// @vitest-environment jsdom
//
// `lib/listNav` against real DOM: `j`/`k` from item to item and across lists in reading order, the
// arrows around a grid, Enter as a click on the item's own "open" element — and the places where the
// keys must stay out of the way (a field, an overlay, a control inside the card).
import { useRef, useState } from "react";
import { afterEach, describe, expect, it, vi } from "vitest";
import { act, cleanup, fireEvent, render, screen, waitFor } from "@testing-library/react";
import { focusNavItem, navItemAttrs, useListNav } from "./listNav";
import { pushLayer, removeLayer } from "./layerStack";

afterEach(cleanup);

function List({
  id,
  count,
  cols = 1,
  mounted,
  reveal,
  measure,
  onOpen = () => {},
}: {
  id: string;
  count: number;
  cols?: number;
  /** Mount only the first N items, the way a virtualized grid leaves the rest out of the DOM. */
  mounted?: number;
  reveal?: (index: number) => void;
  /** Register without a count or columns — a rail or plain grid, measured from the DOM. */
  measure?: boolean;
  onOpen?: (id: string) => void;
}) {
  const ref = useRef<HTMLDivElement>(null);
  useListNav(ref, measure ? { enabled: true } : { enabled: true, count, cols, reveal });
  return (
    <div ref={ref}>
      {Array.from({ length: mounted ?? count }, (_, i) => (
        <div key={i} {...navItemAttrs(i)} data-testid={`${id}${i}`}>
          <a
            href="#"
            data-nav-open=""
            onClick={(e) => {
              e.preventDefault();
              onOpen(`${id}${i}`);
            }}
          >
            title
          </a>
          <button data-testid={`${id}${i}-action`}>action</button>
        </div>
      ))}
    </div>
  );
}

/** A keydown where a real one starts: on whatever holds focus, bubbling to the window listener. */
function press(key: string): KeyboardEvent {
  const e = new KeyboardEvent("keydown", { key, bubbles: true, cancelable: true });
  act(() => {
    (document.activeElement ?? document.body).dispatchEvent(e);
  });
  return e;
}

const focused = () => (document.activeElement as HTMLElement | null)?.dataset.testid;

describe("useListNav", () => {
  it("lands the first j on an item, then steps one item at a time", () => {
    render(<List id="a" count={3} />);
    press("j");
    expect(focused()).toBe("a0");
    press("j");
    expect(focused()).toBe("a1");
    press("k");
    expect(focused()).toBe("a0");
  });

  // The Tab order is the reader's, not ours: only the item the keyboard is on is focusable, and the
  // previous one gives its tabindex back.
  it("roves a single tabindex=-1 and never adds a Tab stop", () => {
    render(<List id="a" count={3} />);
    expect(screen.getByTestId("a0").hasAttribute("tabindex")).toBe(false);
    press("j");
    expect(screen.getByTestId("a0").getAttribute("tabindex")).toBe("-1");
    press("j");
    expect(screen.getByTestId("a0").hasAttribute("tabindex")).toBe(false);
    expect(screen.getByTestId("a1").getAttribute("tabindex")).toBe("-1");
  });

  // The player restores focus to whatever held it when it opened. If the item gave its
  // tabindex back on blur, that restore would silently fail and focus would fall to <body>.
  it("keeps the item focusable after focus leaves it, so a dialog can restore onto it", () => {
    render(
      <>
        <List id="a" count={2} />
        <button data-testid="outside">elsewhere</button>
      </>,
    );
    press("j");
    act(() => screen.getByTestId("outside").focus());
    act(() => screen.getByTestId("a0").focus());
    expect(focused()).toBe("a0");
  });

  it("stops at both ends of the page instead of wrapping", () => {
    render(<List id="a" count={2} />);
    press("j");
    press("k");
    expect(focused()).toBe("a0");
    press("j");
    press("j");
    expect(focused()).toBe("a1");
  });

  // Owner decision: j/k walk every collection on the page in reading order.
  it("continues into the next list, and back, in document order", () => {
    render(
      <>
        <List id="a" count={2} />
        <List id="b" count={2} />
      </>,
    );
    press("j");
    press("j");
    press("j");
    expect(focused()).toBe("b0");
    press("k");
    expect(focused()).toBe("a1");
  });

  it("moves around a grid with the arrows, row by row", () => {
    // 3 columns, 7 items: rows [0 1 2] [3 4 5] [6]
    render(<List id="a" count={7} cols={3} />);
    press("j");
    press("ArrowRight");
    expect(focused()).toBe("a1");
    press("ArrowDown");
    expect(focused()).toBe("a4");
    press("ArrowDown"); // the row below is short: land on its last item
    expect(focused()).toBe("a6");
    press("ArrowDown"); // already on the last row
    expect(focused()).toBe("a6");
    press("ArrowUp");
    expect(focused()).toBe("a3");
    press("ArrowLeft"); // left wraps to the end of the row above — reading order
    expect(focused()).toBe("a2");
  });

  it("works the arrows from a control inside the card too", () => {
    render(<List id="a" count={4} cols={2} />);
    act(() => screen.getByTestId("a0-action").focus());
    press("ArrowDown");
    expect(focused()).toBe("a2");
  });

  // Outside a list an arrow scrolls the page; that native meaning must survive.
  it("leaves the arrows alone when focus is not in a list", () => {
    render(<List id="a" count={4} cols={2} />);
    expect(press("ArrowDown").defaultPrevented).toBe(false);
    expect(focused()).toBeUndefined();
  });

  it("opens the item on Enter by clicking its own open element", () => {
    const onOpen = vi.fn();
    render(<List id="a" count={2} onOpen={onOpen} />);
    press("j");
    press("j");
    expect(press("Enter").defaultPrevented).toBe(true);
    expect(onOpen).toHaveBeenCalledWith("a1");
  });

  it("leaves Enter to a control inside the card", () => {
    const onOpen = vi.fn();
    render(<List id="a" count={2} onOpen={onOpen} />);
    act(() => screen.getByTestId("a0-action").focus());
    expect(press("Enter").defaultPrevented).toBe(false);
    expect(onOpen).not.toHaveBeenCalled();
  });

  it("stays out of a text field", () => {
    render(
      <>
        <input data-testid="field" />
        <List id="a" count={2} />
      </>,
    );
    act(() => screen.getByTestId("field").focus());
    press("j");
    expect(focused()).toBe("field");
  });

  it("is quiet under a layer that owns the keyboard, but not under a tooltip", () => {
    render(<List id="a" count={2} />);
    const modal = pushLayer();
    press("j");
    expect(focused()).toBeUndefined();
    removeLayer(modal);

    const tooltip = pushLayer({ passive: true });
    press("j");
    expect(focused()).toBe("a0");
    removeLayer(tooltip);
  });

  // A virtualized grid only mounts a screen of rows: the next item may not exist yet.
  it("asks the list to reveal an unmounted item, then focuses it once it renders", async () => {
    const reveal = vi.fn();
    const { rerender } = render(<List id="a" count={5} mounted={2} reveal={reveal} />);
    press("j");
    press("j");
    press("j");
    expect(reveal).toHaveBeenCalledWith(2);
    expect(focused()).toBe("a1");
    rerender(<List id="a" count={5} reveal={reveal} />);
    await waitFor(() => expect(focused()).toBe("a2"));
  });

  it("unbinds when the last list unmounts", () => {
    const { unmount } = render(<List id="a" count={2} />);
    unmount();
    expect(press("j").defaultPrevented).toBe(false);
  });
});

// jsdom lays nothing out, so the tests below give each item a box: `boxes` maps an item's test id
// (`a0`, `b3`) to where it sits. Everything else — the list containers — is a zero box at the origin.
function withLayout(
  boxes: (id: string, n: number) => { left: number; top: number } | null,
  run: () => void,
) {
  const spy = vi.spyOn(Element.prototype, "getBoundingClientRect").mockImplementation(function (
    this: Element,
  ) {
    const m = /^([a-z])(\d+)$/.exec((this as HTMLElement).dataset?.testid ?? "");
    const at = m ? boxes(m[1]!, Number(m[2])) : null;
    const { left, top } = at ?? { left: 0, top: 0 };
    const size = at ? 90 : 0;
    return {
      left,
      top,
      right: left + size,
      bottom: top + size,
      width: size,
      height: size,
      x: left,
      y: top,
    } as DOMRect;
  });
  // Restored in `finally`: a spy left behind by a failing assertion would fail every later test.
  try {
    run();
  } finally {
    spy.mockRestore();
  }
}

describe("useListNav · measured lists (rails and plain grids)", () => {
  it("reads the item count and the columns off the DOM when the list does not give them", () => {
    // Three to a row: [0 1 2] [3 4 5] [6]
    withLayout(
      (_, n) => ({ left: (n % 3) * 100, top: Math.floor(n / 3) * 100 }),
      () => {
        render(<List id="a" count={7} measure />);
        press("j");
        press("ArrowDown");
        expect(focused()).toBe("a3");
        press("ArrowDown");
        expect(focused()).toBe("a6");
        press("ArrowRight"); // the last item: nothing past it
        expect(focused()).toBe("a6");
      },
    );
  });

  // Owner decision: ↑↓ from a rail go to the rail above or below, not nowhere.
  it("goes on from a list's bottom row to the next list's nearest item, and back up", () => {
    withLayout(
      // Two rails of four; the lower one sits 30px further right.
      (list, n) => (list === "a" ? { left: n * 100, top: 0 } : { left: n * 100 + 30, top: 200 }),
      () => {
        render(
          <>
            <List id="a" count={4} measure />
            <List id="b" count={4} measure />
          </>,
        );
        press("j");
        press("ArrowRight");
        press("ArrowRight");
        expect(focused()).toBe("a2");
        press("ArrowDown");
        expect(focused()).toBe("b2"); // centre 275 is nearest a2's 45+200
        press("ArrowDown"); // the page's last list: stays
        expect(focused()).toBe("b2");
        press("ArrowUp");
        expect(focused()).toBe("a2");
        press("ArrowRight");
        press("ArrowRight"); // ←→ never leave the rail
        expect(focused()).toBe("a3");
      },
    );
  });

  it("lands the first j on the first card a rail shows, not one scrolled out to the left", () => {
    withLayout(
      (_, n) => ({ left: (n - 2) * 100, top: 0 }), // a0 and a1 sit left of the rail's edge
      () => {
        render(<List id="a" count={4} measure />);
        press("j");
        expect(focused()).toBe("a2");
      },
    );
  });
});

describe("useListNav · keys and lists it must leave alone", () => {
  // DataTable renders its rows twice — a table and a card list, one of them display:none at any width.
  it("skips a list that is not on screen", () => {
    render(
      <>
        <List id="a" count={2} />
        <List id="b" count={2} />
      </>,
    );
    Object.defineProperty(screen.getByTestId("a0").parentElement!, "checkVisibility", {
      value: () => false,
    });
    press("j");
    expect(focused()).toBe("b0");
    press("k");
    expect(focused()).toBe("b0");
  });

  // A playlist row's drag handle moves the row with the arrows during a keyboard drag; dnd-kit handles
  // the key on the document first and prevents its default. Moving focus as well would drop the drag.
  it("leaves a key that something before it already handled", () => {
    render(<List id="a" count={3} />);
    press("j");
    const handled = (e: KeyboardEvent) => e.preventDefault();
    document.addEventListener("keydown", handled);
    try {
      press("ArrowDown");
      press("j");
      expect(focused()).toBe("a0");
    } finally {
      document.removeEventListener("keydown", handled);
    }
    press("ArrowDown");
    expect(focused()).toBe("a1");
  });
});

describe("useListNav · the roving tabindex and a removed item", () => {
  // A tile that is a native <button> is a Tab stop already. A tabindex="-1" on it took it out of the
  // Tab order until the next `j` moved elsewhere: Shift+Tab back to a genre tile skipped it.
  it("leaves an item that is a Tab stop in its own right out of the tabindex it roves", () => {
    function Tiles() {
      const ref = useRef<HTMLDivElement>(null);
      useListNav(ref, { enabled: true });
      return (
        <div ref={ref}>
          {[0, 1].map((i) => (
            <button key={i} type="button" {...navItemAttrs(i)} data-testid={`t${i}`}>
              tile
            </button>
          ))}
        </div>
      );
    }
    render(<Tiles />);
    press("j");
    expect(focused()).toBe("t0");
    expect(screen.getByTestId("t0").hasAttribute("tabindex")).toBe(false);
    press("j");
    expect(focused()).toBe("t1");
    expect(screen.getByTestId("t1").hasAttribute("tabindex")).toBe(false);
  });

  // Landing again on the item that already holds the roved tabindex (focus went to <body> in between)
  // forgot it, so it kept tabindex="-1" for good — and a click on its blank area focused the card.
  it("gives the tabindex back after landing twice on the same item", () => {
    render(<List id="a" count={3} />);
    press("j");
    expect(focused()).toBe("a0");
    act(() => (document.activeElement as HTMLElement).blur());
    press("j");
    expect(focused()).toBe("a0");
    press("j");
    expect(focused()).toBe("a1");
    expect(screen.getByTestId("a0").hasAttribute("tabindex")).toBe(false);
  });

  // Hiding the focused feed card unmounts it and drops focus to <body>; the next `j` started over at
  // the first visible card instead of going on from the hidden card's slot.
  it("goes on from the slot of an item that was removed under the focus", () => {
    function Removable() {
      const [ids, setIds] = useState([0, 1, 2, 3]);
      const ref = useRef<HTMLDivElement>(null);
      useListNav(ref, { enabled: true });
      return (
        <div ref={ref}>
          {ids.map((id, i) => (
            <div key={id} {...navItemAttrs(i)} data-testid={`r${id}`}>
              <button
                data-testid={`r${id}-hide`}
                onClick={() => setIds((xs) => xs.filter((x) => x !== id))}
              >
                hide
              </button>
            </div>
          ))}
        </div>
      );
    }
    withLayout(
      (_, n) => ({ left: 0, top: n * 100 }),
      () => {
        render(<Removable />);
        press("j");
        press("j");
        press("j");
        expect(focused()).toBe("r2");
        act(() => screen.getByTestId("r2-hide").focus());
        fireEvent.click(screen.getByTestId("r2-hide"));
        expect(document.activeElement).toBe(document.body);
        press("j");
        expect(focused()).toBe("r3");
      },
    );
  });
});

describe("useListNav · leaving the list, and naming the item", () => {
  function Swappable({ ids }: { ids: number[] }) {
    const ref = useRef<HTMLDivElement>(null);
    useListNav(ref, { enabled: true });
    return (
      <div ref={ref}>
        {ids.map((id, i) => (
          <div key={id} {...navItemAttrs(i)} data-testid={`r${id}`}>
            <button>act</button>
          </div>
        ))}
      </div>
    );
  }

  // `s`, a query, Escape: the feed stays mounted with new results and the old card is gone. The slot
  // kept for a REMOVED card sent the next `j` to the third new result instead of the first.
  it("starts from the first visible item after focus went on to a field and the items changed", () => {
    withLayout(
      (_, n) => ({ left: 0, top: n * 100 }),
      () => {
        const page = (ids: number[]) => (
          <>
            <input data-testid="field" />
            <Swappable ids={ids} />
          </>
        );
        const { rerender } = render(page([0, 1, 2, 3]));
        press("j");
        press("j");
        press("j");
        expect(focused()).toBe("r2");
        act(() => screen.getByTestId("field").focus());
        rerender(page([4, 5, 6, 7]));
        act(() => screen.getByTestId("field").blur());
        press("j");
        expect(focused()).toBe("r4");
      },
    );
  });

  // A confirm (or the item's own menu) takes the focus before the delete it confirms: back from it, the
  // next `j` still goes on from the deleted row's slot.
  it("keeps the slot when the removal was confirmed in a dialog", () => {
    withLayout(
      (_, n) => ({ left: 0, top: n * 100 }),
      () => {
        const page = (ids: number[]) => (
          <>
            <div role="dialog">
              <button data-testid="ok">ok</button>
            </div>
            <Swappable ids={ids} />
          </>
        );
        const { rerender } = render(page([0, 1, 2, 3]));
        press("j");
        press("j");
        press("j");
        act(() => screen.getByTestId("ok").focus());
        rerender(page([0, 1, 3]));
        act(() => screen.getByTestId("ok").blur());
        press("j");
        expect(focused()).toBe("r3");
      },
    );
  });

  // A card root is a plain <div>: focused by `j` it had no role and no name, so a screen reader read
  // an unlabelled run of text.
  it("names a focused card after what it opens while it holds the focus, then gives the name back", () => {
    render(<List id="a" count={2} />);
    press("j");
    const a0 = screen.getByTestId("a0");
    expect(a0.getAttribute("role")).toBe("group");
    expect(a0.getAttribute("aria-label")).toBe("title");
    press("j");
    expect(a0.hasAttribute("role")).toBe(false);
    expect(a0.hasAttribute("aria-label")).toBe(false);
    expect(screen.getByTestId("a1").getAttribute("aria-label")).toBe("title");
  });

  // A Plex poster's open element is the whole card — badges, title, year, rating and summary — and a
  // season card's holds only the hover caption "Open show": named from that text, every season was
  // "Open show". The item's own name wins.
  it("names a card by the name its item gives, over the text of what it opens", () => {
    function Posters() {
      const ref = useRef<HTMLDivElement>(null);
      useListNav(ref, { enabled: true });
      return (
        <div ref={ref}>
          <div {...navItemAttrs(0, "Season 1")} data-testid="p0">
            <div role="button" tabIndex={0} data-nav-open="">
              Open show
            </div>
          </div>
        </div>
      );
    }
    render(<Posters />);
    press("j");
    expect(screen.getByTestId("p0").getAttribute("aria-label")).toBe("Season 1");
  });

  // Hide a card, then Undo in the toast that put up: focus on the toast's button is not the reader
  // leaving the list, and `j` goes on from the card put back.
  it("keeps the slot when focus went to the Undo of a toast", () => {
    withLayout(
      (_, n) => ({ left: 0, top: n * 100 }),
      () => {
        const page = (ids: number[]) => (
          <>
            <div data-toast-region="">
              <button data-testid="undo">undo</button>
            </div>
            <Swappable ids={ids} />
          </>
        );
        const { rerender } = render(page([0, 1, 2, 3]));
        press("j");
        press("j");
        press("j");
        rerender(page([0, 1, 3]));
        act(() => screen.getByTestId("undo").focus());
        rerender(page([0, 1, 2, 3]));
        act(() => screen.getByTestId("undo").blur());
        press("j");
        expect(focused()).toBe("r2");
      },
    );
  });
});

describe("useListNav · Delete (a playlist row's X became the Delete key)", () => {
  function Deletable({ onDelete }: { onDelete?: boolean }) {
    const [ids, setIds] = useState([0, 1, 2]);
    const ref = useRef<HTMLDivElement>(null);
    useListNav(ref, {
      enabled: true,
      onDelete:
        onDelete === false ? undefined : (i) => setIds((xs) => xs.filter((_, j) => j !== i)),
    });
    return (
      <div ref={ref}>
        {ids.map((id, i) => (
          <div key={id} {...navItemAttrs(i)} data-testid={`d${id}`}>
            <button data-testid={`d${id}-action`}>action</button>
          </div>
        ))}
      </div>
    );
  }
  const gone = (id: string) => screen.queryByTestId(id) === null;

  it("takes the focused item out and moves the focus to the one now in its slot", async () => {
    render(<Deletable />);
    press("j");
    press("j");
    expect(focused()).toBe("d1");
    const e = press("Delete");
    expect(e.defaultPrevented).toBe(true);
    expect(gone("d1")).toBe(true);
    await waitFor(() => expect(focused()).toBe("d2"));
    // …so a second Delete takes the next row.
    press("Delete");
    expect(gone("d2")).toBe(true);
    await waitFor(() => expect(focused()).toBe("d0"));
  });

  it("leaves Delete to a control inside the item", () => {
    render(<Deletable />);
    act(() => screen.getByTestId("d1-action").focus());
    const e = press("Delete");
    expect(e.defaultPrevented).toBe(false);
    expect(gone("d1")).toBe(false);
  });

  it("does nothing in a list that cannot remove", () => {
    render(<Deletable onDelete={false} />);
    press("j");
    const e = press("Delete");
    expect(e.defaultPrevented).toBe(false);
    expect(gone("d0")).toBe(false);
  });
});

describe("focusNavItem", () => {
  it("hands the focus to the control `pick` finds in the item, else to the item", () => {
    Element.prototype.scrollIntoView ??= () => {};
    const { container } = render(<List id="a" count={3} />);
    act(() => focusNavItem(container, 2, (item) => item.querySelector<HTMLElement>("button")));
    expect(focused()).toBe("a2-action");
    act(() => focusNavItem(container, 1));
    expect(focused()).toBe("a1");
  });

  it("brings a virtualized item in first, then focuses its control", async () => {
    Element.prototype.scrollIntoView ??= () => {};
    const reveal = vi.fn();
    const { container, rerender } = render(<List id="a" count={5} mounted={2} reveal={reveal} />);
    act(() => focusNavItem(container, 4, (item) => item.querySelector<HTMLElement>("button")));
    expect(reveal).toHaveBeenCalledWith(4);
    rerender(<List id="a" count={5} reveal={reveal} />);
    await waitFor(() => expect(focused()).toBe("a4-action"));
  });
});