Minecraft portal finding algorithm

gistfile1.java

private final LongHashMap<Long, ChunkCoordinatesPortal> portalCache = new LongHashMap(); // ChunkCoord -> PortalCoord Originally named 'c', used for caching.
private final List<Long> portalChunks = new ArrayList(); // Originally named 'd', list of portal chunk coordinates (??)

public ChunkCoordinates findPortal(double xPos, double yPos, double zPos, int searchRadius) {
        
        //Inserted
        final int worldHeight = this.a.S()
        
        // If world env is END, use spesific algorithm for that
        if (this.a.getWorld().getEnvironment() == org.bukkit.World.Environment.THE_END) { // this.a instanceof WorldServer
            return this.findEndPortal(this.a.worldProvider.h());
        }
        
        // CraftBukkit end
        double currentClosestPortal = -1.0D; // d3
        int finalX = 0; // i
        int finalY = 0; // j
        int finalZ = 0; // k
        // CraftBukkit start
        int xPosI = MathHelper.floor(xPos);
        int zPosI = MathHelper.floor(zPos);
        // CraftBukkit end
        long chunkCoord = ChunkCoordIntPair.a(xPosI, zPosI);
        boolean shouldUpdateCache = true;
        double zPortalOffset;
        int xSearch;

        if (this.portalCache.contains(chunkCoord)) {
            ChunkCoordinatesPortal cachedPortal = (ChunkCoordinatesPortal) this.portalCache.getEntry(chunkCoord);

            currentClosestPortal = 0.0D;
            finalX = cachedPortal.x;
            finalY = cachedPortal.y;
            finalZ = cachedPortal.z;
            cachedPortal.d = this.a.getTime(); // this.a instanceof WorldServer (portals use the current time?)
            shouldUpdateCache = false;
        } else {
            for (xSearch = xPosI - searchRadius; xSearch <= xPosI + searchRadius; ++xSearch) {
                double xPortalOffset = (double) xSearch + 0.5D - xPos; // CraftBukkit

                for (int zSearch = zPosI - searchRadius; zSearch <= zPosI + searchRadius; ++zSearch) {
                    double yPortalOffset = (double) zSearch + 0.5D - zPos; // CraftBukkit

                    for (int ySearch = worldHeight - 1; ySearch >= 0; --ySearch) {
                        if (this.a.getType(xSearch, ySearch, zSearch) == Blocks.PORTAL) {
                            while (this.a.getType(xSearch, ySearch - 1, zSearch) == Blocks.PORTAL) {
                                --ySearch;
                            }

                            zPortalOffset = (double) ySearch + 0.5D - yPos; // CraftBukkit
                            double portalDistance = xPortalOffset * xPortalOffset + zPortalOffset * zPortalOffset + yPortalOffset * yPortalOffset;

                            if (currentClosestPortal < 0.0D || portalDistance < currentClosestPortal) {
                                currentClosestPortal = portalDistance;
                                finalX = xSearch;
                                finalY = ySearch;
                                finalZ = zSearch;
                            }
                        }
                    }
                }
            }
        }

        if (currentClosestPortal >= 0.0D) {
            if (shouldUpdateCache) {
                this.portalCache.put(chunkCoord, new ChunkCoordinatesPortal(this, finalX, finalY, finalZ, this.a.getTime())); // this.a instanceof WorldServer
                this.portalChunks.add(Long.valueOf(chunkCoord));
            }
            // CraftBukkit start - Moved entity teleportation logic into exit
            return new ChunkCoordinates(finalX, finalY, finalZ);
        } else {
            return null;
        }
    }