/**
 * @file PaneGrid.test.ts
 * @description The pane drop preview: it draws where the dragged pane will
 * actually land (`dropPreview` over `applyDrop`), not half of the target's
 * current box, and nothing for a drop that changes nothing; and the label
 * naming what a drop does (`dropAction`).
 * @author Nguyễn Ngọc Trí Vĩ <vinnt@smartgift.vn>
 */

import { describe, expect, it } from "vitest";
import { dropAction, dropPreview } from "../PaneGrid";
import { pane, split, type PaneLayout } from "../../../lib/paneLayout";

const AB: PaneLayout = { root: split("row", pane(0), pane(1)), focus: 0 };

describe("dropPreview", () => {
  it("a shown pane leaves its place first: A onto B's top is the whole top half", () => {
    expect(dropPreview(AB, 0, 1, "top")).toEqual({ slot: 0, x: 0, y: 0, w: 1, h: 0.5 });
  });

  it("a pane from another tab splits the target's current box", () => {
    expect(dropPreview(AB, 2, 1, "bottom")).toEqual({ slot: 2, x: 0.5, y: 0.5, w: 0.5, h: 0.5 });
  });

  it("the center swaps into the target's box", () => {
    expect(dropPreview(AB, 0, 1, "center")).toEqual({ slot: 0, x: 0.5, y: 0, w: 0.5, h: 1 });
  });

  it("nothing on its own pane or on a refused move", () => {
    expect(dropPreview(AB, 0, 0, "left")).toBeNull();
    const full: PaneLayout = {
      root: split("row", split("col", pane(0), pane(1)), split("col", pane(2), pane(3))),
      focus: 0,
    };
    expect(dropPreview(full, 5, 0, "left")).toBeNull();
  });
});

describe("dropAction", () => {
  it("an edge places the pane on that side", () => {
    expect(dropAction(AB, 0, "left")).toBe("panes.drop.left");
    expect(dropAction(AB, 2, "bottom")).toBe("panes.drop.bottom");
  });

  it("the center swaps a shown pane, or shows one from another tab in its place", () => {
    expect(dropAction(AB, 0, "center")).toBe("panes.drop.swap");
    expect(dropAction(AB, 2, "center")).toBe("panes.drop.replace");
  });
});