--(( Settings ))--

local fuelcap = 120
local shaftoffset = 5

local junk = {
	"minecraft:stone",
	"minecraft:cobblestone",
	"minecraft:dirt",
	"minecraft:grass",
	"minecraft:gravel",
	--"minecraft:sand",
	"chisel:marble1",
	"chisel:marble2",
	"chisel:limestone1",
	"chisel:limestone2",
	"chisel:basalt1",
	"chisel:basalt2",
}

local fuel = {
	"minecraft:coal",
	"minecraft:charcoal",
	"minecraft:planks",
	"minecraft:wood",
}

--(( Variables ))--

local depth = 0

--(( Functions ))--



local function selectfromlist(list)
	for slot=1,16 do
		local data = turtle.getItemDetail(slot)

		if data then
			for _,block in ipairs(list) do
				if block == data.name then
					turtle.select(slot)
					return true
				end
			end
		end
	end
	return false
end

local function selectfuel()
	return selectfromlist(fuel)
end

local function selectjunk()
	return selectfromlist(junk)
end

-- side = "", "up", or "down"
local function isvaluable()
	local succ,data = turtle.inspect()

	if not succ then
		return false
	end

	for _,block in ipairs(junk) do
		if data.name == block then
			return false
		end
	end

	return true
end

local function refuel()
	local fuel = turtle.getFuelLevel()
	while fuel < fuelcap do
		print("Searching for fuel...")
		if selectfuel() and turtle.refuel(1) then
			return true
		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)
	if not dir or dir == "forward" then
		dir = ""
	end
	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 move(dir)
	refuel()
	while not turtle[dir]() do
		if dig(dir) == false then
			return false
		end
	end
	return true
end

local function down()
	if move("down") then
		depth = depth + 1
		return true
	end
	return false
end

local function up()
	if move("up") then
		depth = depth - 1
		return true
	end
	return false
end

local function forward()
	return move("forward")
end

local function checksides()
	local turns = {turtle.turnRight,turtle.turnLeft}
	local turn = turns[math.random(1,#turns)]
	for count = 1,4 do
		if isvaluable() then
			dig()
		end
		turn()
	end
end

local function mine()
	-- go down little first
	repeat until down()
	repeat until down()
	if selectjunk() then
		turtle.placeUp()
	end

	-- down to bottom
	while true do
		checksides()
		if not down() then
			print("Bedrock after " .. depth .. " blocks!")
			break
		end
	end

	-- up to miss bedrock noise
	for i=1,5 do
		repeat until up()
	end

	-- move to next shaft
	for i=1,shaftoffset do
		repeat until forward()
	end

	-- up to surface
	while depth > 0 do
		checksides()
		repeat until up()
	end

	-- fill hole
	if selectjunk() then
		turtle.placeDown()
	end
end

local function formatTime(sec)
	if sec > 60 then
		return math.floor(sec/60).." min "..math.floor(sec%60).." sec"
	end
	return math.floor(sec) .. " sec"
end

print("Commencing mining operation!")
local start = os.clock()

mine()

local took = os.clock() - start
print("Operation complete! Took " .. formatTime(took))