using System;
using System.Collections.Generic;
using System.Linq;
using System.Xml.Linq;

namespace HashCalculator.GUI
{
    public class AssetEntry : IEquatable<AssetEntry>
    {
        public string Type { get; }
        public string Name { get; }
        public IEnumerable<string> DisplayLabels { get; }
        public uint Hash => SageHash.CalculateLowercaseHash(Name);

        public string IdString => $"{Type}:{Name}";
        public string HashString => $"{Hash:0X} ({Hash})";

        public AssetEntry(XElement element)
        {
            if (element == null)
            {
                throw new ArgumentNullException($"{nameof(element)} is null");
            }

            if (element.Name.Namespace != ModXml.EalaAsset)
            {
                throw new NotSupportedException();
            }

            Type = element.Name.LocalName;
            var id = element.Attribute("id")?.Value;
            Name = id ?? throw new NotSupportedException();

            var labels = from name in element.Elements(ModXml.EalaAsset + "DisplayName")
                         select name.Value;
            var transformLabels = from name in element.Elements(ModXml.EalaAsset + "DisplayNameTransformed")
                                  select name.Value;
            DisplayLabels = labels.Concat(transformLabels).ToArray();
        }

        public bool Equals(AssetEntry entry)
        {
            return this == entry;
        }

        // override object.Equals
        public override bool Equals(object obj)
        {
            //       
            // See the full list of guidelines at
            //   http://go.microsoft.com/fwlink/?LinkID=85237  
            // and also the guidance for operator== at
            //   http://go.microsoft.com/fwlink/?LinkId=85238
            //

            if (!(obj is AssetEntry entry))
            {
                return false;
            }

            return this == entry;
        }

        public static bool operator ==(AssetEntry a, AssetEntry b)
        {
            if (a is null || b is null)
            {
                return a is null == b is null;
            }

            if (ReferenceEquals(a, b))
            {
                return true;
            }

            return a.Type == b.Type && a.Hash == b.Hash;
        }

        public static bool operator !=(AssetEntry a, AssetEntry b)
        {
            return !(a == b);
        }

        // override object.GetHashCode
        public override int GetHashCode()
        {
            return HashCode.Combine(Type, Hash);
        }
    }
}