Minecraft - Wallbuilder - Simple

-- ------------------------------------------------------
--
-- Wall builder
-- Author: KROM
-- goes forward and down. then steps back and places block in front
-- end of row, move up, turn around and continue.
--
-- simple and untested, use at own risk ;p
--
-- ------------------------------------------------------
local nStepsBackHome = 0
local bDone = false
local bAtHome = true
local nEnergy = 0
local nActiveSlot = 0
local nItemsLeft = 0

local vOffset = vector.new(0,0,0)
local vDir    = vector.new(0,0,1)
-- ------------------------------------------------------
local function goForward()
    if turtle.forward() == true then
        if vDir.z == 1 then vOffset.z = vOffset.z + 1 else vOffset.z = vOffset.z - 1 end
        nEnergy = nEnergy - 1;
        return true
    end
    return false
end
-- ------------------------------------------------------
local function goBack()
    if turtle.back() == true then
        if vDir.z == 1 then vOffset.z = vOffset.z - 1 else vOffset.z = vOffset.z + 1 end
        nEnergy = nEnergy - 1;
        return true
    end
    return false
end
-- ------------------------------------------------------
local function goUp()
    if turtle.up() == true then
        vOffset.y = vOffset.y + 1
        nEnergy = nEnergy - 1;
        return true
    end
    return false
end
-- ------------------------------------------------------
local function goDown()
    if turtle.down() == true then
        vOffset.y = vOffset.y - 1
        nEnergy = nEnergy - 1;
        return true
    end
    return false
end
-- ------------------------------------------------------

local function goHome()
    print("Going home")
    while vOffset.y > 0 do
        if goUp() == false then
            print("ERROR: Return home: no way up")
        end
    end
    if not vDir.z == 1 then
        turtle.turnLeft()
        turtle.turnLeft()
        nEnergy = nEnergy - 2;
        vDir.z = 1
    end
    while vOffset.z > 0 do
        if goForward() == false then
            print("ERROR: Return home: no way forward")
        end
    end
    if vOffset.y == 0 and vOffset.z == 0 then
        bHome = true
        print("Arrived at home")
    end
end
-- ------------------------------------------------------
local function refuel(amount)
    local fuelLevel = turtle.getFuelLevel()
    if fuelLevel == "unlimited" then
        nEnergy = 9999
        return true
    end

    --refuel
    local needed             = amount or 600
    if turtle.getFuelLevel() < needed then
        for n=1,16 do
            if turtle.getItemCount(n) > 0 then
                turtle.select(n)
                if turtle.refuel(1) then
                    needed = needed - 1
                    while turtle.getItemCount(n) > 0 and turtle.getFuelLevel() < needed do
                        turtle.refuel(1)
                    end
                    if turtle.getFuelLevel() >= needed then
                        turtle.select(1)
                        nEnergy = turtle.getFuelLevel()
                        return true
                    end
                end
            end
        end
        nEnergy = turtle.getFuelLevel()
        turtle.select(1)
        return false
    end
    nEnergy = turtle.getFuelLevel()
    turtle.select(1)
    return true
end
-- ------------------------------------------------------
local function getBlock()
    for n=2,16 do
        if turtle.getItemCount(n) > 0 then
            turtle.select(n)
            nItemsLeft = turtle.getItemCount(n)
            nActiveSlot = n
            return true
        end
    end
    return false
end
-- ------------------------------------------------------
local function placeBlock()
    if nItemsLeft > 0 then
        turtle.place()
        nItemsLeft = nItemsLeft - 1
        return true
    else
        if getBlock() == true then
            return placeBlock()
        else
            return false
        end
    end
end
-- ------------------------------------------------------
local function placeBlockDown()
    if nItemsLeft > 0 then
        turtle.placeDown()
        nItemsLeft = nItemsLeft - 1
        return true
    else
        if getBlock() == true then
            return placeBlock()
        else
            return false
        end
    end
end

-- ------------------------------------------------------


while not bDone do


    if bAtHome == true then
        -- if at home

        -- check energy
        if not refuel() or nEnergy < 60 then
            print "Fuel less than 60 and no fuel left. Abort."
            bDone = true
            break
        end

        -- check inventory
        if not getBlock() then
            print "No blocks to place. Abort."
            bDone = true
            break
        end

        while goForward() == true do
        end

        while goDown() == true do
        end

        bAtHome = false
    else

        -- check energy
        if not refuel() or nEnergy < 60 then
            print "Fuel less than 60 and no fuel left. Abort."
            goHome()
            bDone = true
            break
        end

        -- check inventory
        if not getBlock() then
            print "No blocks to place. Abort."
            bDone = true
            goHome()
            break
        end

        -- if on duty
        if goBack() == true then
            if not placeBlock() then
                print("could not place block")
                goHome()
                bDone = true
                break
            end
        else
            if goUp() == true then
                if not placeBlockDown() then
                    print("could not place block below")
                    goHome()
                    bDone = true
                    break
                else
                    -- check if top layer
                    if vOffset.y == 0 then
                        print("Reached home layer. Returning")
                        goHome()
                        bDone = true
                        break
                    end

                    -- check if we can move backwards now
                    if goBack() == true then
                        if not placeBlock() then
                            print("could not place block")
                            goHome()
                            bDone = true
                            break
                        end
                    else
                        -- no we can not. turn around
                        turtle.turnLeft()
                        turtle.turnLeft()
                        nEnergy = nEnergy - 2;
                        vDir.z = 1 - vDir.z
                    end


                end
            else
                print("FATAL ERROR: could not go up")
                bDone = true
                break
            end
        end
    end
end
print("Wall: All done!")
-- ------------------------------------------------------
-- ------------------------------------------------------