import * as prismicT from "@prismicio/types";
import * as RTE from "fp-ts/ReaderTaskEither";
import { pipe } from "fp-ts/function";

import { Dependencies, TypePathKind } from "../types";
import { normalizeDocumentSubtree } from "./normalizeDocumentSubtree";

/**
 * Type guard to verify that the given value is a valid Prismic document.
 */
const documentRefinement = (
	value: unknown,
): value is prismicT.PrismicDocument =>
	typeof value === "object" &&
	value !== null &&
	!Array.isArray(value) &&
	"id" in value &&
	"type" in value;

/**
 * Normalizes values of a Prismic document where necessary.
 *
 * @param doc - Prismic document to normalize.
 *
 * @returns Normalized Prismic document.
 * @see gatsby-source-prismic/lib/normalizeDocumentSubtree.ts
 */
export const normalizeDocument = (
	doc: prismicT.PrismicDocument,
): RTE.ReaderTaskEither<Dependencies, Error, prismicT.PrismicDocument> =>
	pipe(
		normalizeDocumentSubtree(TypePathKind.CustomType, [doc.type], doc),
		RTE.chainW(
			RTE.fromPredicate(
				documentRefinement,
				() =>
					new Error(
						"Document shape is no longer a Document after normalization",
					),
			),
		),
	);