import * as Arr from 'ephox/katamari/api/Arr';
import Jsc from '@ephox/wrap-jsverify';
import { UnitTest, assert } from '@ephox/bedrock';

UnitTest.test('FlattenTest', function () {
  const check = function (expected, input: any[]) {
    assert.eq(expected, Arr.flatten(input));
    assert.eq(expected, Arr.flatten(Object.freeze(input.slice())));
  };

  check([], []);
  check([1], [[1]]);
  check([1, 2], [[1], [2]]);
  check([1, 2, 3, 4, 5], [[1, 2], [], [3], Object.freeze([4, 5]), []]);

  const checkError = function (input) {
    let message;
    try {
      Arr.flatten(input);
    } catch (e) {
      message = e.message ? e.message : e;
    }

    if (message === undefined) {
      assert.fail('Arr.flatten did not throw an error for input ' + input);
    }
  };

  checkError([{}]);
  checkError([function () {}]);
  checkError([42]);

  Jsc.property(
    'Flatten is symmetric with chunking',
    Jsc.array(Jsc.json),
    Jsc.integer(1, 5),
    function (arr, chunkSize) {
      const chunks = Arr.chunk(arr, chunkSize);
      const bound = Arr.flatten(chunks);
      return Jsc.eq(arr, bound);
    }
  );

  Jsc.property('Wrap then flatten array is identity', '[json]', function (arr) {
    return Jsc.eq(
      Arr.flatten(Arr.pure(arr)),
      arr
    );
  });

  Jsc.property('Mapping pure then flattening array is identity', '[json]', function (arr) {
    return Jsc.eq(
      Arr.flatten(Arr.map(arr, Arr.pure)),
      arr
    );
  });

  Jsc.property('Flattening two lists === concat', '[json]', '[json]', function (xs, ys) {
    return Jsc.eq(
      Arr.flatten([xs, ys]),
      xs.concat(ys)
    );
  });
});