using Vellum;

namespace Annulus.Vellum
{
    /// <summary>
    /// Saves a HexIndex as its two axial coordinates.
    /// </summary>
    public sealed class HexIndexConverter : SaveConverter<HexIndex>
    {
        public const string QKey = "q";
        public const string RKey = "r";

        public override SaveNode Write(HexIndex value, SaveSession session)
        {
            SaveNode returnMe = SaveNode.NewTable();
            returnMe.Entries[QKey] = session.ToNode(value.Q);
            returnMe.Entries[RKey] = session.ToNode(value.R);

            return returnMe;
        }

        public override HexIndex Read(SaveNode node, SaveSession session)
        {
            var reader = new SaveReader(node, session);
            int q = reader.Require<int>(QKey);
            int r = reader.Require<int>(RKey);

            return new HexIndex(q, r);
        }

        public override bool TryListChildren(SaveNode node, ChildList children)
        {
            // Everything it reads is built-in, and so left out.
            SaveNode ignored;

            return node.TryGetEntry(QKey, out ignored) && node.TryGetEntry(RKey, out ignored);
        }
    }
}