// Copyright (c) 2017, the Dart project authors.  Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.

import "dart:async";
import "dart:math" show Random;
import "package:async/async.dart";
import "package:test/test.dart";

final someStack = StackTrace.current;
Result<int> res(int n) => Result<int>.value(n);
Result err(n) => ErrorResult("$n", someStack);

/// Helper function creating an iterable of futures.
Iterable<Future<int>> futures(int count, {bool throwWhen(int index)}) sync* {
  for (int i = 0; i < count; i++) {
    if (throwWhen != null && throwWhen(i)) {
      yield Future<int>.error("$i", someStack);
    } else {
      yield Future<int>.value(i);
    }
  }
}

main() {
  test("empty", () async {
    var all = await Result.captureAll<int>(futures(0));
    expect(all, []);
  });

  group("futures only,", () {
    test("single", () async {
      var all = await Result.captureAll<int>(futures(1));
      expect(all, [res(0)]);
    });

    test("multiple", () async {
      var all = await Result.captureAll<int>(futures(3));
      expect(all, [res(0), res(1), res(2)]);
    });

    test("error only", () async {
      var all =
          await Result.captureAll<int>(futures(1, throwWhen: (_) => true));
      expect(all, [err(0)]);
    });

    test("multiple error only", () async {
      var all =
          await Result.captureAll<int>(futures(3, throwWhen: (_) => true));
      expect(all, [err(0), err(1), err(2)]);
    });

    test("mixed error and value", () async {
      var all =
          await Result.captureAll<int>(futures(4, throwWhen: (x) => x.isOdd));
      expect(all, [res(0), err(1), res(2), err(3)]);
    });

    test("completion permutation 1-2-3", () async {
      var cs = List.generate(3, (_) => Completer<int>());
      var all = Result.captureAll<int>(cs.map((c) => c.future));
      expect(all, completion([res(1), res(2), err(3)]));
      await 0;
      cs[0].complete(1);
      await 0;
      cs[1].complete(2);
      await 0;
      cs[2].completeError("3", someStack);
    });

    test("completion permutation 1-3-2", () async {
      var cs = List.generate(3, (_) => Completer<int>());
      var all = Result.captureAll<int>(cs.map((c) => c.future));
      expect(all, completion([res(1), res(2), err(3)]));
      await 0;
      cs[0].complete(1);
      await 0;
      cs[2].completeError("3", someStack);
      await 0;
      cs[1].complete(2);
    });

    test("completion permutation 2-1-3", () async {
      var cs = List.generate(3, (_) => Completer<int>());
      var all = Result.captureAll<int>(cs.map((c) => c.future));
      expect(all, completion([res(1), res(2), err(3)]));
      await 0;
      cs[1].complete(2);
      await 0;
      cs[0].complete(1);
      await 0;
      cs[2].completeError("3", someStack);
    });

    test("completion permutation 2-3-1", () async {
      var cs = List.generate(3, (_) => Completer<int>());
      var all = Result.captureAll<int>(cs.map((c) => c.future));
      expect(all, completion([res(1), res(2), err(3)]));
      await 0;
      cs[1].complete(2);
      await 0;
      cs[2].completeError("3", someStack);
      await 0;
      cs[0].complete(1);
    });

    test("completion permutation 3-1-2", () async {
      var cs = List.generate(3, (_) => Completer<int>());
      var all = Result.captureAll<int>(cs.map((c) => c.future));
      expect(all, completion([res(1), res(2), err(3)]));
      await 0;
      cs[2].completeError("3", someStack);
      await 0;
      cs[0].complete(1);
      await 0;
      cs[1].complete(2);
    });

    test("completion permutation 3-2-1", () async {
      var cs = List.generate(3, (_) => Completer<int>());
      var all = Result.captureAll<int>(cs.map((c) => c.future));
      expect(all, completion([res(1), res(2), err(3)]));
      await 0;
      cs[2].completeError("3", someStack);
      await 0;
      cs[1].complete(2);
      await 0;
      cs[0].complete(1);
    });

    var seed = Random().nextInt(0x100000000);
    int n = 25; // max 32, otherwise rnd.nextInt(1<<n) won't work.
    test("randomized #$n seed:${seed.toRadixString(16)}", () async {
      var cs = List.generate(n, (_) => Completer<int>());
      var all = Result.captureAll<int>(cs.map((c) => c.future));
      var rnd = Random(seed);
      var throwFlags = rnd.nextInt(1 << n); // Bit-flag for throwing.
      bool throws(index) => (throwFlags & (1 << index)) != 0;
      var expected = List.generate(n, (x) => throws(x) ? err(x) : res(x));

      expect(all, completion(expected));

      var completeFunctions = List<Function()>.generate(n, (i) {
        var c = cs[i];
        return () =>
            throws(i) ? c.completeError("$i", someStack) : c.complete(i);
      });
      completeFunctions.shuffle(rnd);
      for (int i = 0; i < n; i++) {
        await 0;
        completeFunctions[i]();
      }
    });
  });
  group("values only,", () {
    test("single", () async {
      var all = await Result.captureAll<int>(<int>[1]);
      expect(all, [res(1)]);
    });
    test("multiple", () async {
      var all = await Result.captureAll<int>(<int>[1, 2, 3]);
      expect(all, [res(1), res(2), res(3)]);
    });
  });
  group("mixed futures and values,", () {
    test("no error", () async {
      var all = await Result.captureAll<int>(<FutureOr<int>>[
        1,
        Future<int>(() => 2),
        3,
        Future<int>.value(4),
      ]);
      expect(all, [res(1), res(2), res(3), res(4)]);
    });
    test("error", () async {
      var all = await Result.captureAll<int>(<FutureOr<int>>[
        1,
        Future<int>(() => 2),
        3,
        Future<int>(() async => await Future.error("4", someStack)),
        Future<int>.value(5)
      ]);
      expect(all, [res(1), res(2), res(3), err(4), res(5)]);
    });
  });
}