#define MAX_PATH 1024

#include <stdio.h>
#include <string.h>

#if defined(_WIN32)
#define SHARED_EXT "dll"
#elif defined(__APPLE__)
#define SHARED_EXT "dylib"
#else
#define SHARED_EXT "so"
#endif

typedef void(*dll_main_t)(int argc, char ** argv);

#if defined(_WIN32)
#include <windows.h>

static void showError() {
    DWORD dwErrCode = GetLastError();
    LPVOID lpMsgBuf;
    if (FormatMessage(FORMAT_MESSAGE_ALLOCATE_BUFFER |
                      FORMAT_MESSAGE_FROM_SYSTEM |
                      FORMAT_MESSAGE_IGNORE_INSERTS,
                      NULL, GetLastError(),
                      MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT), // Default language
                      (LPTSTR) &lpMsgBuf, 0, NULL )) {
        fprintf(stderr, "Error: %s\n", lpMsgBuf);
        LocalFree(lpMsgBuf);
    }
}

static HMODULE LoadLibraryExWrap(LPCTSTR lpFileName, HANDLE hFile, DWORD dwFlags) {
    HMODULE r = LoadLibraryEx(lpFileName, hFile, dwFlags);
    if (!r)
        showError();
    return r;
}

static dll_main_t LoadDllMain(const char * searchpath) {
    HMODULE handle;
    const char * fname = "lua-interface." SHARED_EXT;

    if (!(handle = LoadLibraryExWrap(fname, NULL, LOAD_WITH_ALTERED_SEARCH_PATH)) &&
        !(handle = LoadLibraryExWrap(fname, NULL, NULL))) {
        LuaLoadPlugin(&Input(fname), L);
        return NULL;
    }
    
    dll_main_t dll_main = (dll_main) GetProcAddress(handle, "dll_main");

    if (!dll_main)
        FreeLibrary(handle);
    
    return dll_main;
}

#else
#include <dlfcn.h>

static dll_main_t LoadDllMain(const char * searchpath) {
    const char * fname = "./lua-interface." SHARED_EXT;
    void * handle = dlopen(fname, RTLD_NOW | RTLD_GLOBAL);
    
    if (!handle) {
        char full_fname[MAX_PATH];
        strcpy(full_fname, searchpath);
        strcat(full_fname, "lua-interface." SHARED_EXT);
        handle = dlopen(full_fname, RTLD_NOW | RTLD_GLOBAL);
        if (!handle) {
            return NULL;;
        }
    }
    
    dll_main_t dll_main = (dll_main_t) dlsym(handle, "dll_main");
    
    if (!dll_main)
        dlclose(handle);

    return dll_main;    
}

#endif

int main(int argc, char ** argv) {
    char searchpath[MAX_PATH];
    char * slash;
    strcpy(searchpath, argv[0]);
    slash = strrchr(searchpath, '/');
    if (slash) {
        *(++slash) = 0;
    } else {
        searchpath[0] = 0;
    }
    dll_main_t dll_main = LoadDllMain(searchpath);
    if (dll_main)
        dll_main(argc, argv);
    else
        fprintf(stderr, "Couldn't locate lua-interface's library.\n");
}