import { test, expect, describe } from "bun:test";
import {
  abs1,
  abs2,
  app1,
  app2,
  arr,
  convertToDebruijn,
  infer,
  unitTy,
  var1,
  var2,
} from ".";

describe("convertToDeBruijn", () => {
  test("K combinator", () => {
    const expr = abs1("x", unitTy(), abs1("y", unitTy(), var1("x")));
    const expr2 = abs2(unitTy(), abs2(unitTy(), var2(1)));

    expect(convertToDebruijn(expr)).toEqual(expr2);
  });

  test("S combinator", () => {
    const expr = abs1(
      "x",
      arr(unitTy(), arr(unitTy(), unitTy())),
      abs1(
        "y",
        arr(unitTy(), unitTy()),
        abs1(
          "z",
          unitTy(),
          app1(app1(var1("x"), var1("z")), app1(var1("y"), var1("z"))),
        ),
      ),
    );
    const expr2 = abs2(
      arr(unitTy(), arr(unitTy(), unitTy())),
      abs2(
        arr(unitTy(), unitTy()),
        abs2(unitTy(), app2(app2(var2(2), var2(0)), app2(var2(1), var2(0)))),
      ),
    );

    expect(convertToDebruijn(expr)).toEqual(expr2);
  });
});

describe("infer", () => {
  test("K combinator", () => {
    const expr = abs1("x", unitTy(), abs1("y", unitTy(), var1("x")));
    const expr2 = convertToDebruijn(expr);
    const ty = arr(unitTy(), arr(unitTy(), unitTy()));

    expect(infer(expr2)).toEqual(ty);
  });

  test("K combinator", () => {
    const expr = abs1("x", unitTy(), abs1("y", unitTy(), var1("x")));
    const expr2 = convertToDebruijn(expr);
    const ty = arr(unitTy(), arr(unitTy(), arr(unitTy(), unitTy())));

    expect(infer(expr2)).not.toEqual(ty);
  });
});