export const NAME_MAX_LENGTH = 100;
export const BRAND_MAX_LENGTH = 100;
export const OWNER_MAX_LENGTH = 50;
export const ADDRESS_DETAIL_MAX_LENGTH = 200;
export const MEMO_MAX_LENGTH = 500;

export interface MerchantValues {
  id: string;
  /** 백엔드에 컬럼이 없어 저장되지 않는다 — 기획 시안 유지를 위해 화면에는 남긴다. */
  brandName: string;
  memo: string;
  name: string;
  categoryCode: string;
  businessNumber: string;
  ownerName: string;
  phoneNumber: string;
  address: string;
  addressDetail: string;
  postalCode: string;
  latitude: string;
  longitude: string;
  isVisible: boolean;
}

export type MerchantFormErrors = Partial<
  Record<'name' | 'categoryCode' | 'phoneNumber' | 'address' | 'businessNumber', string>
>;

export type MerchantFormState =
  | { status: 'idle' }
  | { status: 'error'; message?: string; errors?: MerchantFormErrors }
  | { status: 'success' };

export const INITIAL_MERCHANT_FORM_STATE: MerchantFormState = { status: 'idle' };

export const REQUIRED_MESSAGE = '필수입력 사항을 입력하세요.';

/** 사업자등록번호는 선택이지만, 넣었다면 형태를 지킨다(기획 예시 `000-00-00000`). */
const BUSINESS_NUMBER_PATTERN = /^\d{3}-?\d{2}-?\d{5}$/;

type ValidationResult =
  | { ok: true; values: MerchantValues }
  | { ok: false; errors: MerchantFormErrors };

export function validateMerchant(values: MerchantValues): ValidationResult {
  const errors: MerchantFormErrors = {};

  const name = values.name.trim();
  if (!name) {
    errors.name = REQUIRED_MESSAGE;
  } else if (name.length > NAME_MAX_LENGTH) {
    errors.name = `가맹점명은 ${NAME_MAX_LENGTH}자 이내로 입력해 주세요.`;
  }

  if (!values.categoryCode.trim()) {
    errors.categoryCode = REQUIRED_MESSAGE;
  }

  const phoneNumber = values.phoneNumber.trim();
  if (!phoneNumber) {
    errors.phoneNumber = REQUIRED_MESSAGE;
  } else if (!/^[\d-]+$/.test(phoneNumber)) {
    errors.phoneNumber = '전화번호는 숫자와 -만 입력할 수 있습니다.';
  }

  if (!values.address.trim()) {
    errors.address = '주소 검색을 진행해 주세요.';
  }

  const businessNumber = values.businessNumber.trim();
  if (businessNumber && !BUSINESS_NUMBER_PATTERN.test(businessNumber)) {
    errors.businessNumber = '사업자등록번호는 000-00-00000 형식으로 입력해 주세요.';
  }

  if (Object.keys(errors).length > 0) {
    return { ok: false, errors };
  }

  return {
    ok: true,
    values: {
      ...values,
      name,
      brandName: values.brandName.trim().slice(0, BRAND_MAX_LENGTH),
      memo: values.memo.trim().slice(0, MEMO_MAX_LENGTH),
      ownerName: values.ownerName.trim().slice(0, OWNER_MAX_LENGTH),
      phoneNumber,
      businessNumber,
      address: values.address.trim(),
      addressDetail: values.addressDetail.trim().slice(0, ADDRESS_DETAIL_MAX_LENGTH),
    },
  };
}