Basic Tunnel Finished

print("--------------------------------------")
print("Tunnel program - Created by Mjmac85")
print("Bridge materials in slot 1")
print("Torches in slot 2")
print("Fuel in slot 16")
print("--------------------------------------")
--  Make checks for all the items
--  Torch placement works
--  Length works
--  return trip completed
--  Args support
--  Things to add - rednet support
args = {...}
if args[1] == nil then
    write("Length: ")
    local length = tonumber(read())
end

if args[1] ~= nil then
    length = tonumber(args[1])
end


local function fuel(currentSlot)
    while turtle.getFuelLevel() <= 5 do
        turtle.select(16)
        turtle.refuel(1)
        print(turtle.getFuelLevel())
    end

    turtle.select(currentSlot)

end

local function checkDown(currentSlot)
    if turtle.detectDown() == false then
        turtle.select(1)
        turtle.placeDown()
        turtle.select(currentSlot)
    end

end





--local function inventoryCheck()
--    if turtle.getItemCount(14) > 0 then
--        dropItems()
--    end
--end

local function dropItems(distance, currentSlot)
-- Returns back to chest area and drops items
    local selector = 3
    local back = 0
    --turns turtle around and heads back
    turtle.turnRight()
    turtle.turnRight()
    while back <= distance - 1 do
        fuel(currentSlot)
        while turtle.forward() == false do
            turtle.dig()
        end
        checkDown(currentSlot)
        back = back + 1
    end


    --drops items into chest
    turtle.select(3)
    while selector <= 14 do
        turtle.select(selector)
        turtle.drop()
        selector = selector + 1
    end
    turtle.select(currentSlot)
    turtle.turnRight()
    turtle.turnRight()
    back = 0

    --  Heads back into the mine
    while back <= distance - 1 do
        fuel(currentSlot)
        while turtle.forward() == false do
            turtle.dig()
        end
        checkDown(currentSlot)
        back = back + 1
    end

end

local function mine(currentSlot)
    fuel(currentSlot)
    while turtle.forward() == false do
        turtle.dig()
    end
    checkDown(currentSlot)
    turtle.digUp()
end

local function main()
    local fuelSlot = 16
    local currentSlot = 1
    local bridgeSlot = 1
    local torchSlot = 2
    local distance = 0
    local back = 0
    local selector = 3
    while distance <= length - 1 do
        fuel(currentSlot)
        turtle.select(fuelSlot)
        if turtle.getItemCount(14) > 0 then
            dropItems(distance, currentSlot)
        end
        mine(currentSlot)
        -- Torch Drop
        distance = distance + 1
        if distance % 8 == 0 then
            turtle.select(2)
            turtle.back()
            turtle.placeUp()
            turtle.forward()
            turtle.select(currentSlot)
        end
    -- end main distance loop
    end

    -- returns at the end
    turtle.turnRight()
    turtle.turnRight()
    while back <= distance - 1 do
        fuel(currentSlot)
        while turtle.forward() == false do
            turtle.dig()
        end
        checkDown(currentSlot)
        back = back + 1
    end


    --drops items into chest
    turtle.select(3)
    while selector <= 14 do
        turtle.select(selector)
        turtle.drop()
        selector = selector + 1
    end
    turtle.select(currentSlot)
    turtle.turnRight()
    turtle.turnRight()
-- end func
end

main()