using System;
using System.Globalization;
using JD.Kernel.StaticHelpers;

namespace JD.TeaBoxAddinSystem.Addins.Description
{
    /// <summary>
    /// Represents a versioned reference to an <see cref="Addin"/>.
    /// </summary>
    public sealed class AddinReference
    {
        #region Variables

        private readonly string m_name;
        private readonly Version m_minVersion;
        private readonly Version m_maxVersion;

        /// <summary>
        /// Cached versions
        /// </summary>
        internal readonly static Version ZeroVersion = new Version(0, 0, 0, 0);
        internal readonly static Version InfiniteVersion = new Version(int.MaxValue, int.MaxValue);

        #endregion

        #region Constructor

        /// <summary>
        /// Constructor.
        /// </summary>
        /// <param name="name">Name of the referenced addin.</param>
        public AddinReference(string name)
            : this(name, ZeroVersion, InfiniteVersion)
        {
        }

        /// <summary>
        /// Constructor.
        /// </summary>
        /// <param name="name">Name of the referenced addin.</param>
        /// <param name="specificVersion">Version of the referenced addin.</param>
        public AddinReference(string name, Version specificVersion)
            : this(name, specificVersion, specificVersion)
        {
        }

        /// <summary>
        /// Constructor.
        /// </summary>
        /// <param name="name">Name of the referenced addin.</param>
        /// <param name="minVersion">Minimum version of the referenced addin.</param>
        /// <param name="maxVersion">Maximum version of the referenced addin.</param>
        public AddinReference(string name, Version minVersion, Version maxVersion)
        {
            Throw.IfEmpty(name, "name");
            Throw.IfNull(minVersion, "minVersion");
            Throw.IfNull(maxVersion, "maxVersion");

            if (Compare(minVersion, maxVersion) > 0)
            {
                throw new ArgumentException("minVersion cannot be higher than maxVersion");
            }

            m_name = name;
            m_minVersion = minVersion;
            m_maxVersion = maxVersion;
        }

        #endregion

        #region Properties

        /// <summary>
        /// Name of the referenced addin.
        /// </summary>
        public string Name
        {
            get
            {
                return m_name;
            }
        }

        /// <summary>
        /// The minimum version of the referenced addin.
        /// </summary>
        public Version MinimumVersion
        {
            get
            {
                return m_minVersion;
            }
        }

        /// <summary>
        /// The maximum version of the referenced addin.
        /// </summary>
        public Version MaximumVersion
        {
            get
            {
                return m_maxVersion;
            }
        }

        #endregion

        #region Methods

        #region Public Methods

        /// <summary>
        /// Validates that the given version is between the minimum and maximum version.
        /// </summary>
        /// <param name="version">Version to test</param>
        /// <returns>Whether the given bersion is between the minimum and maximum version.</returns>
        public bool Validate(Version version)
        {
            return (Compare(m_minVersion, version) <= 0 && Compare(m_maxVersion, version) >= 0);
        }

        /// <summary>
        /// Checks whether this reference overlaps another reference (i.e. if A intersects B).
        /// </summary>
        /// <param name="reference">Other reference to check</param>
        /// <returns></returns>
        public bool Overlaps(AddinReference reference)
        {
            if (string.Compare(this.Name, reference.Name, StringComparison.Ordinal) != 0)
            {
                return false;
            }

            return ((Compare(m_maxVersion, reference.MinimumVersion) >= 0) && (Compare(m_minVersion, reference.MaximumVersion) <= 0));
        }

        #endregion

        #region Static Methods

        /// <summary>
        /// Compares two version together, ignoring unspecified fields (unlike <see cref="Version.CompareTo(Version)"/>).
        /// </summary>
        /// <param name="a"></param>
        /// <param name="b"></param>
        /// <returns>-1 if a &lt; b, 0 if a == b, 1 if a &gt; b</returns>
        public static int Compare(Version a, Version b)
        {
            if (a.Major != b.Major)
            {
                return a.Major > b.Major ? 1 : -1;
            }

            if (a.Minor != b.Minor)
            {
                return a.Minor > b.Minor ? 1 : -1;
            }

            if (a.Build < 0 || b.Build < 0)
                return 0;

            if (a.Build != b.Build)
            {
                return a.Build > b.Build ? 1 : -1;
            }

            if (a.Revision < 0 || b.Revision < 0)
                return 0;

            if (a.Revision != b.Revision)
            {
                return a.Revision > b.Revision ? 1 : -1;
            }

            return 0;
        }

        #endregion

        #region Operator Overloading

        /// <summary>
        /// Equality Operator
        /// </summary>
        /// <param name="a"></param>
        /// <param name="b"></param>
        /// <returns></returns>
        public static bool operator == (AddinReference a, AddinReference b)
        {
            return (object)a == null ? (object)b == null : a.Equals(b);
        }

        /// <summary>
        /// Inequality Operator
        /// </summary>
        /// <param name="a"></param>
        /// <param name="b"></param>
        /// <returns></returns>
        public static bool operator !=(AddinReference a, AddinReference b)
        {
            return !(a==b);
        }

        /// <summary>
        /// Equals Override
        /// </summary>
        /// <param name="obj"></param>
        /// <returns></returns>
        public override bool Equals(object obj)
        {
            if (object.ReferenceEquals(this, obj))
            {
                return true;
            }

            AddinReference other = obj as AddinReference;

            if ((object)other == null)
            {
                return false;
            }

            return string.Equals(m_name, other.m_name) && Compare(m_minVersion, other.m_minVersion) == 0 && Compare(m_maxVersion, other.m_maxVersion) == 0;
        }

        /// <summary>
        /// GetHashCode Override
        /// </summary>
        /// <returns></returns>
        public override int GetHashCode()
        {
            return m_name.GetHashCode() ^ m_minVersion.GetHashCode() ^ m_maxVersion.GetHashCode();
        }

        /// <summary>
        /// ToString Override
        /// </summary>
        /// <returns></returns>
        public override string ToString()
        {
            string version;

            if (MinimumVersion == ZeroVersion && MaximumVersion == InfiniteVersion)
            {
                version = "Any";
            }
            else if (MinimumVersion == MaximumVersion)
            {
                version = MinimumVersion.ToString();
            }
            else
            {
                if (MinimumVersion == ZeroVersion)
                {
                    version = MaximumVersion.ToString() + " and earlier";
                }
                else if (MaximumVersion == InfiniteVersion)
                {
                    version = MinimumVersion.ToString() + " and later";
                }
                else
                {
                    version = MinimumVersion.ToString() + "-" + MaximumVersion;
                }
            }

            return string.Format(CultureInfo.InvariantCulture, "[Addin={0}, Version={1}]", Name, version);
        }

        #endregion

        #endregion
    }
}