// ==========================================================================
// 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;

namespace Python.Runtime {

    //========================================================================
    // Implements a Python event binding type, similar to a method binding.
    //========================================================================

    internal class EventBinding : ExtensionType {

	EventObject e;
	IntPtr target;

	public EventBinding(EventObject e, IntPtr target) : base() {
	    Runtime.Incref(target);
	    this.target = target;
	    this.e = e;
	}


	//====================================================================
	// EventBinding += operator implementation.
	//====================================================================

	[CallConvCdecl()]
	public static IntPtr nb_inplace_add(IntPtr ob, IntPtr arg) {
	    EventBinding self = (EventBinding)GetManagedObject(ob);

	    if (Runtime.PyCallable_Check(arg) < 1) {
		Exceptions.SetError(Exceptions.TypeError, 
				    "event handlers must be callable"
				    );
		return IntPtr.Zero;
	    }

	    if(!self.e.AddEventHandler(self.target, arg)) {
		return IntPtr.Zero;
	    }

	    Runtime.Incref(self.pyHandle);
	    return self.pyHandle;
	}


	//====================================================================
	// EventBinding -= operator implementation.
	//====================================================================

	[CallConvCdecl()]
	public static IntPtr nb_inplace_subtract(IntPtr ob, IntPtr arg) {
	    EventBinding self = (EventBinding)GetManagedObject(ob);

	    if (Runtime.PyCallable_Check(arg) < 1) {
		Exceptions.SetError(Exceptions.TypeError, 
				    "invalid event handler"
				    );
		return IntPtr.Zero;
	    }

	    if (!self.e.RemoveEventHandler(self.target, arg)) {
		return IntPtr.Zero;
	    }

	    Runtime.Incref(self.pyHandle);
	    return self.pyHandle;
	}


	//====================================================================
	// EventBinding  __hash__ implementation.
	//====================================================================

	[CallConvCdecl()]
	public static IntPtr tp_hash(IntPtr ob) {
	    EventBinding self = (EventBinding)GetManagedObject(ob);
	    long x = 0;
	    long y = 0;

	    if (self.target != IntPtr.Zero) {
		x = Runtime.PyObject_Hash(self.target).ToInt64();
		if (x == -1) {
		    return new IntPtr(-1);
		}
	    }
 
	    y = Runtime.PyObject_Hash(self.e.pyHandle).ToInt64();
	    if (y == -1) {
		return new IntPtr(-1);
	    }

	    x ^= y;

	    if (x == -1) {
		x = -1;
	    }

	    return new IntPtr(x);
	}


	//====================================================================
	// EventBinding __repr__ implementation.
	//====================================================================

	[CallConvCdecl()]
	public static IntPtr tp_repr(IntPtr ob) {
	    EventBinding self = (EventBinding)GetManagedObject(ob);
	    string type = (self.target == IntPtr.Zero) ? "unbound" : "bound";
	    string s = String.Format("", type, self.e.name);
	    return Runtime.PyString_FromString(s);
	}


	//====================================================================
	// EventBinding dealloc implementation.
	//====================================================================

	[CallConvCdecl()]
	public static new void tp_dealloc(IntPtr ob) {
	    EventBinding self = (EventBinding)GetManagedObject(ob);
	    Runtime.Decref(self.target);
	    ExtensionType.FinalizeObject(self);
	}

    }


}