ClaimLink/ClaimLink/ClaimLinkBufferIndex.cs

using System.Collections.Generic;
using Vintagestory.API.MathTools;

namespace ClaimLink;

internal static class ClaimLinkBufferIndex
{
    private static readonly Dictionary<long, HashSet<int>> groupIdsByRegion = new();
    private static readonly Dictionary<int, List<Cuboidi>> buffersByGroupId = new();

    internal static void Rebuild()
    {
        groupIdsByRegion.Clear();
        buffersByGroupId.Clear();

        int regionSize = ClaimLinkModSystem.WorldManager.RegionSize;
        if (regionSize <= 0)
            return;

        foreach (int groupId in ClaimLinkModSystem.Registry.All)
        {
            List<Cuboidi> buffers = ClaimLinkBuffer.GetBuffer(groupId);
            buffersByGroupId[groupId] = buffers;

            HashSet<long> regionKeys = new();
            foreach (Cuboidi buffer in buffers)
            {
                int minRegionX = buffer.MinX / regionSize;
                int maxRegionX = buffer.MaxX / regionSize;
                int minRegionZ = buffer.MinZ / regionSize;
                int maxRegionZ = buffer.MaxZ / regionSize;

                for (int rx = minRegionX; rx <= maxRegionX; rx++)
                    for (int rz = minRegionZ; rz <= maxRegionZ; rz++)
                        regionKeys.Add(ClaimLinkModSystem.WorldManager.MapRegionIndex2D(rx, rz));
            }

            foreach (long regionKey in regionKeys)
            {
                if (!groupIdsByRegion.TryGetValue(regionKey, out HashSet<int>? groupIds))
                    groupIdsByRegion[regionKey] = groupIds = new();
                groupIds.Add(groupId);
            }
        }
    }

    internal static IEnumerable<int> CandidateGroupIds(BlockPos pos)
    {
        int regionSize = ClaimLinkModSystem.WorldManager.RegionSize;
        if (regionSize <= 0)
            return System.Array.Empty<int>();

        long regionKey = ClaimLinkModSystem.WorldManager.MapRegionIndex2D(
            pos.X / regionSize,
            pos.Z / regionSize
        );

        return groupIdsByRegion.TryGetValue(regionKey, out HashSet<int>? groupIds)
            ? groupIds
            : System.Array.Empty<int>();
    }

    internal static List<Cuboidi> CachedBuffer(int groupId) =>
        buffersByGroupId.TryGetValue(groupId, out List<Cuboidi>? buffers)
            ? buffers
            : new List<Cuboidi>();
}