EnderIO/src/main/java/crazypants/enderio/conduit/geom/CollidableCache.java

package crazypants.enderio.conduit.geom;

import java.util.Collection;
import java.util.HashMap;
import java.util.Map;

import net.minecraftforge.common.util.ForgeDirection;

import crazypants.enderio.conduit.IConduit;

public class CollidableCache {

    public static final CollidableCache instance = new CollidableCache();

    private final Map<CacheKey, Collection<CollidableComponent>> cache = new HashMap<>();

    public CacheKey createKey(Class<? extends IConduit> baseType, Offset offset, ForgeDirection dir, boolean isStub) {
        return new CacheKey(baseType, offset, dir, isStub);
    }

    public Collection<CollidableComponent> getCollidables(CacheKey key, IConduit conduit) {
        Collection<CollidableComponent> result = cache.get(key);
        if (result == null) {
            result = conduit.createCollidables(key);
            cache.put(key, result);
        }
        return result;
    }

    public static class CacheKey {

        public final Class<? extends IConduit> baseType;
        public final String className; // used to generate reliable equals /
        // hashcode
        public final Offset offset;
        public final ForgeDirection dir;
        public final boolean isStub;

        public CacheKey(Class<? extends IConduit> baseType, Offset offset, ForgeDirection dir, boolean isStub) {
            this.baseType = baseType;
            className = baseType.getCanonicalName();
            this.offset = offset;
            this.dir = dir;
            this.isStub = isStub;
        }

        @Override
        public int hashCode() {
            final int prime = 31;
            int result = 1;
            result = prime * result + ((className == null) ? 0 : className.hashCode());
            result = prime * result + ((dir == null) ? 0 : dir.hashCode());
            result = prime * result + (isStub ? 1231 : 1237);
            result = prime * result + ((offset == null) ? 0 : offset.hashCode());
            return result;
        }

        @Override
        public boolean equals(Object obj) {
            if (this == obj) {
                return true;
            }
            if (obj == null) {
                return false;
            }
            if (getClass() != obj.getClass()) {
                return false;
            }
            CacheKey other = (CacheKey) obj;
            if (className == null) {
                if (other.className != null) {
                    return false;
                }
            } else if (!className.equals(other.className)) {
                return false;
            }
            if (dir != other.dir) {
                return false;
            }
            if (isStub != other.isStub) {
                return false;
            }
            if (offset != other.offset) {
                return false;
            }
            return true;
        }
    }
}