Vector/packages/ui/src/components/form.tsx

import * as React from 'react';
import * as LabelPrimitive from '@radix-ui/react-label';
import { Slot } from '@radix-ui/react-slot';
import {
  Controller,
  FormProvider,
  useFormContext,
  type ControllerProps,
  type FieldPath,
  type FieldValues,
} from 'react-hook-form';
import { cn } from '../lib/cn.js';
import { Label } from './label.js';

export const Form = FormProvider;

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

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

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

type FormItemContextValue = { id: string };
const FormItemContext = React.createContext<FormItemContextValue>({} as FormItemContextValue);

export const FormItem = React.forwardRef<HTMLDivElement, React.HTMLAttributes<HTMLDivElement>>(
  ({ className, ...props }, ref) => {
    const id = React.useId();
    return (
      <FormItemContext.Provider value={{ id }}>
        <div ref={ref} className={cn('space-y-1.5', className)} {...props} />
      </FormItemContext.Provider>
    );
  },
);
FormItem.displayName = 'FormItem';

export function useFormField() {
  const fieldContext = React.useContext(FormFieldContext);
  const itemContext = React.useContext(FormItemContext);
  const { getFieldState, formState } = useFormContext();
  if (!fieldContext) throw new Error('useFormField must be used within <FormField>');
  const fieldState = getFieldState(fieldContext.name, formState);
  const { id } = itemContext;
  return {
    id,
    name: fieldContext.name,
    formItemId: `${id}-form-item`,
    formDescriptionId: `${id}-form-item-description`,
    formMessageId: `${id}-form-item-message`,
    ...fieldState,
  };
}

export const FormLabel = React.forwardRef<
  React.ElementRef<typeof LabelPrimitive.Root>,
  React.ComponentPropsWithoutRef<typeof LabelPrimitive.Root>
>(({ className, ...props }, ref) => {
  const { error, formItemId } = useFormField();
  return (
    <Label
      ref={ref}
      className={cn(error && 'text-destructive', className)}
      htmlFor={formItemId}
      {...props}
    />
  );
});
FormLabel.displayName = 'FormLabel';

export const FormControl = React.forwardRef<
  React.ElementRef<typeof Slot>,
  React.ComponentPropsWithoutRef<typeof Slot>
>(({ ...props }, ref) => {
  const { error, formItemId, formDescriptionId, formMessageId } = useFormField();
  return (
    <Slot
      ref={ref}
      id={formItemId}
      aria-describedby={error ? `${formDescriptionId} ${formMessageId}` : formDescriptionId}
      aria-invalid={!!error}
      {...props}
    />
  );
});
FormControl.displayName = 'FormControl';

export const FormDescription = React.forwardRef<
  HTMLParagraphElement,
  React.HTMLAttributes<HTMLParagraphElement>
>(({ className, ...props }, ref) => {
  const { formDescriptionId } = useFormField();
  return (
    <p
      ref={ref}
      id={formDescriptionId}
      className={cn('text-xs text-muted-foreground', className)}
      {...props}
    />
  );
});
FormDescription.displayName = 'FormDescription';

export const FormMessage = React.forwardRef<
  HTMLParagraphElement,
  React.HTMLAttributes<HTMLParagraphElement>
>(({ className, children, ...props }, ref) => {
  const { error, formMessageId } = useFormField();
  const body = error ? String(error.message) : children;
  if (!body) return null;
  return (
    <p
      ref={ref}
      id={formMessageId}
      className={cn('text-xs font-medium text-destructive', className)}
      {...props}
    >
      {body}
    </p>
  );
});
FormMessage.displayName = 'FormMessage';