/*
	GoToSocial
	Copyright (C) GoToSocial Authors admin@gotosocial.org
	SPDX-License-Identifier: AGPL-3.0-or-later

	This program is free software: you can redistribute it and/or modify
	it under the terms of the GNU Affero General Public License as published by
	the Free Software Foundation, either version 3 of the License, or
	(at your option) any later version.

	This program is distributed in the hope that it will be useful,
	but WITHOUT ANY WARRANTY; without even the implied warranty of
	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
	GNU Affero General Public License for more details.

	You should have received a copy of the GNU Affero General Public License
	along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/

import { useRef, useMemo } from "react";

import type {
	CreateHookNames,
	HookOpts,
	ArrayInputHook,
	HookedForm,
} from "./types";
import getFormMutations from "./get-form-mutations";

function parseFields(entries: HookedForm[], length: number): HookedForm[] {
	const fields: HookedForm[] = [];

	for (let i = 0; i < length; i++) {
		if (entries[i] != undefined) {
			fields[i] = Object.assign({}, entries[i]);
		} else {
			fields[i] = {};
		}
	}

	return fields;
}

export default function useArrayInput(
	{ name }: CreateHookNames,
	{
		initialValue,
		length = 0,
	}: HookOpts,
): ArrayInputHook {
	const _default: HookedForm[] = Array(length);
	const fields = useRef<HookedForm[]>(_default);

	const value = useMemo(
		() => parseFields(initialValue, length),
		[initialValue, length],
	);

	function hasUpdate() {
		return Object.values(fields.current).some((fieldSet) => {
			const { updatedFields } = getFormMutations(fieldSet, { changedOnly: true });
			return updatedFields.length > 0;
		});
	}

	return {
		_default,
		name,
		Name: "",
		value,
		ctx: fields.current,
		maxLength: length,
		hasChanged: hasUpdate,
		selectedValues() {
			if (hasUpdate()) {
				return Object.values(fields.current)
					// Extract all form fields.
					.flatMap((fieldSet) => {
						return getFormMutations(
							fieldSet,
							{ changedOnly: false },
						).updatedFields;
					})
					// Get just value from each
					// field, discarding name.
					.map((field) => field.value);
			} else {
				return [];
			}
		}
	};
}