form.tsx

import type * as LabelPrimitive from "@radix-ui/react-label";
import { Slot } from "@radix-ui/react-slot";
import { type ComponentProps, type HTMLAttributes, createContext, useContext, useId } from "react";
import {
  Controller,
  type ControllerProps,
  type FieldPath,
  type FieldValues,
  FormProvider,
  useFormContext,
} from "react-hook-form";
import { cn } from "./cn";
import { Label } from "./label";

const Form = FormProvider;

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

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

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

const useFormField = () => {
  const fieldContext = useContext(FormFieldContext);
  const itemContext = 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 = createContext<FormItemContextValue>({} as FormItemContextValue);

function FormItem({ className, dense = true, ...rest }: HTMLAttributes<HTMLDivElement> & { dense?: boolean }) {
  const id = useId();

  return (
    <FormItemContext.Provider value={{ id }}>
      <div className={cn("space-y-2", dense && "space-y-1", className)} {...rest} />
    </FormItemContext.Provider>
  );
}

function FormLabel({ className, ...rest }: ComponentProps<typeof LabelPrimitive.Root>) {
  const { error, formItemId } = useFormField();

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

function FormControl({ ...rest }: ComponentProps<typeof Slot>) {
  const { error, formItemId, formDescriptionId, formMessageId } = useFormField();

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

function FormDescription({ className, ...rest }: HTMLAttributes<HTMLParagraphElement>) {
  const { formDescriptionId } = useFormField();

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

function FormMessage({ className, children, ...rest }: HTMLAttributes<HTMLParagraphElement>) {
  const { error, formMessageId } = useFormField();
  const body = error ? String(error?.message) : children;

  if (!body) {
    return null;
  }

  return (
    <p id={formMessageId} className={cn("animate-head-shake text-destructive text-xs", className)} {...rest}>
      {body}
    </p>
  );
}

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