-- Turbine PID Controller
-- Tries to lock a turbine at a certain RPM

-- Configuration variables
target_rpm = 100
dt = 0.1
Gp = 10
Gi = 0
Gd = 0

-- State variables
previous_error = nil
error_sum = 0

while true do
	-- Get turbine RPM
	current_rpm = peripheral.call("back", "getRotorSpeed")

	-- Calculate RPM error
	current_error = target_rpm - current_rpm

	-- Add to error_sum
	error_sum = error_sum + (current_error * dt)

	-- Calculate proportional component
	proportional = Gp * current_error

	-- Calculate integral component
	integral = Gi * error_sum

	-- Calculate derivative component
	if previous_error ~= nil then
		derivative = Gd * (current_error - previous_error) / dt
	else
		derivative = 0
	end

	-- Set turbine flow rate
	flow_rate = proportional + integral + derivative
	peripheral.call("back", "setFluidFlowRateMax", flow_rate)

	-- Output controller info to left screen
	peripheral.call("left", "clear")
	peripheral.call("left", "setCursorPos", 1, 1)
	peripheral.call("left", "write", "tRPM: " .. math.floor(target_rpm))
	peripheral.call("left", "setCursorPos", 1, 2)
	peripheral.call("left", "write", "E: " .. current_error)
	peripheral.call("left", "setCursorPos", 1, 3)
	peripheral.call("left", "write", "P: " .. proportional)
	peripheral.call("left", "setCursorPos", 1, 4)
	peripheral.call("left", "write", "I: " .. integral)
	peripheral.call("left", "setCursorPos", 1, 5)
	peripheral.call("left", "write", "D: " .. derivative)
	peripheral.call("left", "setCursorPos", 1, 6)
	peripheral.call("left", "write", "tFR: " .. math.floor(flow_rate))

	-- Adjust flow rate for actual flow rate display
	if flow_rate >= 2000 then
		flow_rate = 2000
	elseif flow_rate <= 0 then
		flow_rate = 0
	end

	-- Output turbine info to left screen
	peripheral.call("left", "setCursorPos", 1, 7)
	peripheral.call("left", "write", "aRPM: " .. math.floor(current_rpm))
	peripheral.call("left", "setCursorPos", 1, 8)
	peripheral.call("left", "write", "aFR: " .. math.floor(flow_rate))

	-- Save state for next iteration
	previous_error = current_error

	-- Delay next iteration
	os.sleep(dt)
end