Computercraft excavate that digs 2 levels at a time, working on a third

texcavate.lua

--[[
TExcavate by Tom J Nowell

A modified version of the excavate command, mines 3 layers of rock at a time, and keeps persistent variables

requires: http://www.computercraft.info/forums2/index.php?/topic/1195-132-yet-another-persistent-variables-api-uses-metatable/
]]--

os.loadAPI("apis/persistentVar")         -- Only use this line if you copied the API in your computers apis folder
local state = persistentVar:new( "/vars_texcavate/" )
local startup = persistentVar:new( "/vars_startup/" )

function reset_state_vars()
	state.depth = 0
	state.unloaded = 0
	state.collected = 0

	state.xPos =0
	state.zPos = 0
	state.xDir = 0
	state.zDir = 1
end

if state.running ~= true then

	local tArgs = { ... }
	if #tArgs ~= 1 then
	  print( "Usage: advexcavate <diameter>" )
		return
	end

	-- Mine in a quarry pattern until we hit something we can't dig
	state.size = tonumber( tArgs[1] )
	if state.size < 1 then
		print( "Excavate diameter must be positive" )
		return
	end
else
	state.running = true
	startup.program = "texcavate"
	reset_state_vars()
end


-- state.goTo -- Filled in further down
-- state.refuel -- Filled in further down

local function unload( _bKeepOneFuelStack )
	print( "Unloading items..." )
	local dropUp = false
	if turtle.detect() then
		dropUp = false
	else
		if turtle.detectUp() then
			dropUp = true
		end
	end
	for n=1,16 do
		local nCount = turtle.getItemCount(n)
		if nCount > 0 then
			turtle.select(n)
			local bDrop = true
			if _bKeepOneFuelStack and turtle.state.refuel(0) then
				bDrop = false
				_bKeepOneFuelStack = false
			end
			if bDrop then
				local result = false
				while result == false do
					if dropUp then
						result = turtle.dropUp()
					else
						result = turtle.drop()
					end
				end
				state.unloaded = state.unloaded + nCount
			end
		end
	end
	state.collected = 0
	turtle.select(1)
end

local function returnSupplies()
	local x,y,z,xd,zd = state.xPos,state.depth,state.zPos,state.xDir,state.zDir
	print( "Returning to surface..." )
	state.goTo( 0,0,0,0,-1 )

	local fuelNeeded = 2*(x+y+z) + 1
	if not state.refuel( fuelNeeded ) then
		unload( true )
		print( "Waiting for fuel" )
		while not state.refuel( fuelNeeded ) do
			sleep(1)
		end
	else
		unload( true )
	end

	print( "Resuming mining..." )
	state.goTo( x,y,z,xd,zd )
end

local function collect()
	local bFull = true
	local nTotalItems = 0
	for n=1,16 do
		local nCount = turtle.getItemCount(n)
		if nCount == 0 then
			bFull = false
		end
		nTotalItems = nTotalItems + nCount
	end

	if nTotalItems > state.collected then
		state.collected = nTotalItems
		if math.fmod(state.collected + state.unloaded, 50) == 0 then
			print( "Mined "..(state.collected + state.unloaded).." items." )
		end
	end

	if bFull then
		print( "No empty slots left." )
		return false
	end
	return true
end

function state.refuel( ammount )
	local fuelLevel = turtle.getFuelLevel()
	if fuelLevel == "unlimited" then
		return true
	end

	local needed = ammount or (state.xPos + state.zPos + state.depth + 1)
	if turtle.getFuelLevel() < needed then
		local fueled = false
		for n=1,16 do
			if turtle.getItemCount(n) > 0 then
				turtle.select(n)
				if turtle.state.refuel(1) then
					while turtle.getItemCount(n) > 0 and turtle.getFuelLevel() < needed do
						turtle.state.refuel(1)
					end
					if turtle.getFuelLevel() >= needed then
						turtle.select(1)
						return true
					end
				end
			end
		end
		turtle.select(1)
		return false
	end

	return true
end

local function tryForwards()
	if not state.refuel() then
		print( "Not enough Fuel" )
		returnSupplies()
	end

	if turtle.detectDown() then
		turtle.digDown()
	end

	if state.depth > 0 then
		if turtle.detectUp() then
			turtle.digUp()
		end
	end

	while not turtle.forward() do
		if turtle.detect() or turtle.detectDown() then
			local dug = false
			dug = turtle.dig()
			dugdown = turtle.digDown()
			dugup = turtle.digUp()
			dugboth = dug or dugdown or dugup
			if dugboth then
				if not collect() then
					returnSupplies()
				end
			else
				if not dug then
					return false
				end
			end
		elseif turtle.attack() then
			if not collect() then
				returnSupplies()
			end
		else
			sleep( 0.1 )
		end
	end

	state.xPos = state.xPos + state.xDir
	state.zPos = state.zPos + state.zDir
	return true
end

local function tryDown()
	if not state.refuel() then
		print( "Not enough Fuel" )
		returnSupplies()
	end
	if state.depth > 0 then
		if turtle.detectUp() then
			if turtle.digUp() then
				if not collect() then
					returnSupplies()
				end
			end
		end
	end

	while not turtle.down() do
		if turtle.detectDown() then
			if turtle.digDown() then
				if not collect() then
					returnSupplies()
				end
			else
				return false
			end
		elseif turtle.attackDown() then
			if not collect() then
				returnSupplies()
			end
		else
			sleep( 0.2 )
		end
	end

	state.depth = state.depth + 1
	if math.fmod( state.depth, 10 ) == 0 then
		print( "Descended "..state.depth.." metres." )
	end

	return true
end

local function turnLeft()
	turtle.turnLeft()
	state.xDir, state.zDir = -state.zDir, state.xDir
end

local function turnRight()
	turtle.turnRight()
	state.xDir, state.zDir = state.zDir, -state.xDir
end

function state.goTo( x, y, z, xd, zd )
	while state.depth > y do
		if turtle.up() then
			state.depth = state.depth - 1
		elseif turtle.digUp() or turtle.attackUp() then
			collect()
		else
			sleep( 0.5 )
		end
	end

	if state.xPos > x then
		while state.xDir ~= -1 do
			turnLeft()
		end
		while state.xPos > x do
			if turtle.forward() then
				state.xPos = state.xPos - 1
			elseif turtle.dig() or turtle.attack() then
				collect()
			else
				sleep( 0.5 )
			end
		end
	elseif state.xPos < x then
		while state.xDir ~= 1 do
			turnLeft()
		end
		while state.xPos < x do
			if turtle.forward() then
				state.xPos = state.xPos + 1
			elseif turtle.dig() or turtle.attack() then
				collect()
			else
				sleep( 0.5 )
			end
		end
	end

	if state.zPos > z then
		while state.zDir ~= -1 do
			turnLeft()
		end
		while state.zPos > z do
			if turtle.forward() then
				state.zPos = state.zPos - 1
			elseif turtle.dig() or turtle.attack() then
				collect()
			else
				sleep( 0.5 )
			end
		end
	elseif state.zPos < z then
		while state.zDir ~= 1 do
			turnLeft()
		end
		while state.zPos < z do
			if turtle.forward() then
				state.zPos = state.zPos + 1
			elseif turtle.dig() or turtle.attack() then
				collect()
			else
				sleep( 0.5 )
			end
		end
	end

	while state.depth < y do
		if turtle.down() then
			state.depth = state.depth + 1
		elseif turtle.digDown() or turtle.attackDown() then
			collect()
		else
			sleep( 0.5 )
		end
	end

	while state.zDir ~= zd or state.xDir ~= xd do
		turnLeft()
	end
end

if not state.refuel() then
	print( "Out of Fuel" )
	return
end

print( "Excavating..." )

local reseal = false
turtle.select(1)
if turtle.digDown() then
	reseal = true
end

local alternate = 0
local done = false
while not done do
	for n=1,state.size do
		for m=1,state.size-1 do
			if not tryForwards() then
				done = true
				break
			end
		end
		if done then
			break
		end
		if n<state.size then
			if math.fmod(n + alternate,2) == 0 then
				turnLeft()
				if not tryForwards() then
					done = true
					break
				end
				turnLeft()
			else
				turnRight()
				if not tryForwards() then
					done = true
					break
				end
				turnRight()
			end
		end
	end
	if done then
		break
	end

	if state.size > 1 then
		if math.fmod(state.size,2) == 0 then
			turnRight()
		else
			if alternate == 0 then
				turnLeft()
			else
				turnRight()
			end
			alternate = 1 - alternate
		end
	end

	for i=1, 3, 1 do
		if not tryDown() then
			done = true
			break
		end
	end
end

print( "Returning to surface..." )
-- Return to where we started
state.goTo( 0,0,0,0,-1 )
unload( false )
state.goTo( 0,0,0,0,1 )

-- Seal the hole
if reseal then
	turtle.placeDown()
end

print( "Mined "..(state.collected + state.unloaded).." items total." )

reset_state_vars()
state.running = false
startup.program = nil

note that revision 2 has issues stemming from the persistent variables API, need to research a new one, and consider a wrapper API for the various variables