using System;
using System.ComponentModel;

using BLToolkit.Reflection;

namespace BLToolkit.ComponentModel
{
    public class MemberPropertyDescriptor : PropertyDescriptor
    {
        public MemberPropertyDescriptor(Type componentType, string memberName)
            : base(memberName, null)
        {
            _componentType  = componentType;
            _memberAccessor = TypeAccessor.GetAccessor(componentType)[memberName];
        }

        private readonly Type _componentType;
        public  override Type  ComponentType
        {
            get { return _componentType; }
        }

        public override Type PropertyType
        {
            get { return _memberAccessor.Type; }
        }

        private readonly MemberAccessor _memberAccessor;
        public           MemberAccessor  MemberAccessor
        {
            get { return _memberAccessor; }
        }

        public override bool CanResetValue(object component)
        {
            if (PropertyType.IsValueType)
                return TypeAccessor.GetNullValue(PropertyType) != null;
            return PropertyType == typeof(string);
        }

        public override void ResetValue(object component)
        {
            SetValue(component, TypeAccessor.GetNullValue(PropertyType));
        }

        public override object GetValue(object component)
        {
            return component != null? _memberAccessor.GetValue(component): null;
        }

        public override void SetValue(object component, object value)
        {
            if (component != null)
                _memberAccessor.SetValue(component, value);
        }

        public override bool IsReadOnly
        {
            get { return !_memberAccessor.HasSetter; }
        }

        public override bool ShouldSerializeValue(object component)
        {
            return false;
        }

        private         AttributeCollection _attributes;
        public override AttributeCollection  Attributes
        {
            get
            {
                if (_attributes == null)
                {
                    object[]    memberAttrs = _memberAccessor.GetAttributes();
                    Attribute[] attrs       = new Attribute[memberAttrs == null? 0: memberAttrs.Length];

                    if (memberAttrs != null)
                        memberAttrs.CopyTo(attrs, 0);

                    _attributes = new AttributeCollection(attrs);
                }

                return _attributes;
            }
        }
    }
}