using System;
using System.Linq;

namespace DTS.Serialization.IRIGCh10.Attributes
{
    /// <summary>
    /// allows annotating an enum with a value,
    /// see TABLE 10-7. DATA TYPE NAMES AND DESCRIPTIONS in Chapter 10 pdf
    /// </summary>
    [AttributeUsage(AttributeTargets.All)]
    public class PacketHeaderValueAttribute : Attribute
    {
        /// <summary>Specifies the default value for the <see cref="PacketHeaderValueAttribute" />, which is 0x00. This <see langword="static" /> field is read-only.</summary>
        public static readonly PacketHeaderValueAttribute Default = new PacketHeaderValueAttribute();
        private byte _packetHeader;

        /// <summary>Initializes a new instance of the <see cref="PacketHeaderValueAttribute" /> class with no parameters.</summary>
        public PacketHeaderValueAttribute()
            : this(0x00)
        {
        }

        /// <summary>Initializes a new instance of the <see cref="PacketHeaderValueAttribute" /> class with a PacketHeader.</summary>
        /// <param name="packetHeader">packet header value. </param>
        public PacketHeaderValueAttribute(byte packetHeader)
        {
            _packetHeader = packetHeader;
        }

        /// <summary>Gets the packet header value stored in this attribute.</summary>
        /// <returns>The packet header value stored in this attribute.</returns>
        public virtual byte PacketHeader => PacketHeaderValue;

        /// <summary>Gets or sets the byte stored as the packet header value.</summary>
        /// <returns>The byte stored as the packet header version value. The default value is 0x00.</returns>
        protected byte PacketHeaderValue
        {
            get => _packetHeader;
            set => _packetHeader = value;
        }

        /// <summary>Returns whether the value of the given object is equal to the current <see cref="PacketHeaderValueAttribute" />.</summary>
        /// <param name="obj">The object to test the value equality of. </param>
        /// <returns>
        /// <see langword="true" /> if the value of the given object is equal to that of the current; otherwise, <see langword="false" />.</returns>
        public override bool Equals(object obj)
        {
            if (obj == this)
                return true;
            if (obj is PacketHeaderValueAttribute packetHeaderAttribute)
                return packetHeaderAttribute.PacketHeader == PacketHeader;
            return false;
        }

        /// <summary>Returns the hash code for this instance.</summary>
        /// <returns>A 32-bit signed integer hash code.</returns>
        public override int GetHashCode()
        {
            return PacketHeader.GetHashCode();
        }

        /// <summary>Returns a value indicating whether this is the default <see cref="PacketHeaderValueAttribute" /> instance.</summary>
        /// <returns>
        /// <see langword="true" />, if this is the default <see cref="PacketHeaderValueAttribute" /> instance; otherwise, <see langword="false" />.</returns>
        public override bool IsDefaultAttribute()
        {
            return Equals(Default);
        }

        public static byte GetPacketHeaderValue(Enum value)
        {
            var fi = value.GetType().GetField(value.ToString());
            var attributes = (PacketHeaderValueAttribute[])fi.GetCustomAttributes(
                typeof(PacketHeaderValueAttribute), false);
            if (attributes.Any())
            {
                return attributes.First().PacketHeaderValue;
            }
            return Default.PacketHeaderValue;
        }
    }
}