ImageSharp/src/ImageSharp/Metadata/Profiles/Exif/Values/ExifValue.cs

// Copyright (c) Six Labors.
// Licensed under the Six Labors Split License.

using System.Runtime.CompilerServices;

namespace SixLabors.ImageSharp.Metadata.Profiles.Exif;

internal abstract class ExifValue : IExifValue, IEquatable<ExifTag>
{
    protected ExifValue(ExifTag tag) => this.Tag = tag;

    protected ExifValue(ExifTagValue tag) => this.Tag = new UnkownExifTag(tag);

    internal ExifValue(ExifValue other)
    {
        Guard.NotNull(other, nameof(other));

        this.DataType = other.DataType;
        this.IsArray = other.IsArray;
        this.Tag = other.Tag;

        if (!other.IsArray)
        {
            // All types are value types except for string which is immutable so safe to simply assign.
            this.TrySetValue(other.GetValue());
        }
        else
        {
            // All array types are value types so Clone() is sufficient here.
            Array? array = (Array?)other.GetValue();
            this.TrySetValue(array?.Clone());
        }
    }

    public virtual ExifDataType DataType { get; }

    public virtual bool IsArray { get; }

    public ExifTag Tag { get; }

    public static bool operator ==(ExifValue left, ExifTag right) => Equals(left, right);

    public static bool operator !=(ExifValue left, ExifTag right) => !Equals(left, right);

    public override bool Equals(object? obj)
    {
        if (obj is null)
        {
            return false;
        }

        if (ReferenceEquals(this, obj))
        {
            return true;
        }

        if (obj is ExifTag tag)
        {
            return this.Equals(tag);
        }

        if (obj is ExifValue value)
        {
            return this.Tag.Equals(value.Tag) && Equals(this.GetValue(), value.GetValue());
        }

        return false;
    }

    [MethodImpl(InliningOptions.ShortMethod)]
    public bool Equals(ExifTag? other) => this.Tag.Equals(other);

    [MethodImpl(InliningOptions.ShortMethod)]
    public override int GetHashCode() => HashCode.Combine(this.Tag, this.GetValue());

    public abstract object? GetValue();

    public abstract bool TrySetValue(object? value);

    public abstract IExifValue DeepClone();
}