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/*
This file is part of GNU Taler
(C) 2022-2024 Taler Systems S.A.
GNU Taler is free software; you can redistribute it and/or modify it under the
terms of the GNU General Public License as published by the Free Software
Foundation; either version 3, or (at your option) any later version.
GNU Taler 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 General Public License for more details.
You should have received a copy of the GNU General Public License along with
GNU Taler; see the file COPYING. If not, see <http://www.gnu.org/licenses/>
*/
import { AmountJson, TranslatedString } from "@gnu-taler/taler-util";
import { useState } from "preact/hooks";
export type UIField = {
value: string | undefined;
onUpdate: (s: string) => void;
error: TranslatedString | undefined;
};
type FormHandler<T> = {
[k in keyof T]?: T[k] extends string
? UIField
: T[k] extends AmountJson
? UIField
: FormHandler<T[k]>;
};
export type FormValues<T> = {
[k in keyof T]: T[k] extends string
? string | undefined
: T[k] extends AmountJson
? string | undefined
: FormValues<T[k]>;
};
export type RecursivePartial<T> = {
[k in keyof T]?: T[k] extends string
? string
: T[k] extends AmountJson
? AmountJson
: RecursivePartial<T[k]>;
};
export type FormErrors<T> = {
[k in keyof T]?: T[k] extends string
? TranslatedString
: T[k] extends AmountJson
? TranslatedString
: FormErrors<T[k]>;
};
export type FormStatus<T> =
| {
status: "ok";
result: T;
errors: undefined;
}
| {
status: "fail";
result: RecursivePartial<T>;
errors: FormErrors<T>;
};
function constructFormHandler<T>(
form: FormValues<T>,
updateForm: (d: FormValues<T>) => void,
errors: FormErrors<T> | undefined,
): FormHandler<T> {
const keys = Object.keys(form) as Array<keyof T>;
const handler = keys.reduce((prev, fieldName) => {
const currentValue: unknown = form[fieldName];
const currentError: unknown = errors ? errors[fieldName] : undefined;
function updater(newValue: unknown) {
updateForm({ ...form, [fieldName]: newValue });
}
if (typeof currentValue === "object") {
// @ts-expect-error FIXME better typing
const group = constructFormHandler(currentValue, updater, currentError);
// @ts-expect-error FIXME better typing
prev[fieldName] = group;
return prev;
}
const field: UIField = {
// @ts-expect-error FIXME better typing
error: currentError,
// @ts-expect-error FIXME better typing
value: currentValue,
onUpdate: updater,
};
// @ts-expect-error FIXME better typing
prev[fieldName] = field;
return prev;
}, {} as FormHandler<T>);
return handler;
}
export function useFormState<T>(
defaultValue: FormValues<T>,
check: (f: FormValues<T>) => FormStatus<T>,
): [FormHandler<T>, FormStatus<T>] {
const [form, updateForm] = useState<FormValues<T>>(defaultValue);
const status = check(form);
const handler = constructFormHandler(form, updateForm, status.errors);
return [handler, status];
}
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