Strip Mining Turtle Assistant

----------------------------------------------------------------------------------------------------------
--  04.22.2017 - Started scripting a basic Turtle AI to help out with strip mining.
--      This turtle is not really very smart; it will just mine in a straight line until it runs out of fuel,
--          A pathway 3 blocks tall, placing torches every 5 blocks along the ground (assuming there is valid ground to do so)
--              -- Note: If the turtle runs out of torches, it will also stop.
--
----------------------------------------------------------------------------------------------------------

----------------------------------------------------------------------------------------------------------
-- Settings
----------------------------------------------------------------------------------------------------------
local itemNameFuel = "minecraft:coal" -- The name of the fuel the turtle will be using (Can only accept 1 type of fuel.)
local itemNameTorch = "minecraft:torch" -- The name of the torches we are using.
local distanceBetweenTorches = 7 -- The number of squares between the torches.
local waitForTorchesOnPlaceTorch = true -- If we are set to place a torch right now, and we don't have torches, let's wait for the torch to be put in our inventory.


----------------------------------------------------------------------------------------------------------
--  Function Pointers / Documentation (Helper Functions)
----------------------------------------------------------------------------------------------------------

-- Returns the index of the item in the inventory by the name provided. Returns nil if it can't be found.
-- Note: If you are searching for a nil name, will return the first nil position.
local ScanForItemInInventoryByName

-- If the turtle is less than 90% fuel, will search for fuel in the turtle's inventory to refuel itself.
local HandleFuelLevel

-- If the turtle has a torch, place it. Sits and waits for torches to be added if it has no torches (so no mobs can spawn), if the setting is set to do so.
local PlaceTorch

-- StripMines; main function.
local StripMine

-- Infinite retries moving up.
local RobustUp

-- Infinitely retries moving down.
local RobustDown

-- Infinitely retries moving forward.
local RobustForward

----------------------------------------------------------------------------------------------------------
--  Function Definitions (Helper Functions)
----------------------------------------------------------------------------------------------------------

-- Returns the index of the item in the inventory by the name provided. Returns nil if it can't be found.
-- Note: If you are searching for a nil name, will return the first nil position.
ScanForItemInInventoryByName = function(name, caseInsensitive)
    for i = 1, 16, 1 do
        local item = turtle.getItemDetail(i)

        if item then
            local itemName = item.name

            if caseInsensitive then
                itemName = string.lower(itemName)
                name = string.lower(name)
            end

            if name and string.match(itemName, name) and (name ~= itemNameBoneMeal or (name == itemNameBoneMeal and item.damage == itemMetaDataBoneMeal)) then
                return i
            end
        end

        if item == nil and name == nil then
            return i
        end
    end

    return nil
end

-- If the turtle is less than 90% fuel, will search for fuel in the turtle's inventory to refuel itself.
HandleFuelLevel = function()
    if turtle.getFuelLevel() / turtle.getFuelLimit() < .9 then
        local archivedIndex = turtle.getSelectedSlot()
        local index = ScanForItemInInventoryByName(itemNameFuel)

        if index then
            print("Fuel is below 90%; Detected fuel in inventory. Refueling.")
            local currItem = turtle.getItemDetail(index)

            while turtle.getFuelLevel() < turtle.getFuelLimit() and currItem and currItem.name == itemNameFuel do
                turtle.select(index)
                turtle.refuel(1)
                currItem = turtle.getItemDetail(index)
            end

            print("Fuel: "..turtle.getFuelLevel().." / "..turtle.getFuelLimit().." ("..(100 * (turtle.getFuelLevel() / turtle.getFuelLimit())).."%)")
            turtle.select(archivedIndex)
        else
            if turtle.getFuelLevel() == 0 then
                print("\r\n\r\nALERT! We are out of fuel!!! Weird stuff may happen (We may even crash!) Please give me fuel (Coal or charcoal)\r\n\r\n")
            end
        end
    end
end

-- If the turtle has a torch, place it. Sits and waits for torches to be added if it has no torches (so no mobs can spawn), if the setting is set to do so.
PlaceTorch = function()
    local archivedIndex = turtle.getSelectedSlot()
    local torchIndex = ScanForItemInInventoryByName(itemNameTorch)
    local success = false

    if not torchIndex and waitForTorchesOnPlaceTorch then
        while not torchIndex do
            torchIndex = ScanForItemInInventoryByName(itemNameTorch)
            print("Waiting for item by name of "..itemNameTorch.." to be placed in inventory.")
            sleep(5)
        end
    elseif not torchIndex then
        return
    end

    if torchIndex then
        turtle.select(torchIndex)

        if turtle.placeDown() then
            print("Torch Placed!")
            success = true
        else
            print("Failed to place torch; is there air below?")
            success = false
        end
    end

    turtle.select(archivedIndex)
    return success
end

-- StripMines; main function.
StripMine = function()
    HandleFuelLevel()

    if turtle.getFuelLevel() == 0 then
        print("Terminating Early; turtle started up without fuel. Place fuel in turtle and run program again.")
        return
    end

    local placesMovedSinceLastTorch = distanceBetweenTorches
    while true do
        placesMovedSinceLastTorch = placesMovedSinceLastTorch + 1

        -- Dig up, place a torch if necesary.
        for i = 1, 3, 1 do
            if placesMovedSinceLastTorch >= distanceBetweenTorches and i == 2 then
                if (PlaceTorch()) then
                    placesMovedSinceLastTorch = 0
                end
            end

            turtle.dig()

            if turtle.inspectUp() then
                turtle.digUp()
            end

            RobustUp()
        end

        turtle.dig()
        RobustForward()

        for i = 1, 3, 1 do
            if turtle.inspectDown() then
                turtle.digDown()
            end

            RobustDown()
        end

        HandleFuelLevel()
    end
end

-- Infinite retries moving up.
RobustUp = function()
    local success = false

    while not success do
        success = turtle.up()
    end
end

-- Infinitely retries moving down.
RobustDown = function()
    local success = false

    while not success do
        success = turtle.down()
    end
end

-- Infinitely retries moving forward.
RobustForward = function()
    local success = false

    while not success do
        success = turtle.forward()
    end
end

----------------------------------------------------------------------------------------------------------
-- TESTING!!!
----------------------------------------------------------------------------------------------------------

--HandleFuelLevel()
--PlaceTorch()


----------------------------------------------------------------------------------------------------------
--      Main EntryPoint
----------------------------------------------------------------------------------------------------------
print("Executing StripMine")
StripMine()
print("StripMine Terminated.")