9x9 Builder

function buildLayer()
  moveUp()
  for i=1,4 do
    turtle.placeDown()
    checkBuildingSupply()
    for j=1,8 do
      moveForward()
      turtle.placeDown()
      checkBuildingSupply()
    end
    turtle.turnRight()
  end
end

function checkBuildingSupply()
  if ( turtle.getItemCount(itemSlot) == 0 ) then
    itemSlot = itemSlot + 1
    turtle.select(itemSlot)
  end
end

function digFloor()
  for i=1,9 do
    for j=1,8 do
      moveForward()
    end
    if ( i % 2 == 1 ) then
      if ( i ~= 9 ) then
        turtle.turnRight()
        moveForward()
        turtle.turnRight()
      end
    else
      turtle.turnLeft()
      moveForward()
      turtle.turnLeft()
    end
  end
end

function moveForward()
  while ( not turtle.forward() ) do
    turtle.dig()
  end
end

function moveUp()
  while ( not turtle.up() ) do
    turtle.digUp()
  end
end

function moveDown()
  while ( not turtle.down() ) do
    turtle.digDown()
  end
end

function digDown()
  while ( turtle.detectDown() ) do
    turtle.digDown()
  end
end

function layFloor()
  -- lays the 9x9 floor
  for i=1,9 do
    for j=1,8 do
      digDown()
      turtle.placeDown()
      checkBuildingSupply()
      moveForward()
    end
    digDown()
    turtle.placeDown()
    checkBuildingSupply()
    if ( i%2 == 0 ) then
      turtle.turnLeft()
      moveForward()
      turtle.turnLeft()
    else
      if ( i ~= 9 ) then
        turtle.turnRight()
        moveForward()
        turtle.turnRight()
      end
    end
  end
end

function buildRoof()
  --if building from the top down, then turtle stays on roof
  --if building from the bottom or from the sides, needs to do the edges first, otherwise one side can't get done
  --can it be done by a spiral, so that the turtle finishes in the centre block of the newly built house
  design={}
  design[1]={'b', 'b', 'b', 'b', 'b', 'b', 'b', 'b', 'b'}
  design[2]={'b', 'b', 'b', 'b', 'b', 'b', 'b', 'b'}
  design[3]={'b', 'b', 'b', 'b', 'b', 'b', 'b', 'b'}
  design[4]={'b', 'b', 'b', 'b', 'b', 'b', 'b'}
  design[5]={'b', 'b', 'b', 'b', 'b', 'b', 'b'}
  design[6]={'b', 'b', 'b', 'b', 'b', 'b'}
  design[7]={'b', 'b', 'b', 'b', 'b', 'b'}
  design[8]={'b', 'b', 'b', 'b', 'b'}
  design[9]={'g', 'g', 'b', 'g', 'g'}
  design[10]={'g', 'b', 'g', 'g'}
  design[11]={'g', 'b', 'g', 'g'}
  design[12]={'g', 'b', 'g'}
  design[13]={'g', 'b', 'g'}
  design[14]={'b', 'g'}
  design[15]={'b', 'g'}
  design[16]={'b'}
  turtle.select(itemSlot)
  moveUp()
  for i=1,table.getn(design) do
    for j=1,table.getn(design[i]) do
      if ( design[i][j] == 'b' ) then
        turtle.placeDown()
        checkBuildingSupply()
      elseif ( design[i][j] == 'g' ) then
        turtle.select(16)
        turtle.placeDown()
        turtle.select(itemSlot)
      end
      if ( j == table.getn(design[i]) ) then
        turtle.turnRight()
      end
      moveForward()
    end
  end
  moveDown()
  moveDown()
  turtle.placeUp()
end

function placeTorches()
  moveForward()
  turtle.turnRight()
  moveForward()
  turtle.turnLeft()
  moveDown()
  turtle.select(15)
  for i=1,4 do
    for j=1,6 do
      if ( j % 2 == 0 ) then
             while ( turtle.detectDown() ) do
          turtle.digDown()
        end
        turtle.placeDown()
      end
      moveForward()
    end
    turtle.turnRight()
  end
  moveUp()
  turtle.turnLeft()
  moveForward()
  turtle.turnRight()
  turtle.back()
  turtle.select(itemSlot)
end

function checkInventory()
  -- check that there are 306 identical blocks in slots 1-6
  -- check that there are 12 items in slot 15 (torches)
  -- check that there are 16 items in slot 16 (glass)
  blockCount=turtle.getItemCount(1)
  turtle.select(1)
  for i=2,5 do
    if ( turtle.getItemCount(i) == 0 ) then
      print("Insufficient Base Blocks for building, slots 1-5 must contain identical blocks")
      os.exit(1)
    end
    if ( not turtle.compareTo(i) ) then
      print("Blocks in slot 1 - 5 must be identical")
      os.exit(1)
    end
    blockCount = blockCount + turtle.getItemCount(i)
  end
  if ( blockCount < 306 ) then
    print("Insufficient Base Blocks for building")
    os.exit(1)
  end
  if ( turtle.getItemCount(15) < 12 ) then
    print("Insufficient Torches in slot 15")
    os.exit(1)
  end
  if ( turtle.getItemCount(16) < 16 ) then
    print("Insufficient Glass in slot 16")
    os.exit(1)
  end
end

function rotate()
  for i=1,2 do
    turtle.turnLeft()
  end
end

itemSlot=1
checkInventory()
--moveDown()
--digFloor()
--moveUp()
turtle.select(itemSlot)
--rotate()
layFloor()
rotate()
for i=1,5 do
  buildLayer()
end
placeTorches()
buildRoof()
for i=1,4 do
  moveDown()
end
print("9x9 built")