From 5b7ccf0b671e2999b62befc729a3e517a0433728 Mon Sep 17 00:00:00 2001
From: Bertrand Yuan <bert.yuan@outlook.com>
Date: Mon, 15 Dec 2025 23:48:10 +0800
Subject: initial commit -- the front-end prototype

The initial code is base on Anirudh's work.

More to see at:

    https://github.com/techwithanirudh/shadcn-blog

Therefore, the code in this commit is under MIT license.
---
 src/components/ui/form.tsx | 168 +++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 168 insertions(+)
 create mode 100644 src/components/ui/form.tsx

(limited to 'src/components/ui/form.tsx')

diff --git a/src/components/ui/form.tsx b/src/components/ui/form.tsx
new file mode 100644
index 0000000..5e54b0b
--- /dev/null
+++ b/src/components/ui/form.tsx
@@ -0,0 +1,168 @@
+'use client';
+
+import type * as LabelPrimitive from '@radix-ui/react-label';
+import { Slot } from '@radix-ui/react-slot';
+import * as React from 'react';
+import {
+  Controller,
+  type ControllerProps,
+  type FieldPath,
+  type FieldValues,
+  FormProvider,
+  useFormContext,
+  useFormState,
+} from 'react-hook-form';
+
+import { Label } from '@/components/ui/label';
+import { cn } from '@/lib/utils';
+
+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 } = 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: `${id}-form-item-message`,
+    ...fieldState,
+  };
+};
+
+type FormItemContextValue = {
+  id: string;
+};
+
+const FormItemContext = React.createContext<FormItemContextValue>(
+  {} as FormItemContextValue,
+);
+
+function FormItem({ className, ...props }: React.ComponentProps<'div'>) {
+  const id = React.useId();
+
+  return (
+    <FormItemContext.Provider value={{ id }}>
+      <div
+        data-slot='form-item'
+        className={cn('grid gap-2', className)}
+        {...props}
+      />
+    </FormItemContext.Provider>
+  );
+}
+
+function FormLabel({
+  className,
+  ...props
+}: React.ComponentProps<typeof LabelPrimitive.Root>) {
+  const { error, formItemId } = useFormField();
+
+  return (
+    <Label
+      data-slot='form-label'
+      data-error={!!error}
+      className={cn('data-[error=true]:text-destructive', className)}
+      htmlFor={formItemId}
+      {...props}
+    />
+  );
+}
+
+function FormControl({ ...props }: React.ComponentProps<typeof Slot>) {
+  const { error, formItemId, formDescriptionId, formMessageId } =
+    useFormField();
+
+  return (
+    <Slot
+      data-slot='form-control'
+      id={formItemId}
+      aria-describedby={
+        !error
+          ? `${formDescriptionId}`
+          : `${formDescriptionId} ${formMessageId}`
+      }
+      aria-invalid={!!error}
+      {...props}
+    />
+  );
+}
+
+function FormDescription({ className, ...props }: React.ComponentProps<'p'>) {
+  const { formDescriptionId } = useFormField();
+
+  return (
+    <p
+      data-slot='form-description'
+      id={formDescriptionId}
+      className={cn('text-muted-foreground text-sm', className)}
+      {...props}
+    />
+  );
+}
+
+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 {
+  useFormField,
+  Form,
+  FormItem,
+  FormLabel,
+  FormControl,
+  FormDescription,
+  FormMessage,
+  FormField,
+};
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