/* Nucleo C031C6 - ADC median-filter + validated thermal alarm demo
   Paste into Wokwi Arduino-style project (Nucleo C031C6).
   Wiring: Potentiometer -> left=3V3, right=GND, wiper=PA0/A0
*/

const int ADC_PIN = A0;            // PA0 analog input in Wokwi
const int LED_PIN = LED_BUILTIN;   // on-board LED (PA5 typically)

//
// Configurable parameters
//
const int SAMPLE_RATE_MS = 100;    // sample every 100 ms (10 Hz)
const int WINDOW_SIZE = 5;         // median filter window (must be odd; here 5)
const int VALID_COUNT = 3;         // consecutive filtered samples >= threshold to alarm
const float TEMP_THRESHOLD = 70.0; // degC threshold to consider over-temp
const float HYSTERESIS = 5.0;      // degC hysteresis for clearing alarm
const float TEMP_MAX = 150.0;      // mapping top temperature (ADC_MAX -> TEMP_MAX)

//
// Runtime variables
//
float windowArr[WINDOW_SIZE];
int widx = 0;
int validCounter = 0;
bool alarmState = false;
int ADC_MAX = 4095; // will be detected in setup if actual ADC is 1023

// ---------- Helper functions ----------

// Map ADC raw to temperature (0 .. TEMP_MAX)
float adcToTemp(int raw) {
  if (ADC_MAX <= 0) return 0.0f;
  return ((float)raw / (float)ADC_MAX) * TEMP_MAX;
}

// Median of WINDOW_SIZE elements (WINDOW_SIZE is 5 here)
float median5(const float *v) {
  // copy
  float t[WINDOW_SIZE];
  for (int i = 0; i < WINDOW_SIZE; ++i) t[i] = v[i];

  // insertion sort (small fixed array)
  for (int i = 1; i < WINDOW_SIZE; ++i) {
    float key = t[i];
    int j = i - 1;
    while (j >= 0 && t[j] > key) {
      t[j + 1] = t[j];
      j--;
    }
    t[j + 1] = key;
  }
  return t[WINDOW_SIZE / 2]; // middle element
}

// Slight safe clamp helper (not strictly necessary)
int clampInt(int v, int lo, int hi) {
  if (v < lo) return lo;
  if (v > hi) return hi;
  return v;
}

// ---------- Setup & Loop ----------

void setup() {
  Serial.begin(115200);
  pinMode(LED_PIN, OUTPUT);
  digitalWrite(LED_PIN, LOW);

  // small delay for serial to start
  delay(200);

  // Detect ADC resolution: ask for a single read; if <=1023 assume 10-bit
  int sample = analogRead(ADC_PIN);
  if (sample <= 1023) ADC_MAX = 1023;
  else ADC_MAX = 4095;

  Serial.print("Detected ADC_MAX = ");
  Serial.println(ADC_MAX);
  Serial.print("Mapping ADC -> 0..");
  Serial.print(TEMP_MAX, 1);
  Serial.println(" °C");

  // Initialize median window with current reading to avoid startup artifacts
  for (int i = 0; i < WINDOW_SIZE; ++i) {
    int r = analogRead(ADC_PIN);
    windowArr[i] = adcToTemp(r);
    delay(10);
  }

  Serial.println("Median-filtered alarm demo started");
  Serial.println("Format: RAW_ADC RAW_TEMP°C FILTER°C VALID_CNT ALARM");
}

void loop() {
  // Read raw ADC
  int raw_adc = analogRead(ADC_PIN);
  raw_adc = clampInt(raw_adc, 0, ADC_MAX);

  // Convert raw to temperature
  float rawTemp = adcToTemp(raw_adc);

  // Update sliding window
  windowArr[widx] = rawTemp;
  widx = (widx + 1) % WINDOW_SIZE;

  // Compute median filtered temperature
  float filtTemp = median5(windowArr);

  // Validation logic: require VALID_COUNT consecutive filtered samples >= threshold
  if (filtTemp >= TEMP_THRESHOLD) {
    validCounter++;
    if (validCounter >= VALID_COUNT && !alarmState) {
      alarmState = true;
      digitalWrite(LED_PIN, HIGH);
      Serial.println("🔥 VALIDATED THERMAL ALARM TRIGGERED 🔥");
    }
  } else {
    // Clear only when below (threshold - hysteresis)
    if (filtTemp < (TEMP_THRESHOLD - HYSTERESIS)) {
      // Reset counter and clear alarm
      validCounter = 0;
      if (alarmState) {
        alarmState = false;
        digitalWrite(LED_PIN, LOW);
        Serial.println("✔ Alarm CLEARED");
      }
    } else {
      // inside hysteresis band: gently decay validCounter to avoid sticky counts
      if (validCounter > 0) validCounter = max(validCounter - 1, 0);
    }
  }

  // Print diagnostics
  Serial.print(raw_adc);
  Serial.print("\t");
  Serial.print(rawTemp, 2);
  Serial.print(" C\t");
  Serial.print(filtTemp, 2);
  Serial.print(" C\t");
  Serial.print(validCounter);
  Serial.print("\t");
  Serial.println(alarmState ? "ALARM" : "OK");

  delay(SAMPLE_RATE_MS);
}