from machine import Pin, SoftI2C, time_pulse_us
import ssd1306
import time

# Constants
SPACE_EMPTY_THRESHOLD_CM = 50  # Distance threshold to consider space empty
PARKING_SPACES = 3             # Number of parking spaces to monitor
UPDATE_INTERVAL = 1            # Update interval in seconds

# OLED Display Setup
i2c = SoftI2C(scl=Pin(22), sda=Pin(21))
oled = ssd1306.SSD1306_I2C(128, 64, i2c)

# Parking Sensor Setup
# Format: (trigger_pin, echo_pin)
parking_sensors = [
    (Pin(15, Pin.OUT), Pin(2, Pin.IN)),   # Space 1
    (Pin(4, Pin.OUT), Pin(16, Pin.IN)),   # Space 2
    (Pin(17, Pin.OUT), Pin(5, Pin.IN))    # Space 3
]

# Variables to track parking status
space_status = [False] * PARKING_SPACES  # False = empty, True = occupied
available_spaces = PARKING_SPACES

def measure_distance(trigger, echo):
    """Measure distance using ultrasonic sensor"""
    # Send pulse
    trigger.off()
    time.sleep_us(2)
    trigger.on()
    time.sleep_us(10)
    trigger.off()
    
    # Measure echo pulse duration
    duration = time_pulse_us(echo, 1, 30000)  # Timeout for 30ms (~5m)
    
    # Calculate distance in cm (speed of sound 343m/s = 0.0343cm/µs)
    distance = duration * 0.0343 / 2
    
    return distance if duration > 0 else float('inf')

def update_display():
    """Update the OLED display with current parking status"""
    oled.fill(0)
    
    # Title
    oled.text("Smart Parking", 0, 0)
    oled.text("Assistant", 0, 10)
    
    # Available spaces
    oled.text(f"Available: {available_spaces}/{PARKING_SPACES}", 0, 25)
    
    # Individual space status
    for i in range(PARKING_SPACES):
        status = "OCCUPIED" if space_status[i] else "EMPTY"
        oled.text(f"Space {i+1}: {status}", 0, 35 + i * 10)
    
    # Footer with instructions
    if available_spaces == 0:
        oled.text("FULL - Try Later", 0, 55)
    else:
        oled.text("Spaces Available!", 0, 55)
    
    oled.show()

def check_parking_spaces():
    """Check all parking spaces and update status"""
    global available_spaces
    available_spaces = 0
    
    for i in range(PARKING_SPACES):
        trigger, echo = parking_sensors[i]
        distance = measure_distance(trigger, echo)
        
        # Update space status
        space_status[i] = distance < SPACE_EMPTY_THRESHOLD_CM
        
        # Count available spaces
        if not space_status[i]:
            available_spaces += 1

def main():
    """Main program loop"""
    # Initial display update
    update_display()
    
    while True:
        # Check parking spaces
        check_parking_spaces()
        
        # Update display
        update_display()
        
        # Wait before next update
        time.sleep(UPDATE_INTERVAL)

if __name__ == "__main__":
    main()