[ComputerCraft] Efficient Excavate

--Programmed by Nick Mead(NickM13)

dimension = {}
coordinate = {}
rotation = 0
back = false
blocksMined = 0
minimumFuel = 40
finish = false
name = nil

term.clear()
term.setCursorPos(1, 1)
print("Enter dimensions you would like in the form x z y, eg: 5 5 2")
print("")
print("Height of the area is multiplied by 3 for efficiency")
print("")
print("Entering only x and z will assume you want to dig to the bottom of the map.")
print("")
io.write("Size: ")
input = io.read()

args = {}
i=0
for s in input:gmatch("%S+") do
	i=i+1
	args[i] = s
end

local function setup()
	dimension.x = tonumber(args[1])
	dimension.z = tonumber(args[2])
	if #args == 3 then
		dimension.y = tonumber(args[3])
	else
		dimension.y = 256
	end
	term.clear()
	term.setCursorPos(1, 1)
	print("Width(Right): "..dimension.x.."\nLength(Forward): "..dimension.z.."\nDepth(Down): "..dimension.y * 3)
	coordinate.x = 0
	coordinate.y = 0
	coordinate.z = 0
	print("\nAll fuel will be input at start")
	print("Press the any key to begin")
	os.pullEvent("key")
	if turtle.getItemCount(2) ~= 0 then
		turtle.select(2)
		if turtle.refuel() then
			print("Fuel found")
		else
			print("No fuel found")
		end
	end
	print("Starting fuel: "..turtle.getFuelLevel().." units")
	turtle.select(1)
end

local function deposit()
	slot = 0
	for i=1, 16 do
		name = turtle.getItemDetail(i)
		if name ~= nil and name.name == "minecraft:chest" then
			slot = i
			break
		end
	end
	if slot == 0 then return false end
	turtle.select(slot)
	if not turtle.placeUp() then
		if not turtle.placeDown() then
			print("no place for chest")
			return false
		else chestdir = "down" end
	else chestdir = "up" end
	for i=1, 16 do
		name = turtle.getItemDetail(i)
		if name ~= nil and name.name ~= "minecraft:chest" then
			turtle.select(i)
			if chestdir == "up" then turtle.dropUp()
			else turtle.dropDown() end
		end
	end
	return true
end

local function dig(dir)
	local buffer = 5
	if dir == "up" then
		os.sleep(0.5)
		while turtle.detectUp() do
			if not turtle.digUp() then buffer = buffer - 1 if buffer <= 0 then return false end else
				buffer = 5
				blocksMined = blocksMined + 1
			end
			os.sleep(0.5)
		end
	elseif dir == "front" or dir == "forward" then
		while turtle.detect() do
			if not turtle.dig() then buffer = buffer - 1 if buffer <= 0 then return false end else
				buffer = 5
			end
			blocksMined = blocksMined + 1
			os.sleep(0.1)
		end
	elseif dir == "down" then
		while turtle.detectDown() do
			if not turtle.digDown() then buffer = buffer - 1 if buffer <= 0 then return false end else
				buffer = 5
			end
			blocksMined = blocksMined + 1
		end
	else
		error("dig error")
	end
	return true
end

local function refuel()
	for i=1, 16 do
		name = turtle.getItemDetail(i)
		if name ~= nil and name.name == "minecraft:coal" then
			turtle.select(i)
			turtle.refuel(1)
			return true
		end
	end
	return false
end

local function move(dir)
	local moved = false
	if turtle.getFuelLevel() < minimumFuel then
		print("Low fuel: "..turtle.getFuelLevel())
		refuel()
	end
	while turtle.getFuelLevel() == 0 do
		print("Out of fuel")
		repeat until (refuel())
	end
	turtle.select(1)
	if dir == "forward" then
		while not moved do
			if turtle.forward() then
				moved = true
				if rotation == 0 then
					coordinate.x = coordinate.x + 1
				elseif rotation == 1 then
					coordinate.z = coordinate.z + 1
				elseif rotation == 2 then
					coordinate.x = coordinate.x - 1
				elseif rotation == 3 then
					coordinate.z = coordinate.z - 1
				else
					error("rotation error in move function")
				end
			end
			if not moved then
				if turtle.detect() then if not dig"front" then finish = true return end end
			end
		end
	elseif dir == "up" then
		while not moved do
			if turtle.up() then
				moved = true
				coordinate.y = coordinate.y + 1
			end
			if not moved then
				if turtle.detectUp() then if not dig"up" then finish = true return end end
			end
		end
	elseif dir == "down" then
		while not moved do
			if turtle.down() then
				moved = true
				coordinate.y = coordinate.y - 1
			end
			if not moved then
				if turtle.detectDown() then if not dig"down" then finish = true return end end
			end
		end
	else
		error("move error")
	end
	return moved
end

local function turn(dir)
	if dir == "right" then
		turtle.turnRight()
		rotation = rotation + 1
	elseif dir == "left" then
		turtle.turnLeft()
		rotation = rotation - 1
	else
		error("turn error")
	end
	rotation = rotation%4
end

local function chunk()
	if turtle.getSelectedSlot() ~= 1 then
		turtle.select(1)
	end
	if (not dig"front" and turtle.detect()) then finish = true return end
	move"forward"
	if (not dig"down" and turtle.detectDown()) then finish = true return end
	if (not dig"up" and turtle.detectUp()) then finish = true return end
	if turtle.getItemCount(16) ~= 0 then
		deposit()
	end
end

local function recall()
	local c = 1
	while (c < 4 and coordinate.y < 0) do
		move"up"
		c = c + 1
	end
	while rotation ~= 2 do turn"right" end
	while coordinate.x > 0 do
		move"forward"
	end
	while rotation ~= 3 do turn"right" end
	while coordinate.z > 0 do
		move"forward"
	end
	while rotation ~= 0 do turn"right" end
	while coordinate.y < 0 do
		move"up"
	end
end

setup()

dig"up"
dig"down"

for y=1, dimension.y do
	for z=1, dimension.z, 1 do
		for x=1, dimension.x-1, 1 do
			chunk()
			if finish then break end
		end
		if finish then break end
		if z == dimension.z then break end
		if back then
			turn"left"
			chunk()
			turn"left"
		else
			turn"right"
			chunk()
			turn"right"
		end
		back = not back
	end
	if finish then break end
	if y < dimension.y then
		for j=1, 3, 1 do
			dig"down"
			move"down"
		end
		dig"down"
		turn"right"
		turn"right"
	end
end

deposit()

recall()