import { NextResponse } from 'next/server';
import { getServerSession } from 'next-auth';
import { authOptions } from '@/app/api/auth/[...nextauth]/route';
import { exchangeCodeForTokens } from '@/lib/services/microsoft-oauth';
import { prisma } from '@/lib/prisma';
import { testEmailConnection, saveUserEmailCredentials } from '@/lib/services/email-service';
import { invalidateFolderCache } from '@/lib/redis';
import { cacheEmailCredentials } from '@/lib/redis';

export async function POST(request: Request) {
  try {
    // Authenticate user
    const session = await getServerSession(authOptions);
    if (!session?.user?.id) {
      return NextResponse.json(
        { error: 'Unauthorized' },
        { status: 401 }
      );
    }

    // Parse request body
    const body = await request.json();
    const { code, state } = body;

    if (!code || !state) {
      return NextResponse.json(
        { error: 'Missing required parameters' },
        { status: 400 }
      );
    }

    // Validate state parameter to prevent CSRF
    try {
      const decodedState = JSON.parse(Buffer.from(state, 'base64').toString());
      
      // Check if state contains valid userId and is not expired (10 minutes)
      if (decodedState.userId !== session.user.id || 
          Date.now() - decodedState.timestamp > 10 * 60 * 1000) {
        return NextResponse.json(
          { error: 'Invalid or expired state parameter' },
          { status: 400 }
        );
      }
    } catch (e) {
      return NextResponse.json(
        { error: 'Invalid state parameter' },
        { status: 400 }
      );
    }

    // Exchange code for tokens
    const tokens = await exchangeCodeForTokens(code);

    // Extract user email from session instead of generating a fake one
    // Use the logged-in user's email or a properly formatted address
    let userEmail = '';
    if (session.user?.email) {
      // Use the user's actual email if available
      userEmail = session.user.email;
    } else {
      // Fallback to a default format - don't add @microsoft.com 
      userEmail = `unknown-user-${session.user.id}@outlook.com`;
    }
    
    console.log(`Using email: ${userEmail} for Microsoft account`);
    
    // Create credentials object for Microsoft account
    const credentials = {
      email: userEmail,
      // Password is empty for OAuth accounts - use a placeholder to meet database schema requirements
      password: 'microsoft-oauth2-account',
      // Use Microsoft's IMAP server for Outlook/Office365
      host: 'outlook.office365.com',
      port: 993,
      secure: true,
      
      // OAuth specific fields
      useOAuth: true,  // Make sure this is explicitly set
      accessToken: tokens.access_token,
      refreshToken: tokens.refresh_token,
      tokenExpiry: Date.now() + (tokens.expires_in * 1000),
      
      // Optional fields
      display_name: `Microsoft (${userEmail})`,
      color: '#0078D4',  // Microsoft blue
      
      // SMTP settings for Microsoft
      smtp_host: 'smtp.office365.com',
      smtp_port: 587,
      smtp_secure: false
    };

    // Log Microsoft authentication details
    console.log(`Microsoft OAuth credentials prepared for ${userEmail}:`, {
      useOAuth: credentials.useOAuth,
      host: credentials.host,
      hasAccessToken: !!credentials.accessToken,
      hasRefreshToken: !!credentials.refreshToken,
      tokenExpiry: new Date(credentials.tokenExpiry).toISOString()
    });

    // Test connection before saving
    console.log(`Testing Microsoft OAuth connection for user ${session.user.id}`);
    const testResult = await testEmailConnection(credentials);
    
    if (!testResult.imap) {
      return NextResponse.json(
        { error: `Connection test failed: ${testResult.error || 'Could not connect to Microsoft IMAP server'}` },
        { status: 400 }
      );
    }

    // Save credentials to database and cache
    console.log(`Saving Microsoft account for user: ${session.user.id}`);
    await saveUserEmailCredentials(session.user.id, userEmail, credentials);
    
    // Fetch the created account from the database
    const createdAccount = await prisma.mailCredentials.findFirst({
      where: { userId: session.user.id, email: userEmail },
      select: {
        id: true,
        email: true,
        display_name: true,
        color: true,
      }
    });

    // Invalidate any existing folder caches
    await invalidateFolderCache(session.user.id, userEmail, '*');

    // First cache the credentials in Redis to ensure OAuth data is saved
    await cacheEmailCredentials(session.user.id, userEmail, credentials);

    return NextResponse.json({ 
      success: true,
      account: createdAccount,
      message: 'Microsoft account added successfully'
    });
  } catch (error) {
    console.error('Error processing Microsoft callback:', error);
    return NextResponse.json(
      { 
        error: 'Failed to process Microsoft authentication',
        details: error instanceof Error ? error.message : 'Unknown error'
      },
      { status: 500 }
    );
  }
}