--(( Settings ))--

local fuelcap = 50

--(( Variables ))--

local depth = 0
local items = {}

--(( Functions ))--

local function claim(slot)
	items[slot] = true
end

-- side = "", "up", or "down"
local function isjunk(side)
	side = side or ""
	side = side:sub(1,1):upper() .. side:sub(2):lower()
	for slot,value in pairs(items) do
		turtle.select(slot)
		if turtle["compare"..side]() then
			return true
		end
	end
	return false
end

local function refuel()
	local fuel = turtle.getFuelLevel()
	while fuel < fuelcap do
		print("Searching for fuel..")
		for slot = 1,16 do
			if items[slot] ~= true then
				turtle.select(slot)
				if turtle.refuel(1) then return true end
			end
		end
		print("No fuel found. Press SPACE to search again!")
		local key
		repeat _,key=os.pullEvent("key")
		until key==keys.space
	end
end

local function dig(dir)
	dir = dir or ""
	dir = dir:sub(1,1):upper() .. dir:sub(2):lower()
	turtle.select(1)
	if not turtle["detect"..dir]() then return true end
	while not turtle["dig"..dir]() do
		if not turtle["attack"..dir]() then
			return false
		end
	end
	return true
end

local function down()
	refuel()
	while not turtle.down() do
		if dig("down") == false then
			return false
		end
	end
	return true
end

local function up()
	refuel()
	while not turtle.up() do
		if dig("up") == false then
			return false
		end
	end
	return true
end

local function checksides()
	local turns = {turtle.turnRight,turtle.turnLeft,}
	local turn = turns[math.random(1,#turns)]
	for count = 1,4 do
		if not isjunk() then
			dig()
		end
		turn()
	end
end

local function fill()
	-- first try junk items
	for slot,state in pairs(items) do
		if state == true then
			if turtle.getItemCount(slot) > 1 then
				turtle.select(slot)
				while not turtle.placeDown() do
					turtle.attackDown()
				end
				return
			end
		end
	end
	-- then use storage
	for slot = 1,16 do
		if items[slot] ~= true then
			if turtle.getItemCount(slot) > 0 then
				turtle.select(slot)
				if turtle.placeDown() then
					return
				end
			end
		end
	end
end

local function mine()
	local running = true
	while running do
		checksides()
		if not down() then
			print("Probably hit bedrock!")
			running = false
		else
			depth = depth + 1
		end
	end
	print("Heading back up...")
	for count = 1,depth do
		repeat until up()
	end
	fill()
end

claim(1)--stone
claim(2)--dirt
claim(3)--cobble/gravel
print("Commencing mining operation!")
mine()