import type { Assertion, JestAssertion } from "vitest";
import { describe, expect, test } from "vitest";
import type { Easing } from ".";
import { all, allNames, findEasingByName } from ".";

type NumberAssertion = {
  [K in keyof Assertion<number>]: Assertion<number>[K] extends
    (it: number) => void ? K : never;
}[keyof Assertion<number>];

function expectEasing(
  easing: Easing,
  middle: NumberAssertion,
): void {
  expect(easing.eval(0)).toBe(0);
  // despite the elaborate typing above, it still doesn't work without an as-cast
  const ass = expect(easing.eval(0.5));
  (ass[middle] as (it: number) => void)(0.5);
  expect(easing.eval(1)).toBe(1);
}

describe("easing", () => {
  test("baseline", () => {
    expect(all).toBeDefined();
    expect(allNames).toBeDefined();
    expect(findEasingByName).toBeDefined();
    expect(() => findEasingByName("")).not.toThrow();
    const easing = findEasingByName("");
    expect(easing).toBeDefined();
    expect(easing.name).toBe("Linear");
    expect(easing.eval).toBeDefined();
    expect(() => easing.eval(0)).not.toThrow();
  });
  test("Linear", () => {
    const easing = findEasingByName("Linear");
    expectEasing(easing, "toBe");
  });
  test("InCubic", () => {
    const easing = findEasingByName("InCubic");
    expectEasing(easing, "toBeLessThan");
  });
  test("OutCubic", () => {
    const easing = findEasingByName("OutCubic");
    expectEasing(easing, "toBeGreaterThan");
  });
  test("InOutCubic", () => {
    const easing = findEasingByName("InOutCubic");
    expectEasing(easing, "toBe");
  });
  test("InExpo", () => {
    const easing = findEasingByName("InExpo");
    expectEasing(easing, "toBeLessThan");
  });
  test("OutExpo", () => {
    const easing = findEasingByName("OutExpo");
    expectEasing(easing, "toBeGreaterThan");
  });
  test("InOutExpo", () => {
    const easing = findEasingByName("InOutExpo");
    expectEasing(easing, "toBe");
  });
  test("find", () => {
    expect(allNames).toContain("OutExpo");
    expect(allNames).toContain("InOutCubic");
    for (const name of allNames) {
      const easing = findEasingByName(name);
      expect(easing).toBeDefined();
      expect(easing.name).toBe(name);
      expect(all).toContain(easing);
    }
  });
});