// ==========================================================================
// 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.
// ==========================================================================

using System;
using System.Runtime.InteropServices;
using System.Collections;
using System.Reflection;

namespace Python.Runtime {

    //========================================================================
    // Common base class for all objects that are implemented in managed 
    // code. It defines the common fields that associate CLR and Python
    // objects and common utilities to convert between those identities.
    //========================================================================

    internal abstract class ManagedType {

	internal GCHandle gcHandle; // Native handle
	internal IntPtr pyHandle;   // PyObject *
	internal IntPtr tpHandle;   // PyType *


	//====================================================================
	// Given a Python object, return the associated managed object or null.
	//====================================================================

	internal static ManagedType GetManagedObject(IntPtr ob) {
	    if (ob != IntPtr.Zero) {
		IntPtr tp = Runtime.PyObject_TYPE(ob);
		if (tp == Runtime.PyTypeType || tp == Runtime.PyCLRMetaType) {
		    tp = ob;
		}
		
		int flags = (int)Marshal.ReadIntPtr(tp, TypeOffset.tp_flags);
		if ((flags & TypeFlags.Managed) != 0) {
		    IntPtr op = (tp == ob) ?
			Marshal.ReadIntPtr(tp, TypeOffset.magic()) :
			Marshal.ReadIntPtr(ob, ObjectOffset.magic());
		    GCHandle gc = (GCHandle)op;
		    return (ManagedType)gc.Target;
		}

		// In certain situations, we need to recognize a wrapped
		// exception class and be willing to unwrap the class :(

		if (Runtime.wrap_exceptions) {
		    IntPtr e = Exceptions.UnwrapExceptionClass(ob);
		    if ((e != IntPtr.Zero) && (e != ob)) {
			ManagedType m = GetManagedObject(e);
			Runtime.Decref(e);
			return m;
		    }
		}
	    }
	    return null;
	}


	internal static ManagedType GetManagedObjectErr(IntPtr ob) {
	    ManagedType result = GetManagedObject(ob);
	    if (result == null) {
		Exceptions.SetError(Exceptions.TypeError, 
			   "invalid argument, expected CLR type"
			   );
	    }
	    return result;
	}


	internal static bool IsManagedType(IntPtr ob) {
	    if (ob != IntPtr.Zero) {
		IntPtr tp = Runtime.PyObject_TYPE(ob);
		if (tp == Runtime.PyTypeType || tp == Runtime.PyCLRMetaType) {
		    tp = ob;
		}
		
		int flags = (int)Marshal.ReadIntPtr(tp, TypeOffset.tp_flags);
		if ((flags & TypeFlags.Managed) != 0) {
		    return true;
		}
	    }
	    return false;
	}


    }


}