import { useState } from "react";
import { render, screen } from "@testing-library/react";
import userEvent from "@testing-library/user-event";
import { describe, expect, it } from "vitest";
import { Tabs, TabsContent, TabsList, TabsTrigger } from "./tabs";

const has = (element: HTMLElement, token: string) => element.className.split(/\s+/).includes(token);

function Harness({ initial = "a" }: { initial?: string }) {
  const [value, setValue] = useState(initial);
  return (
    <Tabs value={value} onValueChange={(next) => setValue(String(next))}>
      <TabsList aria-label="Bereiche">
        <TabsTrigger value="a">Völker</TabsTrigger>
        <TabsTrigger value="b">Königinnen</TabsTrigger>
        <TabsTrigger value="c">Ernte</TabsTrigger>
      </TabsList>
      <TabsContent value="a">Panel Völker</TabsContent>
      <TabsContent value="b">Panel Königinnen</TabsContent>
      <TabsContent value="c">Panel Ernte</TabsContent>
    </Tabs>
  );
}

describe("Tabs (spec 10.4)", () => {
  it("arrow keys move the focus, Enter or Space switch the tab, and the panel is labelled by it", async () => {
    const user = userEvent.setup();
    render(<Harness />);
    const first = screen.getByRole("tab", { name: "Völker" });
    await user.click(first);
    await user.keyboard("{ArrowRight}");

    // Manual activation (APG): the panels fetch on mount, so an arrow only moves the focus.
    const second = screen.getByRole("tab", { name: "Königinnen" });
    expect(second).toHaveFocus();
    expect(second).toHaveAttribute("aria-selected", "false");
    expect(screen.getByRole("tabpanel")).toHaveTextContent("Panel Völker");

    await user.keyboard("{Enter}");
    expect(second).toHaveAttribute("aria-selected", "true");
    const panel = screen.getByRole("tabpanel");
    expect(panel).toHaveTextContent("Panel Königinnen");
    expect(panel).toHaveAccessibleName("Königinnen");
    expect(second).toHaveAttribute("aria-controls", panel.id);

    // Focus wraps around at the end (one tab stop, arrows inside the list); Space selects too.
    await user.keyboard("{ArrowRight}{ArrowRight}");
    expect(first).toHaveFocus();
    await user.keyboard(" ");
    expect(first).toHaveAttribute("aria-selected", "true");
    expect(screen.getByRole("tabpanel")).toHaveTextContent("Panel Völker");
  });

  it("the active tab has the surface, bold text and the 3 px ink bar", () => {
    render(<Harness initial="b" />);
    const active = screen.getByRole("tab", { name: "Königinnen" });
    expect(active).toHaveAttribute("data-active");
    for (const token of [
      "data-active:bg-card",
      "data-active:text-foreground",
      "data-active:font-semibold",
      "border-b-3",
      "data-active:border-b-primary-ink",
    ]) {
      expect(has(active, token), token).toBe(true);
    }
    // Inactive tabs: --muted-foreground on --muted (≥ 4.5:1 in all four sets, contrast.spec.ts).
    const inactive = screen.getByRole("tab", { name: "Völker" });
    expect(has(inactive, "text-muted-foreground")).toBe(true);
    expect(inactive.className).not.toMatch(/text-foreground\/\d+/);
    expect(has(screen.getByRole("tablist"), "bg-muted")).toBe(true);
  });

  it("tabs are 44 px for a thumb, compact only with a fine pointer, 16 px text, 4 px apart", () => {
    render(<Harness />);
    const list = screen.getByRole("tablist");
    expect(has(list, "p-1")).toBe(true);
    expect(has(list, "gap-1")).toBe(true);
    for (const tab of screen.getAllByRole("tab")) {
      expect(has(tab, "h-11")).toBe(true);
      expect(has(tab, "pointer-fine:h-9")).toBe(true);
      expect(has(tab, "text-base")).toBe(true);
      expect(tab.className).not.toMatch(/(^|\s)sm:(?:min-)?h-/);
    }
  });

  it("the list wraps on a narrow screen instead of overflowing", () => {
    render(<Harness />);
    const list = screen.getByRole("tablist");
    expect(has(list, "flex-wrap")).toBe(true);
    expect(has(list, "max-w-full")).toBe(true);
    expect(list.className).not.toMatch(/(^|\s)h-10(\s|$)/);
  });

  it("has one variant, segment, and no own focus ring or movement", () => {
    render(<Harness />);
    expect(screen.getByRole("tablist")).toHaveAttribute("data-variant", "segment");
    for (const tab of screen.getAllByRole("tab")) {
      expect(tab.className).not.toMatch(/outline-none|ring-ring|focus-visible:ring|translate|transition-all/);
    }
  });
});