Turtle mining program

local xPos = 0
local yPos = 0
local zPos = 0
local xSize = 0
local ySize = 0
local zSize = 0
local direction = 0
local status = "Let's goooooooooooooo"
local fuelTypes = {'minecraft:coal', 'minecraft:charcoal', 'minicoal2:minicoal', 'minicoal2:minicharcoal'}
local finished = false
local inventorySlot = 1

--[[ local rednetOutputChannel = 1
local rednetInputChannel = 2
local modem = peripheral.find("modem")
modem.open(rednetOutputChannel) ]]

--[[ function rednetOut(message)
 modem.transmit(1, 2, message)
end ]]

--[[ function outputData()
 rednetOut({
  "X position: " .. xPos,
  "Y position: " .. yPos,
  "Z position: " .. zPos,
  "Direction : " .. math.fmod(direction, 4),
  "",
  "Fuel level: " .. turtle.getFuelLevel(),
  "",
  "Status    : " .. status
 })
end ]]

function mine()
    if turtle.detect() then
        turtle.dig()
        turtle.forward()
    else
        turtle.forward()
    end
end

function turn(side)
    if side == "right" then
        turtle.turnRight()
        direction = direction + 1
    elseif side == "left" then
        turtle.turnLeft()
        direction = direction - 1
    else
        error("turn() function called incorrectly. parameter: " .. side .. " needs to be either left or right")
    end
end

function enoughFuel(distance)
 local fuelLevel = turtle.getFuelLevel()

 if fuelLevel > distance then
  return true
 else
  return false
 end
end

function refuel(amount)
 local item = turtle.getItemDetail(16)

 for i=1,table.getn(fuelTypes) do
  if item.name == fuelTypes[i] then
   if item.count > amount then
    turtle.refuel(amount)
    status = "Refuelled. " .. item.count - amount .. " " .. item.name .. " left."
    print("Refuelled. "..item.count - amount.." "..item.name.." left.")
   else
    status = "ERROR: only " .. item.count .. " " .. item.name .. " left. Can't refuel " .. amount .. " items."
    print("ERROR: only "..item.count.." "..item.name.." left. Can't refuel "..amount.." items.")
   end
  end
 end
end

function faceDirection(dir)
    while direction > dir do
        turn("left")
    end

    while direction < dir do
        turn("right")
    end
end

function faceDirectionZero()
    while direction > 0 do
        turn("left")
    end

    while direction < 0 do
        turn("right")
    end
end

function returnToBase()
    print("Returning to base")
    while zPos > 0 do
        turtle.up()
        zPos = zPos - 1
    end

    faceDirectionZero()

    if yPos > 0 then
        turn("right")
        while yPos > 0 do
            turtle.forward()
            yPos = yPos - 1
        end

        if xPos > 0 then
            turn("right")
            while xPos > 0 do
                turtle.forward()
                xPos = xPos - 1
            end
        end
    else
        if xPos > 0 then
            turn("right")
            turn("right")
            while xPos > 0 do
                turtle.forward()
                xPos = xPos - 1
            end
        end
    end

    turtle.forward()
    faceDirectionZero()
end

function moveToPos(x, y, z, dir)
    print("Moving to pos: ["..x..", "..y..", "..z.."]"..".")
    faceDirectionZero()

    while xPos < x do
        turtle.forward()
        xPos = xPos + 1
    end

    if yPos < y then
        turn("left")
        while yPos < y do
            turtle.forward()
            yPos = yPos + 1
        end
    end

    while zPos < z do
        turtle.down()
        zPos = zPos + 1
    end
    faceDirection(dir)
end

function bankItems()
    local success, data = turtle.inspectDown()
    if success and data == 'minecraft:chest' then
        for i=1,16 do
            turtle.select(i)
            turtle.dropDown()
        end
    end
end

function miningAction()
    local layer = math.fmod(zPos, 2)
    local row = math.fmod(xPos, 2)
    local column = math.fmod(yPos, 2)

    if zPos >= zSize - 1 and ySize <= 0 and xSize <= 0 then
        status = "Finished " .. xSize .. "x" .. ySize .. "x" .. zSize .. " cube. Returning to base..."
        returnToBase()
        finished = true
        return
    end


    if yPos >= ySize - 1 and xPos <= 0 and layer == 0 then
        turtle.digDown()
        turtle.down()
        turn("left")
        turn("left")
        zPos = zPos + 1
    elseif yPos <= 0 and xPos <= 0 and layer == 1 then
        turtle.digDown()
        turtle.down()
        turn("right")
        turn("right")
        zPos = zPos + 1
    elseif xPos >= xSize - 1 and column == 1 and layer == 1 then
        turn("right")
        mine()
        turn("right")
        yPos = yPos - 1
    elseif xPos <= 0 and column == 0 and layer == 1 then
        turn("left")
        mine()
        turn("left")
        yPos = yPos - 1
    elseif xPos >= xSize - 1 and column == 0 and layer == 0 then
        turn("left")
        mine()
        turn("left")
        yPos = yPos + 1
    elseif xPos <= 0 and column == 1 and layer == 0 then
        turn("right")
        mine()
        turn("right")
        yPos = yPos + 1
    else
        mine()
        if column == 0 then
            if layer == 0 then
                xPos = xPos + 1
            elseif layer == 1 then
                xPos = xPos - 1
            end
        elseif column == 1 then
            if layer == 0 then
                xPos = xPos - 1
            elseif layer == 1 then
                xPos = xPos + 1
            end
        end
    end
end


textutils.slowPrint("Starting mining program (Mart)")
--print("\nMake sure to meet the following requirements: ")
--print(" - Put down a fuel chest, with the turtle on top of it")
--print(" - Put down another chest two blocks to the left of the fuel chest")
--print(" - Make sure the turtle has a littlebit of fuel on slot 16 (bottom right)")

textutils.slowPrint("\nConfiguring grid size...")
print("How many blocks should i dig forward?")
xSize = tonumber(io.read())
write("\nDigging ")
write(xSize)
write(" blocks forward. How many blocks should i dig sideways?\n")
ySize = tonumber(io.read())
write("Digging a grid of ")
write(xSize)
write("x")
write(ySize)
write("\n")
print("\nHow deep do you want me to dig?")
zSize = tonumber(io.read())
write("Ready to dig ")
write(zSize)
write(" blocks deep.")

textutils.slowPrint("\nInitialization complete. Starting program")

mine()
turtle.select(inventorySlot)
while enoughFuel(100) and finished == false do
    if turtle.getItemSpace(16) <= 0 then
        print("Inventory full. Banking items.")
        local mineXPos = xPos
        local mineYPos = yPos
        local mineZPos = zPos
        local mineDirection = direction
        returnToBase()
        bankItems()
        turtle.forward()
        moveToPos(mineXPos, mineYPos, mineZPos, mineDirection)
        print("Resuming mining")
    end

    miningAction()
    --outputData()
end