feat: Form component (#1358)

* feat: add `Input` component

* feat: add form & related sub-components

* feat(Input): add size variants

* feat: add `Input` stories

* fix: revert `FormDescription` rename

package.json

@@ -44,15 +44,16 @@
     "@lexical/selection": "^0.12.0",
     "@lexical/utils": "^0.12.0",
     "@nouns/assets": "^0.4.2",
+    "@phosphor-icons/react": "^2.1.7",
     "@radix-ui/react-alert-dialog": "^1.1.1",
     "@radix-ui/react-dialog": "^1.1.1",
     "@radix-ui/react-focus-scope": "^1.1.0",
+    "@radix-ui/react-label": "^2.1.0",
     "@radix-ui/react-slot": "^1.1.0",
     "@radix-ui/react-toast": "^1.2.1",
     "@radix-ui/react-toggle": "^1.1.0",
     "@radix-ui/react-toggle-group": "^1.1.0",
     "@radix-ui/react-tooltip": "^1.1.2",
-    "@phosphor-icons/react": "^2.1.7",
     "@snyk/protect": "latest",
     "@t3-oss/env-nextjs": "^0.10.1",
     "@tanstack/react-query": "^5.26.3",

src/app/playground/_components/FormExample.tsx

@@ -0,0 +1,58 @@
+"use client"
+import { Button } from "@/components/ui/Button"
+import {
+  Form,
+  FormControl,
+  FormDescription,
+  FormErrorMessage,
+  FormField,
+  FormItem,
+  FormLabel,
+} from "@/components/ui/Form"
+import { Input } from "@/components/ui/Input"
+import { zodResolver } from "@hookform/resolvers/zod"
+import { useForm } from "react-hook-form"
+import { z } from "zod"
+
+const formSchema = z.object({
+  username: z.string().min(2).max(50),
+})
+
+export function FormExample() {
+  // 1. Define your form.
+  const form = useForm<z.infer<typeof formSchema>>({
+    resolver: zodResolver(formSchema),
+    defaultValues: {
+      username: "",
+    },
+  })
+
+  // 2. Define a submit handler.
+  function onSubmit(values: z.infer<typeof formSchema>) {
+    // Do something with the form values.
+    // ✅ This will be type-safe and validated.
+    console.log(values)
+  }
+
+  return (
+    <Form {...form}>
+      <form onSubmit={form.handleSubmit(onSubmit)} className="space-y-8">
+        <FormField
+          control={form.control}
+          name="username"
+          render={({ field }) => (
+            <FormItem>
+              <FormLabel>Username</FormLabel>
+              <FormControl>
+                <Input placeholder="shadcn" {...field} />
+              </FormControl>
+              <FormDescription>This is your public display name.</FormDescription>
+              <FormErrorMessage />
+            </FormItem>
+          )}
+        />
+        <Button type="submit">Submit</Button>
+      </form>
+    </Form>
+  )
+}

src/app/playground/page.tsx

@@ -3,6 +3,7 @@ import { Metadata } from "next"
 import { PropsWithChildren } from "react"
 import { ThemeToggle } from "../../v2/components/ThemeToggle"
 import { DialogExample } from "./_components/DialogExample"
+import { FormExample } from "./_components/FormExample"
 
 export const metadata: Metadata = {
   title: "Playground",
@@ -33,6 +34,10 @@ export default function Page() {
         <Section title="Modal">
           <DialogExample />
         </Section>
+
+        <Section title="Form">
+          <FormExample />
+        </Section>
       </div>
     </div>
   )

src/v2/components/ui/Button.tsx

@@ -68,7 +68,7 @@ const Button = React.forwardRef<HTMLButtonElement, ButtonProps>(
     const Comp = asChild ? Slot : "button"
     return (
       <Comp
-        className={cn(buttonVariants({ variant, size, className }))}
+        className={buttonVariants({ variant, size, className })}
         ref={ref}
         {...props}
         disabled={isLoading || disabled}

src/v2/components/ui/Form.tsx

@@ -0,0 +1,176 @@
+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 { Label } from "@/components/ui/Label"
+import { cn } from "@/lib/utils"
+import {
+  ComponentPropsWithoutRef,
+  createContext,
+  ElementRef,
+  forwardRef,
+  HTMLAttributes,
+  useContext,
+  useId,
+} from "react"
+
+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>,
+>({
+  ...props
+}: ControllerProps<TFieldValues, TName>) => (
+  <FormFieldContext.Provider value={{ name: props.name }}>
+    <Controller {...props} />
+  </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: `${id}-form-item-message`,
+    ...fieldState,
+  }
+}
+
+type FormItemContextValue = {
+  id: string
+}
+
+const FormItemContext = createContext<FormItemContextValue>(
+  {} as FormItemContextValue
+)
+
+const FormItem = forwardRef<HTMLDivElement, HTMLAttributes<HTMLDivElement>>(
+  ({ className, ...props }, ref) => {
+    const id = useId()
+
+    return (
+      <FormItemContext.Provider value={{ id }}>
+        <div ref={ref} className={cn("space-y-2", className)} {...props} />
+      </FormItemContext.Provider>
+    )
+  }
+)
+FormItem.displayName = "FormItem"
+
+const FormLabel = forwardRef<
+  ElementRef<typeof LabelPrimitive.Root>,
+  ComponentPropsWithoutRef<typeof LabelPrimitive.Root>
+>((props, ref) => {
+  const { formItemId } = useFormField()
+
+  return <Label ref={ref} htmlFor={formItemId} {...props} />
+})
+FormLabel.displayName = "FormLabel"
+
+const FormControl = forwardRef<
+  ElementRef<typeof Slot>,
+  ComponentPropsWithoutRef<typeof Slot>
+>(({ ...props }, ref) => {
+  const { error, formItemId, formDescriptionId, formMessageId } = useFormField()
+
+  return (
+    <Slot
+      ref={ref}
+      id={formItemId}
+      aria-describedby={
+        !error ? `${formDescriptionId}` : `${formDescriptionId} ${formMessageId}`
+      }
+      aria-invalid={!!error}
+      {...props}
+    />
+  )
+})
+FormControl.displayName = "FormControl"
+
+const FormDescription = forwardRef<
+  HTMLParagraphElement,
+  HTMLAttributes<HTMLParagraphElement>
+>(({ className, ...props }, ref) => {
+  const { formDescriptionId } = useFormField()
+
+  return (
+    <p
+      ref={ref}
+      id={formDescriptionId}
+      className={cn("text-[0.8rem] text-muted-foreground", className)}
+      {...props}
+    />
+  )
+})
+FormDescription.displayName = "FormDescription"
+
+const FormErrorMessage = forwardRef<
+  HTMLParagraphElement,
+  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}
+      // TODO: not sure if it is a good idea to use "destructive-ghost-foreground" here? Should we add a completely new CSS variable instead?
+      className={cn(
+        "text-[0.8rem] font-medium text-destructive-ghost-foreground",
+        className
+      )}
+      {...props}
+    >
+      {body}
+    </p>
+  )
+})
+FormErrorMessage.displayName = "FormErrorMessage"
+
+export {
+  Form,
+  FormControl,
+  FormDescription,
+  FormErrorMessage,
+  FormField,
+  FormItem,
+  FormLabel,
+  useFormField,
+}

src/v2/components/ui/Input.stories.ts

@@ -0,0 +1,25 @@
+import type { Meta, StoryObj } from "@storybook/react"
+import { Input, InputProps } from "./Input"
+
+const meta: Meta<typeof Input> = {
+  title: "Design system/Input",
+  component: Input,
+}
+
+export default meta
+
+type Story = StoryObj<typeof Input>
+
+export const Default: Story = {
+  args: {
+    size: "md",
+    placeholder: "Default input",
+  },
+  argTypes: {
+    size: {
+      type: "string",
+      control: "radio",
+      options: ["xs", "sm", "md", "lg"] satisfies InputProps["size"][],
+    },
+  },
+}

src/v2/components/ui/Input.tsx

@@ -0,0 +1,37 @@
+import { cva, VariantProps } from "class-variance-authority"
+import { forwardRef, InputHTMLAttributes } from "react"
+
+const inputVariants = cva(
+  "flex w-full border border-input bg-muted px-3 py-2 text-sm file:border-0 file:bg-transparent file:text-sm file:font-medium placeholder:text-muted-foreground focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-ring disabled:cursor-not-allowed disabled:opacity-50",
+  {
+    variants: {
+      size: {
+        xs: "h-6 rounded-md",
+        sm: "h-8 rounded-lg",
+        md: "h-11 rounded-lg",
+        lg: "h-12 rounded-xl",
+      },
+    },
+    defaultVariants: {
+      size: "md",
+    },
+  }
+)
+
+export interface InputProps
+  extends Omit<InputHTMLAttributes<HTMLInputElement>, "size">,
+    VariantProps<typeof inputVariants> {}
+
+const Input = forwardRef<HTMLInputElement, InputProps>(
+  ({ className, type, size, ...props }, ref) => (
+    <input
+      type={type}
+      className={inputVariants({ size, className })}
+      ref={ref}
+      {...props}
+    />
+  )
+)
+Input.displayName = "Input"
+
+export { Input }