MiningTurtle = {
	position = {
		x = 0,
		y = 0,
		z = 0
	},
	direction = 0
	-- 0 = SOUTH -> Z++
	-- 1 = WEST -> X--
	-- 2 = NORTH -> Z--
	-- 3 = EAST -> X++
}

-- Constructor

function MiningTurtle:new()

	local object = { }

	setmetatable(object, { __index = MiningTurtle })
	return object
end

-- Check if the Turtle needs to be refueled ( <= refuelLevel )
-- if yes, try to refuel it taking the contents of the inventory
-- if this is not possible or not enough, go back to base
function MiningTurtle:requiredRefuel( refuelLevel, requiredFuelLevel )
	local slot

	if refuelLevel == nil then
		refuelLevel 		= 25
	end

	if requiredFuelLevel == nil then
		requiredFuelLevel 	= 500
	end

	-- should we refuel?
	if turtle.getFuelLevel() <= refuelLevel then

		-- iterate through our inventory
		for slot = 1,16 do

			-- select slot
			turtle.select(slot)

			-- refuel from active slot...
			if turtle.refuel( turtle.getItemCount( slot ) ) then

			end

			-- ...and check again
			if turtle.getFuelLevel() >= requiredFuelLevel then
				return true
			end

		end

		-- check if we did not refueled enough alreay
		if not (turtle.getFuelLevel() >= requiredFuelLevel) then
			-- if yes, go back to base

			MiningTurtle:toBase()
			-- refuel: to be implemented!!!!
		end

		return false
	end

	return true
end

-- Go back to the base of the MiningTurtle
function MiningTurtle:toBase( )

end

-- Go to ground
function MiningTurtle:toGround( )

	while not turtle.detectDown() do
		MiningTurtle:down()
	end

end

-- Go the our "base" Ground (z = 0)
function MiningTurtle:toBaseLevel( )

	while self.position.y > 0 do
		MiningTurtle:saveDown()
	end

end

-- forward
function MiningTurtle:forward()
	local ret

	ret = turtle.forward()

	if ret then


		if self.direction == 0 then
			-- 0 = SOUTH -> Z++
			self.position.z = self.position.z + 1

		elseif self.direction == 1 then
			-- 1 = WEST -> X--
			self.position.x = self.position.x - 1

		elseif self.direction == 2 then
			-- 2 = NORTH -> Z--
			self.position.z = self.position.z -  1

		elseif self.direction == 3 then
			-- 3 = EAST -> X++
			self.position.x = self.position.x + 1

		end

	end

	MiningTurtle:outPos()

	return ret
end

-- back
function MiningTurtle:back()
	local ret

	ret = turtle.back()

	if ret then

		-- all directions reverse!!! (moving back)

		if self.direction == 0 then
			-- 0 = SOUTH -> Z++
			self.position.z = self.position.z - 1

		elseif self.direction == 1 then
			-- 1 = WEST -> X--
			self.position.x = self.position.x + 1

		elseif self.direction == 2 then
			-- 2 = NORTH -> Z--
			self.position.z = self.position.z +  1

		elseif self.direction == 3 then
			-- 3 = EAST -> X++
			self.position.x = self.position.x - 1

		end

	end

	MiningTurtle:outPos()

	return ret
end

-- up
function MiningTurtle:up()
	local ret

	ret = turtle.up()

	if ret then
		self.position.y = self.position.y + 1
	end

	MiningTurtle:outPos()

	return ret
end

-- down
function MiningTurtle:down()
	local ret

	ret = turtle.down()

	if ret then
		self.position.y = self.position.y - 1
	end

	MiningTurtle:outPos()

	return ret
end

-- turn Left
function MiningTurtle:turnLeft()
	local ret

	ret = turtle.turnLeft()

	if ret then
		self.direction = self.direction + 1

		while self.direction >= 4 do
			self.direction = self.direction - 4
		end
	end

	MiningTurtle:outPos()

	return ret
end

-- turn Right
function MiningTurtle:turnRight()
	local ret

	ret = turtle.turnRight()

	if ret then
		self.direction = self.direction - 1

		while self.direction < 0 do
			self.direction = self.direction - 4
		end
	end

	MiningTurtle:outPos()

	return ret
end

-- Save forward
function MiningTurtle:saveForward()

	while not MiningTurtle:forward() do
		turtle.dig()
	end
end

-- Save up
function MiningTurtle:saveUp()

	while not MiningTurtle:up() do
		turtle.digUp()
	end
end

-- Save down
function MiningTurtle:saveDown()

	while not MiningTurtle:down() do
		turtle.digDown()
	end
end

-- 180 degree turn
function MiningTurtle:turn()

	MiningTurtle:turnRight()
	MiningTurtle:turnRight()
end

-- output pos data
function MiningTurtle:outPos()

	print("Pos: " .. tostring(self.position.x) .. "|" .. tostring(self.position.z) .. "|" .. tostring(self.position.y) .. " o: " .. tostring(self.direction) .. " f: " .. tostring(turtle.getFuelLevel()) )

end

-- Turn to direction
function MiningTurtle:turnTo( newOrientation )
	while self.direction ~= newOrientation do
		if math.abs(self.direction - newOrientation) < 180 then
			MiningTurtle:turnRight()
		else
			MiningTurtle:turnLeft()
		end
	end
end

-- Go to
function MiningTurtle:goTo( newPosition )
	print("GoTo: " .. newPosition.x .. "|" .. newPosition.z .. "|" .. newPosition.y)

	-- 0 = SOUTH -> Z++
	-- 1 = WEST -> X--
	-- 2 = NORTH -> Z--
	-- 3 = EAST -> X++

	while not ( (newPosition.x - self.position.x) == 0 and (newPosition.z - self.position.z) == 0 and (newPosition.y - self.position.y) == 0 ) do

		if (newPosition.x - self.position.x) < 0 then
			MiningTurtle:turnTo(1)
			MiningTurtle:saveForward()
		elseif (newPosition.x - self.position.x) > 0 then
			MiningTurtle:turnTo(3)
			MiningTurtle:saveForward()
		end

		if (newPosition.z - self.position.z) < 0 then
			MiningTurtle:turnTo(2)
			MiningTurtle:saveForward()
		elseif (newPosition.z - self.position.z) > 0 then
			MiningTurtle:turnTo(0)
			MiningTurtle:saveForward()
		end

		if (newPosition.y - self.position.y) < 0 then
			MiningTurtle:saveDown()
		elseif (newPosition.y - self.position.y) > 0 then
			MiningTurtle:saveUp()
		end

	end

end

-- Make a tunnel
function MiningTurtle:tunnel( length, height, width, ret )

	-- default values for parameters, only length is required (!)
	if height == nil then
		height 	= 2
	end

	if width == nil then
		width 	= 1
	end

	if ret == nil then
		ret 	= false
	end

	-- Save our current positon back for later return

	returnPos = {}
	returnPos.x = self.position.x
	returnPos.z = self.position.z
	returnPos.y = self.position.y
	returnDirection = self.direction

	-- Place the turtle at the lower left corner of the new tunnel (so that we were starting from the middle of the new tunnel)
	-- We only need this, if we have a tonnel with a width > 2 (<=2 means we are already on the right position)

	if width > 2 then

		MiningTurtle:turnLeft()

		for i = 0,math.floor( width / 2 ) do
			MiningTurtle:saveForward()
		end

		MiningTurtle:turnRight()
	end

	-- Length loop

	for i = 0,length-1 do

		MiningTurtle:saveForward()

		if i % 2 == 0 then
			-- even

			-- only change direction if we mine a tunnel wider than 1 block
			if width > 1 then
				MiningTurtle:turnRight()
			end

			for x = 0,width-1 do

				MiningTurtle:tick()

				for y = 0,height-3 do

					if x % 2 == 0 then
						MiningTurtle:saveUp()
					else
						MiningTurtle:saveDown()
					end

				end

				if height > 1 then
					turtle.digUp()
				end

				if x < width-1 then
					MiningTurtle:saveForward()
				end
			end

			-- same as above
			if width > 1 then
				MiningTurtle:turnLeft()
			end

		else
			-- odd

			if width > 1 then
				MiningTurtle:turnLeft()
			end

			for x = 0,width-1 do

				MiningTurtle:tick()

				for y = 0,height-3 do

					if x % 2 == 1 or width % 2 == 0 then
						MiningTurtle:saveUp()
					else
						MiningTurtle:saveDown()
					end

				end

				if height > 1 then
					turtle.digUp()
				end

				if x < width-1 then
					MiningTurtle:saveForward()
				end
			end

			if width > 1 then
				MiningTurtle:turnRight()
			end
		end

	end

	if ret then

		-- Go up to not remove torches on the floow
		MiningTurtle:saveUp()

		MiningTurtle:goTo( returnPos )

		MiningTurtle:turnTo( returnDirection )

	end

end

function MiningTurtle:tick()

	-- refuel loop
	while not MiningTurtle:requiredRefuel( 20, 50 ) do
		sleep(1)
	end
end

--
function MiningTurtle:matrix( rows, cols )

	MiningTurtle:tick()

	--MiningTurtle:toBaseLevel()


	MiningTurtle:tunnel(5, 2, 1, true)


end


-- main program

baby = MiningTurtle:new()

baby:matrix( 10, 10 )