import { describe, expect, it } from "vitest";
import { separateShips, shipRotation, type FlightLayout } from "../src/map/layout";
import { mapStyle } from "../src/map/style";

const deg = (radians: number) => (radians * 180) / Math.PI;

describe("ships in flight (Step 10C.8)", () => {
  it("turns the up-pointing art to face the direction of travel", () => {
    expect(deg(shipRotation({ x: 0, y: 0 }, { x: 10, y: 0 }))).toBeCloseTo(90);
    expect(deg(shipRotation({ x: 0, y: 0 }, { x: 0, y: 10 }))).toBeCloseTo(180);
    expect(deg(shipRotation({ x: 0, y: 10 }, { x: 0, y: 0 }))).toBeCloseTo(0);
    expect(deg(shipRotation({ x: 10, y: 0 }, { x: 0, y: 0 }))).toBeCloseTo(270); // = -90°
  });

  const flight = (dispatchId: string, x = 100, y = 100): FlightLayout => ({
    dispatchId,
    from: { x: 0, y: 100 },
    to: { x: 200, y: 100 },
    center: { x, y },
    rotation: Math.PI / 2,
    size: 24,
    tap: 44,
  });

  it("spreads three ships at the same spot apart, at least a tap target apart", () => {
    const spread = separateShips([flight("a"), flight("b"), flight("c")]);
    const points = spread.map((f) => f.center);
    for (let i = 0; i < points.length; i++) {
      for (let j = i + 1; j < points.length; j++) {
        const d = Math.hypot(points[i]!.x - points[j]!.x, points[i]!.y - points[j]!.y);
        expect(d).toBeGreaterThanOrEqual(mapStyle.minTapPx);
      }
    }
    // Perpendicular to the (horizontal) route, centred on where they were.
    expect(points.map((p) => p.x)).toEqual([100, 100, 100]);
    expect(points.map((p) => p.y).reduce((a, b) => a + b) / 3).toBeCloseTo(100);
  });

  it("leaves ships that are already apart where they are", () => {
    const apart = [flight("a", 20), flight("b", 180)];
    expect(separateShips(apart)).toEqual(apart);
  });
});