import type {
  CreateCardForTemporaryUsePayload,
  DuffelCardFormStrings,
} from '../../../index';
import type { ConditionalFormPayload } from '../forms/CreateCardForTemporaryUseForm';
import { thisMonth } from '../utils/thisMonth';
import { validateCVCFn } from './validateCVCFn';

export type ValidationResult = { valid: boolean; error: string | null };

/**
 * These fields won't be present in the payload,
 * they only aid with keeping data and validation
 */
export interface VirtualFields {
  expiry_date: Date | null;
}

export type KeyToValidate =
  | keyof Omit<CreateCardForTemporaryUsePayload, 'expiry_month' | 'expiry_year'>
  | keyof VirtualFields;

export function validateFieldFn(customStrings: DuffelCardFormStrings) {
  const validateCVC = validateCVCFn(customStrings);

  return (
    fieldName: KeyToValidate,
    data: ConditionalFormPayload<any> & VirtualFields
  ): ValidationResult => {
    if (fieldName === 'number') {
      if (data[fieldName] === '') {
        return { valid: false, error: customStrings.cardNumberRequired };
      } else if (data[fieldName].length < 15 || data[fieldName].length > 16) {
        return {
          valid: false,
          error: customStrings.cardNumberDigitsInvalidMessage,
        };
      } else {
        return { valid: true, error: null };
      }
    }

    if (fieldName === 'expiry_date') {
      if (data[fieldName] === null) {
        return { valid: false, error: customStrings.expiryDateRequiredMessage };
      } else if (data[fieldName] < thisMonth()) {
        return {
          valid: false,
          error: customStrings.expiryDateInThePastMessage,
        };
      } else {
        return { valid: true, error: null };
      }
    }

    if (fieldName === 'name') {
      if (data[fieldName] === '') {
        return { valid: false, error: customStrings.cardholderNameRequired };
      } else {
        return { valid: true, error: null };
      }
    }

    if (fieldName === 'address_line_1') {
      if (data[fieldName] === '') {
        return { valid: false, error: customStrings.addressRequiredMessage };
      } else {
        return { valid: true, error: null };
      }
    }

    if (fieldName === 'address_city') {
      if (data[fieldName] === '') {
        return { valid: false, error: customStrings.cityRequiredMessage };
      } else {
        return { valid: true, error: null };
      }
    }

    if (fieldName === 'address_region') {
      if (data[fieldName] === '') {
        return { valid: false, error: customStrings.regionRequiredMessage };
      } else {
        return { valid: true, error: null };
      }
    }

    if (fieldName === 'address_postal_code') {
      if (
        data.address_country_code === 'US' &&
        !/^\d{5}$/.test(data[fieldName])
      ) {
        return { valid: false, error: customStrings.zipInvalidMessage };
      } else if (
        data.address_country_code === 'CA' &&
        // Allows h2t-1b8, h2z 1b8, H2Z1B8. Disallows: leading Z, W or to contain D, F, I, O, Q or U
        !/^[ABCEGHJ-NPRSTVXY]\d[ABCEGHJ-NPRSTV-Z][ -]?\d[ABCEGHJ-NPRSTV-Z]\d$/i.test(
          data[fieldName]
        )
      ) {
        return { valid: false, error: customStrings.postalCodeInvalidMessage };
      } else if (
        data.address_country_code === 'GB' &&
        !/^[A-Z]{1,2}[0-9R][0-9A-Z]? ?[0-9][A-Z]{2}$/.test(data[fieldName])
      ) {
        return { valid: false, error: customStrings.postcodeInvalidMessage };
      } else if (data[fieldName] === '') {
        return { valid: false, error: customStrings.postalCodeRequiredMessage };
      } else {
        return { valid: true, error: null };
      }
    }

    if (fieldName === 'address_country_code') {
      if (data[fieldName] === 'null' || data[fieldName] === null) {
        return { valid: false, error: customStrings.countryRequiredMessage };
      } else {
        return { valid: true, error: null };
      }
    }

    if (fieldName === 'cvc') {
      return validateCVC((data as CreateCardForTemporaryUsePayload)[fieldName]);
    }

    if (fieldName === 'address_line_2') {
      // we don't validate this, it's optional
      return { valid: true, error: null };
    }

    throw new Error(
      `Attempted to 'validateField' an invalid field: '${fieldName}'`
    );
  };
}