"""

Virtual Sensor API Module

This module simulates a plant monitoring sensor.

"""

import random

import time

# Global state to track connections

_connected_sensors = set()

def connect(sensor_id: str) -> bool:

"""

Connect to a sensor with given ID.

Returns True if successful, False otherwise.

"""

if sensor_id in _connected_sensors:

print(f"Sensor {sensor_id} is already connected!")

return False

_connected_sensors.add(sensor_id)

print(f"Sensor {sensor_id} connected successfully.")

return True

def disconnect(sensor_id: str) -> bool:

"""

Disconnect a sensor with given ID.

Returns True if successful, False otherwise.

"""

if sensor_id not in _connected_sensors:

print(f"Sensor {sensor_id} is not connected!")

return False

_connected_sensors.remove(sensor_id)

print(f"Sensor {sensor_id} disconnected.")

return True

def send_message(message: str) -> str | None:

"""

Send a message to the sensor and get a reading.

Message format: "SENSOR_ID:COMMAND"

Commands: SOIL_HUMIDITY, AIR_HUMIDITY, TEMPERATURE

Returns the reading value or None if error.

"""

try:

sensor_id, command = message.split(":")

if sensor_id not in _connected_sensors:

print(f"Error: Sensor {sensor_id} is not connected!")

return None

# Simulate sensor readings

if command == "SOIL_HUMIDITY":

return str(round(random.uniform(20, 80), 1)) # percentage

elif command == "AIR_HUMIDITY":

return str(round(random.uniform(30, 70), 1)) # percentage

elif command == "TEMPERATURE":

return str(round(random.uniform(15, 30), 1)) # Celsius

else:

print(f"Unknown command: {command}")

return None

except ValueError:

print("Invalid message format! Use 'SENSOR_ID:COMMAND'")

return None