/* BEFORE — the SENSOR->FILTER->ALERT pipeline as a POLLED SUPER-LOOP (no RTOS).
 * Wokwi, ST Nucleo-C031C6.
 *
 * The sensor produces a NEW sample every 250 ms (indexed by wall-clock time). The loop reads
 * whatever sample is available NOW, runs filter+alert, then comes back for the next one. When ALERT
 * does heavy work, TIME passes -- and the samples the sensor produced meanwhile are GONE, because
 * the loop wasn't there to read them. WATCH THE seq NUMBERS SKIP right after a HIGH/CRITICAL.
 *
 * LEDs (optional): yellow on a dropped glitch, red on an alert.
 */
#include "sensor_contract.h"
#define LED_YELLOW PB1
#define LED_RED    PB14

void setup() {
  Serial.begin(115200);
  pinMode(LED_YELLOW, OUTPUT); pinMode(LED_RED, OUTPUT);
  Serial.println("BEFORE: POLLED SUPER-LOOP (watch seq SKIP right after an alert)");
}

void loop() {
  static uint32_t last = 0;
  uint32_t seq = millis() / 250;              // the sample the sensor has available RIGHT NOW
  if (seq <= last) { delay(5); return; }      // no new sample yet -- wait for the next 250 ms tick

  if (seq > last + 1) {                        // we came back late: the sensor moved on without us
    digitalWrite(LED_YELLOW, HIGH);
    Serial.print("   !! MISSED "); Serial.print(seq - last - 1);
    Serial.println(" sample(s) -- loop was busy, the sensor moved on");
    digitalWrite(LED_YELLOW, LOW);
  }
  last = seq;

  SensorSample_t s = hh_make_sample(seq);
  if (!hh_valid(&s)) {                         // FILTER
    digitalWrite(LED_YELLOW, HIGH);
    Serial.print("seq="); Serial.print(seq); Serial.println("  FILTER: drop glitch");
    delay(15); digitalWrite(LED_YELLOW, LOW);
    return;
  }
  const char *lvl = "OK";                      // ALERT
  if (s.spo2_pct < 90.0f) lvl = "CRITICAL"; else if (s.temp_c >= 38.0f) lvl = "HIGH";
  bool a = (lvl[0] != 'O');
  digitalWrite(LED_RED, a ? HIGH : LOW);
  Serial.print("seq="); Serial.print(seq); Serial.print("  ALERT: "); Serial.println(lvl);
  if (a) delay(500);                           // heavy handling -- the loop is STUCK here, missing samples
}