#include "alfpriv.h"

#include <shlwapi.h>

static
DWORD ALF_DllGetVersion(const char *dll)
{
    HMODULE hDll = GetModuleHandleA(dll);

    if (hDll) {
        DLLGETVERSIONPROC pDllGetVersion;
        pDllGetVersion = (DLLGETVERSIONPROC)(void*)GetProcAddress(hDll, "DllGetVersion");

        if (pDllGetVersion) {
            DLLVERSIONINFO dvi;
            HRESULT hr;

            ZeroMemory(&dvi, sizeof(dvi));
            dvi.cbSize = sizeof(dvi);

            hr = (*pDllGetVersion)(&dvi);

            if (SUCCEEDED(hr)) {
                return MAKELONG(dvi.dwMinorVersion, dvi.dwMajorVersion);
            }
        }
    }
    return 0;
}

static int WINAPI
fallbackGetSystemMetricsForDpi(int nIndex, UINT dpi)
{
    (void)dpi;
    return GetSystemMetrics(nIndex);
}

static BOOL WINAPI
fallbackIsAppThemed(void)
{
    return FALSE;
}

ALFCompatFunctions *
ALF_CreateCompatFuncTable(void)
{
    ALFCompatFunctions *compatfn = (ALFCompatFunctions*)HeapAlloc(GetProcessHeap(), HEAP_ZERO_MEMORY|HEAP_GENERATE_EXCEPTIONS, sizeof(ALFCompatFunctions));

#define COMPAT(dll, entrypoint, ordinal, fallback) \
    do { \
        FARPROC p = GetProcAddress(GetModuleHandleA(#dll), #entrypoint); \
        if (!p && ordinal) \
            p = GetProcAddress(GetModuleHandleA(#dll), (char*)ordinal); \
        CopyMemory(&compatfn->entrypoint, &p, sizeof(void*)); \
        \
        if (!compatfn->entrypoint) \
            compatfn->entrypoint = fallback; \
    } while (0)

    COMPAT(comctl32.dll, SetWindowSubclass, 410, NULL);
    COMPAT(comctl32.dll, DefSubclassProc, 413, NULL);
    COMPAT(comctl32.dll, RemoveWindowSubclass, 412, NULL);
    COMPAT(user32.dll, GetSystemMetricsForDpi, 0, fallbackGetSystemMetricsForDpi);

    // IsAppThemed would return TRUE even when we're linked against comctl32 v5
    if (ALF_DllGetVersion("comctl32.dll") >= 0x60000) {
        LoadLibraryA("uxtheme.dll");
        COMPAT(uxtheme.dll, IsAppThemed, 0, fallbackIsAppThemed);
    } else {
        compatfn->IsAppThemed = fallbackIsAppThemed;
    }

#undef COMPAT

    return compatfn;
}