// https://github.com/ysc3839/win32-darkmode/blob/master/win32-darkmode/DarkMode.h

#pragma once
#include <Windows.h>
#include <dwmapi.h>
//#include "IatHook.h"

enum IMMERSIVE_HC_CACHE_MODE
{
    IHCM_USE_CACHED_VALUE,
    IHCM_REFRESH
};

// Insider 18334
enum PreferredAppMode
{
    Default,
    AllowDark,
    ForceDark,
    ForceLight,
    Max
};

using fnRtlGetNtVersionNumbers = void (WINAPI *)(LPDWORD major, LPDWORD minor, LPDWORD build);
// 1809 17763
using fnShouldAppsUseDarkMode = bool (WINAPI *)(); // ordinal 132
using fnAllowDarkModeForWindow = bool (WINAPI *)(HWND hWnd, bool allow); // ordinal 133
using fnAllowDarkModeForApp = bool (WINAPI *)(bool allow); // ordinal 135, removed since 18334
using fnFlushMenuThemes = void (WINAPI *)(); // ordinal 136
using fnRefreshImmersiveColorPolicyState = void (WINAPI *)(); // ordinal 104
using fnIsDarkModeAllowedForWindow = bool (WINAPI *)(HWND hWnd); // ordinal 137
using fnGetIsImmersiveColorUsingHighContrast = bool (WINAPI *)(IMMERSIVE_HC_CACHE_MODE mode); // ordinal 106
using fnOpenNcThemeData = HTHEME(WINAPI *)(HWND hWnd, LPCWSTR pszClassList); // ordinal 49
                                                                             // Insider 18290
using fnShouldSystemUseDarkMode = bool (WINAPI *)(); // ordinal 138
                                                     // Insider 18334
using fnSetPreferredAppMode = PreferredAppMode(WINAPI *)(PreferredAppMode appMode); // ordinal 135, since 18334
using fnIsDarkModeAllowedForApp = bool (WINAPI *)(); // ordinal 139

fnShouldAppsUseDarkMode _ShouldAppsUseDarkMode = nullptr;
fnAllowDarkModeForWindow _AllowDarkModeForWindow = nullptr;
fnAllowDarkModeForApp _AllowDarkModeForApp = nullptr;
fnFlushMenuThemes _FlushMenuThemes = nullptr;
fnRefreshImmersiveColorPolicyState _RefreshImmersiveColorPolicyState = nullptr;
fnIsDarkModeAllowedForWindow _IsDarkModeAllowedForWindow = nullptr;
fnGetIsImmersiveColorUsingHighContrast _GetIsImmersiveColorUsingHighContrast = nullptr;
fnOpenNcThemeData _OpenNcThemeData = nullptr;
// Insider 18290
fnShouldSystemUseDarkMode _ShouldSystemUseDarkMode = nullptr;
// Insider 18334
fnSetPreferredAppMode _SetPreferredAppMode = nullptr;

bool g_darkModeSupported = false;
bool g_darkModeEnabled = false;
DWORD g_buildNumber = 0;

bool AllowDarkModeForWindow(HWND hWnd, bool allow)
{
    if (g_darkModeSupported)
        return _AllowDarkModeForWindow(hWnd, allow);
    return false;
}

bool IsHighContrast()
{
    HIGHCONTRASTW highContrast = { sizeof(highContrast) };
    if (SystemParametersInfoW(SPI_GETHIGHCONTRAST, sizeof(highContrast), &highContrast, FALSE))
        return highContrast.dwFlags & HCF_HIGHCONTRASTON;
    return false;
}

void RefreshTitleBarThemeColor(HWND hWnd)
{
    BOOL dark = FALSE;
    if (_IsDarkModeAllowedForWindow(hWnd) &&
        _ShouldAppsUseDarkMode() &&
        !IsHighContrast())
    {
        dark = TRUE;
    }
    DwmSetWindowAttribute(hWnd, 19, &dark, sizeof(dark));
}

bool IsColorSchemeChangeMessage(LPARAM lParam)
{
    bool is = false;
    if (lParam && CompareStringOrdinal(reinterpret_cast<LPCWCH>(lParam), -1, L"ImmersiveColorSet", -1, TRUE) == CSTR_EQUAL)
    {
        _RefreshImmersiveColorPolicyState();
        is = true;
    }
    _GetIsImmersiveColorUsingHighContrast(IHCM_REFRESH);
    return is;
}

bool IsColorSchemeChangeMessage(UINT message, LPARAM lParam)
{
    if (message == WM_SETTINGCHANGE)
        return IsColorSchemeChangeMessage(lParam);
    return false;
}

void AllowDarkModeForApp(bool allow)
{
    if (_AllowDarkModeForApp)
        _AllowDarkModeForApp(allow);
    else if (_SetPreferredAppMode)
        _SetPreferredAppMode(allow ? AllowDark : Default);
}

void FixDarkScrollBar()
{
#if 0
    auto addr = FindDelayLoadThunkInModule(GetModuleHandleW(L"comctl32.dll"), "uxtheme.dll", 49); // OpenNcThemeData
    if (addr)
    {
        DWORD oldProtect;
        if (VirtualProtect(addr, sizeof(IMAGE_THUNK_DATA), PAGE_READWRITE, &oldProtect))
        {
            auto MyOpenThemeData = [](HWND hWnd, LPCWSTR classList) -> HTHEME {
                if (wcscmp(classList, L"ScrollBar") == 0)
                {
                    hWnd = nullptr;
                    classList = L"Explorer::ScrollBar";
                }
                return _OpenNcThemeData(hWnd, classList);
            };

            addr->u1.Function = reinterpret_cast<ULONG_PTR>(static_cast<fnOpenNcThemeData>(MyOpenThemeData));
            VirtualProtect(addr, sizeof(IMAGE_THUNK_DATA), oldProtect, &oldProtect);
        }
    }
#endif
}

void InitDarkMode()
{
    fnRtlGetNtVersionNumbers RtlGetNtVersionNumbers = reinterpret_cast<fnRtlGetNtVersionNumbers>(GetProcAddress(GetModuleHandleW(L"ntdll.dll"), "RtlGetNtVersionNumbers"));
    if (RtlGetNtVersionNumbers)
    {
        DWORD major, minor;
        RtlGetNtVersionNumbers(&major, &minor, &g_buildNumber);
        g_buildNumber &= ~0xF0000000;
        if (major == 10 && minor == 0 && 17763 <= g_buildNumber && g_buildNumber <= 18362) // Windows 10 1809 10.0.17763 - 1903 10.0.18362
        {
            HMODULE hUxtheme = LoadLibraryExW(L"uxtheme.dll", nullptr, LOAD_LIBRARY_SEARCH_SYSTEM32);
            if (hUxtheme)
            {
                _OpenNcThemeData = reinterpret_cast<fnOpenNcThemeData>(GetProcAddress(hUxtheme, MAKEINTRESOURCEA(49)));
                _RefreshImmersiveColorPolicyState = reinterpret_cast<fnRefreshImmersiveColorPolicyState>(GetProcAddress(hUxtheme, MAKEINTRESOURCEA(104)));
                _GetIsImmersiveColorUsingHighContrast = reinterpret_cast<fnGetIsImmersiveColorUsingHighContrast>(GetProcAddress(hUxtheme, MAKEINTRESOURCEA(106)));
                _ShouldAppsUseDarkMode = reinterpret_cast<fnShouldAppsUseDarkMode>(GetProcAddress(hUxtheme, MAKEINTRESOURCEA(132)));
                _AllowDarkModeForWindow = reinterpret_cast<fnAllowDarkModeForWindow>(GetProcAddress(hUxtheme, MAKEINTRESOURCEA(133)));

                auto ord135 = GetProcAddress(hUxtheme, MAKEINTRESOURCEA(135));
                if (g_buildNumber < 18334)
                    _AllowDarkModeForApp = reinterpret_cast<fnAllowDarkModeForApp>(ord135);
                else
                    _SetPreferredAppMode = reinterpret_cast<fnSetPreferredAppMode>(ord135);

                //_FlushMenuThemes = reinterpret_cast<fnFlushMenuThemes>(GetProcAddress(hUxtheme, MAKEINTRESOURCEA(136)));
                _IsDarkModeAllowedForWindow = reinterpret_cast<fnIsDarkModeAllowedForWindow>(GetProcAddress(hUxtheme, MAKEINTRESOURCEA(137)));

                if (_OpenNcThemeData &&
                    _RefreshImmersiveColorPolicyState &&
                    _ShouldAppsUseDarkMode &&
                    _AllowDarkModeForWindow &&
                    (_AllowDarkModeForApp || _SetPreferredAppMode) &&
                    //_FlushMenuThemes &&
                    _IsDarkModeAllowedForWindow)
                {
                    g_darkModeSupported = true;

                    AllowDarkModeForApp(true);
                    _RefreshImmersiveColorPolicyState();

                    g_darkModeEnabled = _ShouldAppsUseDarkMode() && !IsHighContrast();

                    FixDarkScrollBar();
                }
            }
        }
    }
}