import { NextRequest, NextResponse } from 'next/server';
import { db } from '@/lib/db';
import { signupSchema, getClientIp } from '@/lib/validation';
import {
  hashPassword,
  createSession,
  generateApiKey,
  SESSION_COOKIE_NAME,
} from '@/lib/auth';
import { authRateLimit } from '@/lib/rate-limit';
import { logActivity } from '@/lib/activity';

export async function POST(request: NextRequest) {
  try {
    // ── Rate Limit ────────────────────────────────────────────────────
    const ip = getClientIp(request);
    const { allowed, retryAfterMs } = await authRateLimit(`auth:${ip}`);
    if (!allowed) {
      return NextResponse.json(
        { error: 'Too many signup attempts. Please try again later.' },
        {
          status: 429,
          headers: { 'Retry-After': String(Math.ceil(retryAfterMs / 1000)) },
        }
      );
    }

    // ── Parse & Validate Body ─────────────────────────────────────────
    const body = await request.json();
    const parsed = signupSchema.safeParse(body);
    if (!parsed.success) {
      return NextResponse.json(
        { error: parsed.error.issues[0].message },
        { status: 400 }
      );
    }

    const { name, email, password } = parsed.data;

    // ── Check if Email Exists ─────────────────────────────────────────
    const existing = await db.user.findUnique({ where: { email } });
    if (existing) {
      return NextResponse.json(
        { error: 'An account with this email already exists' },
        { status: 409 }
      );
    }

    // ── Hash Password & Generate API Key ──────────────────────────────
    const [hashedPassword, apiKey] = await Promise.all([
      hashPassword(password),
      generateApiKey(),
    ]);

    // ── Create User ───────────────────────────────────────────────────
    const user = await db.user.create({
      data: {
        name,
        email,
        password: hashedPassword,
        apiKey,
        plan: 'free',
      },
    });

    // ── Create Session ────────────────────────────────────────────────
    const token = await createSession(user.id);

    // ── Determine if behind HTTPS proxy ───────────────────────────────
    const forwardedProto = request.headers.get('x-forwarded-proto');
    const isSecure = forwardedProto === 'https' || process.env.NODE_ENV === 'production';

    // ── Set Cookie & Respond ──────────────────────────────────────────
    const response = NextResponse.json({
      user: {
        id: user.id,
        email: user.email,
        name: user.name,
        plan: user.plan,
        createdAt: user.createdAt,
      },
    });

    response.cookies.set(SESSION_COOKIE_NAME, token, {
      httpOnly: true,
      secure: isSecure,
      sameSite: 'lax',
      path: '/',
      maxAge: 7 * 24 * 60 * 60, // 7 days
    });

    logActivity(user.id, 'signup', 'Account created', user.email);

    return response;
  } catch (error) {
    console.error('[SIGNUP_ERROR]', error);
    return NextResponse.json(
      { error: 'Internal server error' },
      { status: 500 }
    );
  }
}