electric/mods/ebiometrees/sapling.lua

function ebiometrees.grow_closure(nextstage)
  local function growtree(pos)
    minetest.set_node(pos, {name=nextstage})
  end
  return growtree
end


function ebiometrees.where_to_grow_trunk_closure(grow_preferences, leaves_name)
  local function where_to_grow_trunk(pos)
    for _, directions in ipairs(grow_preferences)
    do
      table.shuffle(directions)
      local candidate_dir = directions[1]
      local candidate = vector.copy(pos):add(candidate_dir)
      local node = minetest.get_node_or_nil(candidate)
      corner1 = pos:add({x=-1, y=-1, z=-1}):add(candidate_dir:multiply(2))
      corner2 = pos:add({x= 1, y= 1, z= 1}):add(candidate_dir:multiply(2))
      local spacious, _ = minetest.find_nodes_in_area(
        corner1, corner2, {"group:treetrunk", "group:dirt" }
      )
      if node and node.name == leaves_name and #spacious == 0
      then
        return candidate
      end
    end
  end
  return where_to_grow_trunk
end


function ebiometrees.grow_trunk_closure(trunk_terminal_name, grow_preferences, leaves_name, grow_limit)
  local function grow_trunk(pos)
    local meta = minetest.get_meta(pos)
    if meta:get_int("ebiometrees:distance")  > grow_limit 
    then
      return
    end
    local where = ebiometrees.where_to_grow_trunk_closure(grow_preferences, leaves_name)
    local there = where(pos)
    if there
    then
      minetest.set_node(there, {name=trunk_terminal_name})
      local newmeta = minetest.get_meta(there)
      newmeta:set_int("ebiometrees:distance", meta:get_int("ebiometrees:distance")+1)
      meta:set_int("ebiometrees:distance", meta:get_int("ebiometrees:distance")+1)
    end
  end
  return grow_trunk
end


function ebiometrees.grow_leaves_closure(leaves_name)
  local function grow_leaves(pos)
    local free_node = minetest.find_node_near(pos, 1, "air")
    if free_node
    then
      minetest.set_node(free_node, {name=leaves_name})
    end
    return true
  end
  return grow_leaves
end

function ebiometrees.tree_timer_lifecycle_closure(tree_name)
  leaves_name = tree_name.."_leaves"
  terminal_name = tree_name.."_trunk_growing_terminal"
  nextstage = tree_name.."_trunk_normal_terminal"
  grow_preferences = ebiometrees.registered_trees[tree_name]["growth_preferences"]
  age_max = ebiometrees.registered_trees[tree_name]["age_max"]
  grow_limit = ebiometrees.registered_trees[tree_name]["growth_limit"]

  local grow_trunk =  ebiometrees.grow_trunk_closure(terminal_name, grow_preferences, leaves_name, grow_limit)
  local grow_leaves = ebiometrees.grow_leaves_closure(leaves_name)
  function tree_timer_lifecycle(pos)
    local meta = minetest.get_meta(pos)
    meta:set_int("ebiometrees:age", meta:get_int("ebiometrees:age")+1)
    grow_trunk(pos)
    grow_leaves(pos)
    if nextstage
    then
      if meta:get_int("ebiometrees:age") > age_max
      then
        minetest.set_node(pos, {name=nextstage})
      end
    end
    return true
  end
  return tree_timer_lifecycle
end