// ==========================================================================
// 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.Collections;
using System.Reflection;
using System.Security.Permissions;

namespace Python.Runtime {

    //========================================================================
    // Implements a Python descriptor type that manages CLR properties.
    //========================================================================

    internal class PropertyObject : ExtensionType {

	PropertyInfo info;
	MethodInfo getter;
	MethodInfo setter;

	[StrongNameIdentityPermissionAttribute(SecurityAction.Assert)]
	public PropertyObject(PropertyInfo md) : base() {
	    getter = md.GetGetMethod(true);
	    setter = md.GetSetMethod(true);
	    info = md;
	}


	//====================================================================
	// Descriptor __get__ implementation. This method returns the 
	// value of the property on the given object. The returned value
	// is converted to an appropriately typed Python object.
	//====================================================================

	[CallConvCdecl()]
	public static IntPtr tp_descr_get(IntPtr ds, IntPtr ob, IntPtr tp) {
	    PropertyObject self = (PropertyObject)GetManagedObject(ds);
	    MethodInfo getter = self.getter;
	    IntPtr ts = IntPtr.Zero;
	    Object result;


	    if (getter == null) {
		return Exceptions.RaiseTypeError("property cannot be read");
	    }

	    if ((ob == IntPtr.Zero) || (ob == Runtime.PyNone)) {
		if (!(getter.IsStatic)) {
		    Exceptions.SetError(Exceptions.TypeError, 
			       "instance property must be accessed through " + 
			       "a class instance"
			       );
		    return IntPtr.Zero;
		}

		try {
		    result = self.info.GetValue(null, null);
		    return Converter.ToPython(result, self.info.PropertyType);
		}
		catch(Exception e) {
		    return Exceptions.RaiseTypeError(e.Message);
		}
	    }

	    CLRObject co = GetManagedObject(ob) as CLRObject;
	    if (co == null) {
		return Exceptions.RaiseTypeError("invalid target");
	    }

	    try {
		result = self.info.GetValue(co.inst, null);
		return Converter.ToPython(result, self.info.PropertyType);
	    }
	    catch(Exception e) {
		if (e.InnerException != null) {
		    e = e.InnerException;
		}
		Exceptions.SetError(e);
		return IntPtr.Zero;
	    }
	}


	//====================================================================
	// Descriptor __set__ implementation. This method sets the value of
	// a property based on the given Python value. The Python value must 
	// be convertible to the type of the property.
	//====================================================================

	[CallConvCdecl()]
	public static new int tp_descr_set(IntPtr ds, IntPtr ob, IntPtr val) {
	    PropertyObject self = (PropertyObject)GetManagedObject(ds);
	    MethodInfo setter = self.setter;
	    IntPtr ts = IntPtr.Zero;
	    Object newval;

	    if (val == IntPtr.Zero) {
		Exceptions.RaiseTypeError("cannot delete property");
		return -1;
	    }

	    if (setter == null) {
		Exceptions.RaiseTypeError("property is read-only");
		return -1;
	    }


	    if (!Converter.ToManaged(val, self.info.PropertyType, out newval, 
				      true)) {
		return -1;
	    }

	    bool is_static = setter.IsStatic;

	    if ((ob == IntPtr.Zero) || (ob == Runtime.PyNone)) {
		if (!(is_static)) {
		    Exceptions.RaiseTypeError(
		    "instance property must be set on an instance"
		    );
		    return -1;
		}
	    }

	    try {
		if (!is_static) {
		    CLRObject co = GetManagedObject(ob) as CLRObject;
		    if (co == null) {
			Exceptions.RaiseTypeError("invalid target");
			return -1;
		    }
		    self.info.SetValue(co.inst, newval, null);
		}
		else {
		    self.info.SetValue(null, newval, null);		    
		}
		return 0;
	    }
	    catch(Exception e) {
		if (e.InnerException != null) {
		    e = e.InnerException;
		}
		Exceptions.SetError(e);
		return -1;
	    }

	}


	//====================================================================
	// Descriptor __repr__ implementation.
	//====================================================================

	[CallConvCdecl()]
	public static IntPtr tp_repr(IntPtr ob) {
	    PropertyObject self = (PropertyObject)GetManagedObject(ob);
	    string s = String.Format("", self.info.Name);
	    return Runtime.PyString_FromStringAndSize(s, s.Length);
	}

    }


}