# cpb_ble_sensor.py

# Provide a remote sensing service over Bluetooth Low-Energy (BLE).
# This runs on an Adafruit Circuit Playground Bluefruit.

# This example works with either:
#  1. host_ble_receiver.py running on a host computer
#  2. the Plotter function of the Bluefruit Connect iOS app

# ----------------------------------------------------------------
# Import the standard Python time functions.
import time
# Import the board-specific input/output library.
from adafruit_circuitplayground import cp

# Import the Adafruit Bluetooth library.  Technical reference:
# https://circuitpython.readthedocs.io/projects/ble/en/latest/api.html
from adafruit_ble import BLERadio
from adafruit_ble.advertising.standard import ProvideServicesAdvertisement
from adafruit_ble.services.nordic import UARTService

# ----------------------------------------------------------------
# Initialize global variables for the main loop.

ble = BLERadio()
uart = UARTService()
advertisement = ProvideServicesAdvertisement(uart)

# Flags for detecting state changes.
advertised = False
connected  = False

# The sensor sampling rate is precisely regulated using the following timer variables.
sampling_timer    = 0.0
last_time         = time.monotonic()
sampling_interval = 0.10

# ----------------------------------------------------------------
# Begin the main processing loop.

while True:

    # Read the accelerometer at regular intervals.  Measure elapsed time and
    # wait until the update timer has elapsed.
    now = time.monotonic()
    interval = now - last_time
    last_time = now
    sampling_timer -= interval
    if sampling_timer < 0.0:
        sampling_timer += sampling_interval
        xold, yold, zold = x, y, z
        x, y, z = cp.acceleration
    else:
        x = None
        y = None
        z = None

    if not advertised:
        ble.start_advertising(advertisement)
        print("Waiting for connection.")
        advertised = True

    if not connected and ble.connected:
        print("Connection received.")
        connected = True
        cp.red_led = True

    if connected:
        time.sleep(5)
        if not ble.connected:
            print("Connection lost.")
            connected = False
            advertised = False
            cp.red_led = False
        else:
            if x is not None:
                if(xold - x > 2 or xold - x < -2 or yold - y > 2 or yold - y < -2 or zold - z > 2 or zold - z < -2):
                    uart.write(b"%.3f\n" % 1)
                else:
                    uart.write(b"%.3f\n" % 0)
                #uart.write(b"%.3f,%.3f,%.3f\n" % (x, y, z))