/*
 * Copyright (c) Contributors to the Open 3D Engine Project.
 * For complete copyright and license terms please see the LICENSE at the root of this distribution.
 *
 * SPDX-License-Identifier: Apache-2.0 OR MIT
 *
 */

#include <AzCore/UnitTest/TestTypes.h>
#include <AzCore/std/math.h>

namespace UnitTest
{
    template<typename T>
    class StdMathTest : public ::testing::Test
    {
    };

    using MathTestConfigs = ::testing::Types<float, double, long double>;
    TYPED_TEST_SUITE(StdMathTest, MathTestConfigs);

    TYPED_TEST(StdMathTest, LerpOperations)
    {
        using AZStd::lerp;
        using ::testing::Eq;
        using T = TypeParam;

        constexpr T maxNumber = AZStd::numeric_limits<T>::max();
        constexpr T eps = AZStd::numeric_limits<T>::epsilon();
        constexpr T a{ 42 };

        // exactness: lerp(a,b,0)==a && lerp(a,b,1)==b
        EXPECT_THAT(lerp(eps, maxNumber, T(0)), Eq(eps));
        EXPECT_THAT(lerp(eps, maxNumber, T(1)), Eq(maxNumber));

        // consistency: lerp(a,a,t)==a
        EXPECT_THAT(lerp(a, a, T(0.5)), Eq(a));
        EXPECT_THAT(lerp(eps, eps, T(0.5)), Eq(eps));

        // a few generic tests taken from MathUtilTests.cpp
        EXPECT_EQ(T(2.5), lerp(T(2), T(4), T(0.25)));
        EXPECT_EQ(T(6.0), lerp(T(2), T(4), T(2.0)));
        EXPECT_EQ(T(3.5), lerp(T(2), T(4), T(0.75)));
        EXPECT_EQ(T(0.0), lerp(T(2), T(4), T(-1.0)));
    }
} // namespace UnitTest