#include <Arduino.h>

const int PIR_PIN = 27;
const int LED_PIN = 2;

volatile bool motionFlag = false;
volatile bool endFlag = false;
volatile unsigned long tDetect = 0;
volatile unsigned long tMotionEnd = 0;

unsigned long tLedOn = 0;
unsigned long tLedOff = 0;

unsigned long trials = 0;
unsigned long sumDelta = 0;
unsigned long minDelta = 0xFFFFFFFFUL;
unsigned long maxDelta = 0;

void IRAM_ATTR pirChange() {
  int s = digitalRead(PIR_PIN);
  if (s == HIGH) {
    tDetect = micros();
    motionFlag = true;
  } else {
    tMotionEnd = micros();
    endFlag = true;
  }
}

void setup() {
  pinMode(PIR_PIN, INPUT);
  pinMode(LED_PIN, OUTPUT);
  digitalWrite(LED_PIN, LOW);
  Serial.begin(115200);
  while (!Serial) {}
  Serial.println("event,trial,detect_to_led_on_us,min_us,max_us,avg_us");
  attachInterrupt(digitalPinToInterrupt(PIR_PIN), pirChange, CHANGE);
}

void loop() {
  if (motionFlag) {
    noInterrupts();
    motionFlag = false;
    unsigned long td = tDetect;
    interrupts();

    digitalWrite(LED_PIN, HIGH);
    tLedOn = micros();
    unsigned long d = tLedOn - td;

    trials++;
    sumDelta += d;
    if (d < minDelta) minDelta = d;
    if (d > maxDelta) maxDelta = d;
    unsigned long avg = (trials ? (sumDelta / trials) : 0);

    Serial.print("ON,");
    Serial.print(trials);
    Serial.print(",");
    Serial.print(d);
    Serial.print(",");
    Serial.print(minDelta);
    Serial.print(",");
    Serial.print(maxDelta);
    Serial.print(",");
    Serial.println(avg);
  }

  if (endFlag) {
    noInterrupts();
    endFlag = false;
    unsigned long te = tMotionEnd;
    interrupts();

    digitalWrite(LED_PIN, LOW);
    tLedOff = micros();
    unsigned long dOff = tLedOff - te;

    Serial.print("OFF,");
    Serial.print(trials);
    Serial.print(",");
    Serial.print(dOff);
    Serial.print(",0,0,0");
    Serial.println();
  }
}