better-auth/demo/nextjs/components/ui/form.tsx

"use client";

import * as React from "react";
import * as LabelPrimitive from "@radix-ui/react-label";
import { Slot } from "@radix-ui/react-slot";
import {
	Controller,
	ControllerProps,
	FieldPath,
	FieldValues,
	FormProvider,
	useFormContext,
} from "react-hook-form";

import { cn } from "@/lib/utils";
import { Label } from "@/components/ui/label";

const Form = FormProvider;

type FormFieldContextValue<
	TFieldValues extends FieldValues = FieldValues,
	TName extends FieldPath<TFieldValues> = FieldPath<TFieldValues>,
> = {
	name: TName;
};

const FormFieldContext = React.createContext<FormFieldContextValue>(
	{} as FormFieldContextValue,
);

const FormField = <
	TFieldValues extends FieldValues = FieldValues,
	TName extends FieldPath<TFieldValues> = FieldPath<TFieldValues>,
>({
	...props
}: ControllerProps<TFieldValues, TName>) => {
	return (
		<FormFieldContext.Provider value={{ name: props.name }}>
			<Controller {...props} />
		</FormFieldContext.Provider>
	);
};

const useFormField = () => {
	const fieldContext = React.useContext(FormFieldContext);
	const itemContext = React.useContext(FormItemContext);
	const { getFieldState, formState } = useFormContext();

	const fieldState = getFieldState(fieldContext.name, formState);

	if (!fieldContext) {
		throw new Error("useFormField should be used within <FormField>");
	}

	const { id } = itemContext;

	return {
		id,
		name: fieldContext.name,
		formItemId: `${id}-form-item`,
		formDescriptionId: `${id}-form-item-description`,
		formMessageId: `${id}-form-item-message`,
		...fieldState,
	};
};

type FormItemContextValue = {
	id: string;
};

const FormItemContext = React.createContext<FormItemContextValue>(
	{} as FormItemContextValue,
);

const FormItem = ({
	ref,
	className,
	...props
}: React.HTMLAttributes<HTMLDivElement> & {
	ref: React.RefObject<HTMLDivElement>;
}) => {
	const id = React.useId();

	return (
		<FormItemContext.Provider value={{ id }}>
			<div ref={ref} className={cn("space-y-2", className)} {...props} />
		</FormItemContext.Provider>
	);
};
FormItem.displayName = "FormItem";

const FormLabel = ({
	ref,
	className,
	...props
}: React.ComponentPropsWithoutRef<typeof LabelPrimitive.Root> & {
	ref: React.RefObject<React.ElementRef<typeof LabelPrimitive.Root>>;
}) => {
	const { error, formItemId } = useFormField();

	return (
		<Label
			ref={ref}
			className={cn(error && "text-destructive", className)}
			htmlFor={formItemId}
			{...props}
		/>
	);
};
FormLabel.displayName = "FormLabel";

const FormControl = ({
	ref,
	...props
}: React.ComponentPropsWithoutRef<typeof Slot> & {
	ref: React.RefObject<React.ElementRef<typeof Slot>>;
}) => {
	const { error, formItemId, formDescriptionId, formMessageId } =
		useFormField();

	return (
		<Slot
			ref={ref}
			id={formItemId}
			aria-describedby={
				!error
					? `${formDescriptionId}`
					: `${formDescriptionId} ${formMessageId}`
			}
			aria-invalid={!!error}
			{...props}
		/>
	);
};
FormControl.displayName = "FormControl";

const FormDescription = ({
	ref,
	className,
	...props
}: React.HTMLAttributes<HTMLParagraphElement> & {
	ref: React.RefObject<HTMLParagraphElement>;
}) => {
	const { formDescriptionId } = useFormField();

	return (
		<p
			ref={ref}
			id={formDescriptionId}
			className={cn("text-[0.8rem] text-muted-foreground", className)}
			{...props}
		/>
	);
};
FormDescription.displayName = "FormDescription";

const FormMessage = ({
	ref,
	className,
	children,
	...props
}: React.HTMLAttributes<HTMLParagraphElement> & {
	ref: React.RefObject<HTMLParagraphElement>;
}) => {
	const { error, formMessageId } = useFormField();
	const body = error ? String(error?.message) : children;

	if (!body) {
		return null;
	}

	return (
		<p
			ref={ref}
			id={formMessageId}
			className={cn("text-[0.8rem] font-medium text-destructive", className)}
			{...props}
		>
			{body}
		</p>
	);
};
FormMessage.displayName = "FormMessage";

export {
	useFormField,
	Form,
	FormItem,
	FormLabel,
	FormControl,
	FormDescription,
	FormMessage,
	FormField,
};