#include "deimos/core/os.h"
#include "deimos/core/api_registry.h"
#include "deimos/core/allocator.h"

#define WIN32_LEAN_AND_MEAN
#include <Windows.h>

namespace deimos
{

class Win32ConsoleApiImpl : public OsConsoleApi
{
    HANDLE m_stdout;
    HANDLE m_stderr;

    constexpr HANDLE Handle(OsConsoleType type) const
    {
        switch (type)
        {
            using enum OsConsoleType;
            case kStdOut: return m_stdout;
            case kStdErr: return m_stderr;
        }
    }

public:
    Win32ConsoleApiImpl() :
        m_stdout{::GetStdHandle(STD_OUTPUT_HANDLE)},
        m_stderr{::GetStdHandle(STD_ERROR_HANDLE)}
    {}

    void Write(OsConsoleType type, Span<const std::byte> data) override
    {
        ::WriteConsoleA(Handle(type), data.data(), (DWORD)data.size(), nullptr, nullptr);
    }
};

class Win32DllApiImpl : public OsDllApi
{
public:
    OsDll* Open(gsl::czstring name) override
    {
        return std::bit_cast<OsDll*>(::LoadLibraryA(name));
    }

    void* GetSymbol(OsDll* dll, gsl::czstring name) override
    {
        return std::bit_cast<void*>(::GetProcAddress(std::bit_cast<HMODULE>(dll), name));
    }
};

class Win32VirtualMemoryApiImpl : public OsVirtualMemoryApi
{
public:
    gsl::owner<void*> Map(int64_t size) override
    {
        return ::VirtualAlloc(nullptr, (SIZE_T)size, MEM_COMMIT | MEM_RESERVE, PAGE_READWRITE);
    }

    void Unmap(gsl::owner<void*> ptr) override
    {
        ::VirtualFree(ptr, 0, MEM_RELEASE);
    }

    gsl::owner<void*> Reserve(int64_t size) override
    {
        return ::VirtualAlloc(nullptr, (SIZE_T)size, MEM_RESERVE, PAGE_READWRITE);
    }

    void Commit(void* ptr, int64_t size) override
    {
        ::VirtualAlloc(ptr, (SIZE_T)size, MEM_COMMIT, PAGE_READWRITE);
    }
};

class Win32OsApiImpl : public OsApi
{
    Win32ConsoleApiImpl m_console_api;
    Win32DllApiImpl m_dll_api;
    Win32VirtualMemoryApiImpl m_virtual_memory_api;

public:
    Win32OsApiImpl()
    {
        console = &m_console_api;
        dll = &m_dll_api;
        virtual_memory = &m_virtual_memory_api;
    }
};

void RegisterOsApi(ApiRegistry* api_registry)
{
    auto* allocator_api = api_registry->Get<AllocatorApi>();
    auto* os_api = allocator_api->system->New<Win32OsApiImpl>();
    api_registry->Set(os_api);
}

} // namespace deimos