${response.status}`);
        }
      } else {
        // Reset failure counter on success
        (window as any).__unreadCountFailures = { count: 0, lastFailureTime: 0 };
        
        const data = await response.json();
        const timeAfterCall = performance.now();
        
        // Skip if we got the "pending_refresh" status
        if (data._status === 'pending_refresh') {
          logEmailOp('FETCH_UNREAD', 'Server is refreshing counts, will try again soon');
          
          // Retry after a short delay
          setTimeout(() => {
            fetchUnreadCounts();
          }, 2000);
          
          return;
        }
        
        logEmailOp('FETCH_UNREAD', `Received unread counts in ${(timeAfterCall - timeBeforeCall).toFixed(2)}ms`);
        
        if (data && typeof data === 'object') {
          dispatch({ type: 'SET_UNREAD_COUNTS', payload: data });
          
          // Store in sessionStorage for faster future access
          try {
            sessionStorage.setItem(
              `unread_counts_${session.user.id}`, 
              JSON.stringify({
                data,
                timestamp: now
              })
            );
          } catch (err) {
            // Ignore storage errors
          }
        }
      }
    } catch (error) {
      console.error('Error fetching unread counts:', error);
    } finally {
      dispatch({ type: 'SET_LOADING_UNREAD_COUNTS', payload: false });
    }
  }, [dispatch, session?.user, state.isLoadingUnreadCounts, logEmailOp]);

  // Calculate and update unread counts
  const updateUnreadCounts = useCallback(() => {
    // Skip if no emails or accounts
    if (state.emails.length === 0 || state.accounts.length === 0) return;
    
    // To avoid running this too frequently, check the timestamp of last update
    if (!(window as any).__lastUnreadUpdate) {
      (window as any).__lastUnreadUpdate = { timestamp: 0 };
    }
    
    const now = Date.now();
    const lastUpdate = (window as any).__lastUnreadUpdate;
    const MIN_UPDATE_INTERVAL = 10000; // 10 seconds minimum between updates (increased from 2s)
    
    if (now - lastUpdate.timestamp < MIN_UPDATE_INTERVAL) {
      return; // Skip if updated too recently
    }
    
    // Rather than calculating locally, fetch from the API
    fetchUnreadCounts();
    
    // Update timestamp of last update
    lastUpdate.timestamp = now;
  }, [state.emails.length, state.accounts.length, fetchUnreadCounts]);
  
  // Call updateUnreadCounts when relevant state changes
  useEffect(() => {
    if (!state.emails || state.emails.length === 0) return;
    
    // Debounce unread count updates to prevent rapid multiple updates
    let updateTimeoutId: ReturnType<typeof setTimeout>;
    
    const debounceMs = 5000; // Increase debounce to 5 seconds (from 2s)
    
    // Function to call after debounce period
    const debouncedUpdate = () => {
      updateTimeoutId = setTimeout(() => {
        updateUnreadCounts();
      }, debounceMs);
    };
    
    // Clear any existing timeout and start a new one
    debouncedUpdate();
    
    // Also set up a periodic refresh every minute if the tab is active
    const periodicRefreshId = setInterval(() => {
      if (document.visibilityState === 'visible') {
        updateUnreadCounts();
      }
    }, 60000); // 1 minute
    
    // Cleanup timeout on unmount or state change
    return () => {
      clearTimeout(updateTimeoutId);
      clearInterval(periodicRefreshId);
    };
  // Deliberately exclude unreadCountMap to prevent infinite loops
  }, [state.emails, updateUnreadCounts]);

  // Set up periodic check for new emails
  useEffect(() => {
    if (!state.emails || state.emails.length === 0) return;
    
    // Set up a periodic check for new emails at the same interval as unread counts
    const checkNewEmailsId = setInterval(() => {
      if (document.visibilityState === 'visible') {
        checkForNewEmails();
      }
    }, 60000); // 1 minute - same as unread count refresh
    
    // Cleanup interval on unmount or state change
    return () => {
      clearInterval(checkNewEmailsId);
    };
  }, [state.emails, checkForNewEmails]);

  // Tracking when an email is viewed to optimize unread count refreshes
  const lastViewedEmailRef = useRef<number | null>(null);
  const fetchFailuresRef = useRef<number>(0);
  const lastFetchFailureRef = useRef<number | null>(null);

  // Modify viewEmail to track when an email is viewed
  const viewEmail = useCallback((emailId: string, accountId: string, folder: string, email: Email | null) => {
    dispatch({ 
      type: 'SELECT_EMAIL', 
      payload: { emailId, accountId, folder, email } 
    });
    
    // Track when an email is viewed to delay unread count refresh
    if (email) {
      lastViewedEmailRef.current = Date.now();
      
      // If email is unread, mark it as read
      if (email.flags && !email.flags.seen) {
        dispatch({
          type: 'MARK_EMAIL_AS_READ',
          payload: { emailId, isRead: true, accountId }
        });
      }
    } else {
      // Email was deselected, schedule a refresh of unread counts after delay
      setTimeout(() => {
        fetchUnreadCounts();
      }, 2000);
    }
  }, [dispatch, fetchUnreadCounts]);

  // Set up a function to manually trigger checking for new emails
  const forceCheckForNewEmails = useCallback(() => {
    // Don't check if we're already loading
    if (state.isLoading) return;
    
    // Log that we're manually checking
    logEmailOp('MANUAL_CHECK', 'Manually checking for new emails');
    
    // Reset to page 1 to ensure we get the newest emails
    dispatch({ type: 'SET_PAGE', payload: 1 });
    
    // Perform a complete refresh of emails
    loadEmails(1, state.perPage, false);
    
    // Also update unread counts
    fetchUnreadCounts();
  }, [state.isLoading, state.perPage, loadEmails, logEmailOp, dispatch, fetchUnreadCounts]);

  // Return all state values and actions
  return {
    // State values
    ...state,
    
    // Actions
    loadEmails,
    handleEmailSelect,
    toggleEmailSelection,
    toggleSelectAll,
    markEmailAsRead,
    toggleStarred,
    changeFolder,
    deleteEmails,
    sendEmail,
    searchEmails,
    formatEmailForAction,
    setPage,
    setEmails,
    selectAccount,
    handleLoadMore,
    fetchUnreadCounts,
    viewEmail,
    checkForNewEmails,
    forceCheckForNewEmails
  };
};