#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;
}

static UINT WINAPI
fallbackGetDpiForWindow(HWND win)
{
    (void)win;

    UINT dpi = 0;

    HDC hdcScreen = GetDC(NULL);
    if (hdcScreen) {
        dpi = GetDeviceCaps(hdcScreen, LOGPIXELSY);
        ReleaseDC(NULL, hdcScreen);
    }

    if (!dpi) {
        dpi = 96; // FIXME! fallback to default DPI
    }

    return dpi;
}

static BOOL WINAPI
fallbackSystemParametersInfoForDpi(UINT uiAction, UINT uiParam, PVOID pvParam, UINT fWinIni, UINT dpi)
{
    (void)dpi;

    return SystemParametersInfo(uiAction, uiParam, pvParam, fWinIni);
}

static BOOL WINAPI
fallbackAdjustWindowRectExForDpi(LPRECT lpRect, DWORD dwStyle, BOOL bMenu, DWORD dwExStyle, UINT dpi)
{
    (void)dpi;

    return AdjustWindowRectEx(lpRect, dwStyle, bMenu, dwExStyle);
}

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);
    COMPAT(user32.dll, GetDpiForWindow, 0, fallbackGetDpiForWindow);

    // FIXME: SystemParametersInfoForDpi is Unicode-Only.
    // Writing a wrapper function would have been The Right Way, but such a function
    // is yet to be written. So the current practical recommendation is to make
    // ANSI builds System DPI aware only.
#ifdef UNICODE
    COMPAT(user32.dll, SystemParametersInfoForDpi, 0, fallbackSystemParametersInfoForDpi);
#else
    compatfn->SystemParametersInfoForDpi = fallbackSystemParametersInfoForDpi;
#endif

    COMPAT(user32.dll, AdjustWindowRectExForDpi, 0, fallbackAdjustWindowRectExForDpi);

    // 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;
}

long
ALF_GetAveCharWidth(HDC hdc)
{
    // see: HOWTO: Calculate Dialog Units When Not Using the System Font

    SIZE s;
    GetTextExtentPoint32A(hdc, "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz", 52, &s);

    return (s.cx / 26 + 1) / 2;
}