import { useEffect, useState, type ReactNode } from "react"
import type { Meta, StoryObj } from "@storybook/react-vite"
import { AspectRatio, Card, CardContent, Carousel, CarouselContent, CarouselItem, CarouselNext, CarouselPrevious, type CarouselApi } from "@hm-design/ui"
import { StateBoard } from "@/components/story-board"
import { StoryPage, StoryPageHeader, StorySection } from "@/components/story-page"

// The representative Story shows real, draggable carousels; the same specimens also exist as Stories tagged `verification`
// (hidden from the sidebar). Slide widths (`basis-*`) are the consumer's `className` on CarouselItem; Card and AspectRatio are
// Story composition (Carousel imports neither). `setApi` feeds the "slide n / total" readout.

const frame = (node: ReactNode) => <div style={{ width: "100%", maxWidth: 420, minWidth: 0 }}>{node}</div>

const svg = (n: number) =>
  "data:image/svg+xml;utf8," +
  encodeURIComponent(
    `<svg xmlns="http://www.w3.org/2000/svg" width="480" height="270"><rect width="480" height="270" fill="${["#266651", "#3e3523", "#205241", "#604f32", "#123328"][n % 5]}"/><text x="24" y="52" font-family="sans-serif" font-size="34" fill="#ffffff">Slide ${n + 1}</text></svg>`
  )

function SlideCard({ n }: { n: number }) {
  return (
    <Card>
      <CardContent className="grid h-24 place-items-center text-2xl font-bold">{n + 1}</CardContent>
    </Card>
  )
}

function useReadout() {
  const [api, setApi] = useState<CarouselApi>()
  const [current, setCurrent] = useState(0)
  const [count, setCount] = useState(0)
  useEffect(() => {
    if (!api) return
    setCount(api.scrollSnapList().length)
    setCurrent(api.selectedScrollSnap() + 1)
    api.on("select", () => setCurrent(api.selectedScrollSnap() + 1))
  }, [api])
  return { setApi, current, count }
}

// `showValue={false}` hides the value readout on the representative page; the verification Stories keep it.
function Basic({ showValue = true }: { showValue?: boolean }) {
  const { setApi, current, count } = useReadout()
  return frame(
    <div className="grid gap-2">
      <Carousel setApi={setApi} aria-label="기본 carousel">
        <CarouselContent>
          {Array.from({ length: 5 }, (_, i) => (
            <CarouselItem key={i}>
              <SlideCard n={i} />
            </CarouselItem>
          ))}
        </CarouselContent>
        <CarouselPrevious />
        <CarouselNext />
      </Carousel>
      {showValue ? <span className="text-center text-sm text-muted-foreground" data-testid="readout">{`slide ${current} / ${count}`}</span> : null}
    </div>
  )
}

function Multiple() {
  return frame(
    <Carousel opts={{ align: "start" }} aria-label="여러 항목 carousel">
      <CarouselContent>
        {Array.from({ length: 8 }, (_, i) => (
          <CarouselItem key={i} className="basis-1/2">
            <SlideCard n={i} />
          </CarouselItem>
        ))}
      </CarouselContent>
      <CarouselPrevious />
      <CarouselNext />
    </Carousel>
  )
}

function Loop({ showValue = true }: { showValue?: boolean }) {
  const { setApi, current, count } = useReadout()
  return frame(
    <div className="grid gap-2">
      <Carousel opts={{ loop: true }} setApi={setApi} aria-label="loop carousel">
        <CarouselContent>
          {Array.from({ length: 3 }, (_, i) => (
            <CarouselItem key={i}>
              <SlideCard n={i} />
            </CarouselItem>
          ))}
        </CarouselContent>
        <CarouselPrevious />
        <CarouselNext />
      </Carousel>
      {showValue ? <span className="text-center text-sm text-muted-foreground" data-testid="loop-readout">{`slide ${current} / ${count}`}</span> : null}
    </div>
  )
}

function Vertical() {
  return (
    <div style={{ width: 220, height: 260 }}>
      <Carousel orientation="vertical" opts={{ align: "start" }} aria-label="세로 carousel" className="h-full">
        <CarouselContent style={{ height: 260 }}>
          {Array.from({ length: 4 }, (_, i) => (
            <CarouselItem key={i} className="basis-1/2">
              <SlideCard n={i} />
            </CarouselItem>
          ))}
        </CarouselContent>
        <CarouselPrevious />
        <CarouselNext />
      </Carousel>
    </div>
  )
}

function Media() {
  return frame(
    <Carousel aria-label="미디어 carousel">
      <CarouselContent>
        {Array.from({ length: 4 }, (_, i) => (
          <CarouselItem key={i}>
            <AspectRatio ratio={16 / 9}>
              <img src={svg(i)} alt={`슬라이드 ${i + 1}`} className="size-full rounded-md object-cover" />
            </AspectRatio>
          </CarouselItem>
        ))}
      </CarouselContent>
      <CarouselPrevious />
      <CarouselNext />
    </Carousel>
  )
}

const sections = [
  { id: "basic", label: "Basic", node: <Basic showValue={false} /> },
  { id: "multiple", label: "Multiple items", node: <Multiple /> },
  { id: "loop", label: "Loop", node: <Loop showValue={false} /> },
  { id: "vertical", label: "Vertical", node: <Vertical /> },
  { id: "media", label: "Media", node: <Media /> },
]

const meta = { title: "Components/Data & Display/Carousel", component: Carousel, parameters: { layout: "padded" } } satisfies Meta<typeof Carousel>
export default meta
type Story = StoryObj<typeof meta>

// Representative-page layout (Storybook presentation only): equal columns on PC (iframe width 1000px and up), fewer below that
// (200px minimum). Each specimen sits in its own single-column StateBoard (min larger than any column), so every subtitle and divider
// has the width of its column; a section with fewer specimens than columns leaves the remaining columns empty.
// The Media example spans two columns; carousels fill their column by design.
const specimenColumns = {
  2: "min-[1000px]:grid-cols-2",
  3: "min-[1000px]:grid-cols-3",
  4: "min-[1000px]:grid-cols-4",
} as const

function SpecimenGrid({ ids, columns, spans = {} }: { ids: string[]; columns: 2 | 3 | 4; spans?: Record<string, 2> }) {
  return (
    <div className={`grid items-start gap-6 [grid-template-columns:repeat(auto-fill,minmax(min(100%,200px),1fr))] ${specimenColumns[columns]}`}>
      {ids.map((id) => {
        const s = sections.find((section) => section.id === id)!
        return (
          <div key={id} className={spans[id] ? "min-[1000px]:col-span-2" : undefined}>
            <StateBoard min={10000} states={[{ id: s.id, label: s.label, children: s.node }]} />
          </div>
        )
      })}
    </div>
  )
}

// Representative Story: the common Story page; the sections group the same specimens.
// Representative Story: Overview (Basic) is merged into Variants (Basic, Multiple items, Loop, Vertical), 4 columns on PC; Media stays under Usage.
export const All: Story = {
  name: "Carousel",
  parameters: { layout: "fullscreen", controls: { disable: true } },
  render: () => (
    <StoryPage>
      <StoryPageHeader title="Carousel" />
      <StorySection title="Variants">
        <SpecimenGrid ids={["basic", "multiple", "loop", "vertical"]} columns={4} />
      </StorySection>
      <StorySection title="Usage">
        <SpecimenGrid ids={["media"]} columns={4} spans={{ media: 2 }} />
      </StorySection>
    </StoryPage>
  ),
}

export const BasicCarousel: Story = { tags: ["verification"], name: "Basic", render: () => <Basic /> }
export const MultipleItems: Story = { tags: ["verification"], name: "Multiple Items", render: () => <Multiple /> }
export const LoopCarousel: Story = { tags: ["verification"], name: "Loop", render: () => <Loop /> }
export const VerticalCarousel: Story = { tags: ["verification"], name: "Vertical", render: () => <Vertical /> }