import { NextRequest, NextResponse } from 'next/server';
import { z } from 'zod';
import bcrypt from 'bcryptjs';
import { randomBytes } from 'crypto';
import { eq, count } from 'drizzle-orm';
import { db } from '@/lib/db';
import { users, verificationTokens } from '@/lib/db/schema';
import { sendEmail } from '@/lib/email';
import { verificationEmail } from '@/lib/email/templates';
import { isSignupsEnabled } from '@/lib/site-config';

const RegisterSchema = z.object({
  email: z.string().email(),
  name: z.string().min(1).max(255),
  password: z.string().min(8).max(128),
});

export async function POST(req: NextRequest): Promise<NextResponse> {
  let body: unknown;
  try {
    body = await req.json();
  } catch {
    return NextResponse.json({ error: 'Invalid JSON' }, { status: 400 });
  }

  const signupsEnabled = await isSignupsEnabled();
  if (!signupsEnabled) {
    return NextResponse.json({ error: 'Signups are currently disabled' }, { status: 403 });
  }

  const parsed = RegisterSchema.safeParse(body);
  if (!parsed.success) {
    return NextResponse.json(
      { error: parsed.error.issues.map((i) => i.message).join('; ') },
      { status: 400 },
    );
  }

  const { email, name, password } = parsed.data;
  const normalizedEmail = email.toLowerCase();

  const [existing] = await db.select({ id: users.id }).from(users).where(eq(users.email, normalizedEmail)).limit(1);
  if (existing) {
    return NextResponse.json({ error: 'Email already registered' }, { status: 409 });
  }

  const [{ total }] = await db.select({ total: count() }).from(users);
  const role = total === 0 ? 'admin' : 'learner';

  const passwordHash = await bcrypt.hash(password, 12);
  const [user] = await db
    .insert(users)
    .values({ email: normalizedEmail, name, passwordHash, role })
    .returning({ id: users.id });

  const token = randomBytes(32).toString('hex');
  const expires = new Date(Date.now() + 86_400_000); // 24 hours
  await db.insert(verificationTokens).values({ identifier: normalizedEmail, token, expires });
  const { subject, html, text } = verificationEmail(token);
  void sendEmail({ to: normalizedEmail, subject, html, text }).catch(() => {});

  return NextResponse.json({ userId: user.id }, { status: 201 });
}