Turtle Miner

---- Introduction
-- This is a Lua script written for the Mining Turtle, which is included in a mod ComputerCraft (www.computercraft.info) created for Minecraft (minecraft.net).
-- The script makes the turtle mine shafts in parallel lines until it runs out of fuel.
-- Uploaded to (and explained): github.com/Franco22hu/MiningTurtle
-- Version: 2.4


---- Constants
local SHAFT_LENGTH = 20 -- The length of a shaft mined
local GO_LEFT = false -- Create shafts to the left or right
local START_SHAFT = 0 -- Which shaft to begin from
local BLOCKS_BETWEEN = 2 -- How far apart shafts should be


---- Functions
local function tryGoForward()
    while not turtle.forward() do
        if turtle.detect() then
            turtle.dig()
        elseif turtle.attack() then
        else sleep( 0.5 )
        end
    end
end
local function tryGoUp()
    while not turtle.up() do
        if turtle.detectUp() then
            turtle.digUp()
        elseif turtle.attackUp() then
        else sleep( 0.5 )
        end
    end
end
local function tryGoDown()
    while not turtle.down() do
        if turtle.detectDown() then
            turtle.digDown()
        elseif turtle.attackDown() then
        else sleep( 0.5 )
        end
    end
end
local function tryDigUp()
    while turtle.detectUp() do
        turtle.digUp()
    end
end
local function unload()
    for n=1,16 do
        local nCount = turtle.getItemCount(n)
        if nCount > 0 then
            turtle.select(n)
            turtle.dropDown()
        end
    end
    turtle.select(1)
end


---- Main
print("Input start shaft number. Ignore to start at the first shaft.")
local shaftsMined = tonumber(read()) or 0
-- local shaftsMined = START_SHAFT

while true do

    -- Calculate fuel needed
    local fuelNeeded = (shaftsMined * (BLOCKS_BETWEEN+1) * 2) + (SHAFT_LENGTH * 4) + (2 * 6)
    --   (getting to the shaft) + (through the shaft) + (ups and downs)

    -- Refuel
    print("Refueling. Fuel needed: ", fuelNeeded)
    if turtle.getFuelLevel() < fuelNeeded then
        turtle.turnLeft()
        turtle.turnLeft()
        while turtle.getFuelLevel() < fuelNeeded do
            if not turtle.suck(1) then
                print("Not enough fuel detected! Stopping")
                turtle.turnRight()
                turtle.turnRight()
                return
            end
            turtle.refuel()
        end
        turtle.turnRight()
        turtle.turnRight()
    end

    -- Go to shaft
    print("Starting next shaft: ", shaftsMined)
    if shaftsMined > 0 then
        if GO_LEFT then turtle.turnLeft()
        else turtle.turnRight() end

        for n=1,(shaftsMined*(BLOCKS_BETWEEN+1)) do
            tryGoForward()
            tryDigUp()
        end

        if GO_LEFT then turtle.turnRight()
        else turtle.turnLeft() end
    end

    -- Dig shaft
    for n=1,2 do

        for n=1,SHAFT_LENGTH do
            tryGoForward()
            tryDigUp()
        end

        turtle.turnLeft()
        turtle.turnLeft()

        tryGoUp()
        tryGoUp()

        for n=1,SHAFT_LENGTH do
            tryDigUp()
            tryGoForward()
        end

        turtle.turnRight()
        turtle.turnRight()

        if n ~= 2 then
            tryGoUp()
            tryGoUp()
        end
    end

    for n=1,6 do
        tryGoDown()
    end

    -- Go to chests
    if shaftsMined > 0 then
        if GO_LEFT then turtle.turnRight()
        else turtle.turnLeft() end

        for n=1,(shaftsMined*(BLOCKS_BETWEEN+1)) do
            tryGoForward()
        end

        if GO_LEFT then turtle.turnLeft()
        else turtle.turnRight() end
    end

    -- Finish
    print("Finished. Unloading")
    unload()
    shaftsMined = shaftsMined + 1

    -- Repeat
end