import { ok, err } from "@tailor-platform/erp-kit/core";
import type { Transaction } from "../generated/kysely-tailordb";
import {
  InvalidEmailError,
  MissingRequiredFieldError,
  UserAlreadyExistsError,
} from "../lib/errors.generated";

interface CreateUserInput {
  email: string;
  name: string;
}

const EMAIL_PATTERN = /^[^\s@]+@[^\s@]+\.[^\s@]+$/;

/**
 * Function: createUser
 *
 * Creates a new user account in PENDING status.
 * Validates email format and uniqueness.
 */
export async function run<CF extends Record<string, unknown>>(
  db: Transaction,
  input: CreateUserInput & CF,
) {
  const { email, name, ...customFields } = input;

  if (!email || email.trim() === "") {
    return err(new MissingRequiredFieldError("email"));
  }

  if (!name || name.trim() === "") {
    return err(new MissingRequiredFieldError("name"));
  }

  if (!EMAIL_PATTERN.test(email)) {
    return err(new InvalidEmailError(email));
  }

  const existingUser = await db
    .selectFrom("User")
    .selectAll()
    .where("email", "=", email)
    .forUpdate()
    .executeTakeFirst();

  if (existingUser) {
    return err(new UserAlreadyExistsError(email));
  }

  const user = await db
    .insertInto("User")
    .values({
      ...(customFields as Record<string, unknown>),
      email,
      name,
      status: "PENDING",
    })
    .returningAll()
    .executeTakeFirstOrThrow();

  return ok({ user });
}