Unicopia/src/main/java/com/minelittlepony/unicopia/item/ItemSpellbook.java

package com.minelittlepony.unicopia.item;

import com.minelittlepony.unicopia.Predicates;
import com.minelittlepony.unicopia.entity.EntitySpellbook;

import net.minecraft.block.BlockDispenser;
import net.minecraft.creativetab.CreativeTabs;
import net.minecraft.dispenser.BehaviorDefaultDispenseItem;
import net.minecraft.dispenser.IBehaviorDispenseItem;
import net.minecraft.dispenser.IBlockSource;
import net.minecraft.entity.player.EntityPlayer;
import net.minecraft.item.ItemBook;
import net.minecraft.item.ItemStack;
import net.minecraft.util.math.BlockPos;
import net.minecraft.util.EnumActionResult;
import net.minecraft.util.EnumFacing;
import net.minecraft.util.EnumHand;
import net.minecraft.world.World;

public class ItemSpellbook extends ItemBook {
    private static final IBehaviorDispenseItem dispenserBehavior = new BehaviorDefaultDispenseItem() {
        @Override
        protected ItemStack dispenseStack(IBlockSource source, ItemStack stack) {
            EnumFacing facing = source.getBlockState().getValue(BlockDispenser.FACING);
            BlockPos pos = source.getBlockPos().offset(facing);
            int yaw = 0;


            //0deg == SOUTH
            //90deg == WEST
            //180deg == NORTH
            //270deg == EAST

            /*switch (facing) {
            case NORTH: yaw -= 90; break;
            case SOUTH: yaw += 90; break;
            case EAST: yaw += 180; break;
            default:
            }*/

            yaw = facing.getOpposite().getHorizontalIndex() * 90;
            placeBook(source.getWorld(), pos.getX(), pos.getY(), pos.getZ(), yaw);
            stack.shrink(1);
            return stack;
        }
    };

    public ItemSpellbook(String domain, String name) {
        super();
        setTranslationKey(name);
        setRegistryName(domain, name);

        setMaxDamage(0);
        maxStackSize = 1;
        setCreativeTab(CreativeTabs.BREWING);
        BlockDispenser.DISPENSE_BEHAVIOR_REGISTRY.putObject(this, dispenserBehavior);
    }

    public EnumActionResult onItemUse(EntityPlayer player, World world, BlockPos pos, EnumHand hand, EnumFacing side, float hitX, float hitY, float hitZ) {

        if (!world.isRemote && Predicates.MAGI.test(player)) {
            pos = pos.offset(side);

            double diffX = player.posX - (pos.getX() + 0.5);
            double diffZ = player.posZ - (pos.getZ() + 0.5);
            float yaw = (float)Math.toDegrees(Math.atan2(diffZ, diffX) + Math.PI);

            placeBook(world, pos.getX(), pos.getY(), pos.getZ(), yaw);

            if (!player.capabilities.isCreativeMode) {
                player.getHeldItem(hand).shrink(1);
            }

            return EnumActionResult.SUCCESS;
        }
        return EnumActionResult.PASS;
    }

    private static void placeBook(World world, int x, int y, int z, float yaw) {
        EntitySpellbook book = new EntitySpellbook(world);

        book.setPositionAndRotation(x + 0.5, y, z + 0.5, yaw, 0);
        book.renderYawOffset = 0;
        book.prevRotationYaw = yaw;

        world.spawnEntity(book);
    }
}