namespace Nbt.Tag;

public interface INbtValue : INbtTag
{
    object Value { get; set; }
}

public interface INbtValue<T> : INbtValue where T : notnull
{
    new T Value { get; set; }
}

public abstract class NbtValue<T> : INbtValue<T> where T : notnull
{
    private static readonly EqualityComparer<T> ValueComparer = EqualityComparer<T>.Default;

    protected T value;

    internal protected NbtValue(T value) : base() => this.value = value;

    public abstract NbtTagType Type { get; }

    INbtTag INbtTag.this[string tagName] { get => throw new NotSupportedException(); set => throw new NotSupportedException(); }

    INbtTag INbtTag.this[int tagIndex] { get => throw new NotSupportedException(); set => throw new NotSupportedException(); }

    INbtTag INbtTag.this[INbtPathElement tagPath] { get => throw new NotSupportedException(); set => throw new NotSupportedException(); }

    INbtList INbtTag.AsList() => throw new NotSupportedException();

    INbtCompound INbtTag.AsCompound() => throw new NotSupportedException();

    INbtValue INbtTag.AsValue() => this;

    INbtValue<U> INbtTag.AsValue<U>() => (INbtValue<U>)this;

    INbtArray INbtTag.AsArray() => (INbtArray)this;

    INbtArray<U> INbtTag.AsArray<U>() => (INbtArray<U>)this;

    INbtTag INbtTag.Copy() => Copy();
    public NbtValue<T> Copy() => NewInstance(CopyValue());

    object INbtValue.Value
    {
        get => Value;
        set => Value = (T)Convert.ChangeType(value, typeof(T));
    }

    public T Value
    {
        get => value;
        set => this.value = value ?? throw new ArgumentNullException(nameof(value));
    }

    protected virtual T CopyValue() => value;
    protected abstract NbtValue<T> NewInstance(T value);

    public bool Equals(INbtTag? other) => ReferenceEquals(other, this) || other is NbtValue<T> o && ValueComparer.Equals(value, o.value);

    public override bool Equals(object? obj) => ReferenceEquals(obj, this) || obj is NbtValue<T> other && ValueComparer.Equals(value, other.value);

    public override int GetHashCode() => value.GetHashCode();
}