_GLFWlibrary _glfw = { GLFW_FALSE };

// These are outside of _glfw so they can be used before initialization and
// after termination without special handling when _glfw is cleared to zero
//
static _GLFWerror _glfwMainThreadError;
static GLFWerrorfun _glfwErrorCallback;
static GLFWallocator _glfwInitAllocator;
static _GLFWinitconfig _glfwInitHints =
{
    GLFW_TRUE,      // hat buttons
    GLFW_ANGLE_PLATFORM_TYPE_NONE, // ANGLE backend
    GLFW_ANY_PLATFORM, // preferred platform
    NULL,           // vkGetInstanceProcAddr function
    {
        GLFW_TRUE,  // macOS menu bar
        GLFW_TRUE   // macOS bundle chdir
    },
    {
        GLFW_TRUE,  // X11 XCB Vulkan surface
    },
};

// The allocation function used when no custom allocator is set
//
static void* defaultAllocate(size_t size, void* user)
{
    return malloc(size);
}

// The deallocation function used when no custom allocator is set
//
static void defaultDeallocate(void* block, void* user)
{
    free(block);
}

// The reallocation function used when no custom allocator is set
//
static void* defaultReallocate(void* block, size_t size, void* user)
{
    return realloc(block, size);
}

// Terminate the library
//
static void terminate(void)
{
    int i;

    memset(&_glfw.callbacks, 0, sizeof(_glfw.callbacks));

    while (_glfw.windowListHead)
        glfwDestroyWindow((GLFWwindow*) _glfw.windowListHead);

    while (_glfw.cursorListHead)
        glfwDestroyCursor((GLFWcursor*) _glfw.cursorListHead);

    for (i = 0;  i < _glfw.monitorCount;  i++)
    {
        _GLFWmonitor* monitor = _glfw.monitors[i];
        if (monitor->originalRamp.size)
            _glfw.platform.setGammaRamp(monitor, &monitor->originalRamp);
        _glfwFreeMonitor(monitor);
    }

    _glfw_free(_glfw.monitors);
    _glfw.monitors = NULL;
    _glfw.monitorCount = 0;

    _glfw_free(_glfw.mappings);
    _glfw.mappings = NULL;
    _glfw.mappingCount = 0;

    _glfwTerminateVulkan();
    _glfw.platform.terminateJoysticks();
    _glfw.platform.terminate();

    _glfw.initialized = GLFW_FALSE;

    while (_glfw.errorListHead)
    {
        _GLFWerror* error = _glfw.errorListHead;
        _glfw.errorListHead = error->next;
        _glfw_free(error);
    }

    _glfwPlatformDestroyTls(&_glfw.contextSlot);
    _glfwPlatformDestroyTls(&_glfw.errorSlot);
    _glfwPlatformDestroyMutex(&_glfw.errorLock);

    memset(&_glfw, 0, sizeof(_glfw));
}


//////////////////////////////////////////////////////////////////////////
//////                       GLFW internal API                      //////
//////////////////////////////////////////////////////////////////////////

// Encode a Unicode code point to a UTF-8 stream
// Based on cutef8 by Jeff Bezanson (Public Domain)
//
size_t _glfwEncodeUTF8(char* s, uint32_t codepoint)
{
    size_t count = 0;

    if (codepoint < 0x80)
        s[count++] = (char) codepoint;
    else if (codepoint < 0x800)
    {
        s[count++] = (codepoint >> 6) | 0xc0;
        s[count++] = (codepoint & 0x3f) | 0x80;
    }
    else if (codepoint < 0x10000)
    {
        s[count++] = (codepoint >> 12) | 0xe0;
        s[count++] = ((codepoint >> 6) & 0x3f) | 0x80;
        s[count++] = (codepoint & 0x3f) | 0x80;
    }
    else if (codepoint < 0x110000)
    {
        s[count++] = (codepoint >> 18) | 0xf0;
        s[count++] = ((codepoint >> 12) & 0x3f) | 0x80;
        s[count++] = ((codepoint >> 6) & 0x3f) | 0x80;
        s[count++] = (codepoint & 0x3f) | 0x80;
    }

    return count;
}

char* _glfw_strdup(const char* source)
{
    const size_t length = strlen(source);
    char* result = _glfw_calloc(length + 1, 1);
    strcpy(result, source);
    return result;
}

float _glfw_fminf(float a, float b)
{
    if (a != a)
        return b;
    else if (b != b)
        return a;
    else if (a < b)
        return a;
    else
        return b;
}

float _glfw_fmaxf(float a, float b)
{
    if (a != a)
        return b;
    else if (b != b)
        return a;
    else if (a > b)
        return a;
    else
        return b;
}

void* _glfw_calloc(size_t count, size_t size)
{
    if (count && size)
    {
        void* block;

        if (count > SIZE_MAX / size)
        {
            _glfwInputError(GLFW_INVALID_VALUE, "Allocation size overflow");
            return NULL;
        }

        block = _glfw.allocator.allocate(count * size, _glfw.allocator.user);
        if (block)
            return memset(block, 0, count * size);
        else
        {
            _glfwInputError(GLFW_OUT_OF_MEMORY, NULL);
            return NULL;
        }
    }
    else
        return NULL;
}

void* _glfw_realloc(void* block, size_t size)
{
    if (block && size)
    {
        void* resized = _glfw.allocator.reallocate(block, size, _glfw.allocator.user);
        if (resized)
            return resized;
        else
        {
            _glfwInputError(GLFW_OUT_OF_MEMORY, NULL);
            return NULL;
        }
    }
    else if (block)
    {
        _glfw_free(block);
        return NULL;
    }
    else
        return _glfw_calloc(1, size);
}

void _glfw_free(void* block)
{
    if (block)
        _glfw.allocator.deallocate(block, _glfw.allocator.user);
}


//////////////////////////////////////////////////////////////////////////
//////                         GLFW event API                       //////
//////////////////////////////////////////////////////////////////////////

// Notifies shared code of an error
//
void _glfwInputError(int code, const char* format, ...)
{
    _GLFWerror* error;
    char description[_GLFW_MESSAGE_SIZE];

    if (format)
    {
        va_list vl;

        va_start(vl, format);
        vsnprintf(description, sizeof(description), format, vl);
        va_end(vl);

        description[sizeof(description) - 1] = '\0';
    }
    else
    {
        if (code == GLFW_NOT_INITIALIZED)
            strcpy(description, "The GLFW library is not initialized");
        else if (code == GLFW_NO_CURRENT_CONTEXT)
            strcpy(description, "There is no current context");
        else if (code == GLFW_INVALID_ENUM)
            strcpy(description, "Invalid argument for enum parameter");
        else if (code == GLFW_INVALID_VALUE)
            strcpy(description, "Invalid value for parameter");
        else if (code == GLFW_OUT_OF_MEMORY)
            strcpy(description, "Out of memory");
        else if (code == GLFW_API_UNAVAILABLE)
            strcpy(description, "The requested API is unavailable");
        else if (code == GLFW_VERSION_UNAVAILABLE)
            strcpy(description, "The requested API version is unavailable");
        else if (code == GLFW_PLATFORM_ERROR)
            strcpy(description, "A platform-specific error occurred");
        else if (code == GLFW_FORMAT_UNAVAILABLE)
            strcpy(description, "The requested format is unavailable");
        else if (code == GLFW_NO_WINDOW_CONTEXT)
            strcpy(description, "The specified window has no context");
        else if (code == GLFW_CURSOR_UNAVAILABLE)
            strcpy(description, "The specified cursor shape is unavailable");
        else if (code == GLFW_FEATURE_UNAVAILABLE)
            strcpy(description, "The requested feature cannot be implemented for this platform");
        else if (code == GLFW_FEATURE_UNIMPLEMENTED)
            strcpy(description, "The requested feature has not yet been implemented for this platform");
        else if (code == GLFW_PLATFORM_UNAVAILABLE)
            strcpy(description, "The requested platform is unavailable");
        else
            strcpy(description, "ERROR: UNKNOWN GLFW ERROR");
    }

    if (_glfw.initialized)
    {
        error = _glfwPlatformGetTls(&_glfw.errorSlot);
        if (!error)
        {
            error = _glfw_calloc(1, sizeof(_GLFWerror));
            _glfwPlatformSetTls(&_glfw.errorSlot, error);
            _glfwPlatformLockMutex(&_glfw.errorLock);
            error->next = _glfw.errorListHead;
            _glfw.errorListHead = error;
            _glfwPlatformUnlockMutex(&_glfw.errorLock);
        }
    }
    else
        error = &_glfwMainThreadError;

    error->code = code;
    strcpy(error->description, description);

    if (_glfwErrorCallback)
        _glfwErrorCallback(code, description);
}


//////////////////////////////////////////////////////////////////////////
//////                        GLFW public API                       //////
//////////////////////////////////////////////////////////////////////////

GLFWAPI int glfwInit(void)
{
    if (_glfw.initialized)
        return GLFW_TRUE;

    memset(&_glfw, 0, sizeof(_glfw));
    _glfw.hints.init = _glfwInitHints;

    _glfw.allocator = _glfwInitAllocator;
    if (!_glfw.allocator.allocate)
    {
        _glfw.allocator.allocate   = defaultAllocate;
        _glfw.allocator.reallocate = defaultReallocate;
        _glfw.allocator.deallocate = defaultDeallocate;
    }

    if (!_glfwSelectPlatform(_glfw.hints.init.platformID, &_glfw.platform))
        return GLFW_FALSE;

    if (!_glfw.platform.init())
    {
        terminate();
        return GLFW_FALSE;
    }

    if (!_glfwPlatformCreateMutex(&_glfw.errorLock) ||
        !_glfwPlatformCreateTls(&_glfw.errorSlot) ||
        !_glfwPlatformCreateTls(&_glfw.contextSlot))
    {
        terminate();
        return GLFW_FALSE;
    }

    _glfwPlatformSetTls(&_glfw.errorSlot, &_glfwMainThreadError);

    _glfwInitGamepadMappings();

    _glfwPlatformInitTimer();
    _glfw.timer.offset = _glfwPlatformGetTimerValue();

    _glfw.initialized = GLFW_TRUE;

    glfwDefaultWindowHints();
    return GLFW_TRUE;
}

GLFWAPI void glfwTerminate(void)
{
    if (!_glfw.initialized)
        return;

    terminate();
}

GLFWAPI void glfwInitHint(int hint, int value)
{
    switch (hint)
    {
        case GLFW_JOYSTICK_HAT_BUTTONS:
            _glfwInitHints.hatButtons = value;
            return;
        case GLFW_ANGLE_PLATFORM_TYPE:
            _glfwInitHints.angleType = value;
            return;
        case GLFW_PLATFORM:
            _glfwInitHints.platformID = value;
            return;
        case GLFW_COCOA_CHDIR_RESOURCES:
            _glfwInitHints.ns.chdir = value;
            return;
        case GLFW_COCOA_MENUBAR:
            _glfwInitHints.ns.menubar = value;
            return;
        case GLFW_X11_XCB_VULKAN_SURFACE:
            _glfwInitHints.x11.xcbVulkanSurface = value;
            return;
    }

    _glfwInputError(GLFW_INVALID_ENUM,
                    "Invalid init hint 0x%08X", hint);
}

GLFWAPI void glfwInitAllocator(const GLFWallocator* allocator)
{
    if (allocator)
    {
        if (allocator->allocate && allocator->reallocate && allocator->deallocate)
            _glfwInitAllocator = *allocator;
        else
            _glfwInputError(GLFW_INVALID_VALUE, "Missing function in allocator");
    }
    else
        memset(&_glfwInitAllocator, 0, sizeof(GLFWallocator));
}

GLFWAPI void glfwInitVulkanLoader(PFN_vkGetInstanceProcAddr loader)
{
    _glfwInitHints.vulkanLoader = loader;
}

GLFWAPI void glfwGetVersion(int* major, int* minor, int* rev)
{
    if (major != NULL)
        *major = GLFW_VERSION_MAJOR;
    if (minor != NULL)
        *minor = GLFW_VERSION_MINOR;
    if (rev != NULL)
        *rev = GLFW_VERSION_REVISION;
}

GLFWAPI int glfwGetError(const char** description)
{
    _GLFWerror* error;
    int code = GLFW_NO_ERROR;

    if (description)
        *description = NULL;

    if (_glfw.initialized)
        error = _glfwPlatformGetTls(&_glfw.errorSlot);
    else
        error = &_glfwMainThreadError;

    if (error)
    {
        code = error->code;
        error->code = GLFW_NO_ERROR;
        if (description && code)
            *description = error->description;
    }

    return code;
}

GLFWAPI GLFWerrorfun glfwSetErrorCallback(GLFWerrorfun cbfun)
{
    _GLFW_SWAP(GLFWerrorfun, _glfwErrorCallback, cbfun);
    return cbfun;
}

