Not so Simple!

module interop.net;
import core.sys.windows.windows;
import core.sys.windows.com;
import core.sys.windows.objidl;
import core.sys.windows.oaidl;
import core.sys.windows.wtypes;

pragma(lib, "mscoree.lib");

extern (Windows)
{
    enum CLSID_CorRuntimeHost = GUID(0xcb2f6723, 0xab3a, 0x11d2, [0x9c, 0x40,
                0x00, 0xc0, 0x4f, 0xa3, 0x0a, 0x3e]);
    enum IID_ICorRuntimeHost = GUID(0xcb2f6722, 0xab3a, 0x11d2, [0x9c, 0x40,
                0x00, 0xc0, 0x4f, 0xa3, 0x0a, 0x3e]);

    enum CLSID_CLRMetaHost = GUID(0x9280188d, 0xe8e, 0x4867, [0xb3, 0xc, 0x7f,
                0xa8, 0x38, 0x84, 0xe8, 0xde]);
    enum IID_ICLRMetaHost = GUID(0xD332DB9E, 0xB9B3, 0x4125, [0x82, 0x07, 0xA1,
                0x48, 0x84, 0xF5, 0x32, 0x16]);
    enum IID_ICLRRuntimeInfo = GUID(0xBD39D1D2, 0xBA2F, 0x486a, [0x89, 0xB0,
                0xB4, 0xB0, 0xCB, 0x46, 0x68, 0x91]);

    enum IID_AppDomain = GUID(0x05F696DC, 0x2B29, 0x3663, [0xAD, 0x8B, 0xC4,
                0x38, 0x9C, 0xF2, 0xA7, 0x13]);

    HRESULT CLRCreateInstance(REFCLSID clsid, REFIID riid, LPVOID* ppInterface);

    alias void function(void* pRuntimeInfo, void* pfnCallbackThreadSet,
            void* pfnCallbackThreadUnset) RuntimeLoadedCallbackFnPtr;
}

interface ICLRMetaHost : IUnknown
{
extern (Windows):
    HRESULT GetRuntime(LPCWSTR pwzVersion, REFIID riid, LPVOID* ppRuntime);
    HRESULT GetVersionFromFile(LPCWSTR pwzFilePath, LPWSTR pwzBuffer, DWORD* pcchBuffer);
    HRESULT EnumerateInstalledRuntimes(IEnumUnknown** ppEnumerator);
    HRESULT EnumerateLoadedRuntimes(HANDLE hndProcess, IEnumUnknown** ppEnumerator);
    HRESULT RequestRuntimeLoadedNotification(RuntimeLoadedCallbackFnPtr pCallbackFunction);
    HRESULT QueryLegacyV2RuntimeBinding(REFIID riid, LPVOID* ppUnk);
    HRESULT ExitProcess(INT32 iExitCode);
}

interface ICLRRuntimeInfo : IUnknown
{
extern (Windows):
    HRESULT GetVersionString(LPWSTR pwzBuffer, DWORD* pcchBuffer);
    HRESULT GetRuntimeDirectory(LPWSTR pwzBuffer, DWORD* pcchBuffer);
    HRESULT IsLoaded(HANDLE hndProcess, BOOL* pbLoaded);
    HRESULT LoadErrorString(UINT iResourceID, LPWSTR pwzBuffer, DWORD* pcchBuffer, LONG iLocaleID);
    HRESULT LoadLibrary(LPCWSTR pwzDllName, HMODULE* phndModule);
    HRESULT GetProcAddress(LPCSTR pszProcName, LPVOID* ppProc);
    HRESULT GetInterface(REFCLSID rclsid, REFIID riid, LPVOID* ppUnk);
    HRESULT IsLoadable(BOOL* pbLoadable);
    HRESULT SetDefaultStartupFlags(DWORD dwStartupFlags, LPCWSTR pwzHostConfigFile);
    HRESULT GetDefaultStartupFlags(DWORD* pdwStartupFlags,
            LPWSTR pwzHostConfigFile, DWORD* pcchHostConfigFile);
    HRESULT BindAsLegacyV2Runtime();
    HRESULT IsStarted(BOOL* pbStarted, DWORD* pdwStartupFlags);
}

interface ICorConfiguration : IUnknown
{
}

alias void* HDOMAINENUM;

interface ICorRuntimeHost : IUnknown
{
extern (Windows):
    HRESULT CreateLogicalThreadState();
    HRESULT DeleteLogicalThreadState();
    HRESULT SwitchInLogicalThreadState(DWORD* pFiberCookie);
    HRESULT SwitchOutLogicalThreadState(DWORD** pFiberCookie);
    HRESULT LocksHeldByLogicalThread(DWORD* pCount);
    HRESULT MapFile(HANDLE hFile, HMODULE* hMapAddress);
    HRESULT GetConfiguration(ICorConfiguration** pConfiguration);
    HRESULT Start();
    HRESULT Stop();
    HRESULT CreateDomain(LPCWSTR pwzFriendlyName, IUnknown* pIdentityArray,
            IUnknown** pAppDomain);
    HRESULT GetDefaultDomain(IUnknown** pAppDomain);
    HRESULT EnumDomains(HDOMAINENUM* hEnum);
    HRESULT NextDomain(HDOMAINENUM hEnum, IUnknown** pAppDomain);
    HRESULT CloseEnum(HDOMAINENUM hEnum);
    HRESULT CreateDomainEx(LPCWSTR pwzFriendlyName, IUnknown* pSetup,
            IUnknown* pEvidence, IUnknown** pAppDomain);
    HRESULT CreateDomainSetup(IUnknown** pAppDomainSetup);
    HRESULT CreateEvidence(IUnknown** pEvidence);
    HRESULT UnloadDomain(IUnknown* pAppDomain);
    HRESULT CurrentDomain(IUnknown** pAppDomain);
}

//{17156360-2F1A-384A-BC52-FDE93C215C5B}
interface Assembly : IDispatch
{
extern (Windows):
    HRESULT ToString();
    HRESULT Equals();
    HRESULT GetHashCode();
    HRESULT GetType();
    HRESULT get_CodeBase();
    HRESULT get_EscapedCodeBase();
    HRESULT GetName();
    HRESULT GetName_2();
    HRESULT get_FullName();
    HRESULT get_EntryPoint();
    HRESULT GetType_2(BSTR name, IUnknown* retVal);
    HRESULT GetType_3();
    HRESULT GetExportedTypes();
    HRESULT GetTypes();
    HRESULT GetManifestResourceStream();
    HRESULT GetManifestResourceStream_2();
    HRESULT GetFile();
    HRESULT GetFiles();
    HRESULT GetFiles_2();
    HRESULT GetManifestResourceNames();
    HRESULT GetManifestResourceInfo();
    HRESULT get_Location();
    HRESULT get_Evidence();
    HRESULT GetCustomAttributes();
    HRESULT GetCustomAttributes_2();
    HRESULT IsDefined();
    HRESULT GetObjectData();
    HRESULT add_ModuleResolve();
    HRESULT remove_ModuleResolve();
    HRESULT GetType_4();
    HRESULT GetSatelliteAssembly();
    HRESULT GetSatelliteAssembly_2();
    HRESULT LoadModule();
    HRESULT LoadModule_2();
    HRESULT CreateInstance(BSTR bstrClassName, VARIANT* vtObject);
}

interface _AppDomain : IUnknown
{
extern (Windows):
    HRESULT GetTypeInfoCount();
    HRESULT GetTypeInfo();
    HRESULT GetIDsOfNames();
    HRESULT Invoke();
    HRESULT get_ToString();
    HRESULT Equals();
    HRESULT GetHashCode();
    HRESULT GetType();
    HRESULT InitializeLifetimeService();
    HRESULT GetLifetimeService();
    HRESULT Get_Evidence();
    HRESULT add_DomainUnload();
    HRESULT remove_DomainUnload();
    HRESULT add_AssemblyLoad();
    HRESULT remove_AssemblyLoad();
    HRESULT add_ProcessExit();
    HRESULT remove_ProcessExit();
    HRESULT add_TypeResolve();
    HRESULT remove_TypeResolve();
    HRESULT add_ResourceResolve();
    HRESULT remove_ResourceResolve();
    HRESULT add_AssemblyResolve();
    HRESULT remove_AssemblyResolve();
    HRESULT add_UnhandledException();
    HRESULT remove_UnhandledException();
    HRESULT DefineDynamicAssembly();
    HRESULT DefineDynamicAssembly_2();
    HRESULT DefineDynamicAssembly_3();
    HRESULT DefineDynamicAssembly_4();
    HRESULT DefineDynamicAssembly_5();
    HRESULT DefineDynamicAssembly_6();
    HRESULT DefineDynamicAssembly_7();
    HRESULT DefineDynamicAssembly_8();
    HRESULT DefineDynamicAssembly_9();
    HRESULT CreateInstance();
    HRESULT CreateInstanceFrom();
    HRESULT CreateInstance_2();
    HRESULT CreateInstanceFrom_2();
    HRESULT CreateInstance_3();
    HRESULT CreateInstanceFrom_3();
    HRESULT Load();
    HRESULT Load_2(BSTR assemblyString, Assembly* retVal);
}

enum BindingFlags
{
    Default = 0,
    IgnoreCase = 1,
    DeclaredOnly = 2,
    Instance = 4,
    Static = 8,
    Public = 16,
    NonPublic = 32,
    FlattenHierarchy = 64,
    InvokeMethod = 256,
    CreateInstance = 512,
    GetField = 1024,
    SetField = 2048,
    GetProperty = 4096,
    SetProperty = 8192,
    PutDispProperty = 16384,
    PutRefDispProperty = 32768,
    ExactBinding = 65536,
    SuppressChangeType = 131072,
    OptionalParamBinding = 262144,
    IgnoreReturn = 16777216
}

interface _Binder : IDispatch
{
}

interface _Type : IUnknown
{
    HRESULT GetTypeInfoCount();
    HRESULT GetTypeInfo();
    HRESULT GetIDsOfNames();
    HRESULT Invoke();
    HRESULT ToString();
    HRESULT Equals();
    HRESULT GetHashCode();
    HRESULT GetType();
    HRESULT get_MemberType();
    HRESULT get_name();
    HRESULT get_DeclaringType();
    HRESULT get_ReflectedType();
    HRESULT GetCustomAttributes();
    HRESULT GetCustomAttributes_2();
    HRESULT IsDefined();
    HRESULT get_Guid();
    HRESULT get_Module();
    HRESULT get_Assembly();
    HRESULT get_TypeHandle();
    HRESULT get_FullName();
    HRESULT get_Namespace();
    HRESULT get_AssemblyQualifiedName();
    HRESULT GetArrayRank();
    HRESULT get_BaseType();
    HRESULT GetConstructors();
    HRESULT GetInterface();
    HRESULT GetInterfaces();
    HRESULT FindInterfaces();
    HRESULT GetEvent();
    HRESULT GetEvents();
    HRESULT GetEvents_2();
    HRESULT GetNestedTypes();
    HRESULT GetNestedType();
    HRESULT GetMember();
    HRESULT GetDefaultMembers();
    HRESULT FindMembers();
    HRESULT GetElementType();
    HRESULT IsSubclassOf();
    HRESULT IsInstanceOfType();
    HRESULT IsAssignableFrom();
    HRESULT GetInterfaceMap();
    HRESULT GetMethod();
    HRESULT GetMethod_2();
    HRESULT GetMethods();
    HRESULT GetField();
    HRESULT GetFields();
    HRESULT GetProperty();
    HRESULT GetProperty_2();
    HRESULT GetProperties();
    HRESULT GetMember_2();
    HRESULT GetMembers();
    HRESULT InvokeMember();
    HRESULT get_UnderlyingSystemType();
    HRESULT InvokeMember_2();
    HRESULT InvokeMember_3(BSTR name, BindingFlags invokeAttr, _Binder* Binder,
            VARIANT Target, VARIANT args, VARIANT* pRetVal);
}

import std.utf;
import std.conv;

void main()
{
    auto clsid = CLSID_CLRMetaHost;
    auto iid = IID_ICLRMetaHost;
    ICLRMetaHost pMetaHost;
    auto hr = CLRCreateInstance(&clsid, &iid, cast(void**)&pMetaHost);

    ICLRRuntimeInfo pRuntimeInfo;
    iid = IID_ICLRRuntimeInfo;
    auto pszVersion = "v4.0.30319".toUTF16z;
    hr = pMetaHost.GetRuntime(pszVersion, &iid, cast(void**)&pRuntimeInfo);

    BOOL fLoadable;
    hr = pRuntimeInfo.IsLoadable(&fLoadable);
    if (!fLoadable)
        return;

    ICorRuntimeHost pCorRuntimeHost;
    clsid = CLSID_CorRuntimeHost;
    iid = IID_ICorRuntimeHost;
    hr = pRuntimeInfo.GetInterface(&clsid, &iid, cast(void**)&pCorRuntimeHost);

    hr = pCorRuntimeHost.Start();

    IUnknown spAppDomainThunk;
    hr = pCorRuntimeHost.GetDefaultDomain(cast(IUnknown**)&spAppDomainThunk);

    _AppDomain spDefaultAppDomain;
    iid = IID_AppDomain;
    hr = spAppDomainThunk.QueryInterface(&iid, cast(void**)&spDefaultAppDomain);

    import interop.bstring;

    Assembly assembly;
    auto assemblyName = bstring(
            "System.Windows.Forms, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089");
    hr = spDefaultAppDomain.Load_2(assemblyName, cast(Assembly*)&assembly);

    auto name = bstring("System.Windows.Forms.Form");
    _Type type;
    hr = assembly.GetType_2(name, cast(IUnknown*)&type);

    VARIANT object;
    hr = assembly.CreateInstance(name, cast(VARIANT*)&object);

    VARIANT result;
    VARIANT empty;
    type.InvokeMember_3(bstring("ShowDialog"),
            BindingFlags.InvokeMethod | BindingFlags.Instance | BindingFlags.Public,
            null, object, empty, cast(VARIANT*)&result);

}