@prismicio/types-internal/src/validators/DefaultOrElse.ts

Prismic types for Custom Types and Prismic Data

import { isRight } from "fp-ts/lib/Either"
import * as t from "io-ts"

import { EmptyArray, EmptyObject } from "./BasicTypes"

export const DefaultOrElse = <I, A, O = A>(inputValidator: t.Type<I>) => {
	return (codec: t.Type<A, O>) =>
		new t.Type<A | null, O | undefined>(
			`DefaultOrElse<${inputValidator.name}, ${codec.name}>`,
			(u: unknown): u is A | null => null === u || codec.is(u),
			(u: unknown, c) => {
				if (isRight(inputValidator.validate(u, c))) return t.success(null)
				return codec.validate(u, c)
			},
			(chunk) => (chunk ? codec.encode(chunk) : undefined),
		)
}

export const NullOrElse = <A, O = A>(codec: t.Type<A, O>) =>
	DefaultOrElse<null, A, O>(t.null)(codec)
export const EmptyObjectOrElse = <A, O = A>(codec: t.Type<A, O>) =>
	DefaultOrElse<Record<never, never>, A, O>(EmptyObject)(codec)
export const EmptyArrayOrElse = <A, O = A>(codec: t.Type<A, O>) =>
	DefaultOrElse<never[], A, O>(EmptyArray)(codec)