MiningTurtle = { 
	position = { 
		x = 0, 
		y = 0,
		z = 0
	},
	direction = 0
}

-- 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 )

	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
	end
	
	return false
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

-- forward
function MiningTurtle:forward()
	local ret
	
	ret = turtle.forward()
	
	if ret then
		
		
		if self.direction == 0 then
			
			self.position.x = self.position.x + 1
			
		elseif self.direction == 90 then
		
			self.position.y = self.position.y + 1
		
		elseif self.direction == 180 then
		
			self.position.x = self.position.x - 1
		
		elseif self.direction == 270 then
		
			self.position.y = self.position.y - 1
		
		end
		
	end
	
	return ret
end

-- back
function MiningTurtle:back()
	local ret
	
	ret = turtle.back()
	
	if ret then
		
		if self.direction == 0 then
			
			self.position.x = self.position.x - 1
			
		elseif self.direction == 90 then
		
			self.position.y = self.position.y - 1
		
		elseif self.direction == 180 then
		
			self.position.x = self.position.x + 1
		
		elseif self.direction == 270 then
		
			self.position.y = self.position.y + 1
		
		end
		
	end
	
	return ret
end

-- up
function MiningTurtle:up()
	local ret
	
	ret = turtle.up()
	
	if ret then
		self.position.z = self.position.z + 1
	end
	
	return ret
end

-- down
function MiningTurtle:down()
	local ret
	
	ret = turtle.down()
	
	if ret then
		self.position.z = self.position.z - 1
	end
	
	return ret
end

-- turn Left
function MiningTurtle:turnLeft()
	local ret
	
	ret = turtle.turnLeft()
	
	if ret then
		self.direction = self.direction + 90
		
		while self.direction >= 360 do
			self.direction = self.direction - 360
		end
	end
	
	return ret
end

-- turn Right
function MiningTurtle:turnRight()
	local ret
	
	ret = turtle.turnRight()
	
	if ret then
		self.direction = self.direction - 90
		
		while self.direction < 0 do
			self.direction = self.direction + 360
		end
	end
	
	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
     
-- Make a tunnel
function MiningTurtle:tunnel( length, height, width, ret )
	
	if height == nil then
		height 	= 2
	end
	
	if height == nil then
		height 	= 2
	end
	
	if ret == nil then
		ret 	= false
	end
	
	-- Length loop
	
	for i = 1,length do

		MiningTurtle:saveForward()
	
		if i % 2 == 0 then
			-- even
			
			MiningTurtle:turnLeft()
			
			for x = 0,width do
				
				for y = 0,height do
				
					if x % 2 == 0 then
						MiningTurtle:saveUp()						
					else					
						MiningTurtle:saveDown()					
					end
					
				end
				
				if x < width then
					MiningTurtle:saveForward()
				end
			end
			
			MiningTurtle:turnRight()
		
		else
			-- odd
			
			MiningTurtle:turnRight()
			
			for x = 0,width do
				
				for y = 0,height do
				
					if x % 2 == 0 then
						MiningTurtle:saveUp()						
					else					
						MiningTurtle:saveDown()					
					end
					
				end
				
				if x < width then
					MiningTurtle:saveForward()
				end
			end
			
			MiningTurtle:turnLeft()
		
		end
	
	end
	
	if ret then
		
		MiningTurtle:turn()
	end
	
end


-- 
function MiningTurtle:matrix( rows, cols )

	

end


-- main

while not MiningTurtle:requiredRefuel() do
	print("Waiting for MiningTurtle to have enough fuel")
end

MiningTurtle:toGround()
MiningTurtle:tunnel(10)