// ==========================================================================
// 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.Reflection;
using System.Runtime.InteropServices;

namespace Python.Runtime {

    /// 
    /// Provides the implementation for reflected interface types. Managed
    /// interfaces are represented in Python by actual Python type objects.
    /// Each of those type objects is associated with an instance of this
    /// class, which provides the implementation for the Python type.
    /// 

    internal class InterfaceObject : ClassBase {

	internal ConstructorInfo ctor;

	internal InterfaceObject(Type tp) : base(tp) {
	    CoClassAttribute coclass = (CoClassAttribute) 
	      Attribute.GetCustomAttribute(tp, cc_attr);
	    if (coclass != null) {
		ctor = coclass.CoClass.GetConstructor(Type.EmptyTypes);
	    }
	}

	static Type cc_attr;

	static InterfaceObject() {
	    cc_attr = typeof(CoClassAttribute);
	}

	//====================================================================
	// Implements __new__ for reflected interface types.
	//====================================================================

	[CallConvCdecl()]
	public static IntPtr tp_new(IntPtr tp, IntPtr args, IntPtr kw) {
	    InterfaceObject self = (InterfaceObject)GetManagedObject(tp);
	    int nargs = Runtime.PyTuple_Size(args);
	    Type type = self.type;
	    Object obj;

	    if (nargs == 1) {
		IntPtr inst = Runtime.PyTuple_GetItem(args, 0);
		CLRObject co = GetManagedObject(inst) as CLRObject;

		if ((co == null) || (!type.IsInstanceOfType(co.inst))) {
		    string msg = "object does not implement " + type.Name;
		    Exceptions.SetError(Exceptions.TypeError, msg);
		    return IntPtr.Zero;
		}

		obj = co.inst;
	    }

	    else if ((nargs == 0) && (self.ctor != null)) {
		obj = self.ctor.Invoke(null);

		if (obj == null || !type.IsInstanceOfType(obj)) {
		    Exceptions.SetError(Exceptions.TypeError,
		               "CoClass default constructor failed" 
			       );
		    return IntPtr.Zero;
		}
	    }

	    else {
		Exceptions.SetError(Exceptions.TypeError,
				    "interface takes exactly one argument"
				    );
		return IntPtr.Zero;
	    }

	    return CLRObject.GetInstHandle(obj, self.pyHandle);
	}


    }	


}