import { describe, expect, it } from "vitest";
import { contentRect, cropToSourcePx } from "./cropGeometry";

describe("contentRect (display-px letterbox mapping)", () => {
  it("returns the full box when box aspect matches the video aspect", () => {
    // 16:9 picture in a 16:9 box → no bars, content == box
    expect(contentRect(1600, 900, 16 / 9)).toEqual({
      left: 0,
      top: 0,
      width: 1600,
      height: 900,
    });
  });

  it("pillarboxes (bars left/right) when the box is wider than the picture", () => {
    // 16:9 picture in a 2:1 box → full height, narrower centered width
    const r = contentRect(2000, 1000, 16 / 9)!;
    expect(r.height).toBe(1000);
    expect(r.width).toBeCloseTo(1000 * (16 / 9), 3);
    expect(r.top).toBe(0);
    expect(r.left).toBeCloseTo((2000 - 1000 * (16 / 9)) / 2, 3);
  });

  it("letterboxes (bars top/bottom) when the box is taller than the picture", () => {
    // 16:9 picture in a 1:1 box → full width, shorter centered height
    const r = contentRect(1000, 1000, 16 / 9)!;
    expect(r.width).toBe(1000);
    expect(r.height).toBeCloseTo(1000 / (16 / 9), 3);
    expect(r.left).toBe(0);
    expect(r.top).toBeCloseTo((1000 - 1000 / (16 / 9)) / 2, 3);
  });

  it("returns null for unmeasurable inputs", () => {
    expect(contentRect(0, 900, 16 / 9)).toBeNull();
    expect(contentRect(1600, 0, 16 / 9)).toBeNull();
    expect(contentRect(1600, 900, 0)).toBeNull();
    expect(contentRect(1600, 900, NaN)).toBeNull();
  });
});

describe("cropToSourcePx (fraction-of-content → even source px)", () => {
  it("scales content fractions straight to source pixels", () => {
    // A marquee anchored to the content rect: a fraction is a fraction of the real picture.
    expect(cropToSourcePx({ x: 0.25, y: 0.25, w: 0.5, h: 0.5 }, 1920, 1080)).toEqual({
      x: 480,
      y: 270,
      w: 960,
      h: 540,
    });
  });

  it("rounds to even dimensions", () => {
    // 0.1 * 1920 = 192 (even); 0.333 * 1080 = 359.64 → 360
    const c = cropToSourcePx({ x: 0.1, y: 0.333, w: 0.2, h: 0.111 }, 1920, 1080)!;
    expect(c.w % 2).toBe(0);
    expect(c.h % 2).toBe(0);
    expect(c.x % 2).toBe(0);
    expect(c.y % 2).toBe(0);
  });

  it("allows a top-left origin (x/y may be 0)", () => {
    const c = cropToSourcePx({ x: 0, y: 0, w: 0.5, h: 0.5 }, 1920, 1080)!;
    expect(c.x).toBe(0);
    expect(c.y).toBe(0);
  });

  it("clamps the window inside the frame so even-rounding can't overflow", () => {
    // A full-frame crop must stay exactly at the source size, not round past it.
    const c = cropToSourcePx({ x: 0, y: 0, w: 1, h: 1 }, 1921, 1081)!;
    expect(c.w).toBeLessThanOrEqual(1921);
    expect(c.h).toBeLessThanOrEqual(1081);
    expect(c.x + c.w).toBeLessThanOrEqual(1921);
    expect(c.y + c.h).toBeLessThanOrEqual(1081);
  });

  it("keeps x+w within the frame for an off-square region near the right edge", () => {
    const srcW = 1280;
    const srcH = 720;
    const c = cropToSourcePx({ x: 0.7, y: 0.1, w: 0.3, h: 0.8 }, srcW, srcH)!;
    expect(c.x + c.w).toBeLessThanOrEqual(srcW);
    expect(c.y + c.h).toBeLessThanOrEqual(srcH);
  });

  it("returns null for an unusable source size", () => {
    expect(cropToSourcePx({ x: 0, y: 0, w: 1, h: 1 }, 0, 1080)).toBeNull();
    expect(cropToSourcePx({ x: 0, y: 0, w: 1, h: 1 }, 1920, 0)).toBeNull();
  });
});