////////////////////////////////////////////////////////////////////////////////
/// @brief test case for Futures/Try object
///
/// @file
///
/// DISCLAIMER
///
/// Copyright 2018 ArangoDB GmbH, Cologne, Germany
///
/// Licensed under the Apache License, Version 2.0 (the "License");
/// you may not use this file except in compliance with the License.
/// You may obtain a copy of the License at
///
///     http://www.apache.org/licenses/LICENSE-2.0
///
/// Unless required by applicable law or agreed to in writing, software
/// distributed under the License is distributed on an "AS IS" BASIS,
/// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
/// See the License for the specific language governing permissions and
/// limitations under the License.
///
/// Copyright holder is ArangoDB GmbH, Cologne, Germany
///
/// @author Simon Grätzer
////////////////////////////////////////////////////////////////////////////////

#include "Futures/Promise.h"

#include "gtest/gtest.h"

using namespace arangodb::futures;

namespace {
auto makeValid() {
  auto valid = Promise<int>();
  EXPECT_TRUE(valid.valid());
  return valid;
}
auto makeInvalid() {
  auto invalid = Promise<int>::makeEmpty();
  EXPECT_FALSE(invalid.valid());
  return invalid;
}
template <typename T>
constexpr typename std::decay<T>::type copy(T&& value) noexcept(
    noexcept(typename std::decay<T>::type(std::forward<T>(value)))) {
  return std::forward<T>(value);
}

typedef std::domain_error eggs_t;
static eggs_t eggs("eggs");
}  // namespace

// -----------------------------------------------------------------------------
// --SECTION--                                                        test suite
// -----------------------------------------------------------------------------

TEST(PromiseTest, makeEmpty) {
  auto p = Promise<int>::makeEmpty();
  ASSERT_TRUE(p.isFulfilled());
}

TEST(PromiseTest, special) {
  ASSERT_FALSE(std::is_copy_constructible<Promise<int>>::value);
  ASSERT_FALSE(std::is_copy_assignable<Promise<int>>::value);
  ASSERT_TRUE(std::is_move_constructible<Promise<int>>::value);
  ASSERT_TRUE(std::is_move_assignable<Promise<int>>::value);
}

TEST(PromiseTest, getFuture) {
  Promise<int> p;
  Future<int> f = p.getFuture();
  ASSERT_FALSE(f.isReady());
}

TEST(PromiseTest, setValueUnit) {
  Promise<Unit> p;
  p.setValue();
}

TEST(PromiseTest, ctorPostconditionValid) {
  // Ctors/factories that promise valid -- postcondition: valid()

#define DOIT(CREATION_EXPR)    \
  do {                         \
    auto p1 = (CREATION_EXPR); \
    ASSERT_TRUE(p1.valid());   \
    auto p2 = std::move(p1);   \
    ASSERT_FALSE(p1.valid()); \
    ASSERT_TRUE(p2.valid());   \
  } while (false)

  DOIT(makeValid());
  DOIT(Promise<int>());
  DOIT(Promise<int>{});
  DOIT(Promise<Unit>());
  DOIT(Promise<Unit>{});

#undef DOIT
}

TEST(PromiseTest, ctorPostconditionInvali) {
  // Ctors/factories that promise invalid -- postcondition: !valid()

#define DOIT(CREATION_EXPR)    \
  do {                         \
    auto p1 = (CREATION_EXPR); \
    ASSERT_FALSE(p1.valid()); \
    auto p2 = std::move(p1);   \
    ASSERT_FALSE(p1.valid()); \
    ASSERT_FALSE(p2.valid()); \
  } while (false)

  DOIT(makeInvalid());
  DOIT(Promise<int>::makeEmpty());

#undef DOIT
}

TEST(PromiseTest, lacksPreconditionValid) {
  // Ops that don't throw PromiseInvalid if !valid() --
  // without precondition: valid()

#define DOIT(STMT)        \
  do {                    \
    auto p = makeValid(); \
    { STMT; }             \
    copy(std::move(p));   \
    STMT;                 \
  } while (false)

  // misc methods that don't require isValid()
  DOIT(p.valid());
  DOIT(p.isFulfilled());

  // move-ctor - move-copy to local, copy(), pass-by-move-value
  DOIT(auto other = std::move(p));
  DOIT(copy(std::move(p)));
  DOIT(([](auto) {})(std::move(p)));

  // move-assignment into either {valid | invalid}
  DOIT({
    auto other = makeValid();
    other = std::move(p);
  });
  DOIT({
    auto other = makeInvalid();
    other = std::move(p);
  });

#undef DOIT
}

TEST(PromiseTest, hasPreconditionValid) {
  // Ops that require validity; precondition: valid();
  // throw PromiseInvalid if !valid()

#define DOIT(STMT)        \
  do {                    \
    auto p = makeValid(); \
    STMT;                 \
    ::copy(std::move(p)); \
    EXPECT_ANY_THROW(STMT); \
  } while (false)

  auto const except = std::logic_error("foo");
  auto const ewrap = std::make_exception_ptr(except);

  DOIT(p.getFuture());
  DOIT(p.setException(except));
  DOIT(p.setException(ewrap));
  // DOIT(p.setInterruptHandler([](auto&) {}));
  DOIT(p.setValue(42));
  DOIT(p.setTry(Try<int>(42)));
  DOIT(p.setTry(Try<int>(ewrap)));
  DOIT(p.setWith([] { return 42; }));

#undef DOIT
}

TEST(PromiseTest, hasPostconditionValid) {
  // Ops that preserve validity -- postcondition: valid()

#define DOIT(STMT)          \
  do {                      \
    auto p = makeValid();   \
    STMT;                   \
    ASSERT_TRUE(p.valid()); \
  } while (false)

  auto const swallow = [](auto) {};

  DOIT(swallow(p.valid()));  // p.valid() itself preserves validity
  DOIT(swallow(p.isFulfilled()));

#undef DOIT
}

TEST(PromiseTest, hasPostconditionInvalid) {
  // Ops that consume *this -- postcondition: !valid()

#define DOIT(CTOR, STMT)      \
  do {                        \
    auto p = (CTOR);          \
    STMT;                     \
    ASSERT_FALSE(p.valid()); \
  } while (false)

  // move-ctor of {valid|invalid}
  DOIT(makeValid(), { auto other{std::move(p)}; });
  DOIT(makeInvalid(), { auto other{std::move(p)}; });

  // move-assignment of {valid|invalid} into {valid|invalid}
  DOIT(makeValid(), {
    auto other = makeValid();
    other = std::move(p);
  });
  DOIT(makeValid(), {
    auto other = makeInvalid();
    other = std::move(p);
  });
  DOIT(makeInvalid(), {
    auto other = makeValid();
    other = std::move(p);
  });
  DOIT(makeInvalid(), {
    auto other = makeInvalid();
    other = std::move(p);
  });

  // pass-by-value of {valid|invalid}
  DOIT(makeValid(), {
    auto const byval = [](auto) {};
    byval(std::move(p));
  });
  DOIT(makeInvalid(), {
    auto const byval = [](auto) {};
    byval(std::move(p));
  });

#undef DOIT
}

TEST(PromiseTest, setValue) {
  Promise<int> fund;
  auto ffund = fund.getFuture();
  fund.setValue(42);
  ASSERT_TRUE(42 == ffund.get());

  struct Foo {
    std::string name;
    int value;
  };

  Promise<Foo> pod;
  auto fpod = pod.getFuture();
  Foo f = {"the answer", 42};
  pod.setValue(f);
  Foo f2 = fpod.get();
  ASSERT_TRUE(f.name == f2.name);
  ASSERT_TRUE(f.value == f2.value);

  pod = Promise<Foo>();
  fpod = pod.getFuture();
  pod.setValue(std::move(f2));
  Foo f3 = fpod.get();
  ASSERT_TRUE(f.name == f3.name);
  ASSERT_TRUE(f.value == f3.value);

  Promise<std::unique_ptr<int>> mov;
  auto fmov = mov.getFuture();
  mov.setValue(std::make_unique<int>(42));
  std::unique_ptr<int> ptr = std::move(fmov).get();
  ASSERT_TRUE(42 == *ptr);

  Promise<Unit> v;
  auto fv = v.getFuture();
  v.setValue();
  ASSERT_TRUE(fv.isReady());
}

TEST(PromiseTest, setException) {
  {
    Promise<int> p;
    auto f = p.getFuture();
    p.setException(eggs);
    EXPECT_THROW(f.get(), eggs_t);
  }
  {
    Promise<int> p;
    auto f = p.getFuture();
    p.setException(std::make_exception_ptr(eggs));
    EXPECT_THROW(f.get(), eggs_t);
  }
}

TEST(PromiseTest, setWith) {
  {
    Promise<int> p;
    auto f = p.getFuture();
    p.setWith([] { return 42; });
    ASSERT_TRUE(42 == f.get());
  }
  {
    Promise<int> p;
    auto f = p.getFuture();
    p.setWith([]() -> int { throw eggs; });
    EXPECT_THROW(f.get(), eggs_t);
  }
}

TEST(PromiseTest, isFulfilled) {
  Promise<int> p;

  ASSERT_FALSE(p.isFulfilled());
  p.setValue(42);
  ASSERT_TRUE(p.isFulfilled());
}

TEST(PromiseTest, isFulfilledWithFuture) {
  Promise<int> p;
  auto f = p.getFuture();  // so core_ will become null

  ASSERT_FALSE(p.isFulfilled());
  p.setValue(42);  // after here
  ASSERT_TRUE(p.isFulfilled());
}

TEST(PromiseTest, brokenOnDelete) {
  auto p = std::make_unique<Promise<int>>();
  auto f = p->getFuture();

  ASSERT_FALSE(f.isReady());

  p.reset();

  ASSERT_TRUE(f.isReady());

  auto t = f.getTry();

  ASSERT_TRUE(t.hasException());
  EXPECT_THROW(t.throwIfFailed(), FutureException);
  // ASSERT_TRUE(t.hasException<BrokenPromise>());
}

/*TEST(PromiseTest, brokenPromiseHasTypeInfo) {
    auto pInt = std::make_unique<Promise<int>>();
    auto fInt = pInt->getFuture();

    auto pFloat = std::make_unique<Promise<float>>();
    auto fFloat = pFloat->getFuture();

    pInt.reset();
    pFloat.reset();

  try {
    auto whatInt = fInt.getTry().exception().what();
  } catch(e) {

  }
    auto whatFloat = fFloat.getTry().exception().what();

    ASSERT_TRUE(whatInt != whatFloat);
  }*/