///////////////////////////////////////////////////////////////////////////////
//
// Copyright (c) 2015 Microsoft Corporation. All rights reserved.
//
// This code is licensed under the MIT License (MIT).
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.
//
///////////////////////////////////////////////////////////////////////////////

#include <catch/catch.hpp>

#include <gsl/gsl>

#include <memory>
#include <string>
#include <vector>

using namespace gsl;

struct MyBase
{
};
struct MyDerived : public MyBase
{
};
struct Unrelated
{
};

// stand-in for a user-defined ref-counted class
template <typename T>
struct RefCounted
{
    RefCounted(T* p) : p_(p) {}
    operator T*() { return p_; }
    T* p_;
};

// user defined smart pointer with comparison operators returning non bool value
template <typename T>
struct CustomPtr
{
    CustomPtr(T* p) : p_(p) {}
    operator T*() { return p_; }
    bool operator!=(std::nullptr_t) const { return p_ != nullptr; }
    T* p_ = nullptr;
};

template <typename T, typename U>
std::string operator==(CustomPtr<T> const& lhs, CustomPtr<U> const& rhs)
{
    return reinterpret_cast<const void*>(lhs.p_) == reinterpret_cast<const void*>(rhs.p_) ? "true"
                                                                                          : "false";
}

template <typename T, typename U>
std::string operator!=(CustomPtr<T> const& lhs, CustomPtr<U> const& rhs)
{
    return reinterpret_cast<const void*>(lhs.p_) != reinterpret_cast<const void*>(rhs.p_) ? "true"
                                                                                          : "false";
}

template <typename T, typename U>
std::string operator<(CustomPtr<T> const& lhs, CustomPtr<U> const& rhs)
{
    return reinterpret_cast<const void*>(lhs.p_) < reinterpret_cast<const void*>(rhs.p_) ? "true"
                                                                                         : "false";
}

template <typename T, typename U>
std::string operator>(CustomPtr<T> const& lhs, CustomPtr<U> const& rhs)
{
    return reinterpret_cast<const void*>(lhs.p_) > reinterpret_cast<const void*>(rhs.p_) ? "true"
                                                                                         : "false";
}

template <typename T, typename U>
std::string operator<=(CustomPtr<T> const& lhs, CustomPtr<U> const& rhs)
{
    return reinterpret_cast<const void*>(lhs.p_) <= reinterpret_cast<const void*>(rhs.p_) ? "true"
                                                                                          : "false";
}

template <typename T, typename U>
std::string operator>=(CustomPtr<T> const& lhs, CustomPtr<U> const& rhs)
{
    return reinterpret_cast<const void*>(lhs.p_) >= reinterpret_cast<const void*>(rhs.p_) ? "true"
                                                                                          : "false";
}

bool helper(not_null<int*> p) { return *p == 12; }

TEST_CASE("TestNotNullConstructors")
{
#ifdef CONFIRM_COMPILATION_ERRORS
    not_null<int*> p = nullptr;         // yay...does not compile!
    not_null<std::vector<char>*> p = 0; // yay...does not compile!
    not_null<int*> p;                   // yay...does not compile!
    std::unique_ptr<int> up = std::make_unique<int>(120);
    not_null<int*> p = up;

    // Forbid non-nullptr assignable types
    not_null<std::vector<int>> f(std::vector<int>{1});
    not_null<int> z(10);
    not_null<std::vector<int>> y({1, 2});
#endif
    int i = 12;
    auto rp = RefCounted<int>(&i);
    not_null<int*> p(rp);
    CHECK(p.get() == &i);

    not_null<std::shared_ptr<int>> x(
        std::make_shared<int>(10)); // shared_ptr<int> is nullptr assignable
}

TEST_CASE("TestNotNullCasting")
{
    MyBase base;
    MyDerived derived;
    Unrelated unrelated;
    not_null<Unrelated*> u = &unrelated;
    (void) u;
    not_null<MyDerived*> p = &derived;
    not_null<MyBase*> q = &base;
    q = p; // allowed with heterogeneous copy ctor
    CHECK(q == p);

#ifdef CONFIRM_COMPILATION_ERRORS
    q = u; // no viable conversion possible between MyBase* and Unrelated*
    p = q; // not possible to implicitly convert MyBase* to MyDerived*

    not_null<Unrelated*> r = p;
    not_null<Unrelated*> s = reinterpret_cast<Unrelated*>(p);
#endif
    not_null<Unrelated*> t = reinterpret_cast<Unrelated*>(p.get());
    CHECK(reinterpret_cast<void*>(p.get()) == reinterpret_cast<void*>(t.get()));
}

TEST_CASE("TestNotNullAssignment")
{
    int i = 12;
    not_null<int*> p = &i;
    CHECK(helper(p));

    int* q = nullptr;
    CHECK_THROWS_AS(p = q, fail_fast);
}

TEST_CASE("TestNotNullRawPointerComparison")
{
    int ints[2] = {42, 43};
    int* p1 = &ints[0];
    const int* p2 = &ints[1];

    using NotNull1 = not_null<decltype(p1)>;
    using NotNull2 = not_null<decltype(p2)>;

    CHECK((NotNull1(p1) == NotNull1(p1)) == true);
    CHECK((NotNull1(p1) == NotNull2(p2)) == false);

    CHECK((NotNull1(p1) != NotNull1(p1)) == false);
    CHECK((NotNull1(p1) != NotNull2(p2)) == true);

    CHECK((NotNull1(p1) < NotNull1(p1)) == false);
    CHECK((NotNull1(p1) < NotNull2(p2)) == (p1 < p2));
    CHECK((NotNull2(p2) < NotNull1(p1)) == (p2 < p1));

    CHECK((NotNull1(p1) > NotNull1(p1)) == false);
    CHECK((NotNull1(p1) > NotNull2(p2)) == (p1 > p2));
    CHECK((NotNull2(p2) > NotNull1(p1)) == (p2 > p1));

    CHECK((NotNull1(p1) <= NotNull1(p1)) == true);
    CHECK((NotNull1(p1) <= NotNull2(p2)) == (p1 <= p2));
    CHECK((NotNull2(p2) <= NotNull1(p1)) == (p2 <= p1));

    CHECK((NotNull1(p1) >= NotNull1(p1)) == true);
    CHECK((NotNull1(p1) >= NotNull2(p2)) == (p1 >= p2));
    CHECK((NotNull2(p2) >= NotNull1(p1)) == (p2 >= p1));
}

TEST_CASE("TestNotNullSharedPtrComparison")
{
    auto sp1 = std::make_shared<int>(42);
    auto sp2 = std::make_shared<const int>(43);

    using NotNullSp1 = not_null<decltype(sp1)>;
    using NotNullSp2 = not_null<decltype(sp2)>;

    CHECK((NotNullSp1(sp1) == NotNullSp1(sp1)) == true);
    CHECK((NotNullSp1(sp1) == NotNullSp2(sp2)) == false);

    CHECK((NotNullSp1(sp1) != NotNullSp1(sp1)) == false);
    CHECK((NotNullSp1(sp1) != NotNullSp2(sp2)) == true);

    CHECK((NotNullSp1(sp1) < NotNullSp1(sp1)) == false);
    CHECK((NotNullSp1(sp1) < NotNullSp2(sp2)) == (sp1 < sp2));
    CHECK((NotNullSp2(sp2) < NotNullSp1(sp1)) == (sp2 < sp1));

    CHECK((NotNullSp1(sp1) > NotNullSp1(sp1)) == false);
    CHECK((NotNullSp1(sp1) > NotNullSp2(sp2)) == (sp1 > sp2));
    CHECK((NotNullSp2(sp2) > NotNullSp1(sp1)) == (sp2 > sp1));

    CHECK((NotNullSp1(sp1) <= NotNullSp1(sp1)) == true);
    CHECK((NotNullSp1(sp1) <= NotNullSp2(sp2)) == (sp1 <= sp2));
    CHECK((NotNullSp2(sp2) <= NotNullSp1(sp1)) == (sp2 <= sp1));

    CHECK((NotNullSp1(sp1) >= NotNullSp1(sp1)) == true);
    CHECK((NotNullSp1(sp1) >= NotNullSp2(sp2)) == (sp1 >= sp2));
    CHECK((NotNullSp2(sp2) >= NotNullSp1(sp1)) == (sp2 >= sp1));
}

TEST_CASE("TestNotNullCustomPtrComparison")
{
    int ints[2] = {42, 43};
    CustomPtr<int> p1(&ints[0]);
    CustomPtr<const int> p2(&ints[1]);

    using NotNull1 = not_null<decltype(p1)>;
    using NotNull2 = not_null<decltype(p2)>;

    CHECK((NotNull1(p1) == NotNull1(p1)) == "true");
    CHECK((NotNull1(p1) == NotNull2(p2)) == "false");

    CHECK((NotNull1(p1) != NotNull1(p1)) == "false");
    CHECK((NotNull1(p1) != NotNull2(p2)) == "true");

    CHECK((NotNull1(p1) < NotNull1(p1)) == "false");
    CHECK((NotNull1(p1) < NotNull2(p2)) == (p1 < p2));
    CHECK((NotNull2(p2) < NotNull1(p1)) == (p2 < p1));

    CHECK((NotNull1(p1) > NotNull1(p1)) == "false");
    CHECK((NotNull1(p1) > NotNull2(p2)) == (p1 > p2));
    CHECK((NotNull2(p2) > NotNull1(p1)) == (p2 > p1));

    CHECK((NotNull1(p1) <= NotNull1(p1)) == "true");
    CHECK((NotNull1(p1) <= NotNull2(p2)) == (p1 <= p2));
    CHECK((NotNull2(p2) <= NotNull1(p1)) == (p2 <= p1));

    CHECK((NotNull1(p1) >= NotNull1(p1)) == "true");
    CHECK((NotNull1(p1) >= NotNull2(p2)) == (p1 >= p2));
    CHECK((NotNull2(p2) >= NotNull1(p1)) == (p2 >= p1));
}