EnderIO/src/main/java/crazypants/enderio/power/PowerDistributor.java

package crazypants.enderio.power;

import java.util.ArrayList;
import java.util.List;
import java.util.ListIterator;

import net.minecraft.tileentity.TileEntity;
import net.minecraft.world.World;
import net.minecraftforge.common.util.ForgeDirection;

import com.enderio.core.common.util.BlockCoord;

import crazypants.enderio.machine.AbstractMachineEntity;

public class PowerDistributor {

    private final List<Receptor> receptors = new ArrayList<Receptor>();
    private ListIterator<Receptor> receptorIterator = receptors.listIterator();
    private boolean receptorsDirty = true;

    private final BlockCoord bc;

    public PowerDistributor(BlockCoord bc) {
        this.bc = bc;
    }

    public void neighboursChanged() {
        receptorsDirty = true;
    }

    public int transmitEnergy(World worldObj, int available) {

        int transmitted = 0;
        checkReceptors(worldObj);
        if (!receptors.isEmpty() && !receptorIterator.hasNext()) {
            receptorIterator = receptors.listIterator();
        }

        int appliedCount = 0;
        int numReceptors = receptors.size();
        while (receptorIterator.hasNext() && available > 0 && appliedCount < numReceptors) {
            Receptor receptor = receptorIterator.next();
            IPowerInterface pp = receptor.receptor;
            if (pp != null && pp.getMinEnergyReceived(receptor.fromDir.getOpposite()) <= available) {
                int used = pp.recieveEnergy(receptor.fromDir.getOpposite(), available);
                transmitted += used;
                available -= used;
            }
            if (available <= 0) {
                break;
            }

            if (!receptors.isEmpty() && !receptorIterator.hasNext()) {
                receptorIterator = receptors.listIterator();
            }
            appliedCount++;
        }
        return transmitted;
    }

    private void checkReceptors(World worldObj) {
        if (!receptorsDirty) {
            return;
        }
        receptors.clear();
        for (ForgeDirection dir : ForgeDirection.VALID_DIRECTIONS) {
            TileEntity transmitter = worldObj.getTileEntity(bc.x, bc.y, bc.z);
            if (!(transmitter instanceof AbstractMachineEntity)
                    || ((AbstractMachineEntity) transmitter).getIoMode(dir).canOutput()) {
                BlockCoord checkLoc = bc.getLocation(dir);
                TileEntity te = worldObj.getTileEntity(checkLoc.x, checkLoc.y, checkLoc.z);
                IPowerInterface pi = PowerHandlerUtil.create(te);
                if (pi != null && pi.canConduitConnect(dir)) {
                    receptors.add(new Receptor(pi, dir));
                }
            }
        }
        receptorIterator = receptors.listIterator();
        receptorsDirty = false;
    }

    static class Receptor {

        IPowerInterface receptor;
        ForgeDirection fromDir;

        private Receptor(IPowerInterface rec, ForgeDirection fromDir) {
            this.receptor = rec;
            this.fromDir = fromDir;
        }
    }
}