CE-modern/src/main/java/net/kanawo/bcxmodern/tile/TileEMCBuilder.java

package net.kanawo.bcxmodern.tile;

import java.util.ArrayList;
import java.util.List;
import java.util.UUID;

import net.minecraft.entity.EntityLivingBase;
import net.minecraft.entity.player.EntityPlayer;
import net.minecraft.item.ItemStack;
import net.minecraft.nbt.NBTTagCompound;

import buildcraft.builders.TileBuilder;
import buildcraft.core.blueprints.BptBuilderBase;
import buildcraft.core.blueprints.BptBuilderBlueprint;
import buildcraft.core.blueprints.RequirementItemStack;
import io.netty.buffer.ByteBuf;
import moze_intel.projecte.utils.EMCHelper;

/**
 * A Builder that pays for building materials with EMC.
 * <p>
 * The EMC is not stored in the tile but in its owner's balance in {@link EmcPool}, so all EMC Builders a player owns
 * in a world share it. The owner is the player who placed the builder, or for one built from a blueprint, the first
 * player who opens it.
 * <p>
 * BuildCraft only builds blocks whose materials are present in the builder's inventory, and consumes them by
 * shrinking the stacks it finds there. While {@link #build()} runs, this tile therefore appends virtual slots after
 * the real inventory, one per needed item that has an EMC value, sized to what the stored EMC can afford. After the
 * build step the amount taken from each virtual slot is charged at 1 EMC per EMC value. Real items in the material
 * slots come first in the inventory, so they are used before EMC.
 * <p>
 * Outside {@link #build()} the virtual slots are hidden, so GUIs, hoppers, pipes and robots only ever see the real
 * inventory.
 */
public class TileEMCBuilder extends TileBuilder {

    /** NBT keys of the owner's UUID; SchematicEMCBuilder removes them from blueprints. */
    public static final String OWNER_MOST = "OwnerUUIDMost";
    public static final String OWNER_LEAST = "OwnerUUIDLeast";

    private static final int EMC_SYNC_INTERVAL = 10;

    private UUID owner;

    /** Owner's balance as last received from the server. Client side only. */
    private double clientEmc;
    /** Owner's balance as last sent to clients. Server side only. */
    private double sentEmc = -1;
    private int ticksSinceEmcSync;

    private final List<EmcSlot> emcSlots = new ArrayList<>();
    private boolean emcSlotsExposed;

    /** A virtual material slot backed by stored EMC. */
    private static final class EmcSlot {

        final long emcPerItem;
        final int initialSize;
        ItemStack stack;

        EmcSlot(ItemStack stack, long emcPerItem) {
            this.stack = stack;
            this.emcPerItem = emcPerItem;
            this.initialSize = stack.stackSize;
        }

        int consumed() {
            return stack == null ? initialSize : initialSize - stack.stackSize;
        }
    }

    /** The owner's EMC balance; on the client, as last synced. */
    public double getStoredEmc() {
        if (worldObj.isRemote) {
            return clientEmc;
        }

        return owner == null ? 0
            : EmcPool.get(worldObj)
                .get(owner);
    }

    /** Makes the player the owner if the builder has none yet. Server side only. */
    public void claimOwner(EntityPlayer player) {
        if (owner == null) {
            owner = player.getUniqueID();
            markDirty();
        }
    }

    @Override
    public void onBlockPlacedBy(EntityLivingBase entity, ItemStack stack) {
        super.onBlockPlacedBy(entity, stack);

        if (entity instanceof EntityPlayer) {
            owner = entity.getUniqueID();
        }
    }

    /** Converts the whole stack into EMC for the owner. Server side only. */
    public void consumeForEmc(ItemStack stack) {
        long value = EMCHelper.getEmcValue(stack);

        if (owner == null || value <= 0 || stack.stackSize <= 0) {
            return;
        }

        EmcPool.get(worldObj)
            .add(owner, (double) value * stack.stackSize);
        stack.stackSize = 0;
        sendNetworkUpdate();
    }

    @Override
    public void updateEntity() {
        super.updateEntity();

        if (worldObj.isRemote) {
            return;
        }

        // The balance can also change through the owner's other EMC Builders, so poll it.
        if (++ticksSinceEmcSync >= EMC_SYNC_INTERVAL) {
            ticksSinceEmcSync = 0;

            if (getStoredEmc() != sentEmc) {
                sendNetworkUpdate();
            }
        }
    }

    @Override
    public void build() {
        BptBuilderBase bpt = getBlueprint();
        double emc = getStoredEmc();

        if (!(bpt instanceof BptBuilderBlueprint) || emc <= 0) {
            super.build();
            return;
        }

        // The needed item list is only filled once the builder has been initialized.
        bpt.initialize();
        prepareEmcSlots(((BptBuilderBlueprint) bpt).getNeededItems(), emc);

        emcSlotsExposed = true;

        try {
            super.build();
        } finally {
            emcSlotsExposed = false;
            chargeEmcSlots();
        }
    }

    private void prepareEmcSlots(List<RequirementItemStack> needs, double emc) {
        emcSlots.clear();

        if (needs == null) {
            return;
        }

        for (RequirementItemStack need : needs) {
            if (need.stack == null || need.stack.getItem() == null || need.size <= 0) {
                continue;
            }

            long value = EMCHelper.getEmcValue(need.stack);

            if (value <= 0) {
                continue;
            }

            int affordable = (int) Math.min(Integer.MAX_VALUE, Math.floor(emc / value));
            int size = Math.min(Math.min(need.stack.getMaxStackSize(), need.size), affordable);

            if (size <= 0) {
                continue;
            }

            ItemStack stack = need.stack.copy();
            stack.stackSize = size;
            emcSlots.add(new EmcSlot(stack, value));
        }
    }

    private void chargeEmcSlots() {
        double cost = 0;

        for (EmcSlot slot : emcSlots) {
            cost += (double) slot.consumed() * slot.emcPerItem;
        }

        emcSlots.clear();

        if (cost > 0) {
            EmcPool.get(worldObj)
                .add(owner, -cost);
        }
    }

    private int realSize() {
        return super.getSizeInventory();
    }

    private EmcSlot emcSlot(int i) {
        return emcSlotsExposed && i >= realSize() ? emcSlots.get(i - realSize()) : null;
    }

    @Override
    public int getSizeInventory() {
        return emcSlotsExposed ? realSize() + emcSlots.size() : realSize();
    }

    @Override
    public ItemStack getStackInSlot(int i) {
        EmcSlot slot = emcSlot(i);
        return slot != null ? slot.stack : super.getStackInSlot(i);
    }

    @Override
    public ItemStack decrStackSize(int i, int amount) {
        EmcSlot slot = emcSlot(i);

        if (slot == null) {
            return super.decrStackSize(i, amount);
        }

        if (slot.stack == null) {
            return null;
        }

        ItemStack taken = slot.stack.splitStack(Math.min(amount, slot.stack.stackSize));

        if (slot.stack.stackSize <= 0) {
            slot.stack = null;
        }

        return taken;
    }

    @Override
    public void setInventorySlotContents(int i, ItemStack stack) {
        EmcSlot slot = emcSlot(i);

        if (slot == null) {
            super.setInventorySlotContents(i, stack);
            return;
        }

        // Schematic.useItem only writes to a slot once its stack is used up (possibly leaving a container item
        // behind). Either way the whole virtual stack has been consumed; container items are not kept.
        slot.stack = null;
    }

    @Override
    public ItemStack getStackInSlotOnClosing(int i) {
        return emcSlot(i) != null ? null : super.getStackInSlotOnClosing(i);
    }

    @Override
    public boolean isItemValidForSlot(int i, ItemStack stack) {
        return emcSlot(i) == null && super.isItemValidForSlot(i, stack);
    }

    @Override
    public void readFromNBT(NBTTagCompound nbt) {
        super.readFromNBT(nbt);
        owner = nbt.hasKey(OWNER_MOST) ? new UUID(nbt.getLong(OWNER_MOST), nbt.getLong(OWNER_LEAST)) : null;
    }

    @Override
    public void writeToNBT(NBTTagCompound nbt) {
        super.writeToNBT(nbt);

        if (owner != null) {
            nbt.setLong(OWNER_MOST, owner.getMostSignificantBits());
            nbt.setLong(OWNER_LEAST, owner.getLeastSignificantBits());
        }
    }

    @Override
    public void writeData(ByteBuf stream) {
        super.writeData(stream);
        sentEmc = getStoredEmc();
        stream.writeDouble(sentEmc);
    }

    @Override
    public void readData(ByteBuf stream) {
        super.readData(stream);
        clientEmc = stream.readDouble();
    }
}