/*
 * 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:
 *      2016-2017, Danny Robson <danny@nerdcruft.net>
 */

#ifndef CRUFT_VK_OBJECT_HPP
#define CRUFT_VK_OBJECT_HPP

#include "./traits.hpp"
#include "./except.hpp"

#include <utility>
#include <vector>

namespace cruft::vk {
    /// the base class for all non-trivial vulkan objects requiring lifetime
    /// management.
    template <typename SelfT>
    struct object {
        using native_type = native_t<SelfT>;

        object (native_t<SelfT> _native):
            m_native (_native)
        {
            CHECK_NEQ (m_native, VK_NULL_HANDLE);
        }

        object (object &&rhs):
            m_native (VK_NULL_HANDLE)
        { std::swap (m_native, rhs.m_native); }

        object (const object&) = delete;

        const auto& native (void) const& { return m_native; }
        auto& native (void)& { return m_native; }

    protected:
        native_t<SelfT> m_native;
    };


    ///////////////////////////////////////////////////////////////////////////
    template <typename SelfT>
    struct root : public object<SelfT> {
        template <typename ...Args>
        root (Args &&...args):
            object<SelfT> (
                cruft::vk::error::try_query (
                    life_traits<native_t<SelfT>>::create,
                    std::forward<Args> (args)...
                )
            )
        { ; }

        ~root ()
        {
            life_traits<native_t<SelfT>>::destroy (this->native (), nullptr);
        }
    };


    ///////////////////////////////////////////////////////////////////////////
    /// a vulkan object that must be directly instantiated through
    /// constructor arguments, rather than being enumerated and owned by
    /// another object.
    template <typename SelfT>
    struct descendant : public object<SelfT> {
        template <typename ParentT, typename ...Args>
        descendant (ParentT &parent, Args &&...args):
            object<SelfT> (
                cruft::vk::error::try_query(
                    life_traits<native_t<SelfT>>::create,
                    parent.native (),
                    std::forward<Args> (args)...
                )
            )
        { ; }


        //---------------------------------------------------------------------
        ~descendant ()
        {
            life_traits<native_t<SelfT>>::destroy (this->native (), nullptr);
        }
    };


    ///////////////////////////////////////////////////////////////////////////
    /// a vulkan object that is obtained by listings from a parent object.
    template <typename SelfT, typename ParentT>
    struct enumerated : public object<SelfT> {
        using object<SelfT>::object;

        static std::vector<SelfT>
        find (const ParentT &parent)
        {
            return error::try_handles<SelfT> (
                enum_traits<native_t<SelfT>>::enumerate, parent.native ()
            );
        }
    };


    ///////////////////////////////////////////////////////////////////////////
    /// a vulkan object that is directly owned by a parent object.
    ///
    /// typically implies that this object must be freed using a reference to
    /// the parent object.
    template <typename SelfT, typename OwnerT>
    struct owned : public object<SelfT> {
        using owner_t = OwnerT;

        using object<SelfT>::object;

        ///////////////////////////////////////////////////////////////////////
        template <typename ...Args>
        owned (OwnerT &owner, Args &&...args):
            object<SelfT> (
                error::try_query (
                    life_traits<native_t<SelfT>>::create,
                    owner.native (),
                    std::forward<Args> (args)...
                )
            )
        { ; }


        //---------------------------------------------------------------------
        owned (owned &&rhs):
            object<SelfT> (std::move (rhs))
        { ; }


        //---------------------------------------------------------------------
        ~owned ()
        {
            CHECK_EQ (this->native (), VK_NULL_HANDLE);
        }


        //---------------------------------------------------------------------
        void
        destroy (OwnerT &owner)
        {
            life_traits<native_t<SelfT>>::destroy (owner.native (), this->native (), nullptr);
            this->m_native = VK_NULL_HANDLE;
        }
    };


    ///////////////////////////////////////////////////////////////////////////
    template <typename T>
    class owned_ptr {
    public:
        owned_ptr (T &&_self, owner_t<T> &_owner):
            m_self (std::move (_self)),
            m_owner (_owner)
        { ; }

        owned_ptr (owned_ptr &&rhs):
            m_self (std::move (rhs.m_self)),
            m_owner (rhs.m_owner)
        { ; }

        ~owned_ptr ()
        {
            m_self.destroy (m_owner);
        }

        // it's unclear whether we want to work around reseating m_owner,
        // or if this operation just isn't sufficiently prevalent to
        // justify the work.
        owned_ptr& operator= (owned_ptr &&rhs) = delete;

        T& operator* ()&
        { return m_self; }

        T*
        operator-> ()&
        { return &m_self; }

    private:
        T m_self;
        owner_t<T> &m_owner;
    };



    //-------------------------------------------------------------------------
    template <typename SelfT, typename OwnerT, typename ...Args>
    auto
    make_owned (OwnerT &owner, Args &&...args)
    {
        return owned_ptr<SelfT> {
            SelfT { owner, std::forward<Args> (args)... },
            owner
        };
    };
};

#endif