import { NextRequest, NextResponse } from 'next/server';
import { kv } from '@vercel/kv';
import { validateEmail, isDisposableEmail } from '@/lib/email-validation';
import { checkRateLimit, getClientIp } from '@/lib/rate-limit';

/**
 * Email signup storage key
 */
const SIGNUP_LIST_KEY = 'signups:emails';

/**
 * POST /api/signup
 * Handle email signup submissions
 */
export async function POST(request: NextRequest) {
  try {
    // Parse request body
    const body = await request.json();
    const { email } = body;

    if (!email || typeof email !== 'string') {
      return NextResponse.json(
        { error: 'Email is required' },
        { status: 400 }
      );
    }

    // Validate email format
    const validation = validateEmail(email);
    if (!validation.success) {
      return NextResponse.json(
        { error: validation.error },
        { status: 400 }
      );
    }

    const sanitizedEmail = validation.email!;

    // Check for disposable email
    if (isDisposableEmail(sanitizedEmail)) {
      return NextResponse.json(
        { error: 'Disposable email addresses are not allowed' },
        { status: 400 }
      );
    }

    // Rate limiting
    const clientIp = getClientIp(request);
    const rateLimitResult = await checkRateLimit(clientIp);

    if (!rateLimitResult.allowed) {
      return NextResponse.json(
        {
          error: 'Too many requests. Please try again later.',
          resetAt: rateLimitResult.resetAt,
        },
        {
          status: 429,
          headers: {
            'Retry-After': Math.ceil((rateLimitResult.resetAt - Date.now()) / 1000).toString(),
          },
        }
      );
    }

    // Check if email already exists
    const existingSignup = await kv.hget(SIGNUP_LIST_KEY, sanitizedEmail);
    
    if (existingSignup) {
      return NextResponse.json(
        { error: 'This email is already registered' },
        { status: 409 }
      );
    }

    // Store email with timestamp
    const signupData = {
      email: sanitizedEmail,
      timestamp: new Date().toISOString(),
      ip: clientIp,
    };

    await kv.hset(SIGNUP_LIST_KEY, {
      [sanitizedEmail]: JSON.stringify(signupData),
    });

    // Return success response
    return NextResponse.json(
      {
        success: true,
        message: 'Successfully added to waitlist',
      },
      {
        status: 200,
        headers: {
          'X-RateLimit-Remaining': rateLimitResult.remaining.toString(),
          'X-RateLimit-Reset': rateLimitResult.resetAt.toString(),
        },
      }
    );
  } catch (error) {
    console.error('Signup error:', error);
    
    return NextResponse.json(
      { error: 'An error occurred. Please try again.' },
      { status: 500 }
    );
  }
}

/**
 * GET /api/signup
 * Return 405 Method Not Allowed
 */
export async function GET() {
  return NextResponse.json(
    { error: 'Method not allowed' },
    { status: 405 }
  );
}