-- Digs a 3x3 hole to a user specified depth. 99% guarenteed to not lose anything.
-- requirements: 2 identical storage devices (chests, enderchests, diamond chests, ect), fuel, mining turtle.

local downs = 0
local ups = 1
local refuelcounts = 0

function threesquare() --mine a 3x3 square directly around the turtle
	turtle.turnLeft()
	turtle.dig()
	turtle.forward()
	turtle.turnRight()
	turtle.dig()
	turtle.forward()
	turtle.turnRight()
	turtle.dig()
	turtle.forward()
	turtle.dig()
	turtle.forward()
	turtle.turnRight()
	turtle.dig()
	turtle.forward()
	turtle.dig()
	turtle.forward()
	turtle.turnRight()
	turtle.dig()
	turtle.forward()
	turtle.dig()
	turtle.forward()
	turtle.turnRight()
	turtle.forward()
	turtle.turnRight()
	turtle.forward()
	turtle.turnLeft()
	depth()
end

function refueltry (n) -- how many times have we tried to refuel
      n = n or 1
      refuelcounts = refuelcounts + n
    end

function refuel()
	while turtle.getFuelLevel() < 130 do --130 fuel allows to dig to bedrock from approximatley z=119.
		turtle.select(15) -- keep fuel of some kind in this slot
		turtle.refuel(1)
		turtle.select(1)
		refueltry() --keep track of how many times we've tried to refuel
		if refuelcounts > 30 then --The weakest fuel, sticks, has 5 fuel value. Filling from 0 to 130 is 26 sticks, if the counter reaches 30 it means we have no fuel.
			error("You must provide aditional fuel\n")
			break
		end

	end
end

function dropall() --drop all the shit we just collected
	turtle.select(1)
	turtle.drop()
	turtle.select(2)
	turtle.drop()
	turtle.select(3)
	turtle.drop()
	turtle.select(4)
	turtle.drop()
	turtle.select(5)
	turtle.drop()
	turtle.select(6)
	turtle.drop()
	turtle.select(7)
	turtle.drop()
	turtle.select(8)
	turtle.drop()
	turtle.select(9)
	turtle.drop()
	turtle.select(10)
	turtle.drop()
	turtle.select(11)
	turtle.drop()
	turtle.select(12)
	turtle.drop()
	turtle.select(13)
	turtle.drop()
	turtle.select(14)
	turtle.drop()
	turtle.select(1)
end

function depth (n) -- how deep has the turtle gone
      n = n or 1
      downs = downs + n
    end
function dive()
	for d=1,ups do
	turtle.digDown()
	turtle.down()
	end
	threesquare()
end
function surface() --however deep we went now we gotta go back up the same number of times
	for i=1,downs do
		turtle.up()
	end
	deeper()
end
function deeper (n)
      n = n or 1
      ups = ups + n
end
write("How Deep? ")
local howdeep = io.read()
for q=1,howdeep do
	refuel() -- if we don't refuel here the turtle will start diving where it's placed and then go haywire when told to go "back" where the chest is supposed to be
	refuelcounts = 0 -- set the refuel atempt counter back to 0 so it doesn't eff up subsequent refuelings.
	turtle.forward()
	turtle.forward()
	refuel()
	refuelcounts = 0
	dive() -- handles counting how far down we need to go/have gone, calls the 3x3 digging function.
	refuel()
	refuelcounts = 0
	surface()
	turtle.back()
	turtle.back()
	turtle.turnRight() --place some kind of storage (chest, enderchest, diamond chest, whatever) on the right side of the turtle where it starts.
	turtle.select(16) -- place the same kind of storage in slot 16
local chestfound = turtle.compare() -- make sure we're at a chest so we don't dump stuff in lava or whatever, just in case we got off course.
	if chestfound == true then
		dropall()
	else
		error("missing deposit chest\n") -- 99% of the time this means you forgot to put a chest to the right of the turtle. 1% of the time there's actually an issue
		break
	end
	turtle.turnLeft()
end