namespace EC.Helper.RabbitFunc.Compiler;

[Serializable]
public readonly struct IndexSpan : IEquatable<IndexSpan>
{
    private readonly int start;
    private readonly int length;

    public IndexSpan(int start, int length)
    {
        if (start < 0)
            throw new ArgumentOutOfRangeException(nameof(start));
        if (length < 0)
            throw new ArgumentOutOfRangeException(nameof(length));

        this.start = start;
        this.length = length;
    }

    public int Start => start;

    public int End => start + length;

    public int Length => length;

    public bool IsEmpty => length == 0;

    public static bool operator ==(IndexSpan left, IndexSpan right)
    {
        return left.start == right.start && left.length == right.length;
    }

    public static bool operator !=(IndexSpan left, IndexSpan right)
    {
        return left.start != right.start || left.length != right.length;
    }

    public bool Equals(IndexSpan other)
    {
        return other.start == start && other.length == length;
    }

    public override bool Equals(object obj)
    {
        return obj is IndexSpan other && Equals(other);
    }

    public override int GetHashCode()
    {
        return (start.GetHashCode() << 16) ^ length.GetHashCode();
    }

    public override string ToString()
    {
        return string.Format("{{start:{0} length:{1}}}", start, length);
    }
}