using System;
using System.Collections;
using System.ComponentModel;
using System.Runtime.InteropServices;

using BLToolkit.ComponentModel;
using BLToolkit.Mapping;
using BLToolkit.Validation;

namespace BLToolkit.Common
{
    [Serializable, Trimmable, ComVisible(true), JetBrains.Annotations.UsedImplicitly]
    public abstract class EntityBase : ICustomTypeDescriptor
    {
        #region Protected members

        protected virtual ICustomTypeDescriptor CreateTypeDescriptor()
        {
            return new CustomTypeDescriptorImpl(GetType());
        }

        #endregion

        #region ICustomTypeDescriptor Members

        private static readonly Hashtable _hashDescriptors = new Hashtable();

        [NonSerialized]
        private ICustomTypeDescriptor _typeDescriptor;
        private ICustomTypeDescriptor  TypeDescriptor
        {
            get
            {
                if (_typeDescriptor == null)
                {
                    Type key = GetType();

                    _typeDescriptor = (ICustomTypeDescriptor)_hashDescriptors[key];

                    if (_typeDescriptor == null)
                        _hashDescriptors[key] = _typeDescriptor = CreateTypeDescriptor();
                }

                return _typeDescriptor;
            }
        }

        AttributeCollection ICustomTypeDescriptor.GetAttributes()
        {
            return TypeDescriptor.GetAttributes();
        }

        string ICustomTypeDescriptor.GetClassName()
        {
            return TypeDescriptor.GetClassName();
        }

        string ICustomTypeDescriptor.GetComponentName()
        {
            return TypeDescriptor.GetComponentName();
        }

        TypeConverter ICustomTypeDescriptor.GetConverter()
        {
            return TypeDescriptor.GetConverter();
        }

        EventDescriptor ICustomTypeDescriptor.GetDefaultEvent()
        {
            return TypeDescriptor.GetDefaultEvent();
        }

        PropertyDescriptor ICustomTypeDescriptor.GetDefaultProperty()
        {
            return TypeDescriptor.GetDefaultProperty();
        }

        object ICustomTypeDescriptor.GetEditor(Type editorBaseType)
        {
            return TypeDescriptor.GetEditor(editorBaseType);
        }

        EventDescriptorCollection ICustomTypeDescriptor.GetEvents(Attribute[] attributes)
        {
            return TypeDescriptor.GetEvents(attributes);
        }

        EventDescriptorCollection ICustomTypeDescriptor.GetEvents()
        {
            return TypeDescriptor.GetEvents();
        }

        PropertyDescriptorCollection ICustomTypeDescriptor.GetProperties(Attribute[] attributes)
        {
            return TypeDescriptor.GetProperties(attributes);
        }

        PropertyDescriptorCollection ICustomTypeDescriptor.GetProperties()
        {
            return TypeDescriptor.GetProperties();
        }

        object ICustomTypeDescriptor.GetPropertyOwner(PropertyDescriptor pd)
        {
            // Do not relay this call to TypeDescriptor. We are the owner.
            //
            return this;
        }

        #endregion

        #region Validation

        public virtual void Validate()
        {
            Validator.Validate(this);
        }

        public virtual bool IsValid(string fieldName)
        {
            return Validator.IsValid(this, fieldName);
        }

        public virtual string[] GetErrorMessages(string fieldName)
        {
            return Validator.GetErrorMessages(this, fieldName);
        }

        #endregion
    }
}