import neopixel
import _thread
from machine import Pin, ADC
from time import sleep, sleep_us, time_ns


SOUND_SPEED = 0.034
CM_TO_INCH = 0.393701

p5_trigger = Pin(5, Pin.OUT)
p18_echo = Pin(18, Pin.IN)

ledstrip = neopixel.NeoPixel(Pin(4), 1)


global ledcolor
ledcolor = 0

def measure(trig_pin : Pin, echo_pin : Pin):

        trig_pin.off()
        sleep_us(2)
        trig_pin.on()
        sleep_us(10)
        trig_pin.off()
        start_pulse = time_ns()
        while not echo_pin.value():
            pass
        end_pulse = time_ns() 
        while echo_pin.value():
            end_pulse = time_ns()
        duration = end_pulse - start_pulse
        distanceCm = (duration / 2000) * SOUND_SPEED
        return distanceCm

def set_distance_to_color(trig_pin : Pin, echo_pin : Pin) -> tuple:
    distance = measure(trig_pin, echo_pin)
    # normalization
    if distance < 0:
        distance = 0
    elif distance > 255:
        distance = 255

    color_bright = 255 - distance # the closer the brighter
    return int(color_bright)
 
def run_ultrasonic_color_manipulation(trig_pin : Pin, echo_pin : Pin):
    '''
    This function should update the global variable "ledcolor" according to
    the supersonic sensor read.
    @param trig_pin: trigger pin of a sound sensor
    @param echo_pin: echo pin of the same sound sensor
    '''
    while True:
        global ledcolor
        ledcolor = set_distance_to_color(trig_pin, echo_pin)
        


def main():
    global ledcolor
    _thread.start_new_thread(run_ultrasonic_color_manipulation, (p5_trigger, p18_echo))
    while True:
        sleep(0.1)
        ledstrip[0] = (ledcolor, 0, 255)
        print(ledstrip[0])
        ledstrip.write()

main()