local function sign(v)
	return v > 0 and 1 or (v == 0 and 0 or -1)
end

do -- Robot state
	local turtleState = {
		position = {x = 85, y = 66, z = 165},
		orientation = {x = 0, z = -1},
	}

	local _turtleForward = turtle.forward
	turtle.forward = function()
		turtleState.position.x = turtleState.position.x + turtleState.orientation.x
		turtleState.position.z = turtleState.position.z + turtleState.orientation.z

		return _turtleForward()
	end

	local _turtleBack = turtle.back
	turtle.back = function(...)
		turtleState.position.x = turtleState.position.x - turtleState.orientation.x
		turtleState.position.z = turtleState.position.z - turtleState.orientation.z

		return _turtleBack(...)
	end

	local _turtleUp = turtle.up
	turtle.up = function(...)
		turtleState.position.y = turtleState.position.y + 1

		return _turtleUp(...)
	end

	local _turtleDown = turtle.down
	turtle.down = function(...)
		turtleState.position.y = turtleState.position.y - 1

		return _turtleDown(...)
	end

	local _turtleTurnLeft = turtle.turnLeft
	turtle.turnLeft = function(...)
		local oldOrientationX = turtleState.orientation.x
		local oldOrientationZ = turtleState.orientation.z

		turtleState.orientation.x =  oldOrientationZ
		turtleState.orientation.z = -oldOrientationX

		return _turtleTurnLeft(...)
	end

	local _turtleTurnRight = turtle.turnRight
	turtle.turnRight = function(...)
		local oldOrientationX = turtleState.orientation.x
		local oldOrientationZ = turtleState.orientation.z

		turtleState.orientation.x = -oldOrientationZ
		turtleState.orientation.z =  oldOrientationX

		return _turtleTurnRight(...)
	end

	turtle.getPosition = function()
		return turtleState.position.x, turtleState.position.y, turtleState.position.z
	end

	turtle.getOrientation = function()
		return turtleState.orientation.x, turtleState.orientation.z
	end

	turtle.orientX = function(targetX)
		if (turtleState.orientation.x == targetX) then
			return
		end

		if (turtleState.orientation.x == -targetX) then
			turtle.turnLeft()
			turtle.turnLeft()

			return
		end

		if (turtleState.orientation.z == targetX) then
			turtle.turnLeft()

			return
		end

		if (turtleState.orientation.z == -targetX) then
			turtle.turnRight()

			return
		end
	end

	turtle.orientZ = function(targetZ)
		if (turtleState.orientation.z == targetZ) then
			return
		end

		if (turtleState.orientation.z == -targetZ) then
			turtle.turnLeft()
			turtle.turnLeft()

			return
		end

		if (turtleState.orientation.x == targetZ) then
			turtle.turnRight()

			return
		end

		if (turtleState.orientation.x == -targetZ) then
			turtle.turnLeft()

			return
		end
	end

	turtle.gotoX = function(targetX)
		local dx = targetX - turtleState.position.x

		if (dx == 0) then
			return
		end

		turtle.orientX(sign(dx))

		for i = 1, math.abs(dx) do
			turtle.forward()
		end
	end

	turtle.gotoZ = function(targetZ)
		local dz = targetZ - turtleState.position.z

		if (dz == 0) then
			return
		end

		turtle.orientZ(sign(dz))

		for i = 1, math.abs(dz) do
			turtle.forward()
		end
	end
end

local function tryChop()
	if (turtle.detect()) then
		turtle.dig()
		turtle.forward()

		while (turtle.detectUp()) do
			turtle.digUp()
			turtle.up()
		end

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

		turtle.digDown()
	end
end

local function harvest()
	turtle.forward()
	turtle.up()

	turtle.gotoZ(160)

	turtle.gotoX(73)

	for i = 0, 5 do
		turtle.gotoZ(156 - i * 4)
	end
end

harvest()

local x, y, z = turtle.getPosition()
print(x, y, z)

local ox, oz = turtle.getOrientation()
print(ox, oz)