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import { TargetedEvent, useContext, useState } from "preact/compat";
import { FormContext, InputFieldState } from "./FormProvider.js";
export interface InputFieldHandler<Type> {
value: Type;
onChange: (s: Type) => void;
state: InputFieldState;
isDirty: boolean;
}
export function useField<T>(name: keyof T): InputFieldHandler<T[keyof T]> {
const {
initialValue,
value: formValue,
computeFormState,
onUpdate,
} = useContext(FormContext);
type P = typeof name;
type V = T[P];
const [isDirty, setDirty] = useState(false);
const formState = computeFormState ? computeFormState(formValue) : {};
const fieldValue = readField(formValue, String(name)) as V;
const fieldState = readField<Partial<InputFieldState>>(
formState,
String(name),
);
//default state
const state: InputFieldState = {
disabled: fieldState?.disabled ?? false,
readonly: fieldState?.readonly ?? false,
hidden: fieldState?.hidden ?? false,
error: fieldState?.error,
};
function onChange(value: V): void {
setDirty(true);
return onUpdate((prev: any) => {
return setValueDeeper(prev, String(name).split("."), value);
});
}
return {
value: fieldValue,
onChange,
isDirty,
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) };
}
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