shadcn-ui/apps/v4/examples/base/date-picker-demo.tsx

"use client"

import * as React from "react"
import { Button } from "@/examples/base/ui/button"
import { Calendar } from "@/examples/base/ui/calendar"
import {
  Popover,
  PopoverContent,
  PopoverTrigger,
} from "@/examples/base/ui/popover"
import { format } from "date-fns"
import { CalendarIcon } from "lucide-react"

import { cn } from "@/lib/utils"

export function DatePickerDemo() {
  const [date, setDate] = React.useState<Date>()

  return (
    <Popover>
      <PopoverTrigger
        render={
          <Button
            variant={"outline"}
            className={cn(
              "w-[240px] justify-start text-left font-normal",
              !date && "text-muted-foreground"
            )}
          />
        }
      >
        <CalendarIcon />
        {date ? format(date, "PPP") : <span>Pick a date</span>}
      </PopoverTrigger>
      <PopoverContent className="w-auto p-0" align="start">
        <Calendar
          mode="single"
          selected={date}
          onSelect={setDate}
          initialFocus
        />
      </PopoverContent>
    </Popover>
  )
}