from machine import Pin, Timer
import time

# -------- Settings --------
GREEN_TIME = 5000
YELLOW_TIME = 2000
RED_TIME = 5000
DEBOUNCE_MS = 200

# -------- Pins --------
green_led = Pin(25, Pin.OUT)
yellow_led = Pin(26, Pin.OUT)
red_led = Pin(27, Pin.OUT)

button = Pin(4, Pin.IN, Pin.PULL_UP)

# -------- State --------
last_press = 0
pedestrian_request = False

# traffic states
GREEN = 0
YELLOW = 1
RED = 2

current_state = GREEN

# timer
traffic_timer = Timer(0)

# -------- LED Control --------
def set_lights(state):
    green_led.off()
    yellow_led.off()
    red_led.off()

    if state == GREEN :
        green_led.on()
    
    elif state == YELLOW :
        yellow_led.on()
    
    elif state == RED :
        red_led.on()

# -------- Interrupt --------
def button_pressed(pin):
    global last_press , pedestrian_request

    now = time.ticks_ms()
    if time.ticks_diff(now, last_press) >= DEBOUNCE_MS :
        pedestrian_request = True
        print("pedestrain requested")
        last_press = now

# -------- Timer Callback --------
def change_traffic(timer):
    global current_state, pedestrian_request

    # Pedestrain request
    if pedestrian_request and current_state != RED:
        current_state = RED
        set_lights(RED)
        pedestrian_request = False
        print("pedestrain crossing")
        traffic_timer.init(
            period = RED_TIME,
            mode = Timer.ONE_SHOT,
            callback = change_traffic
        )
        return

    # normal case
    if current_state == GREEN:
        current_state = YELLOW
        set_lights(YELLOW)
        traffic_timer.init(
            period = YELLOW_TIME,
            mode = Timer.ONE_SHOT,
            callback = change_traffic
        )

    elif current_state == YELLOW:
        current_state = RED
        set_lights(RED)
        traffic_timer.init(
            period = RED_TIME,
            mode = Timer.ONE_SHOT,
            callback = change_traffic
        )

    elif current_state == RED:
        current_state = GREEN
        set_lights(GREEN)
        traffic_timer.init(
            period = GREEN_TIME,
            mode = Timer.ONE_SHOT,
            callback = change_traffic
        )


# attach interrupt
button.irq(trigger = Pin.IRQ_FALLING, handler = button_pressed)

# -------- Start System --------
print("Traffic Light System Started")
set_lights(GREEN)
traffic_timer.init(
    period = YELLOW_TIME,
        mode = Timer.ONE_SHOT,
        callback = change_traffic
    )

# -------- Main Loop --------
while True:

    # main loop stays free
    time.sleep_ms(10)