Paper/src/main/java/net/minecraft/server/BlockSapling.java

package net.minecraft.server;

import java.util.Random;
// CraftBukkit start
import org.bukkit.BlockChangeDelegate;
import org.bukkit.Bukkit;
import org.bukkit.Location;
import org.bukkit.TreeType;
import org.bukkit.block.BlockState;
import org.bukkit.craftbukkit.util.StructureGrowDelegate;
import org.bukkit.entity.Player;
import org.bukkit.event.world.StructureGrowEvent;
// CraftBukkit end

public class BlockSapling extends BlockFlower {

    protected BlockSapling(int i, int j) {
        super(i, j);
        float f = 0.4F;

        this.a(0.5F - f, 0.0F, 0.5F - f, 0.5F + f, f * 2.0F, 0.5F + f);
    }

    public void a(World world, int i, int j, int k, Random random) {
        if (!world.isStatic) {
            super.a(world, i, j, k, random);
            if (world.getLightLevel(i, j + 1, k) >= 9 && random.nextInt(7) == 0) {
                int l = world.getData(i, j, k);

                if ((l & 8) == 0) {
                    world.setData(i, j, k, l | 8);
                } else {
                    this.grow(world, i, j, k, random, false, null, null); // CraftBukkit - added bonemeal, player and itemstack
                }
            }
        }
    }

    public int a(int i, int j) {
        j &= 3;
        return j == 1 ? 63 : (j == 2 ? 79 : (j == 3 ? 30 : super.a(i, j)));
    }

    // CraftBukkit - added bonemeal, player and itemstack
    public void grow(World world, int i, int j, int k, Random random, boolean bonemeal, Player player, ItemStack itemstack) {
        int l = world.getData(i, j, k) & 3;
        int i1 = 0;
        int j1 = 0;
        // CraftBukkit start - records tree generation and calls StructureGrowEvent
        StructureGrowDelegate delegate = new StructureGrowDelegate(world);
        TreeType treeType = null;
        TreeGenerator gen = null;
        boolean grownTree = false;
        boolean flag = false;

        if (l == 1) {
            treeType = TreeType.REDWOOD;
            gen = new WorldGenTaiga2(false);
        } else if (l == 2) {
            treeType = TreeType.BIRCH;
            gen = new WorldGenForest(false);
        } else if (l == 3) {
            for (i1 = 0; i1 >= -1; --i1) {
                for (j1 = 0; j1 >= -1; --j1) {
                    if (world.getTypeId(i + i1, j, k + j1) == this.id && world.getTypeId(i + i1 + 1, j, k + j1) == this.id && world.getTypeId(i + i1, j, k + j1 + 1) == this.id && world.getTypeId(i + i1 + 1, j, k + j1 + 1) == this.id) {
                        treeType = TreeType.JUNGLE;
                        gen = new WorldGenMegaTree(false, 10 + random.nextInt(20), 3, 3);
                        flag = true;
                        break;
                    }
                }

                if (gen != null) {
                    break;
                }
            }

            if (gen == null) {
                j1 = 0;
                i1 = 0;
                treeType = TreeType.TREE;
                gen = new WorldGenTrees(false, 4 + random.nextInt(7), 3, 3, false);
            }
        } else {
            treeType = TreeType.TREE;
            gen = new WorldGenTrees(false);
            if (random.nextInt(10) == 0) {
                treeType = TreeType.BIG_TREE;
                gen = new WorldGenBigTree(false);
            }
        }

        if (flag) {
            world.setRawTypeId(i + i1, j, k + j1, 0);
            world.setRawTypeId(i + i1 + 1, j, k + j1, 0);
            world.setRawTypeId(i + i1, j, k + j1 + 1, 0);
            world.setRawTypeId(i + i1 + 1, j, k + j1 + 1, 0);
        } else {
            world.setRawTypeId(i, j, k, 0);
        }
        grownTree = gen.generate(delegate, random, i + i1, j, k + j1);
        if (grownTree) {
            Location location = new Location(world.getWorld(), i, j, k);
            StructureGrowEvent event = new StructureGrowEvent(location, treeType, bonemeal, player, delegate.getBlocks());
            Bukkit.getPluginManager().callEvent(event);
            if (event.isCancelled()) {
                grownTree = false;
            } else {
                for (BlockState state : event.getBlocks()) {
                    state.update(true);
                }
                if (event.isFromBonemeal() && itemstack != null) {
                    --itemstack.count;
                }
            }
        }
        if (!grownTree) {
            if (flag) {
                world.setRawTypeIdAndData(i + i1, j, k + j1, this.id, l);
                world.setRawTypeIdAndData(i + i1 + 1, j, k + j1, this.id, l);
                world.setRawTypeIdAndData(i + i1, j, k + j1 + 1, this.id, l);
                world.setRawTypeIdAndData(i + i1 + 1, j, k + j1 + 1, this.id, l);
            } else {
                world.setRawTypeIdAndData(i, j, k, this.id, l);
            }
        }
        // CraftBukkit end
    }

    protected int getDropData(int i) {
        return i & 3;
    }

    // CraftBukkit start
    interface TreeGenerator {

        public boolean a(World world, Random random, int i, int j, int k);

        public boolean generate(BlockChangeDelegate world, Random random, int i, int j, int k);
    }
    // CraftBukkit end
}