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import { TargetedEvent, useContext, useState } from "preact/compat";
import {
FormContext,
InputArrayFieldState,
InputFieldState,
} from "./FormProvider.js";
export interface InputFieldHandler<Type> {
value: Type;
onChange: (s: Type) => void;
state: InputFieldState;
isDirty: boolean;
}
export function useField<T extends object, K extends keyof T>(
name: K,
): InputFieldHandler<T[K]> {
const {
initialValue,
value: formValue,
computeFormState,
onUpdate: notifyUpdate,
} = useContext(FormContext);
type P = typeof name;
type V = T[P];
const formState = computeFormState ? computeFormState(formValue.current) : {};
const fieldValue = readField(formValue.current, String(name)) as V;
const [currentValue, setCurrentValue] = useState<any | undefined>(fieldValue);
const fieldState =
readField<Partial<InputFieldState>>(formState, String(name)) ?? {};
//compute default state
const state = {
disabled: fieldState.disabled ?? false,
readonly: fieldState.readonly ?? false,
hidden: fieldState.hidden ?? false,
error: fieldState.error,
elements: "elements" in fieldState ? fieldState.elements ?? [] : [],
};
function onChange(value: V): void {
setCurrentValue(value);
formValue.current = setValueDeeper(
formValue.current,
String(name).split("."),
value,
);
if (notifyUpdate) {
notifyUpdate(formValue.current);
}
}
return {
value: fieldValue,
onChange,
isDirty: currentValue !== undefined,
state,
};
}
/**
* read the field of an object an support accessing it using '.'
*
* @param object
* @param name
* @returns
*/
function readField<T>(object: any, name: string): T | undefined {
return name
.split(".")
.reduce((prev, current) => prev && prev[current], object);
}
function setValueDeeper(object: any, names: string[], value: any): any {
if (names.length === 0) return value;
const [head, ...rest] = names;
if (object === undefined) {
return { [head]: setValueDeeper({}, rest, value) };
}
return { ...object, [head]: setValueDeeper(object[head] ?? {}, rest, value) };
}
type TTT<T extends object, K extends keyof T, R> = K extends keyof T
? R extends T[K]
? number
: never
: never;
function impl<T extends object, K extends keyof T, R extends T[K]>(
obj: T,
name: K,
): T[K] {
return obj[name];
}
interface Pepe {
name: string;
when: Date;
size: number;
}
const p: Pepe = {
name: "n",
when: new Date(),
size: 1,
};
const a = impl(p, "size");
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