import { createHash, randomInt } from "crypto";

import { sql } from "@/lib/db";
import { hashPassword } from "@/lib/password";
import { sendEmail } from "@/lib/mailer";

const normalizePhone = (raw: string): string => {
  const cleaned = raw.replace(/[^\d+]/g, "");
  if (cleaned.startsWith("+")) return cleaned;
  return `+961${cleaned.replace(/^0+/, "")}`;
};

const hashCode = (email: string, code: string): string =>
  createHash("sha256").update(`${email}:${code}`).digest("hex");

export async function POST(req: Request) {
  const { name, email, phone, password } = await req.json();

  if (!name?.trim() || !email?.trim() || !password) {
    return Response.json(
      { error: "Name, email and password are required." },
      { status: 400 },
    );
  }

  if (typeof password !== "string" || password.length < 8) {
    return Response.json(
      { error: "Password must be at least 8 characters." },
      { status: 400 },
    );
  }

  try {
    const existing = await sql<{ id: string; email_verified: boolean }>`
      SELECT id, email_verified FROM users WHERE email = ${email.trim().toLowerCase()}
    `;

    if (existing[0]?.email_verified) {
      return Response.json(
        { error: "An account with this email already exists. Please sign in." },
        { status: 409 },
      );
    }

    // Unverified rows may be re-registered (e.g. the first mail never arrived).
    await sql`
      INSERT INTO users (name, email, phone, password_hash, email_verified)
      VALUES (
        ${name.trim()},
        ${email.trim().toLowerCase()},
        ${phone ? normalizePhone(phone) : null},
        ${hashPassword(password)},
        FALSE
      )
      ON CONFLICT (email) DO UPDATE SET
        name = EXCLUDED.name,
        phone = COALESCE(EXCLUDED.phone, users.phone),
        password_hash = EXCLUDED.password_hash
    `;

    const code = String(randomInt(0, 1_000_000)).padStart(6, "0");

    await sql`
      INSERT INTO email_verification_codes (email, code_hash, expires_at)
      VALUES (
        ${email.trim().toLowerCase()},
        ${hashCode(email.trim().toLowerCase(), code)},
        CURRENT_TIMESTAMP + INTERVAL '15 minutes'
      )
      ON CONFLICT (email) DO UPDATE SET
        code_hash = EXCLUDED.code_hash,
        expires_at = EXCLUDED.expires_at,
        attempts = 0
    `;

    await sendEmail(
      email.trim().toLowerCase(),
      "Your Waseel verification code",
      `Welcome to Waseel!\n\nYour verification code is: ${code}\n\nIt expires in 15 minutes.`,
    );

    return Response.json({ data: { sent: true } }, { status: 201 });
  } catch (error) {
    console.error("[REGISTER]: ", error);
    return Response.json({ error: "Internal Server Error" }, { status: 500 });
  }
}