Skybridge v1.0

-- ---------------------------------
-- Various Variables and Settings --
local currentSlot = 1
local materialReferenceSlot = 14
local anchorSlot = 15
local torchSlot = 16
local supplied = true
local rowCount = 0
local lampFreq = 6

-- --------------------
-- Utility Functions --

-- checkSupply ensures that there is material to build with on hand
local function checkSupply()
	turtle.select(currentSlot)
	-- If the current slot is empty
	if turtle.getItemCount(currentSlot) == 0 then
		-- bump up a slot
		currentSlot = currentSlot + 1

		-- make sure it is not past the reference slot
		if currentSlot == (anchorSlot + 1) then
			supplied = false
			currentSlot = currentSlot - 1
			return
		end

		-- still in the supplies section, so that is good
		turtle.select(currentSlot)

		-- make sure it has the right material
		if turtle.compareTo(materialReferenceSlot) then
			supplied = true
		else
			supplied = false
		end
	-- if the current slot is NOT empty
	else
		-- make sure that the current slot still has the right material in it
		if turtle.compareTo(materialReferenceSlot) then
			supplied = true
		else
			supplied = false
		end
	end
end

--
local function forwardDig(mode)
	if turtle.detect() then
		turtle.dig()
	end
	if mode == "place" then
		checkSupply()
		turtle.place()
	elseif mode == "move" then
		turtle.forward()
	else
		-- do nothing
	end
end

local function downDig(mode)
	if turtle.detectDown() then
		turtle.digDown()
	end
	if mode == "place" then
		checkSupply()
		turtle.placeDown()
	elseif mode == "move" then
		turtle.down()
	else
		-- do nothing
	end
end

local function upDig(mode)
	if turtle.detectUp() then
		turtle.digUp()
	end
	if mode == "place" then
		checkSupply()
		turtle.placeUp()
	elseif mode == "move" then
		turtle.up()
	else
		-- do nothing
	end
end

local function turnAround()
	-- It is not an ambiturn.
	turtle.turnRight()
	turtle.turnRight()
end

local function placeTorch(whichWay)
	turtle.select(torchSlot)
	if whichWay == "forward" then
		turtle.place()
	elseif whichWay == "up" then
		turtle.placeUp()
	end
	turtle.select(currentSlot)
end

local function placeAnchor()
	turtle.select(anchorSlot)
	turtle.place()
	turtle.select(currentSlot)
end

-- -----------------
-- Main Functions --

-- ensures the things needed (fuel, material, torches, world anchors) are on hand
local function checkStarting()
	local ReadyToGo = true
	local ErrorList = {}

	-- Check that the 14th slot has a material for reference
	if turtle.getItemCount(materialReferenceSlot) == 0 then
		ReadyToGo = false
		table.insert(ErrorList,"Reference Material missing in slot 14.")
	end

	-- Slots 1 throuth 13 need to be at least 64 of the material in slot 14
	for i = 1, 13 do
		turtle.select(i)
		if turtle.getItemCount(i) == 0 then
			ReadyToGo = false
			table.insert(ErrorList,"Missing material in slot "..tostring(i))
		else
			if not turtle.compareTo(14) then
				ReadyToGo = false
				table.insert(ErrorList,"Wrong material in slot "..tostring(i))
			end
		end
	end

	-- Slot 15 needs to be at least 12 world anchor type objects
	if turtle.getItemCount(anchorSlot) == 0 then
		ReadyToGo = false
		table.insert(ErrorList,"Anchor type object missing in slot 15.")
	end

	-- Slot 16 needs to be at least 60 torch type objects
	if turtle.getItemCount(torchSlot) <= 59 then
		ReadyToGo = false
		table.insert(ErrorList,"Insufficient torch objects missing in slot 16, should be 60-64.")
	end

	-- Based on my calculations, with the above payload, it will go about 180 meters/blocks.
	-- That will take about 1,290 fuel with the movements planned
	if turtle.getFuelLevel() < 1290 then
		ReadyToGo = false
		table.insert(ErrorList,"Turtle should have at least 1,290 fuel (17 coal/charcoal).  Please refuel.")
	end

	if not ReadyToGo then
		print("Cannot start building.  Issues:")
		for i=1,#ErrorList do
			print("  -"..tostring(ErrorList[i]))
		end
	else
		print("Supplies/fuel appear to be ready.")
		print("Starting...")
	end
	supplied = ReadyToGo
	return ReadyToGo
end

-- Create normal segment pair
local function createNormal()
	-- First section
	forwardDig("move")
	turtle.turnRight()
	downDig("place")
	forwardDig("place")
	upDig("move")
	upDig("")
	turnAround()
	forwardDig("move")
	downDig("move")
	downDig("place")
	forwardDig("place")
	turtle.turnRight()
	forwardDig("move")
	-- Second section
	turtle.turnLeft()
	downDig("place")
	forwardDig("place")
	upDig("move")
	upDig("")
	turnAround()
	forwardDig("move")
	downDig("move")
	downDig("place")
	forwardDig("place")
	turtle.turnLeft()
end

-- Create arch/light pair
local function createArch()
	-- First section, same as normal
	forwardDig("move")
	turtle.turnRight()
	downDig("place")
	forwardDig("place")
	upDig("move")
	upDig("")
	turnAround()
	forwardDig("move")
	downDig("move")
	downDig("place")
	forwardDig("place")
	turtle.turnRight()
	forwardDig("move")
	-- Second section, quite different, is an arch with torches
	turtle.turnLeft()
	downDig("place")
	forwardDig("place")
	upDig("move")
	forwardDig("place")
	upDig("move")
	forwardDig("place")
	upDig("place")
	turnAround()
	forwardDig("move")
	turnAround()
	placeTorch("forward")
	turnAround()
	upDig("place")
	forwardDig("place")
	downDig("move")
	placeTorch("up")
	forwardDig("place")
	downDig("move")
	forwardDig("place")
	downDig("place")
	turtle.turnLeft()
end

-- Place/collect World Anchors to not overload system, but keep going sans player
local function rollingAnchor()
	turtle.back()
	turtle.back()
	placeAnchor()
	turnAround()
	for i = 1,16 do
		turtle.forward()
	end
	turtle.dig()  -- nix the old world anchor
	turtle.suck() -- try to pick it back up
	turnAround()
	for i = 1,16 do
		turtle.forward()
	end
	-- Move over the new WA back to 'current position'
	turtle.up()
	turtle.forward()
	turtle.forward()
	turtle.down()
end

-- --------
-- Main --

if checkStarting() then
	-- setup a first anchor
	turnAround()
	placeAnchor()
	turnAround()

	while supplied do
		for i = 1,3 do
			createNormal()
			createNormal()
			createArch()
		end
		rollingAnchor()
	end
end