b.lua (back X blocks)

version = 20230801.1200
-- https://pastebin.com/g7DjxRbr
-- pastebin get g7DjxRbr b.lua
-- Last edited: see version YYYYMMDD.HHMM
local usage = {}
usage.backwards = [[
b 10  :moves 10 blocks back unless
obstructed. No blocks broken

b 10 d :moves 10 blocks back unless
bedrock. Blocks are removed.

'd' or any character / string is ok]]
usage.down = [[
d 10  :moves 10 blocks down unless
obstructed. No blocks broken

d 10 d :moves 10 blocks down unless
bedrock. Blocks are removed.

'd' or any character / string is ok]]
usage.forwards = [[
f 10  :moves 10 blocks forward unless
obstructed. No blocks broken

f 10 d :moves 10 blocks forward unless
bedrock. Blocks are removed.

'd' or any character / string is ok]]
usage.up = [[
u 10  :moves 10 blocks up unless
obstructed. No blocks broken

u 10 d :moves 10 blocks up unless
bedrock. Blocks are removed.

'd' or any character / string is ok]]
args = {...}

function checkArgs(direction)
    local numBlocksRequested = 1
    local doDig = false
    if args[1] ~= nil then
        if args[1]:lower() == "h" then
            term.clear()
            term.setCursorPos(1,1)
            print(usage[direction])
            print("Fuel Level: "..turtle.getFuelLevel())
            error()
        else
            numBlocksRequested = tonumber(args[1])
            if numBlocksRequested == nil then
                print("Use a number as argument, not "..args[1])
                error()
            end
        end
        if args[2] ~= nil then -- any character here will work
            doDig = true
        end
    end
    return numBlocksRequested, doDig
end

function turnRound()
    turtle.turnRight()
    turtle.turnRight()
end

function doMoves(numBlocksRequested, doDig, direction)
    local errorMsg = nil
    local numBlocksMoved = 0
    local Move, Dig, Detect
    local turned = false

    -- re-assign turtle functions to new variables
    if direction == "forwards" then
        Move = turtle.forward
        Dig = turtle.dig
        Detect = turtle.detect
    elseif direction == "backwards" then
        Move = turtle.back
        Dig = turtle.dig
        Detect = turtle.detect
    elseif direction == "up" then
        Move = turtle.up
        Dig = turtle.digUp
        Detect = turtle.detectUp
    else
        Move = turtle.down
        Dig = turtle.digDown
        Detect = turtle.detectDown
    end

    for i = 1, numBlocksRequested, 1 do
        local moveOK, moveError = Move() -- try to move forward/up/down
        if doDig then
            if moveOK then
                numBlocksMoved = numBlocksMoved + 1
            else -- did not move due to obstruction
                -- while moveOK == false do -- same effect if you prefer.
                if direction == "backwards" and not turned then
                    turnRound()
                    turned = true
                    Move = turtle.forward
                end
                while not moveOK do -- did not move if obstruction
                    local digOK, digError = Dig()
                    if digOK then
                        sleep(0.5) -- allow sand / gravel to drop if digging forward / up
                    else -- unable to dig, or nothing to dig
                        if digError == "Unbreakable block detected" then
                            errorMsg = digError
                            break
                        end
                    end
                    moveOK, moveError = Move() -- try to move forward/up/down again
                    if moveOK then
                        numBlocksMoved = numBlocksMoved + 1
                    end
                end
            end
        else
            if moveOK then
                numBlocksMoved = numBlocksMoved + 1
            else -- move did not succeed
                errorMsg = moveError
                break
            end
        end
    end

    if turned then -- was "backwards" but obstuction rotated 180 so need to turn round again
        turnRound()
    end

    return numBlocksMoved, errorMsg
end

function printLog(direction, numBlocksRequested, numBlocksMoved, errorMsg)
    print("Moved "..direction.." "..numBlocksMoved.. " / ".. numBlocksRequested)
    if errorMsg ~= nil then
        print (errorMsg)
    end
end

function main()
    local directions = {"backwards", "down", "forwards", "up"}
    --***********************************************************************************************
    --Change this to 1-4 to suit application (forwards, up, down, backwards) f.lua, u.lua, d.lua, b.lua
    local directionIndex = 1 -- this is for b.lua
    --***********************************************************************************************
    local direction = directions[directionIndex] -- e.g backwards
    local numBlocksRequested, doDig = checkArgs(direction)
    if turtle.getFuelLevel() == 0 then
        print("No fuel")
    else
        print("Fuel level: "..turtle.getFuelLevel())
        local numBlocksMoved, errorMsg = doMoves(numBlocksRequested, doDig, direction)
        printLog(direction, numBlocksRequested, numBlocksMoved, errorMsg)
    end
end

main()