import { describe, expect, test } from "bun:test";
import { rotatedRectBounds, rotatedRectCorners } from "./rotated-rect";

describe("rotated rectangle geometry", () => {
  test("interprets rotation as radians and keeps the center anchored", () => {
    const corners = rotatedRectCorners({ x: 10, y: 20, w: 40, h: 20 }, Math.PI / 2);

    expectPoint(corners[0], { x: 40, y: 10 });
    expectPoint(corners[1], { x: 40, y: 50 });
    expectPoint(corners[2], { x: 20, y: 10 });
    expectPoint(corners[3], { x: 20, y: 50 });
    expect((corners[0].x + corners[3].x) / 2).toBeCloseTo(30);
    expect((corners[0].y + corners[3].y) / 2).toBeCloseTo(30);
  });

  test("expands axis-aligned clipping bounds around a rotated quad", () => {
    const bounds = rotatedRectBounds({ x: 10, y: 20, w: 40, h: 20 }, Math.PI / 2);

    expect(bounds.x).toBeCloseTo(20);
    expect(bounds.y).toBeCloseTo(10);
    expect(bounds.w).toBeCloseTo(20);
    expect(bounds.h).toBeCloseTo(40);
  });

  test("preserves an unrotated rectangle exactly", () => {
    const rect = { x: 10, y: 20, w: 40, h: 20 };
    expect(rotatedRectBounds(rect, 0)).toBe(rect);
    expect(rotatedRectCorners(rect, 0)).toEqual([
      { x: 10, y: 20 },
      { x: 50, y: 20 },
      { x: 10, y: 40 },
      { x: 50, y: 40 },
    ]);
  });
});

function expectPoint(actual: { x: number; y: number }, expected: { x: number; y: number }) {
  expect(actual.x).toBeCloseTo(expected.x);
  expect(actual.y).toBeCloseTo(expected.y);
}