--  ____ ____ _  _ ____ _  _ ____ ____ ____ ____
--  [__  |___ |  | |___ |\ | [__  |___ |__| [__   ____ ____ ____ ___    ____ __ _ ___    ____ ____
--  ___] |___  \/  |___ | \| ___] |___ |  | ___]  |___ [__] |--< |--'   |--| | \| |__>   |___ [__]
--
--
-- NOTES :
-- This program must achieve the following.
-- 1) Maintain the ability to dig a straight tunnel without fail.
-- 2) Lighting the tunnel in order on maintain a safe work environment.
-- 3) Return to a drop off point when the turtle detects a full load.
--

-- VARIABLES --
interval = 100 -- User input.
loop = 0
turtleDetect = turtle.detect()
turtleDirection = 1 -- 1 is forward; 0 is left; 2 is right.
turtlePosition = 0 -- 0 is defined as lower position whereas 1 is defined as the higher position.

-- FUNCTIONS --
function checkInventory(x)
		turtle.select(16)
		if (turtle.getItemCount() > 0) then
			if (turtleDirection == 0) then
				turtle.turnLeft()
			elseif (turtleDirection == 1) then
				turtle.turnLeft()
				turtle.turnLeft()
			elseif (turtleDirection == 2) then
				turtle.turnRight()
			end
			for i=0,x do
				turtle.forward()
			end
			turtle.turnLeft()
			turtle.turnLeft()
			exit()
		else
			turtle.select(1)
		end
end

function turtleDig(x)
		turtle.dig()
		checkInventory(x)
		sleep(.15)
		if (turtleDetect == true) then
			turtle.dig()
		end
end

function turtleDigRow(x)
		turtle.turnRight()
		turtleDirection = 2
		turtleDig(x)
		turtle.turnLeft()
		turtleDirection = 1
		turtleDig(x)
		turtle.turnLeft()
		turtleDirection = 0
		turtleDig(x)
		turtle.turnRight()
		turtleDirection = 1
end

function turtleDigFunction(x)
	if (turtlePosition == 0) then
		turtleDigRow(x)
		turtle.digUp()
		turtle.up()
		turtlePosition = 1
	elseif (turtlePosition == 1) then
		turtleDigRow(x)
		turtle.digUp()
		turtle.up()
		turtlePosition = 2
	elseif (turtlePosition == 2) then
		turtleDigRow(x)
		turtle.forward()
		turtle.digDown()
		turtle.down()
		turtle.digDown()
		turtle.down()
		turtlePosition = 0
	end
end

-- // MAIN SCRIPT //
while (loop < interval) do
	turtleDigFunction(loop)
	loop = loop + 1
end
turtle.turnRight()
turtle.turnRight()
for i=0, interval do
	turtle.forward()
	turtle.turnRight()
	turtle.turnRight()
end