#include "gtkloader.h"

extern "C" {
#include "gtk-imports.h"
}

#include <string>

#ifdef _WIN32
#include <windows.h>
#include <direct.h>
#endif

#ifdef __linux
#include <dlfcn.h>
#endif

void GtkLoader::loadLibraryWin64(const char *lib, void **handle)
{
#ifdef _WIN32
    #define DIR "C:\\devel\\yellownotes\\gtk3\\bin"
    HMODULE dll = nullptr;
    std::string dir = DIR;

    *handle = nullptr;

    auto mklibname = [](const char *libname) {
        std::string dll;
        dll = std::string(DIR) + "\\" + libname + ".dll";
        return dll;
    };

    std::string library;
    library = mklibname(lib);

    char *cwd = _getcwd(NULL, 0);
    if (cwd == nullptr) {
        throw std::string("Cannot get current working directory");
    }

    _chdir(dir.c_str());
    dll = LoadLibraryA(library.c_str());
    _chdir(cwd);
    free(cwd);
    if (dll == nullptr) {
        throw std::string("Cannot load library '") + lib + "'";
    }

    *handle = reinterpret_cast<void *>(dll);
#endif
}

void GtkLoader::loadLibraryLinux(const char *lib, void **handle)
{
#ifdef __linux
    *handle = ::dlopen(lib, RTLD_LAZY);
    if (*handle == NULL) {
        throw std::string("Cannot load library '") + lib + "'";
    }
#endif
}

void GtkLoader::loadFunctionWin64(const char *func, void **func_ptr)
{
#ifdef _WIN32

    FARPROC fp = nullptr;
    std::list<void *>::const_iterator it = library_handles.begin();
    while (fp == nullptr && it != library_handles.end()) {
        HMODULE handle = reinterpret_cast<HMODULE>(*it);
        fp = GetProcAddress(handle, func);
        it++;
    }

    *func_ptr = reinterpret_cast<void *>(fp);
    if (fp == nullptr) {
        throw std::string("Cannot load function '") + func;
    }

#endif
}

void GtkLoader::loadFunctionLinux(const char *func, void **func_ptr)
{
#ifdef __linux
    *func_ptr = nullptr;
    std::list<void *>::const_iterator it = library_handles.begin();
    while(*func_ptr == nullptr && it != library_handles.end()) {
        void *handle = *it;
        *func_ptr = dlsym(handle, func);
        it++;
    }
    if (*func_ptr == nullptr) {
        throw std::string("Cannot load function '") + func;
    }
#endif
}

void GtkLoader::dlopen()
{
    if (library_handles.size() == 0) {
#ifdef _WIN32
        const char *libs[] = {
            "gobject-2.0-0",
            "gtk-3-vs17",
            "glib-2.0-0",
            "gio-2.0-0",
            "gdk-3-vs17",
            "gdk_pixbuf-2.0-0",
            NULL
        };
        int i;
        for(i = 0; libs[i] != NULL; i++) {
            void *lib;
            loadLibraryWin64(libs[i], &lib);
            if (lib) { library_handles.push_back(lib); }
        }
#endif
#ifdef __linux
        const char *libs[] = {
            "libgtk-3.so",
            "libgobject-2.0.so",
            "libgio-2.0.so",
            "libglib-2.0.so",
            "libgdk-3.so",
            NULL
        };
        int i;
        for(i = 0; libs[i] != NULL; i++) {
            void *lib;
            loadLibraryLinux(libs[i], &lib);
            if (lib) { library_handles.push_back(lib); }
        }
#endif
    }
}

void GtkLoader::loadFunction(const char *func, void **func_ptr)
{
#ifdef _WIN32
    loadFunctionWin64(func, func_ptr);
#endif
#ifdef __linux
    loadFunctionLinux(func, func_ptr);
#endif
}

static void loader(const char *func, void **func_ptr, void *user_data)
{
    GtkLoader *l = reinterpret_cast<GtkLoader *>(user_data);
    l->loadFunction(func, func_ptr);
}

void GtkLoader::loadGtk()
{
    dlopen();
    loadGtkFunctions(loader, this);
}

GtkLoader::GtkLoader()
{
}