Branch Mine Main Corridor 3x3

--Branch Mine Main Corridor

--Slots
---12, 13: Blocks
---14, 15: Torches
---16: Fuel

--Declaring Variables
local distance = 0
local n = 0

--Declaring Functions
function dig()
    while turtle.detect() do
        turtle.dig()
    end
    turtle.forward()
    turtle.digDown()
    while turtle.detectUp() do
        turtle.digUp()
    end
end

function torch()
    turtle.select(14)
    if turtle.getItemCount(14) == 0 then
        turtle.select(15)
    end
    turtle.turnRight()
    turtle.turnRight()
    turtle.place()
    turtle.turnRight()
    turtle.turnRight()
end

function fuel()
    if turtle.getFuelLevel() <= 50 then
        turtle.select(16)
        turtle.refuel(5)
    end
end

function block()
    turtle.select(13)
    if turtle.getItemCount(13) == 0 then
        turtle.select(14)
    end
end

function placeblockforward()
    if not turtle.detect() then
        turtle.place()
    end
end

function shaftleft()
    block()
    turtle.up()
    if not turtle.detectUp() then
        turtle.placeUp()
    end
    turtle.turnLeft()
    placeblockforward()
    turtle.down()
    placeblockforward()
    turtle.down()
    placeblockforward()
    turtle.turnRight()
    if not turtle.detectDown() then
        turtle.placeDown()
    end
    turtle.up()
end

function shaftmiddle()
    block()
    turtle.up()
    if not turtle.detectUp() then
        turtle.placeUp()
    end
    turtle.down()
    turtle.down()
    if not turtle.detectDown() then
        turtle.placeDown()
    end
    turtle.up()
end

function shaftright()
    block()
    turtle.up()
    if not turtle.detectUp() then
        turtle.placeUp()
    end
    turtle.turnRight()
    placeblockforward()
    turtle.down()
    placeblockforward()
    turtle.down()
    placeblockforward()
    turtle.turnLeft()
    if not turtle.detectDown() then
        turtle.placeDown()
    end
    turtle.up()
end

--Opening Instructions
print("Welcome to the 3x3 Branch Mine Corridor v1.0!")
sleep(1)
print("Before we begin, make sure your turtle is positioned one block off of the floor of the corridor, on the right side, one block into the corridor.")
sleep(1)
print("Are you sure the turtle is positioned correctly?")
sleep(1)
print("Press any key to continue...")
os.pullEvent("char")

--Defining Length
term.clear()
term.setCursorPos(1,1)
term.write("How long should the corridor be? ")
distance = read()

--Making the Right Corridor
n = 0
for i = 2, distance do
    fuel()
    dig()
    shaftright()
    n = n + 1
    if n == 4 then
        torch()
        n = 0
    end
end

--Right to Middle Transition
turtle.turnLeft()
dig()
turtle.turnRight()
block()
turtle.up()
if not turtle.detectUp() then
    turtle.placeUp()
end
placeblockforward()
turtle.down()
placeblockforward()
turtle.down()
placeblockforward()
turtle.turnLeft()
turtle.turnLeft()
if not turtle.detectDown() then
    turtle.placeDown()
end
turtle.up()

--Making the Middle Corridor
for i = 2, distance do
    fuel()
    dig()
    shaftmiddle()
end

--Middle to Left Transition
turtle.turnRight()
dig()
turtle.up()
block()
if not turtle.detectUp() then
    turtle.placeUp()
end
placeblockforward()
turtle.down()
placeblockforward()
turtle.down()
placeblockforward()
turtle.turnRight()
if not turtle.detectDown() then
    turtle.placeDown()
end
turtle.up()

--Making the Left Corridor
n = 0
for i = 2, distance do
    fuel()
    dig()
    shaftright()
    n = n + 1
    if n == 4 then
        torch()
        n = 0
    end
end

--Returning Home
turtle.turnRight()
turtle.forward()
turtle.turnRight()
turtle.down()
for i = 1, distance do
    fuel()
    turtle.forward()
end