'use client';

import React, { useState, useEffect } from 'react';
import { useRouter } from 'next/navigation';
import { useSession } from 'next-auth/react';
import { 
  Mail, Loader2, AlertCircle, 
  MoreVertical, Settings, Plus as PlusIcon, Trash2, Edit, 
  Inbox, Send, Star, Trash, Plus, ChevronLeft, ChevronRight, 
  Search, ChevronDown, Folder, ChevronUp, Reply, Forward, ReplyAll, 
  MoreHorizontal, FolderOpen, X, Paperclip, MessageSquare, Copy, EyeOff, 
  AlertOctagon, Archive, RefreshCw
} from 'lucide-react';
import { Dialog, DialogContent } from '@/components/ui/dialog';
import { Alert, AlertDescription, AlertTitle } from '@/components/ui/alert';
import {
  AlertDialog,
  AlertDialogAction,
  AlertDialogCancel,
  AlertDialogContent,
  AlertDialogDescription,
  AlertDialogFooter,
  AlertDialogHeader,
  AlertDialogTitle,
} from "@/components/ui/alert-dialog";
import { ScrollArea } from '@/components/ui/scroll-area';
import { Avatar, AvatarFallback } from '@/components/ui/avatar';
import { Button } from '@/components/ui/button';

// Import components
import EmailSidebar from '@/components/email/EmailSidebar';
import EmailList from '@/components/email/EmailList';
import EmailSidebarContent from '@/components/email/EmailSidebarContent';
import EmailDetailView from '@/components/email/EmailDetailView';
import ComposeEmail from '@/components/email/ComposeEmail';
import { DeleteConfirmDialog, LoginNeededAlert } from '@/components/email/EmailDialogs';

// Import the custom hook
import { useCourrier, EmailData } from '@/hooks/use-courrier';

// Import the prefetching function
import { prefetchFolderEmails } from '@/lib/services/prefetch-service';

// Import the RedisCacheStatus component
import { RedisCacheStatus } from '@/components/debug/RedisCacheStatus';

// Simplified version for this component
function SimplifiedLoadingFix() {
  // In production, don't render anything
  if (process.env.NODE_ENV === 'production') {
    return null;
  }
  
  // Simple debugging component
  return (
    <div className="fixed bottom-4 right-4 z-50 p-2 bg-white/80 shadow rounded-lg text-xs">
      Debug: Email app loaded
    </div>
  );
}

interface Account {
  id: number;
  name: string;
  email: string;
  color: string;
  folders?: string[];
}

export default function CourrierPage() {
  const router = useRouter();
  const { data: session } = useSession();
  
  // Get all the email functionality from the hook
  const {
    emails = [],
    selectedEmail,
    selectedEmailIds,
    currentFolder,
    mailboxes,
    isLoading,
    isSending,
    error,
    searchQuery,
    page,
    totalPages,
    loadEmails,
    handleEmailSelect,
    markEmailAsRead,
    toggleStarred,
    sendEmail,
    deleteEmails,
    toggleEmailSelection,
    toggleSelectAll,
    changeFolder,
    searchEmails,
    formatEmailForAction,
    setPage,
  } = useCourrier();

  // UI state
  const [showComposeModal, setShowComposeModal] = useState(false);
  const [composeType, setComposeType] = useState<'new' | 'reply' | 'reply-all' | 'forward'>('new');
  const [showDeleteConfirm, setShowDeleteConfirm] = useState(false);
  const [showLoginNeeded, setShowLoginNeeded] = useState(false);
  const [sidebarOpen, setSidebarOpen] = useState(true);
  const [mobileSidebarOpen, setMobileSidebarOpen] = useState(false);
  const [accountsDropdownOpen, setAccountsDropdownOpen] = useState(true);
  const [currentView, setCurrentView] = useState('INBOX');
  const [unreadCount, setUnreadCount] = useState(0);
  const [loading, setLoading] = useState(false);
  const [prefetchStarted, setPrefetchStarted] = useState(false);
  const [showFolders, setShowFolders] = useState(true);
  
  // Mock accounts for the sidebar
  const [accounts, setAccounts] = useState<Account[]>([
    { id: 0, name: 'All', email: '', color: 'bg-gray-500' },
    { id: 1, name: 'Mail', email: 'user@example.com', color: 'bg-blue-500', folders: mailboxes }
  ]);
  const [selectedAccount, setSelectedAccount] = useState<Account | null>(null);
  
  // Update account folders when mailboxes change
  useEffect(() => {
    setAccounts(prev => {
      const updated = [...prev];
      if (updated[1]) {
        updated[1].folders = mailboxes;
      }
      return updated;
    });
  }, [mailboxes]);
  
  // Calculate unread count (this would be replaced with actual data in production)
  useEffect(() => {
    // Example: counting unread emails in the inbox
    const unreadInInbox = (emails || []).filter(email => !email.read && currentFolder === 'INBOX').length;
    setUnreadCount(unreadInInbox);
  }, [emails, currentFolder]);
  
  // Initialize session and start prefetching
  useEffect(() => {
    // Flag to prevent multiple initialization attempts
    let isMounted = true;
    let initAttempted = false;
    
    const initSession = async () => {
      if (initAttempted) return;
      initAttempted = true;
      
      try {
        setLoading(true);
        
        // First check if Redis is ready before making API calls
        const redisStatus = await fetch('/api/redis/status')
          .then(res => res.json())
          .catch(() => ({ ready: false }));
        
        if (!isMounted) return;
        
        // Call the session API to check email credentials and start prefetching
        const response = await fetch('/api/courrier/session');
        const data = await response.json();
        
        if (!isMounted) return;
        
        if (data.authenticated) {
          if (data.hasEmailCredentials) {
            console.log('Session initialized, prefetch status:', data.prefetchStarted ? 'running' : 'not started');
            setPrefetchStarted(Boolean(data.prefetchStarted));
            
            // Preload first page of emails for faster initial rendering
            if (session?.user?.id) {
              await loadEmails();
              
              // If the user hasn't opened this page recently, trigger a background refresh
              if (data.lastVisit && Date.now() - data.lastVisit > 5 * 60 * 1000) {
                // It's been more than 5 minutes, refresh in background
                try {
                  const refreshResponse = await fetch('/api/courrier/refresh', { 
                    method: 'POST',
                    headers: { 'Content-Type': 'application/json' },
                    body: JSON.stringify({ folder: currentFolder })
                  });
                  console.log('Background refresh triggered');
                } catch (error) {
                  console.error('Failed to trigger background refresh', error);
                }
              }
            }
          } else {
            // User is authenticated but doesn't have email credentials
            setShowLoginNeeded(true);
          }
        }
      } catch (error) {
        console.error('Error initializing session:', error);
      } finally {
        if (isMounted) {
          setLoading(false);
        }
      }
    };
    
    if (session?.user?.id) {
      initSession();
    }
    
    return () => {
      isMounted = false;
    };
  }, [session?.user?.id, loadEmails, currentFolder]);
  
  // Helper to get folder icons
  const getFolderIcon = (folder: string) => {
    const folderLower = folder.toLowerCase();
    
    if (folderLower.includes('inbox')) {
      return Inbox;
    } else if (folderLower.includes('sent')) {
      return Send;
    } else if (folderLower.includes('trash')) {
      return Trash;
    } else if (folderLower.includes('archive')) {
      return Archive;
    } else if (folderLower.includes('draft')) {
      return Edit;
    } else if (folderLower.includes('spam') || folderLower.includes('junk')) {
      return AlertOctagon;
    } else {
      return Folder;
    }
  };
  
  // Helper to format folder names
  const formatFolderName = (folder: string) => {
    return folder.charAt(0).toUpperCase() + folder.slice(1).toLowerCase();
  };
  
  // Check for more emails
  const hasMoreEmails = page < totalPages;

  // Handle loading more emails on scroll
  const handleLoadMore = () => {
    if (hasMoreEmails && !isLoading) {
      // Increment the page
      const nextPage = page + 1;
      setPage(nextPage);
      
      console.log(`Requesting page ${nextPage} for folder ${currentFolder}`);
      
      // Immediately trigger a load for this page rather than relying on the useEffect
      // This helps ensure we get the data faster
      loadEmails(true).catch(error => {
        console.error(`Error loading page ${nextPage}:`, error);
      });
      
      // Also prefetch additional pages to make scrolling smoother
      if (session?.user?.id) {
        // Prefetch next page beyond the one we're loading
        const pagesToPrefetch = 2; // Prefetch 2 pages ahead
        
        // Small delay to let the current request start first
        setTimeout(() => {
          console.log(`Prefetching pages ${nextPage + 1} to ${nextPage + pagesToPrefetch}`);
          prefetchFolderEmails(session.user.id, currentFolder, pagesToPrefetch, nextPage + 1)
            .catch(err => {
              console.error(`Error prefetching additional pages for ${currentFolder}:`, err);
            });
        }, 200);
      }
    }
  };

  // Handle bulk actions
  const handleBulkAction = async (action: 'delete' | 'mark-read' | 'mark-unread' | 'archive') => {
    if (selectedEmailIds.length === 0) return;
    
    switch (action) {
      case 'delete':
        setShowDeleteConfirm(true);
        break;
        
      case 'mark-read':
        // Mark all selected emails as read
        for (const emailId of selectedEmailIds) {
          await markEmailAsRead(emailId, true);
        }
        break;
        
      case 'mark-unread':
        // Mark all selected emails as unread
        for (const emailId of selectedEmailIds) {
          await markEmailAsRead(emailId, false);
        }
        break;
        
      case 'archive':
        // Archive functionality would be implemented here
        break;
    }
  };

  // Handle email actions
  const handleReply = () => {
    if (!selectedEmail) return;
    setComposeType('reply');
    setShowComposeModal(true);
  };
  
  const handleReplyAll = () => {
    if (!selectedEmail) return;
    setComposeType('reply-all');
    setShowComposeModal(true);
  };
  
  const handleForward = () => {
    if (!selectedEmail) return;
    setComposeType('forward');
    setShowComposeModal(true);
  };
  
  const handleComposeNew = () => {
    setComposeType('new');
    setShowComposeModal(true);
  };
  
  // Handle mailbox change with prefetching
  const handleMailboxChange = (folder: string) => {
    // Reset to page 1 when changing folders
    setPage(1);
    
    // Change folder in the state
    changeFolder(folder);
    setCurrentView(folder);
    
    // Start prefetching additional pages for this folder
    if (session?.user?.id && folder) {
      // First two pages are most important - prefetch immediately
      prefetchFolderEmails(session.user.id, folder, 3).catch(err => {
        console.error(`Error prefetching ${folder}:`, err);
      });
    }
  };

  // Handle sending email
  const handleSendEmail = async (emailData: EmailData) => {
    return await sendEmail(emailData);
  };

  // Handle delete confirmation
  const handleDeleteConfirm = async () => {
    await deleteEmails(selectedEmailIds);
    setShowDeleteConfirm(false);
  };
  
  // Check login on mount
  useEffect(() => {
    // Check if the user is logged in after a short delay
    const timer = setTimeout(() => {
      if (error?.includes('Not authenticated') || error?.includes('No email credentials found')) {
        setShowLoginNeeded(true);
      }
    }, 2000);
    
    return () => clearTimeout(timer);
  }, [error]);

  // Go to login page
  const handleGoToLogin = () => {
    router.push('/courrier/login');
  };

  return (
    <>
      <SimplifiedLoadingFix />
      <RedisCacheStatus />
      
      {/* Main layout */}
      <main className="w-full h-screen bg-black">
        <div className="w-full h-full px-4 pt-12 pb-4">
          <div className="flex h-full bg-carnet-bg">
            {/* Sidebar */}
            <div className={`${sidebarOpen ? 'w-60' : 'w-16'} bg-white/95 backdrop-blur-sm border-r border-gray-100 flex flex-col transition-all duration-300 ease-in-out
                          ${mobileSidebarOpen ? 'fixed inset-y-0 left-0 z-40' : 'hidden'} md:block`}>
              {/* Courrier Title */}
              <div className="p-3 border-b border-gray-100">
                <div className="flex items-center gap-2">
                  <Mail className="h-6 w-6 text-gray-600" />
                  <span className="text-xl font-semibold text-gray-900">COURRIER</span>
                </div>
              </div>

              {/* Compose button and refresh button */}
              <div className="p-2 border-b border-gray-100 flex items-center gap-2">
                <Button 
                  className="flex-1 bg-blue-600 text-white rounded-lg hover:bg-blue-700 flex items-center justify-center transition-all py-1.5 text-sm"
                  onClick={handleComposeNew}
                >
                  <div className="flex items-center gap-2">
                    <PlusIcon className="h-3.5 w-3.5" />
                    <span>Compose</span>
                  </div>
                </Button>
                <Button 
                  variant="ghost" 
                  size="icon"
                  className="h-9 w-9 text-gray-400 hover:text-gray-600"
                  onClick={() => {
                    setLoading(true);
                    // Reset to page 1 when manually refreshing
                    setPage(1);
                    // Trigger a scroll reset
                    if (typeof window !== 'undefined') {
                      window.dispatchEvent(new CustomEvent('reset-email-scroll'));
                    }
                    // Load emails
                    loadEmails().finally(() => setLoading(false));
                  }}
                >
                  <RefreshCw className={`h-4 w-4 ${loading ? 'animate-spin' : ''}`} />
                </Button>
              </div>

              {/* Accounts Section */}
              <div className="p-3 border-b border-gray-100">
                <Button 
                  variant="ghost"
                  className="w-full justify-between mb-2 text-sm font-medium text-gray-500"
                  onClick={() => setAccountsDropdownOpen(!accountsDropdownOpen)}
                >
                  <span>Accounts</span>
                  {accountsDropdownOpen ? <ChevronUp className="h-4 w-4" /> : <ChevronDown className="h-4 w-4" />}
                </Button>
                
                {accountsDropdownOpen && (
                  <div className="space-y-1 pl-2">
                    {accounts.map(account => (
                      <div key={account.id} className="relative group">
                        <Button
                          variant="ghost"
                          className="w-full justify-between px-2 py-1.5 text-sm group"
                          onClick={() => {
                            if (account.id !== 0) {
                              // Only toggle folders for non-All accounts
                              setShowFolders(!showFolders);
                            }
                            setSelectedAccount(account);
                          }}
                        >
                          <div className="flex items-center gap-2">
                            <div className={`w-2.5 h-2.5 rounded-full ${account.color}`}></div>
                            <span className="font-medium text-gray-700">{account.name}</span>
                          </div>
                          {account.id !== 0 && (
                            showFolders ? 
                              <ChevronDown className="h-3.5 w-3.5 text-gray-500" /> : 
                              <ChevronRight className="h-3.5 w-3.5 text-gray-500" />
                          )}
                        </Button>
                        
                        {/* Show folders for email accounts (not for "All" account) without the "Folders" header */}
                        {account.id !== 0 && showFolders && (
                          <div className="pl-4 mt-1 mb-2 space-y-0.5 border-l border-gray-200">
                            {account.folders && account.folders.length > 0 ? (
                              account.folders.map((folder) => (
                                <Button
                                  key={folder}
                                  variant="ghost"
                                  className={`w-full justify-start py-1 px-2 text-xs ${
                                    currentView === folder ? 'bg-gray-100 text-gray-900' : 'text-gray-600 hover:text-gray-900'
                                  }`}
                                  onClick={(e) => {
                                    e.stopPropagation();
                                    handleMailboxChange(folder);
                                  }}
                                >
                                  <div className="flex items-center justify-between w-full gap-1.5">
                                    <div className="flex items-center gap-1.5">
                                      {React.createElement(getFolderIcon(folder), { className: "h-3.5 w-3.5" })}
                                      <span className="truncate">{folder}</span>
                                    </div>
                                    {folder === 'INBOX' && unreadCount > 0 && (
                                      <span className="ml-auto bg-blue-600 text-white text-xs px-1.5 py-0.5 rounded-full text-[10px]">
                                        {unreadCount}
                                      </span>
                                    )}
                                  </div>
                                </Button>
                              ))
                            ) : (
                              <div className="px-2 py-2">
                                <div className="flex flex-col space-y-2">
                                  {/* Create placeholder folder items with shimmer effect */}
                                  {Array.from({ length: 5 }).map((_, index) => (
                                    <div key={index} className="flex items-center gap-1.5 animate-pulse">
                                      <div className="h-3.5 w-3.5 bg-gray-200 rounded-sm"></div>
                                      <div className="h-3 w-24 bg-gray-200 rounded"></div>
                                    </div>
                                  ))}
                                </div>
                              </div>
                            )}
                          </div>
                        )}
                      </div>
                    ))}
                  </div>
                )}
              </div>
            </div>
            
            {/* Email List and Content View */}
            <div className="flex-1 flex overflow-hidden">
              {/* Email List */}
              <EmailList 
                emails={emails}
                selectedEmailIds={selectedEmailIds}
                selectedEmail={selectedEmail}
                currentFolder={currentFolder}
                isLoading={isLoading}
                totalEmails={emails.length}
                hasMoreEmails={hasMoreEmails}
                onSelectEmail={handleEmailSelect}
                onToggleSelect={toggleEmailSelection}
                onToggleSelectAll={toggleSelectAll}
                onBulkAction={handleBulkAction}
                onToggleStarred={toggleStarred}
                onLoadMore={handleLoadMore}
                onSearch={searchEmails}
              />
              
              {/* Email Content View */}
              <div className="flex-1 bg-white/95 backdrop-blur-sm flex flex-col">
                {selectedEmail ? (
                  <EmailDetailView
                    email={selectedEmail}
                    onBack={() => handleEmailSelect('')}
                    onReply={handleReply}
                    onReplyAll={handleReplyAll}
                    onForward={handleForward}
                    onToggleStar={() => toggleStarred(selectedEmail.id)}
                  />
                ) : (
                  <div className="flex-1 flex flex-col items-center justify-center text-center p-8">
                    <Mail className="h-12 w-12 text-gray-300 mb-4" />
                    <h3 className="text-lg font-medium text-gray-900 mb-1">Select an email to read</h3>
                    <p className="text-sm text-gray-500 max-w-sm">
                      Choose an email from the list or compose a new message to get started.
                    </p>
                    <Button
                      className="mt-6 bg-blue-600 hover:bg-blue-700"
                      onClick={handleComposeNew}
                    >
                      <PlusIcon className="mr-2 h-4 w-4" />
                      Compose New
                    </Button>
                  </div>
                )}
              </div>
            </div>
          </div>
        </div>
      </main>
      
      {/* Login needed alert */}
      <LoginNeededAlert 
        show={showLoginNeeded}
        onLogin={handleGoToLogin}
        onClose={() => setShowLoginNeeded(false)}
      />
      
      {/* Compose Modal */}
      {showComposeModal && (
        <ComposeEmail
          initialEmail={selectedEmail}
          type={composeType}
          onClose={() => setShowComposeModal(false)}
          onSend={async (emailData: EmailData) => {
            await sendEmail(emailData);
          }}
        />
      )}
      
      {/* Delete Confirmation Dialog */}
      <DeleteConfirmDialog
        show={showDeleteConfirm}
        selectedCount={selectedEmailIds.length}
        onConfirm={handleDeleteConfirm}
        onCancel={() => setShowDeleteConfirm(false)}
      />
    </>
  );
}