content: package net.minecraft.world.gen.feature;
  
  import net.minecraft.block.Block;
  import net.minecraft.block.BlockOldLeaf;
  import net.minecraft.block.BlockOldLog;
  import net.minecraft.block.BlockPlanks;
  import net.minecraft.block.material.Material;
  import net.minecraft.block.state.IBlockState;
  import net.minecraft.init.Blocks;
  import net.minecraft.util.BlockPos;
  import net.minecraft.world.World;
  
  import java.util.Random;
  
  public class WorldGenForest extends WorldGenAbstractTree {
      private static final IBlockState field_181629_a = Blocks.log.getDefaultState().withProperty(BlockOldLog.VARIANT, BlockPlanks.EnumType.BIRCH);
      private static final IBlockState field_181630_b = Blocks.leaves.getDefaultState().withProperty(BlockOldLeaf.VARIANT, BlockPlanks.EnumType.BIRCH).withProperty(BlockOldLeaf.CHECK_DECAY, false);
      private final boolean useExtraRandomHeight;
  
      public WorldGenForest(boolean p_i45449_1_, boolean p_i45449_2_) {
          super(p_i45449_1_);
          this.useExtraRandomHeight = p_i45449_2_;
      }
  
      public boolean generate(World worldIn, Random rand, BlockPos position) {
          int i = rand.nextInt(3) + 5;
  
          if (this.useExtraRandomHeight) {
              i += rand.nextInt(7);
          }
  
          boolean flag = true;
  
          if (position.getY() >= 1 && position.getY() + i + 1 <= 256) {
              for (int j = position.getY(); j <= position.getY() + 1 + i; ++j) {
                  int k = 1;
  
                  if (j == position.getY()) {
                      k = 0;
                  }
  
                  if (j >= position.getY() + 1 + i - 2) {
                      k = 2;
                  }
  
                  BlockPos.MutableBlockPos blockpos$mutableblockpos = new BlockPos.MutableBlockPos();
  
                  for (int l = position.getX() - k; l <= position.getX() + k && flag; ++l) {
                      for (int i1 = position.getZ() - k; i1 <= position.getZ() + k && flag; ++i1) {
                          if (j >= 0 && j < 256) {
                              if (!this.func_150523_a(worldIn.getBlockState(blockpos$mutableblockpos.set(l, j, i1)).getBlock())) {
                                  flag = false;
                              }
                          } else {
                              flag = false;
                          }
                      }
                  }
              }
  
              if (!flag) {
                  return false;
              } else {
                  Block block1 = worldIn.getBlockState(position.down()).getBlock();
  
                  if ((block1 == Blocks.grass || block1 == Blocks.dirt || block1 == Blocks.farmland) && position.getY() < 256 - i - 1) {
                      this.func_175921_a(worldIn, position.down());
  
                      for (int i2 = position.getY() - 3 + i; i2 <= position.getY() + i; ++i2) {
                          int k2 = i2 - (position.getY() + i);
                          int l2 = 1 - k2 / 2;
  
                          for (int i3 = position.getX() - l2; i3 <= position.getX() + l2; ++i3) {
                              int j1 = i3 - position.getX();
  
                              for (int k1 = position.getZ() - l2; k1 <= position.getZ() + l2; ++k1) {
                                  int l1 = k1 - position.getZ();
  
                                  if (Math.abs(j1) != l2 || Math.abs(l1) != l2 || rand.nextInt(2) != 0 && k2 != 0) {
                                      BlockPos blockpos = new BlockPos(i3, i2, k1);
                                      Block block = worldIn.getBlockState(blockpos).getBlock();
  
                                      if (block.getMaterial() == Material.air || block.getMaterial() == Material.leaves) {
                                          this.setBlockAndNotifyAdequately(worldIn, blockpos, field_181630_b);
                                      }
                                  }
                              }
                          }
                      }
  
                      for (int j2 = 0; j2 < i; ++j2) {
                          Block block2 = worldIn.getBlockState(position.up(j2)).getBlock();
  
                          if (block2.getMaterial() == Material.air || block2.getMaterial() == Material.leaves) {
                              this.setBlockAndNotifyAdequately(worldIn, position.up(j2), field_181629_a);
                          }
                      }
  
                      return true;
                  } else {
                      return false;
                  }
              }
          } else {
              return false;
          }
      }
  }
  