using System;
using System.Xml.Serialization;

namespace DTS.Common.XMLUtils
{
    //FB 24428 https://stackoverflow.com/questions/244953/how-to-serialize-a-nullable-int-without-xsinil-being-added-to-the-resulting-x
    public class NullableElement<T>
    {
        public NullableElement(T value)
        {
            _value = value;
            _hasValue = true;
        }

        public NullableElement()
        {
            _hasValue = false;
        }

        [XmlText]
        public T Value
        {
            get
            {
                if (!HasValue)
                    throw new InvalidOperationException();
                return _value;
            }
            set
            {
                _value = value;
                _hasValue = true;
            }
        }

        [XmlIgnore]
        public bool HasValue
        { get { return _hasValue; } }

        public T GetValueOrDefault()
        { return _value; }
        public T GetValueOrDefault(T i_defaultValue)
        { return HasValue ? _value : i_defaultValue; }

        public static explicit operator T(NullableElement<T> i_value)
        { return i_value.Value; }
        public static implicit operator NullableElement<T>(T i_value)
        { return new NullableElement<T>(i_value); }

        public override bool Equals(object i_other)
        {
            if (!HasValue)
                return (i_other == null);
            if (i_other == null)
                return false;
            return _value.Equals(i_other);
        }

        public override int GetHashCode()
        {
            if (!HasValue)
                return 0;
            return _value.GetHashCode();
        }

        public override string ToString()
        {
            if (!HasValue)
                return "";
            return _value.ToString();
        }

        bool _hasValue;
        T _value;
    }
}