minecraft-kajetans-mod/src/main/java/me/km/blocks/leaves/WorldGenTree.java

package me.km.blocks.leaves;

import java.util.Random;
import net.minecraft.block.Block;
import net.minecraft.block.material.Material;
import net.minecraft.block.state.IBlockState;
import net.minecraft.init.Blocks;
import net.minecraft.util.EnumFacing;
import net.minecraft.util.math.BlockPos;
import net.minecraft.world.World;
import net.minecraft.world.gen.feature.WorldGenAbstractTree;

public class WorldGenTree extends WorldGenAbstractTree
{
    private final IBlockState log; 
    private final IBlockState leaf; 

    public WorldGenTree(boolean notify, IBlockState log, IBlockState leaf)
    {
        super(notify);
        this.log = log;
        this.leaf = leaf;
    }
    
    @Override
    protected boolean canGrowInto(Block blockType)
    {
        Material material = blockType.getDefaultState().getMaterial();
        return material == Material.AIR || material == Material.LEAVES || 
                blockType == Blocks.GRASS || blockType == Blocks.DIRT || 
                blockType == Blocks.LOG || blockType == Blocks.LOG2 || 
                blockType == Blocks.SAPLING || blockType == Blocks.VINE ||
                blockType instanceof BlockLeaves;
    }

    @Override
    public boolean generate(World worldIn, Random rand, BlockPos pos)
    {
        int i = rand.nextInt(3) + 5;
        boolean flag = true;
        if(pos.getY() >= 1 && pos.getY() + i + 1 <= 256)
        {
            for(int j = pos.getY(); j <= pos.getY() + 1 + i; j++)
            {
                int k = 1;
                if (j == pos.getY())
                {
                    k = 0;
                }
                if (j >= pos.getY() + 1 + i - 2)
                {
                    k = 2;
                }

                BlockPos.MutableBlockPos mPos = new BlockPos.MutableBlockPos();
                for(int x = pos.getX() - k; x <= pos.getX() + k && flag; x++)
                {
                    for(int z = pos.getZ() - k; z <= pos.getZ() + k && flag; z++)
                    {
                        if(j >= 0 && j < worldIn.getHeight())
                        {
                            if(!this.isReplaceable(worldIn, mPos.setPos(x, j, z)))
                            {
                                flag = false;
                            }
                        }
                        else
                        {
                            flag = false;
                        }
                    }
                }
            }
            if(!flag)
            {
                return false;
            }
            else
            {
                BlockPos down = pos.down();
                IBlockState state = worldIn.getBlockState(down);
                boolean isSoil = state.getBlock().canSustainPlant(state, worldIn, down, EnumFacing.UP, (net.minecraft.block.BlockSapling) Blocks.SAPLING);

                if(isSoil && pos.getY() < worldIn.getHeight() - i - 1)
                {
                    state.getBlock().onPlantGrow(state, worldIn, down, pos);
                    for(int y = pos.getY() - 3 + i; y <= pos.getY() + i; y++)
                    {
                        int k = y - (pos.getY() + i);
                        int l = 1 - k / 2;
                        for(int x = pos.getX() - l; x <= pos.getX() + l; x++)
                        {
                            int j = x - pos.getX();
                            for(int z = pos.getZ() - l; z <= pos.getZ() + l; z++)
                            {
                                int m = z - pos.getZ();
                                if(Math.abs(j) != l || Math.abs(m) != l || rand.nextInt(2) != 0 && k != 0)
                                {
                                    BlockPos blockpos = new BlockPos(x, y, z);
                                    IBlockState state2 = worldIn.getBlockState(blockpos);
                                    if(state2.getBlock().isAir(state2, worldIn, blockpos) || state2.getBlock().isAir(state2, worldIn, blockpos))
                                    {
                                        this.setBlockAndNotifyAdequately(worldIn, blockpos, leaf);
                                    }
                                }
                            }
                        }
                    }
                    for(int j = 0; j < i; j++)
                    {
                        BlockPos upN = pos.up(j);
                        IBlockState state2 = worldIn.getBlockState(upN);
                        if (state2.getBlock().isAir(state2, worldIn, upN) || state2.getBlock().isLeaves(state2, worldIn, upN))
                        {
                            this.setBlockAndNotifyAdequately(worldIn, pos.up(j), log);
                        }
                    }
                    return true;
                }
                else
                {
                    return false;
                }
            }
        }
        else
        {
            return false;
        }
    }
}