// ==========================================================================
// This software is subject to the provisions of the Zope Public License,
// Version 2.0 (ZPL).  A copy of the ZPL should accompany this distribution.
// THIS SOFTWARE IS PROVIDED "AS IS" AND ANY AND ALL EXPRESS OR IMPLIED
// WARRANTIES ARE DISCLAIMED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
// WARRANTIES OF TITLE, MERCHANTABILITY, AGAINST INFRINGEMENT, AND FITNESS
// FOR A PARTICULAR PURPOSE.
// ==========================================================================

//============================================================================
// This file is a hand-maintained stub - it implements clr.dll, which can be
// loaded by a standard CPython interpreter as an extension module. When it
// is loaded, it bootstraps the managed runtime integration layer and defers
// to it to do initialization and put the clr module into sys.modules, etc.

// The "USE_PYTHON_RUNTIME_*" defines control what extra evidence is used
// to help the CLR find the appropriate Python.Runtime assembly.

// If defined, the "pythonRuntimeVersionString" variable must be set to
// Python.Runtime's current version.
#define USE_PYTHON_RUNTIME_VERSION

// If defined, the "PythonRuntimePublicKeyTokenData" data array must be
// set to Python.Runtime's public key token.
//#define USE_PYTHON_RUNTIME_PUBLIC_KEY_TOKEN

// If DEBUG_PRINT is defined, a few System.Console.WriteLine calls are made
// to indicate what's going on during the load...
//#define DEBUG_PRINT
//============================================================================

.assembly extern mscorlib
{
	.publickeytoken = (B7 7A 5C 56 19 34 E0 89 )
	.ver 4:0:0:0
}

.assembly clr
{
	.hash algorithm 0x00008004
	.ver 2:4:2:7
}

.module clr.dll
.imagebase 0x00400000
.subsystem 0x00000003
.file alignment 512

// This includes the platform-specific IL.  The include search path
// is set depending on whether we're compiling 32 or 64 bit.
// This MUST come before any other .data directives!
// Why, oh why, can't ilasm support command line #defines? :(
#include "clrmodule-platform.il"

#ifdef USE_PYTHON_RUNTIME_PUBLIC_KEY_TOKEN
.data PythonRuntimePublicKeyTokenData = bytearray (64 e1 4e 84 5a bf 2e 60)
#endif

.class public auto ansi beforefieldinit clrModule extends [mscorlib]System.Object
{
#ifdef USE_PYTHON_RUNTIME_PUBLIC_KEY_TOKEN
	.field static assembly int64 PythonRuntimePublicKeyToken at PythonRuntimePublicKeyTokenData
#endif

	.method public hidebysig specialname rtspecialname instance void
		.ctor() cil managed
	{
		.maxstack 1
		ldarg.0
		call		instance void [mscorlib]System.Object::.ctor()
		ret
	}

	.method public hidebysig static void modopt([mscorlib]System.Runtime.CompilerServices.CallConvCdecl)
		initclr() cil managed
	{
		.vtentry 1:1
		.export [1] as initclr

		.maxstack  6
		.locals init (
			class [mscorlib]System.Reflection.Assembly		pythonRuntime,
			class [mscorlib]System.Reflection.Assembly		executingAssembly,
			class [mscorlib]System.Reflection.AssemblyName	pythonRuntimeName,
			class [mscorlib]System.Type						pythonEngineType,
			int8[]											publicKeyToken,
			string											assemblyDirectory,
			string											pythonRuntimeVersionString,
			string											pythonRuntimeDllPath)

		// pythonRuntime = null;
		ldnull
		stloc		pythonRuntime

		.try
		{
#ifdef DEBUG_PRINT
			ldstr		"Attempting to load Python.Runtime using standard binding rules... "
			call		void [mscorlib]System.Console::Write(string)
#endif

			// Attempt to find and load Python.Runtime using standard assembly binding rules.
			// This roughly translates into looking in order:
			// - GAC
			// - ApplicationBase
			// - A PrivateBinPath under ApplicationBase
			// With an unsigned assembly, the GAC is skipped.

			// System.Reflection.AssemblyName pythonRuntimeName = new System.Reflection.AssemblyName();
			newobj		instance void [mscorlib]System.Reflection.AssemblyName::.ctor()
			stloc		pythonRuntimeName

			// pythonRuntimeName.Name = "Python.Runtime";
			ldloc		pythonRuntimeName
			ldstr		"Python.Runtime"
			callvirt	instance void [mscorlib]System.Reflection.AssemblyName::set_Name(string)

#ifdef USE_PYTHON_RUNTIME_VERSION
			// pythonRuntimeVersionString = "...";
			ldstr		"2.0.0.2"
			stloc		pythonRuntimeVersionString

			// pythonRuntimeName.Version = new Version(pythonRuntimeVersionString);
			ldloc		pythonRuntimeName
			ldloc		pythonRuntimeVersionString
			newobj		instance void [mscorlib]System.Version::.ctor(string)
			callvirt	instance void [mscorlib]System.Reflection.AssemblyName::set_Version(class [mscorlib]System.Version)
#endif

#ifdef USE_PYTHON_RUNTIME_PUBLIC_KEY_TOKEN
			// publicKeyToken = new byte[] { ... };
			ldc.i4.8
			newarr		[mscorlib]System.Byte
			dup
			ldtoken		field int64 clrModule::PythonRuntimePublicKeyToken
			call		void [mscorlib]System.Runtime.CompilerServices.RuntimeHelpers::InitializeArray(class [mscorlib]System.Array, valuetype [mscorlib]System.RuntimeFieldHandle)
			stloc		publicKeyToken

			// pythonRuntimeName.SetPublicKeyToken(publicKeyToken);
			ldloc		pythonRuntimeName
			ldloc		publicKeyToken
			callvirt	instance void [mscorlib]System.Reflection.AssemblyName::SetPublicKeyToken(uint8[])
#endif

			// pythonRuntimeName.CultureInfo = System.Globalization.CultureInfo.InvariantCulture;
			ldloc		pythonRuntimeName
			call		class [mscorlib]System.Globalization.CultureInfo [mscorlib]System.Globalization.CultureInfo::get_InvariantCulture()
			callvirt	instance void [mscorlib]System.Reflection.AssemblyName::set_CultureInfo(class [mscorlib]System.Globalization.CultureInfo)

			// return System.Reflection.Assembly.Load(pythonRuntimeName);
			ldloc		pythonRuntimeName
			call		class [mscorlib]System.Reflection.Assembly [mscorlib]System.Reflection.Assembly::Load(class [mscorlib]System.Reflection.AssemblyName)
			stloc		pythonRuntime

#ifdef DEBUG_PRINT
			ldstr		"Success!"
			call		void [mscorlib]System.Console::WriteLine(string)
#endif
			leave.s		LOADED_PYTHON_RUNTIME
		}
		catch [mscorlib]System.Object
		{
#ifdef DEBUG_PRINT
			ldstr		"Failed."
			call		void [mscorlib]System.Console::WriteLine(string)
#endif
			leave.s		EXIT_CLR_LOAD
		}
		EXIT_CLR_LOAD: nop

		.try
		{
			// If the above fails for any reason, we fallback to attempting to load "Python.Runtime.dll"
			// from the directory this assembly is running in. "This assembly" is probably "clr.pyd",
			// sitting somewhere in PYTHONPATH.  This is using Assembly.LoadFrom, and inherits all the
			// caveats of that call.  See MSDN docs for details.
			// Suzanne Cook's blog is also an excellent source of info on this:
			// http://blogs.msdn.com/suzcook/
			// http://blogs.msdn.com/suzcook/archive/2003/05/29/57143.aspx
			// http://blogs.msdn.com/suzcook/archive/2003/06/13/57180.aspx
			// executingAssembly = System.Reflection.Assembly.GetExecutingAssembly();
			call		class [mscorlib]System.Reflection.Assembly [mscorlib]System.Reflection.Assembly::GetExecutingAssembly()
			stloc		executingAssembly

			// assemblyDirectory = System.IO.Path.GetDirectoryName(executingAssembly.Location);
			ldloc		executingAssembly
			callvirt	instance string [mscorlib]System.Reflection.Assembly::get_Location()
			call		string [mscorlib]System.IO.Path::GetDirectoryName(string)
			stloc		assemblyDirectory

			// pythonRuntimeDllPath = System.IO.Path.Combine(assemblyDirectory, "Python.Runtime.dll");
			ldloc		assemblyDirectory
			ldstr		"Python.Runtime.dll"
			call		string [mscorlib]System.IO.Path::Combine(string, string)
			stloc		pythonRuntimeDllPath

#ifdef DEBUG_PRINT
			ldstr		"Attempting to load Python.Runtime from: '{0}'... "
			ldloc		pythonRuntimeDllPath
			call		void [mscorlib]System.Console::Write(string, object)
#endif

			// pythonRuntime = System.Reflection.Assembly.LoadFrom(pythonRuntimeDllPath);
			ldloc		pythonRuntimeDllPath
			call		class [mscorlib]System.Reflection.Assembly [mscorlib]System.Reflection.Assembly::LoadFrom(string)
			stloc		pythonRuntime

#ifdef DEBUG_PRINT
			ldstr		"Success!"
			call		void [mscorlib]System.Console::WriteLine(string)
			
			ldloc		pythonRuntime
			callvirt	instance string	[mscorlib]System.Reflection.Assembly::get_CodeBase()
			call		void [mscorlib]System.Console::WriteLine(string)
#endif
			leave.s		LOADED_PYTHON_RUNTIME
		}
		catch [mscorlib]System.Object
		{
#ifdef DEBUG_PRINT
			ldstr		"Failed."
			call		void [mscorlib]System.Console::WriteLine(string)
#endif
			leave.s		EXIT_PYTHONPATH_LOAD
		}
		EXIT_PYTHONPATH_LOAD: nop

		// If we get here, we haven't loaded Python.Runtime, so bail.
#ifdef DEBUG_PRINT
		ldstr		"Could not load Python.Runtime, so sad."
		call		void [mscorlib]System.Console::WriteLine(string)
#endif
		ret;

		// Once here, we've successfully loaded SOME version of Python.Runtime
		// So now we get the PythonEngine and execute the InitExt method on it.
		LOADED_PYTHON_RUNTIME: nop
		.try
		{
#ifdef DEBUG_PRINT
			ldstr		"Running Python.Runtime.PythonEngine.InitExt()"
			call		void [mscorlib]System.Console::WriteLine(string)
#endif
			// pythonEngineType = pythonRuntime.GetType("Python.Runtime.PythonEngine");
			ldloc		pythonRuntime
			ldstr		"Python.Runtime.PythonEngine"
			callvirt	instance class [mscorlib]System.Type [mscorlib]System.Reflection.Assembly::GetType(string)
			stloc		pythonEngineType

			// pythonEngineType.InvokeMember("InitExt", System.Reflection.BindingFlags.InvokeMethod, null, null, null);
			ldloc		pythonEngineType
			ldstr		"InitExt"
			ldc.i4		0x100
			ldnull
			ldnull
			ldnull
			callvirt	instance object [mscorlib]System.Type::InvokeMember(	string,
																				valuetype [mscorlib]System.Reflection.BindingFlags,
																				class [mscorlib]System.Reflection.Binder,
																				object,
																				object[])
			pop
			leave.s    EXIT_TRY_INVOKE
		}
		catch [mscorlib]System.Object
		{
#ifdef DEBUG_PRINT
			ldstr		"Error calling Python.Runtime.PythonEngine.InitExt()."
			call		void [mscorlib]System.Console::WriteLine(string)
#endif
			leave.s    EXIT_TRY_INVOKE
		}
		EXIT_TRY_INVOKE: nop

		ret
	}
}