import { useReducer, useCallback, useEffect } 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-formatter';

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

  // 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 (isLoadMore = false, accountId?: string) => {
    if (!session?.user?.id) return;
    
    dispatch({ type: 'SET_LOADING', payload: true });
    
    try {
      // Get normalized parameters using helper function
      const { normalizedFolder, effectiveAccountId, prefixedFolder } = 
        normalizeFolderAndAccount(state.currentFolder, accountId);
      
      logEmailOp('LOAD_EMAILS', `Loading emails for ${prefixedFolder} (account: ${effectiveAccountId})`);
      
      // Construct query parameters
      const queryParams = new URLSearchParams({
        folder: normalizedFolder,
        page: state.page.toString(),
        perPage: state.perPage.toString(),
        accountId: effectiveAccountId
      });
      
      // Try to get cached emails first
      logEmailOp('CACHE_CHECK', `Checking cache for ${prefixedFolder}, page: ${state.page}`);
      const cachedEmails = await getCachedEmailsWithTimeout(
        session.user.id,
        prefixedFolder,
        state.page,
        state.perPage,
        100,
        effectiveAccountId
      );
      
      if (cachedEmails) {
        logEmailOp('CACHE_HIT', `Using cached data for ${prefixedFolder}`);
        
        // Ensure cached data has emails array property
        if (Array.isArray(cachedEmails.emails)) {
          // Dispatch appropriate action based on if we're loading more
          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 });
          }
        }
        
        // Still refresh in background for fresh data
        logEmailOp('BACKGROUND_REFRESH', `Starting background refresh for ${prefixedFolder}`);
        refreshEmailsInBackground(
          session.user.id,
          normalizedFolder,
          state.page,
          state.perPage,
          effectiveAccountId
        ).catch(err => {
          console.error('Background refresh error:', err);
        });
        
        return;
      }
      
      // Fetch emails from API if no cache hit
      logEmailOp('API_FETCH', `Fetching emails from API: ${queryParams.toString()}`);
      const response = await fetch(`/api/courrier?${queryParams.toString()}`);
      
      if (!response.ok) {
        const errorData = await response.json();
        throw new Error(errorData.error || 'Failed to fetch emails');
      }
      
      const data = await response.json();
      
      // Ensure all emails have proper account ID and folder format
      if (Array.isArray(data.emails)) {
        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}`;
          }
        });
      }
      
      // Update state with fetched data
      dispatch({ 
        type: isLoadMore ? 'APPEND_EMAILS' : 'SET_EMAILS', 
        payload: Array.isArray(data.emails) ? data.emails : [] 
      });
      
      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'
      });
    }
  }, [session?.user?.id, state.currentFolder, state.page, state.perPage, toast, logEmailOp]);

  // Change folder
  const changeFolder = useCallback(async (folder: string, accountId?: string) => {
    logEmailOp('CHANGE_FOLDER', `Changing to folder ${folder} with account ${accountId || 'default'}`);
    
    try {
      // This will handle all the state updates in a single atomic operation
      dispatch({ 
        type: 'CHANGE_FOLDER', 
        payload: { folder, accountId: accountId || 'default' } 
      });
      
      // After dispatch, the state will be updated with consistent values
      // We'll load emails in the useEffect that watches for folder changes
    } 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' 
      });
    }
  }, [logEmailOp]);

  // 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 }
      });
      
      // 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();
      
      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]);

  // 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' });
      
      // Reload emails to get updated list
      loadEmails();
      
      toast({
        title: "Emails Deleted",
        description: `${emailIds.length} email(s) moved to trash`
      });
      
      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, toast, loadEmails, logEmailOp]);

  // 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"
      });
      
      // Refresh emails to show the sent email
      loadEmails();
      
      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]);
  
  // 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(() => {
    if (state.page < state.totalPages && !state.isLoading) {
      dispatch({ type: 'INCREMENT_PAGE' });
    }
  }, [state.page, state.totalPages, state.isLoading]);

  // Effect to load emails when folder changes
  useEffect(() => {
    if (session?.user?.id && state.currentFolder) {
      // Extract account ID from folder for consistent loading
      const { effectiveAccountId } = normalizeFolderAndAccount(state.currentFolder);
      
      logEmailOp('FOLDER_CHANGE', `Loading emails for folder ${state.currentFolder} with account ${effectiveAccountId}`);
      
      // Load emails with the correct account ID
      loadEmails(false, effectiveAccountId);
    }
  }, [session?.user?.id, state.currentFolder, loadEmails, logEmailOp]);

  // Effect to load more emails when page changes
  useEffect(() => {
    if (session?.user?.id && state.page > 1) {
      // Extract account ID for consistency
      const { effectiveAccountId } = normalizeFolderAndAccount(state.currentFolder);
      
      logEmailOp('PAGINATION', `Loading page ${state.page} for ${state.currentFolder} with account ${effectiveAccountId}`);
      
      // Load more emails with the correct account ID
      loadEmails(true, effectiveAccountId);
    }
  }, [session?.user?.id, state.page, state.currentFolder, loadEmails, logEmailOp]);

  // 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
  };
};