/*
  ==============================================================================

   This file is part of the JUCE 6 technical preview.
   Copyright (c) 2020 - Raw Material Software Limited

   You may use this code under the terms of the GPL v3
   (see www.gnu.org/licenses).

   For this technical preview, this file is not subject to commercial licensing.

   JUCE IS PROVIDED "AS IS" WITHOUT ANY WARRANTY, AND ALL WARRANTIES, WHETHER
   EXPRESSED OR IMPLIED, INCLUDING MERCHANTABILITY AND FITNESS FOR PURPOSE, ARE
   DISCLAIMED.

  ==============================================================================
*/

#if JUCE_ENABLE_ALLOCATION_HOOKS
#define JUCE_FAIL_ON_ALLOCATION_IN_SCOPE const UnitTestAllocationChecker checker (*this)
#else
#define JUCE_FAIL_ON_ALLOCATION_IN_SCOPE
#endif

namespace juce
{
namespace dsp
{
namespace
{

class ConstructCounts
{
    auto tie() const noexcept { return std::tie (constructions, copies, moves, calls, destructions); }

public:
    int constructions = 0;
    int copies        = 0;
    int moves         = 0;
    int calls         = 0;
    int destructions  = 0;

    ConstructCounts withConstructions (int i) const noexcept { auto c = *this; c.constructions = i; return c; }
    ConstructCounts withCopies        (int i) const noexcept { auto c = *this; c.copies        = i; return c; }
    ConstructCounts withMoves         (int i) const noexcept { auto c = *this; c.moves         = i; return c; }
    ConstructCounts withCalls         (int i) const noexcept { auto c = *this; c.calls         = i; return c; }
    ConstructCounts withDestructions  (int i) const noexcept { auto c = *this; c.destructions  = i; return c; }

    bool operator== (const ConstructCounts& other) const noexcept { return tie() == other.tie(); }
    bool operator!= (const ConstructCounts& other) const noexcept { return tie() != other.tie(); }
};

String& operator<< (String& str, const ConstructCounts& c)
{
    return str << "{ constructions: " << c.constructions
               << ", copies: " << c.copies
               << ", moves: " << c.moves
               << ", calls: " << c.calls
               << ", destructions: " << c.destructions
               << " }";
}

class FixedSizeFunctionTest  : public UnitTest
{
    static void toggleBool (bool& b) { b = ! b; }

    struct ConstructCounter
    {
        explicit ConstructCounter (ConstructCounts& countsIn)
            : counts (countsIn) {}

        ConstructCounter (const ConstructCounter& c)
            : counts (c.counts)
        {
            counts.copies += 1;
        }

        ConstructCounter (ConstructCounter&& c) noexcept
            : counts (c.counts)
        {
            counts.moves += 1;
        }

        ~ConstructCounter() noexcept { counts.destructions += 1; }

        void operator()() const noexcept { counts.calls += 1; }

        ConstructCounts& counts;
    };

public:
    FixedSizeFunctionTest()
        : UnitTest ("Fixed Size Function", UnitTestCategories::dsp)
    {}

    void runTest() override
    {
        beginTest ("Can be constructed and called from a lambda");
        {
            JUCE_FAIL_ON_ALLOCATION_IN_SCOPE;

            const auto result = 5;
            bool wasCalled = false;
            const auto lambda = [&] { wasCalled = true; return result; };

            const FixedSizeFunction<sizeof (lambda), int()> fn (lambda);
            const auto out = fn();

            expect (wasCalled);
            expectEquals (result, out);
        }

        beginTest ("void fn can be constructed from function with return value");
        {
            JUCE_FAIL_ON_ALLOCATION_IN_SCOPE;

            bool wasCalled = false;
            const auto lambda = [&] { wasCalled = true; return 5; };
            const FixedSizeFunction<sizeof (lambda), void()> fn (lambda);

            fn();
            expect (wasCalled);
        }

        beginTest ("Can be constructed and called from a function pointer");
        {
            JUCE_FAIL_ON_ALLOCATION_IN_SCOPE;

            bool state = false;

            const FixedSizeFunction<sizeof (void*), void (bool&)> fn (toggleBool);

            fn (state);
            expect (state);

            fn (state);
            expect (! state);

            fn (state);
            expect (state);
        }

        beginTest ("Default constructed functions throw if called");
        {
            const auto a = FixedSizeFunction<8, void()>();
            expectThrowsType (a(), std::bad_function_call)

            const auto b = FixedSizeFunction<8, void()> (nullptr);
            expectThrowsType (b(), std::bad_function_call)
        }

        beginTest ("Functions can be moved");
        {
            JUCE_FAIL_ON_ALLOCATION_IN_SCOPE;

            ConstructCounts counts;

            auto a = FixedSizeFunction<sizeof (ConstructCounter), void()> (ConstructCounter { counts });
            expectEquals (counts, ConstructCounts().withMoves (1).withDestructions (1)); // The temporary gets destroyed

            a();
            expectEquals (counts, ConstructCounts().withMoves (1).withDestructions (1).withCalls (1));

            const auto b = std::move (a);
            expectEquals (counts, ConstructCounts().withMoves (2).withDestructions (1).withCalls (1));

            b();
            expectEquals (counts, ConstructCounts().withMoves (2).withDestructions (1).withCalls (2));

            b();
            expectEquals (counts, ConstructCounts().withMoves (2).withDestructions (1).withCalls (3));
        }

        beginTest ("Functions are destructed properly");
        {
            JUCE_FAIL_ON_ALLOCATION_IN_SCOPE;

            ConstructCounts counts;
            const ConstructCounter toCopy { counts };

            {
                auto a = FixedSizeFunction<sizeof (ConstructCounter), void()> (toCopy);
                expectEquals (counts, ConstructCounts().withCopies (1));
            }

            expectEquals (counts, ConstructCounts().withCopies (1).withDestructions (1));
        }

        beginTest ("Avoid destructing functions that fail to construct");
        {
            struct BadConstructor
            {
                explicit BadConstructor (ConstructCounts& c)
                    : counts (c)
                {
                    counts.constructions += 1;
                    throw std::runtime_error { "this was meant to happen" };
                }

                ~BadConstructor() noexcept { counts.destructions += 1; }

                void operator()() const noexcept { counts.calls += 1; }

                ConstructCounts& counts;
            };

            ConstructCounts counts;

            expectThrowsType ((FixedSizeFunction<sizeof (BadConstructor), void()> (BadConstructor { counts })),
                              std::runtime_error)

            expectEquals (counts, ConstructCounts().withConstructions (1));
        }

        beginTest ("Equality checks work");
        {
            JUCE_FAIL_ON_ALLOCATION_IN_SCOPE;

            FixedSizeFunction<8, void()> a;
            expect (! bool (a));
            expect (a == nullptr);
            expect (nullptr == a);
            expect (! (a != nullptr));
            expect (! (nullptr != a));

            FixedSizeFunction<8, void()> b ([] {});
            expect (bool (b));
            expect (b != nullptr);
            expect (nullptr != b);
            expect (! (b == nullptr));
            expect (! (nullptr == b));
        }

        beginTest ("Functions can be cleared");
        {
            JUCE_FAIL_ON_ALLOCATION_IN_SCOPE;

            FixedSizeFunction<8, void()> fn ([] {});
            expect (bool (fn));

            fn = nullptr;
            expect (! bool (fn));
        }

        beginTest ("Functions can be assigned");
        {
            JUCE_FAIL_ON_ALLOCATION_IN_SCOPE;

            using Fn = FixedSizeFunction<8, void()>;

            int numCallsA = 0;
            int numCallsB = 0;

            Fn x;
            Fn y;
            expect (! bool (x));
            expect (! bool (y));

            x = [&] { numCallsA += 1; };
            y = [&] { numCallsB += 1; };
            expect (bool (x));
            expect (bool (y));

            x();
            expectEquals (numCallsA, 1);
            expectEquals (numCallsB, 0);

            y();
            expectEquals (numCallsA, 1);
            expectEquals (numCallsB, 1);

            x = std::move (y);
            expectEquals (numCallsA, 1);
            expectEquals (numCallsB, 1);

            x();
            expectEquals (numCallsA, 1);
            expectEquals (numCallsB, 2);
        }

        beginTest ("Functions may mutate internal state");
        {
            JUCE_FAIL_ON_ALLOCATION_IN_SCOPE;

            using Fn = FixedSizeFunction<64, void()>;

            Fn x;
            expect (! bool (x));

            int numCalls = 0;
            x = [&numCalls, counter = 0]() mutable { counter += 1; numCalls = counter; };
            expect (bool (x));

            expectEquals (numCalls, 0);

            x();
            expectEquals (numCalls, 1);

            x();
            expectEquals (numCalls, 2);
        }

        beginTest ("Functions can sink move-only parameters");
        {
            JUCE_FAIL_ON_ALLOCATION_IN_SCOPE;

            using Fn = FixedSizeFunction<64, int (std::unique_ptr<int>)>;

            auto value = 5;
            auto ptr = std::make_unique<int> (value);

            Fn fn = [] (std::unique_ptr<int> p) { return *p; };

            expect (value == fn (std::move (ptr)));
        }

        beginTest ("Functions be converted from smaller functions");
        {
            JUCE_FAIL_ON_ALLOCATION_IN_SCOPE;

            using SmallFn = FixedSizeFunction<20, void()>;
            using LargeFn = FixedSizeFunction<21, void()>;

            bool smallCalled = false;
            bool largeCalled = false;

            SmallFn small = [&smallCalled, a = std::array<char, 8>{}] { smallCalled = true; juce::ignoreUnused (a); };
            LargeFn large = [&largeCalled, a = std::array<char, 8>{}] { largeCalled = true; juce::ignoreUnused (a); };

            large = std::move (small);

            large();

            expect (smallCalled);
            expect (! largeCalled);
        }
    }
};

FixedSizeFunctionTest fixedSizedFunctionTest;

}
}
}
#undef JUCE_FAIL_ON_ALLOCATION_IN_SCOPE