Terrain Leveler

-- Default settings.
local HOUSE_WIDTH = 15       -- House width (excluding borders)
local HOUSE_LENGTH = 20      -- House length (excluding borders)
-- Leveling area: house dimensions + 1 block border on each side
local LEVEL_WIDTH = HOUSE_WIDTH + 2
local LEVEL_LENGTH = HOUSE_LENGTH + 2

-- Vertical clearance: only the immediate block by default.
local CLEARANCE = 1

-- FILL_DEPTH determines how many blocks downward to fill when a hole is encountered.
local FILL_DEPTH = 2         -- Default fill depth; can be overridden via command-line argument

-- Global variable to store the desired material name.
local desiredMaterial = nil

-- Function to get the desired material from the inventory.
-- It first checks slot 1; if that is empty, it searches all slots.
local function getDesiredMaterial()
  local detail = turtle.getItemDetail(1)
  if detail then
    desiredMaterial = detail.name
    return desiredMaterial
  else
    for i = 2, 16 do
      local d = turtle.getItemDetail(i)
      if d then
        desiredMaterial = d.name
        return desiredMaterial
      end
    end
  end
  error("No material found in inventory. Please add the desired material.")
end

-- Function that searches the inventory for the desired material.
-- It selects the first slot containing that material.
function ensureMaterialFromSlot1()
  local materialName = getDesiredMaterial()
  for i = 1, 16 do
    local detail = turtle.getItemDetail(i)
    if detail and detail.name == materialName and detail.count > 0 then
      turtle.select(i)
      return true
    end
  end
  error("Out of material: " .. materialName)
end

-- Function to remove tall grass below the turtle.
-- It checks the block below, and if it is "minecraft:grass" or "minecraft:tall_grass", it digs it.
function removeTallGrassDown()
  local success, block = turtle.inspectDown()
  if success and (block.name == "minecraft:grass" or block.name == "minecraft:tall_grass") then
    turtle.digDown()
    os.sleep(0.2)
  end
end

-- Function to check if the block below should be replaced.
-- Returns true if no block is detected or if the block below is air.
function isHoleBelow()
  if not turtle.detectDown() then
    return true
  end
  local success, data = turtle.inspectDown()
  if not success then
    return true
  else
    if data.name == "minecraft:air" then
      return true
    else
      return false
    end
  end
end

-- Safe forward movement with obstacle removal and mob detection.
function safeForward()
  local attempts = 0
  while not turtle.forward() do
    if turtle.detect() then
      local success, data = turtle.inspect()
      if success then
        turtle.dig()
      else
        turtle.attack()
      end
    else
      turtle.attack()
    end
    attempts = attempts + 1
    if attempts >= 5 then
      print("Persistent obstacle detected in front. Attempting to bypass...")
      turtle.turnLeft()
      safeForward()  -- try sidestepping
      turtle.turnRight()
      attempts = 0
    end
    os.sleep(0.5)
  end
end

-- Safe upward movement with obstacle removal and mob detection.
function safeUp()
  local attempts = 0
  while not turtle.up() do
    if turtle.detectUp() then
      local success, data = turtle.inspectUp()
      if success then
        turtle.digUp()
      else
        turtle.attackUp()
      end
    else
      turtle.attackUp()
    end
    attempts = attempts + 1
    if attempts >= 5 then
      print("Persistent obstacle detected above. Attempting alternative maneuver...")
      turtle.turnLeft()
      safeForward()  -- move sideways
      turtle.turnRight()
      attempts = 0
    end
    os.sleep(0.5)
  end
end

-- Safe downward movement with obstacle removal and basic mob check.
function safeDown()
  local attempts = 0
  while not turtle.down() do
    if turtle.detectDown() then
      local success, data = turtle.inspectDown()
      if success then
        turtle.digDown()
      else
        turtle.attack()
      end
    else
      turtle.attack()
    end
    attempts = attempts + 1
    if attempts >= 5 then
      print("Persistent obstacle detected below. Waiting before retrying...")
      attempts = 0
    end
    os.sleep(0.5)
  end
end

-- Function to check vertical clearance above the turtle.
function checkVerticalClearance(clearance)
  if turtle.detectUp() then
    return false
  end
  if clearance > 1 then
    for i = 2, clearance do
      safeUp()
      if turtle.detectUp() then
        for j = 1, i do safeDown() end
        return false
      end
    end
    for i = 2, clearance do safeDown() end
  end
  return true
end

-- Function fillHole(fillDepth)
-- Fills a hole downward to the specified depth, starting from the lowest level.
-- Before placing a block, it calls removeTallGrassDown() so that only individual tall grass is removed.
function fillHole(fillDepth)
  if fillDepth <= 1 then
    if isHoleBelow() then
      removeTallGrassDown()
      ensureMaterialFromSlot1()
      turtle.placeDown()
      os.sleep(0.2)
    end
    return
  end

  -- Descend to the lowest level (up to fillDepth-1 times)
  local descent = 0
  for i = 1, fillDepth - 1 do
    if isHoleBelow() then
      removeTallGrassDown()
      safeDown()
      descent = descent + 1
    else
      break
    end
  end

  -- At the lowest level, place a block after removing tall grass if present
  if isHoleBelow() then
    removeTallGrassDown()
    ensureMaterialFromSlot1()
    turtle.placeDown()
    os.sleep(0.2)
  end

  -- Ascend back, filling the hole on the way up
  for i = 1, descent do
    safeUp()
    if isHoleBelow() then
      removeTallGrassDown()
      ensureMaterialFromSlot1()
      turtle.placeDown()
      os.sleep(0.2)
    end
  end
end

-- Function levelGround()
-- Traverses the leveling area in a snake pattern.
-- When a hole is detected, fillHole(fillDepth) is called.
function levelGround(width, length, clearance, fillDepth)
  clearance = clearance or CLEARANCE
  fillDepth = fillDepth or FILL_DEPTH
  for row = 1, length do
    for col = 1, width do
      if isHoleBelow() then
        fillHole(fillDepth)
      end
      if not checkVerticalClearance(clearance) then
        turtle.digUp()
        os.sleep(0.1)
      end
      if col < width then
        safeForward()
      end
    end
    if row < length then
      if row % 2 == 1 then
        turtle.turnRight()
        safeForward()
        turtle.turnRight()
      else
        turtle.turnLeft()
        safeForward()
        turtle.turnLeft()
      end
    end
  end
  repositionToStart(width, length)
end

-- Function repositionToStart()
-- Returns the turtle to the starting position after traversing the area.
function repositionToStart(width, length)
  if length % 2 == 1 then
    turtle.turnRight()
    turtle.turnRight()  -- now facing west
    for i = 1, (width - 1) do
      safeForward()
    end
    turtle.turnLeft()   -- now facing south
    for i = 1, (length - 1) do
      safeForward()
    end
    turtle.turnLeft()   -- returns to original orientation (east)
  else
    turtle.turnLeft()   -- turn from west to south
    for i = 1, (length - 1) do
      safeForward()
    end
    turtle.turnLeft()   -- now facing east
  end
end

-- Main function.
-- Command-line parameters:
-- 1: Leveling area width, 2: length, 3: vertical clearance, 4: fill depth.
function main(...)
  local args = {...}
  local width = tonumber(args[1]) or LEVEL_WIDTH
  local length = tonumber(args[2]) or LEVEL_LENGTH
  local clearance = tonumber(args[3]) or CLEARANCE
  local fillDepth = tonumber(args[4]) or FILL_DEPTH

  print("Leveling area size: " .. width .. " x " .. length)
  print("Vertical clearance: " .. clearance .. " block(s)")
  print("Fill depth: " .. fillDepth .. " block(s)")

  levelGround(width, length, clearance, fillDepth)

  print("Leveling complete. The area is ready for building.")
end

-- Run main function with command-line parameters.
main(...)