import { NextResponse } from 'next/server';
import { getServerSession } from 'next-auth';
import { authOptions } from '@/lib/auth';
import { EmailService } from '@/lib/services/email-service';
import { prisma } from '@/lib/prisma';
import { MailCredentials } from '@prisma/client';

// Keep track of last prefetch time for each user
const lastPrefetchMap = new Map<string, number>();
const PREFETCH_COOLDOWN_MS = 30000; // 30 seconds cooldown between prefetches

// Cache TTL for folders in Redis (5 minutes)
const FOLDERS_CACHE_TTL = 3600; // 1 hour

// Redis key for folders cache
const FOLDERS_CACHE_KEY = (userId: string, accountId: string) => `email:folders:${userId}:${accountId}`;

/**
 * This endpoint is called when the app initializes to check if the user has email credentials
 * and to start prefetching email data in the background if they do
 */
export async function GET() {
  try {
    // Authentication check
    const session = await getServerSession(authOptions);
    if (!session?.user?.id) {
      return NextResponse.json({ error: 'Unauthorized' }, { status: 401 });
    }

    // Get user with their accounts
    const user = await prisma.user.findUnique({
      where: { id: session.user.id },
      include: { 
        mailCredentials: {
          select: {
            id: true,
            email: true,
            password: true,
            host: true,
            port: true,
            userId: true,
            createdAt: true,
            updatedAt: true
          }
        }
      }
    });

    if (!user) {
      return NextResponse.json({ error: 'User not found' }, { status: 404 });
    }

    const accounts = Array.isArray(user.mailCredentials) ? user.mailCredentials : [];
    if (accounts.length === 0) {
      return NextResponse.json({ 
        authenticated: true,
        accounts: [],
        message: 'No email accounts found'
      });
    }

    // Get folders for each account using EmailService
    const emailService = EmailService.getInstance();
    const accountsWithFolders = await Promise.all(
      accounts.map(async (account: MailCredentials) => {
        const folders = await emailService.getFolders(user.id, {
          ...account,
          imapHost: account.host,
          imapPort: account.port,
          imapSecure: true
        });
        return {
          ...account,
          folders
        };
      })
    );

    return NextResponse.json({
      authenticated: true,
      accounts: accountsWithFolders
    });
  } catch (error) {
    console.error('Error in session route:', error);
    return NextResponse.json(
      { error: 'Internal server error' },
      { status: 500 }
    );
  }
}