using System;
using System.Xml.Linq;
using System.Globalization;

namespace DataFileAnalyzer
{
    /// <summary>
    /// The key of a data file.
    /// This is only used on a local computer. Never shared between users.
    /// </summary>
    public struct DataFileKey : IComparable, IComparable<DataFileKey>
    {
        /// <summary>
        /// The invalid key value
        /// </summary>
        public static readonly UInt64 InvalidKeyValue = 0xFFFFFFFFFFFFFFFF;

        /// <summary>
        /// The invalid key
        /// </summary>
        public static readonly DataFileKey Invalid = new DataFileKey(InvalidKeyValue);

        /// <summary>
        /// The value of the key
        /// </summary>
        private UInt64 m_keyValue;

        /// <summary>
        /// The value of the key
        /// </summary>
        public UInt64 KeyValue { get { return m_keyValue; } set { m_keyValue = value; } }

        /// <summary>
        /// Constructor
        /// </summary>
        public DataFileKey(UInt64 _value) { m_keyValue = _value; }

        /// <summary>
        /// Comparison
        /// </summary>
        public override bool Equals(object _other)
        {
            return
                _other.GetType() == typeof(DataFileKey) &&
                m_keyValue == ((DataFileKey)_other).m_keyValue;
        }

        /// <summary>
        /// Comparison
        /// </summary>
        public static bool operator ==(DataFileKey k1, DataFileKey k2)
        {
            return k1.Equals(k2);
        }

        /// <summary>
        /// Comparison
        /// </summary>
        public static bool operator !=(DataFileKey k1, DataFileKey k2)
        {
            return !k1.Equals(k2);
        }

        /// <summary>
        /// Hash code
        /// </summary>
        public override int GetHashCode()
        {
            return KeyValue.GetHashCode();
        }

        /// <summary>
        /// ToString
        /// </summary>
        public override string ToString()
        {
            return KeyValue.ToString("X16");
        }

        /// <summary>
        /// Is it an invalid key?
        /// </summary>
        public bool IsInvalid()
        {
            return m_keyValue == InvalidKeyValue;
        }

        /// <summary>
        /// Set this key as invalid
        /// </summary>
        public void SetInvalid()
        {
            m_keyValue = InvalidKeyValue;
        }

        /// <summary>
        /// Save to an XML element
        /// </summary>
        public static bool Save(DataFileKey _key, XElement _element)
        {
            _element.SetAttributeValue("Key", _key.ToString());
            return true;
        }

        /// <summary>
        /// Load from an XML element
        /// </summary>
        public static DataFileKey Load(XElement _element)
        {
            UInt64 keyValue;
            if (UInt64.TryParse(_element.Attribute("Key").Value, NumberStyles.HexNumber, CultureInfo.InvariantCulture, out keyValue))
                return new DataFileKey(keyValue);
            return DataFileKey.Invalid;
        }

        public int CompareTo(object obj)
        {
            if (!(obj is DataFileKey))
                return 1;
            return CompareTo((DataFileKey)obj);
        }

        public int CompareTo(DataFileKey other)
        {
            return ToString().CompareTo(other.ToString());
        }
    }
}