"use client"

/**
 * Carousel — Embla-based, mirroring shadcn's API.
 *
 * MOTION EXCEPTION: Embla animates scrolling with a physics attraction
 * simulation, not CSS transitions, so this component intentionally does NOT use
 * the kit's `ease-in-out` / `duration-*` motion tokens for slide movement — it
 * structurally can't. The only tuning knob is Embla's `opts.duration` (a
 * physics value, roughly 20–60, NOT milliseconds, with no easing curve). This
 * is the industry-standard engine (shadcn uses it too); the trade is
 * best-in-class drag/touch/momentum over token-exact easing. The arrow buttons
 * still use the kit's <Button> motion, and reduced-motion is respected via the
 * global fallback in globals.css.
 */

import * as React from "react"
import useEmblaCarousel, {
  type UseEmblaCarouselType,
} from "embla-carousel-react"
import { ArrowLeft, ArrowRight } from "lucide-react"

import { cn } from "@/registry/lib/utils"
import { Button } from "@/registry/ui/button"

type CarouselApi = UseEmblaCarouselType[1]
type UseCarouselParameters = Parameters<typeof useEmblaCarousel>
type CarouselOptions = UseCarouselParameters[0]
type CarouselPlugin = UseCarouselParameters[1]

type CarouselProps = {
  opts?: CarouselOptions
  plugins?: CarouselPlugin
  orientation?: "horizontal" | "vertical"
  setApi?: (api: CarouselApi) => void
}

type CarouselContextProps = {
  carouselRef: ReturnType<typeof useEmblaCarousel>[0]
  api: ReturnType<typeof useEmblaCarousel>[1]
  scrollPrev: () => void
  scrollNext: () => void
  canScrollPrev: boolean
  canScrollNext: boolean
} & CarouselProps

const CarouselContext = React.createContext<CarouselContextProps | null>(null)

function useCarousel() {
  const context = React.useContext(CarouselContext)
  if (!context) {
    throw new Error("useCarousel must be used within a <Carousel />")
  }
  return context
}

function Carousel({
  orientation = "horizontal",
  opts,
  setApi,
  plugins,
  className,
  children,
  ...props
}: React.ComponentProps<"div"> & CarouselProps) {
  const [carouselRef, api] = useEmblaCarousel(
    {
      ...opts,
      axis: orientation === "horizontal" ? "x" : "y",
    },
    plugins
  )
  const [canScrollPrev, setCanScrollPrev] = React.useState(false)
  const [canScrollNext, setCanScrollNext] = React.useState(false)

  const onSelect = React.useCallback((api: CarouselApi) => {
    if (!api) return
    setCanScrollPrev(api.canScrollPrev())
    setCanScrollNext(api.canScrollNext())
  }, [])

  const scrollPrev = React.useCallback(() => {
    api?.scrollPrev()
  }, [api])

  const scrollNext = React.useCallback(() => {
    api?.scrollNext()
  }, [api])

  const handleKeyDown = React.useCallback(
    (event: React.KeyboardEvent<HTMLDivElement>) => {
      if (event.key === "ArrowLeft") {
        event.preventDefault()
        scrollPrev()
      } else if (event.key === "ArrowRight") {
        event.preventDefault()
        scrollNext()
      }
    },
    [scrollPrev, scrollNext]
  )

  React.useEffect(() => {
    if (!api || !setApi) return
    setApi(api)
  }, [api, setApi])

  React.useEffect(() => {
    if (!api) return
    onSelect(api)
    api.on("reInit", onSelect)
    api.on("select", onSelect)
    return () => {
      api?.off("select", onSelect)
    }
  }, [api, onSelect])

  return (
    <CarouselContext.Provider
      value={{
        carouselRef,
        api,
        opts,
        orientation:
          orientation || (opts?.axis === "y" ? "vertical" : "horizontal"),
        scrollPrev,
        scrollNext,
        canScrollPrev,
        canScrollNext,
      }}
    >
      <div
        data-slot="carousel"
        onKeyDownCapture={handleKeyDown}
        className={cn("relative", className)}
        role="region"
        aria-roledescription="carousel"
        {...props}
      >
        {children}
      </div>
    </CarouselContext.Provider>
  )
}

function CarouselContent({ className, ...props }: React.ComponentProps<"div">) {
  const { carouselRef, orientation } = useCarousel()
  return (
    <div
      ref={carouselRef}
      data-slot="carousel-content"
      className="overflow-hidden"
      // Embla positions slides purely via transform, so the viewport must never
      // scroll natively. Focusing a control inside an off-screen slide makes the
      // browser scroll this container to reveal it, which silently desyncs every
      // slide from Embla's transform. Pin the native scroll offset to 0.
      onScroll={(event) => {
        event.currentTarget.scrollLeft = 0
        event.currentTarget.scrollTop = 0
      }}
    >
      <div
        className={cn(
          "flex",
          orientation === "horizontal" ? "-ml-4" : "-mt-4 flex-col",
          className
        )}
        {...props}
      />
    </div>
  )
}

function CarouselItem({ className, ...props }: React.ComponentProps<"div">) {
  const { orientation } = useCarousel()
  return (
    <div
      role="group"
      aria-roledescription="slide"
      data-slot="carousel-item"
      className={cn(
        "min-w-0 shrink-0 grow-0 basis-full",
        orientation === "horizontal" ? "pl-4" : "pt-4",
        className
      )}
      {...props}
    />
  )
}

function CarouselPrevious({
  className,
  variant = "outline",
  size = "icon",
  ...props
}: React.ComponentProps<typeof Button>) {
  const { orientation, scrollPrev, canScrollPrev } = useCarousel()
  return (
    <Button
      data-slot="carousel-previous"
      variant={variant}
      size={size}
      className={cn(
        "absolute rounded-full",
        orientation === "horizontal"
          ? "top-1/2 left-2 -translate-y-1/2 sm:-left-12"
          : "-top-12 left-1/2 -translate-x-1/2 rotate-90",
        className
      )}
      disabled={!canScrollPrev}
      onClick={scrollPrev}
      aria-label="Previous slide"
      {...props}
    >
      <ArrowLeft />
    </Button>
  )
}

function CarouselNext({
  className,
  variant = "outline",
  size = "icon",
  ...props
}: React.ComponentProps<typeof Button>) {
  const { orientation, scrollNext, canScrollNext } = useCarousel()
  return (
    <Button
      data-slot="carousel-next"
      variant={variant}
      size={size}
      className={cn(
        "absolute rounded-full",
        orientation === "horizontal"
          ? "top-1/2 right-2 -translate-y-1/2 sm:-right-12"
          : "-bottom-12 left-1/2 -translate-x-1/2 rotate-90",
        className
      )}
      disabled={!canScrollNext}
      onClick={scrollNext}
      aria-label="Next slide"
      {...props}
    >
      <ArrowRight />
    </Button>
  )
}

export {
  type CarouselApi,
  Carousel,
  CarouselContent,
  CarouselItem,
  CarouselPrevious,
  CarouselNext,
}
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