Tekkit Leaf Placer Turtle

-- ======================================
-- Moon Leaf Placer Turtle
-- brendan@slayweb.com 2013-06-03
-- ======================================

-- ======================
-- Variables
-- ======================

local programrunning = true
local walllength = 18

-- ======================
-- Functions
-- ======================

function refuel()
   -- refuel turtle from one of the bottom four slots
   if turtle.getItemCount(16)==64 then
      turtle.select(16)
      turtle.refuel(64)
   else
       if turtle.getItemCount(15)==64 then
          turtle.select(15)
          turtle.refuel(64)
       else
           if turtle.getItemCount(14)==64 then
              turtle.select(14)
              turtle.refuel(64)
           else
               if turtle.getItemCount(13)==64 then
                  turtle.select(13)
                  turtle.refuel(64)
               else
                  programrunning = false
                  print("Error: Ran out of fuel")
               end
           end
       end
   end
end

function check_fuel()
   if turtle.getFuelLevel()<1 then
      refuel()
   end
end

function place_leaf()
   if turtle.getItemCount(1)>0 then
      turtle.select(1)
      turtle.place()
   else
       if turtle.getItemCount(2)>0 then
          turtle.select(2)
          turtle.place()
       else
           if turtle.getItemCount(3)>0 then
              turtle.select(3)
              turtle.place()
           else
               if turtle.getItemCount(4)>0 then
                  turtle.select(4)
                  turtle.place()
               else
                  programrunning = false
                  print("Error: Ran out of leaves")
               end
           end
       end
   end
end

function need_fuel()
   if turtle.getItemCount(13)==0 then
      turtle.select(13)
      turtle.suck()
   end
   if turtle.getItemCount(14)==0 then
      turtle.select(14)
      turtle.suck()
   end
   if turtle.getItemCount(15)==0 then
      turtle.select(15)
      turtle.suck()
   end
   if turtle.getItemCount(16)==0 then
      turtle.select(16)
      turtle.suck()
   end
end

function need_leaves()
   if turtle.getItemCount(1)==0 then
      turtle.select(1)
      turtle.suck()
   end
   if turtle.getItemCount(2)==0 then
      turtle.select(2)
      turtle.suck()
   end
   if turtle.getItemCount(3)==0 then
      turtle.select(3)
      turtle.suck()
   end
   if turtle.getItemCount(4)==0 then
      turtle.select(4)
      turtle.suck()
   end
end

-- ======================
-- Main Program
-- ======================

while programrunning==true do

   -- start in front of fuel box

   -- do we need to pick up more fuel?
   need_fuel()
   -- do we need to refuel?
   check_fuel()

   -- move to leaf box
   turtle.turnLeft()
   turtle.forward()
   turtle.turnRight()

   -- do we need to restock on leaves?
   need_leaves()

   -- about face
   turtle.turnLeft()
   turtle.turnLeft()

   -- move to top
   turtle.up()
   check_fuel()
   turtle.up()
   check_fuel()
   turtle.up()
   check_fuel()

   -- check row 1 of leaves
    for n = 1,walllength,1 do
        check_fuel()
        if turtle.detect()==false then
            -- move forward
            turtle.forward()
            check_fuel()
            -- place leaf if not there
            if turtle.detect()==false then
               place_leaf()
            end
            -- move back
            turtle.back()
            check_fuel()
            -- place leaf
            place_leaf()
        end
        turtle.turnLeft()
        turtle.forward()
        check_fuel()
        turtle.turnRight()
    end

    -- down for next row
    turtle.down()
    check_fuel()

    -- check row 2 of leaves
    for n = 1,walllength,1 do
        check_fuel()
        if turtle.detect()==false then
            -- move forward
            turtle.forward()
            check_fuel()
            -- place leaf if not there
            if turtle.detect()==false then
               place_leaf()
            end
            -- move back
            turtle.back()
            check_fuel()
            -- place leaf
            place_leaf()
        end
        turtle.turnRight()
        turtle.forward()
        check_fuel()
        turtle.turnLeft()
    end

    -- down for next row
    turtle.down()
    check_fuel()

    -- check row 3 of leaves
    for n = 1,walllength,1 do
        check_fuel()
        if turtle.detect()==false then
            -- move forward
            turtle.forward()
            check_fuel()
            -- place leaf if not there
            if turtle.detect()==false then
               place_leaf()
            end
            -- move back
            turtle.back()
            check_fuel()
            -- place leaf
            place_leaf()
        end
        turtle.turnLeft()
        turtle.forward()
        check_fuel()
        turtle.turnRight()
    end

    -- down for next row
    turtle.down()
    check_fuel()

    -- check row 4 of leaves
    for n = 1,walllength,1 do
        check_fuel()
        if turtle.detect()==false then
            -- move forward
            turtle.forward()
            check_fuel()
            -- place leaf if not there
            if turtle.detect()==false then
               place_leaf()
            end
            -- move back
            turtle.back()
            check_fuel()
            -- place leaf
            place_leaf()
        end
        turtle.turnRight()
        turtle.forward()
        check_fuel()
        turtle.turnLeft()
    end

    -- back to start
    turtle.turnLeft()
    turtle.forward()
    turtle.turnLeft()


end