import "dotenv/config";
import Prando from 'prando';
import { Gen, listOf, property, shrinklist, someInt } from "./property";

function arrayEquals<A>(a: A[], b: A[]): boolean {
  return Array.isArray(a) &&
    Array.isArray(b) &&
    a.length === b.length &&
    a.every((val, index) => val === b[index]);
}

function reverse<A>(arr: A[]): A[] {
  let result = [];
  for (let i = arr.length - 1; i >= 0; i--) {
    result.push(arr[i]);
  }
  return result;
}

function reverse_is_self_inverse(arr: number[]): boolean {
  return arrayEquals(reverse(reverse(arr)), arr);
}

function gen2lists<A>(gen: Gen<A>): Gen<[A[], A[]]> {
  return (rng: Prando) => {
    let gl = listOf(gen)(rng);
    return (size: number) => {
      return [gl(size), gl(size)]
    };
  };
}

function reverse_with_two_lists<A>(arrs: [A[], A[]]): boolean {
  return arrayEquals(reverse(arrs[0].concat(arrs[1])),
    reverse(arrs[0]).concat(reverse(arrs[1])));
}

function shrink2lists<A>([l1, l2]: [A[], A[]]): [A[], A[]][] {
  let result: [A[], A[]][] = [];
  let s1 = shrinklist(l1);
  let s2 = shrinklist(l2);
  for (let i = 0; i < s1.length; i++) {
    let j = s2.length - i -1;
    let news2 = j >= 0 ? s2[j] : [];
    result.push([s1[i], news2]);
  }
  return result;
}

let prop_reverse_with_two_lists =
  property<[number[], number[]]>(reverse_with_two_lists, gen2lists(someInt), shrink2lists);

let prop_reverse_is_self_inverse =
  property(reverse_is_self_inverse, listOf(someInt), shrinklist);

async function main() {
  let rng = new Prando(Math.random() * 1000);
  let reverse_append_result = prop_reverse_with_two_lists(rng, 0);
  let reverse_reverse_result = prop_reverse_is_self_inverse(rng, 0);
  console.log('result: ' + JSON.stringify(reverse_append_result));
  console.log('result: ' + JSON.stringify(reverse_reverse_result));
}

main();