validation.ts

import moment from 'moment';

export const EMAIL_REGEXP = /[a-zA-Z0-9!#$%&'*+/=?^_`{|}~-]+(?:\.[a-zA-Z0-9!#$%&'*+/=?^_`{|}~-]+)*@(?:[a-zA-Z0-9](?:[a-zA-Z0-9-]*[a-zA-Z0-9])?\.)+[a-zA-Z0-9](?:[a-zA-Z0-9-]*[a-zA-Z0-9])/;

const isInRange = (date: moment, [from, to]: [moment, moment]): boolean =>
  date.isSameOrAfter(from, 'day') && date.isSameOrBefore(to, 'day');

type ValidatorReturn = string | null;
type Validator<T> = (value: T) => ValidatorReturn;
type Predicate<T> = (value: T) => boolean;

export const validate =
  <T>(predicate: Predicate<T>, message: string) =>
  (value: T): ValidatorReturn =>
    predicate(value) ? null : message;

export const required = (value: string): boolean => !!value.trim().length;

export const is =
  (valueToMatch: unknown) =>
  (value: unknown): boolean =>
    value === valueToMatch;

const emptyPredicate = (value: string): boolean => value === "";

export const empty: Validator<string> = validate(
  emptyPredicate,
  "This field is required"
);

export const not =
  <T>(validator: Validator<T>): Validator<T> =>
  (value: T): ValidatorReturn =>
    validator(value) ? null : "Not valid";

export const string =
  (validator: Validator<string>) =>
  (value: unknown): ValidatorReturn =>
    typeof value === "string" ? validator(value) : "Not a string";

const minLengthPredicate =
  (length: number) =>
  (value: string): boolean =>
    value.length >= length;

export const minLength = (length: number) =>
  validate(minLengthPredicate(length), "Too short");

const maxLengthPredicate =
  (length: number) =>
  (value: string): boolean =>
    value.length <= length;

export const maxLength = (length: number) =>
  validate(maxLengthPredicate(length), "Too long");

export const exactLength =
  (length: number) =>
  (value: string): boolean =>
    typeof value === "string" ? value.length === length : length === 0;

export const matches =
  (regex: RegExp) =>
  (value: unknown): boolean =>
    regex.test(typeof value === "string" ? value : "");

export const and =
  <T>(...validators: Validator<T>[]) =>
  (value: T): ValidatorReturn =>
    validators.reduce<ValidatorReturn>(
      (error, validator) => (error ? error : validator(value)),
      null
    );

export const or =
  <T>(...validators: Validator<T>[]) =>
  (value: T): ValidatorReturn =>
    validators.reduce<ValidatorReturn>(
      (error, validator) => (error ? validator(value) : null),
      "error"
    );

export const matches = (regex: RegExp) => (value: unknown): boolean => regex.test(typeof value === 'string' ? value : '');
export const email = (value: unknown = ''): boolean => (typeof value === 'string' ? !!value.match(EMAIL_REGEXP) : false);

export const dateInRange = (minDate: moment, maxDate: moment) => (value: unknown) =>
  typeof value === 'string' && isInRange(moment(value), [minDate, maxDate]);

export const dateValid = (value: unknown) => typeof value === 'string' && moment(value).isValid();