"use client";

import * as React from "react";
import {
  Controller,
  FormProvider,
  useFormContext,
  useFormState,
  type ControllerProps,
  type FieldPath,
  type FieldValues,
} 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
);

function 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>
  );
}

type FormItemContextValue = {
  id: string;
};

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

function useFormField() {
  const fieldContext = React.useContext(FormFieldContext);
  const itemContext = React.useContext(FormItemContext);
  const { getFieldState } = useFormContext();
  const formState = useFormState({ name: fieldContext.name });
  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,
  };
}

function FormItem({ className, ...props }: React.ComponentProps<"div">) {
  const id = React.useId();

  return (
    <FormItemContext.Provider value={{ id }}>
      <div
        data-slot="form-item"
        className={cn("grid gap-1.5", className)}
        {...props}
      />
    </FormItemContext.Provider>
  );
}

function FormLabel({
  className,
  ...props
}: React.ComponentProps<typeof Label>) {
  const { error, formItemId } = useFormField();

  return (
    <Label
      data-slot="form-label"
      data-error={!!error}
      className={cn("data-[error=true]:text-destructive", className)}
      htmlFor={formItemId}
      {...props}
    />
  );
}

// Not built on a generic "asChild" slot primitive — this project's forms
// always wrap a single form control (shadcn <Input>, <Select>, <RadioGroup>,
// ...), so cloning the id/aria props directly onto that one child is simpler
// than pulling in a polymorphic composition primitive for a use case that
// doesn't need one. Every one of those controls forwards unknown props
// (including id/aria-*) to its underlying DOM element, so the child's own
// prop type doesn't need to name them.
function FormControl({
  children,
}: {
  children: React.ReactElement<Record<string, unknown>>;
}) {
  const { error, formItemId, formDescriptionId, formMessageId } =
    useFormField();

  return React.cloneElement(children, {
    id: formItemId,
    "aria-describedby": !error
      ? formDescriptionId
      : `${formDescriptionId} ${formMessageId}`,
    "aria-invalid": !!error,
  });
}

function FormMessage({ className, ...props }: React.ComponentProps<"p">) {
  const { error, formMessageId } = useFormField();
  const body = error ? String(error?.message ?? "") : props.children;

  if (!body) return null;

  return (
    <p
      data-slot="form-message"
      id={formMessageId}
      className={cn("text-destructive text-sm", className)}
      {...props}
    >
      {body}
    </p>
  );
}

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