[feature] Move + alias account via settings panel (#2519)

* [feature] Move + alias account via settings panel

* lint

* type a bit more diligently

web/source/settings/lib/form/array.ts

@@ -0,0 +1,92 @@
+/*
+	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 [];
+			}
+		}
+	};
+}