/*
  Smart Security Light (Event Detection) - ESP32 on Wokwi
  Sensors:
    - LDR (analog, voltage divider) -> ADC1_CH6 (GPIO34)
    - PIR Motion Sensor (digital)   -> GPIO27
  Actuators:
    - Buzzer (digital)              -> GPIO25
    - LED (digital)                 -> GPIO26

  Event:
    If DARK (LDR_ADC < LDR_THRESHOLD) AND MOTION (PIR == HIGH):
      -> Buzzer ON for 5 seconds (non-blocking using millis)
      -> LED ON while event active

  Serial Monitor:
    Prints raw ADC, mapped light %, PIR state, and event status.
*/

// ---- Pin Map ----
const int PIN_LDR   = 34; // ADC1_CH6 (input only)
const int PIN_PIR   = 27; // digital input
const int PIN_BUZZ  = 25; // digital output
const int PIN_LED   = 26; // digital output

// ---- Thresholds & Timings ----
int   LDR_THRESHOLD      = 1500;     // Tune in setup() using calibration prints (0..4095). Lower = darker with typical divider.
float LIGHT_PERCENT_CEIL = 90.0;     // For mapping ADC to an approximate "light %" (cosmetic)
unsigned long BUZZ_MS    = 5000;     // buzzer duration on event (ms)
unsigned long DEBOUNCE_MS= 200;      // small debounce for PIR changes
unsigned long COOLDOWN_MS= 3000;     // cooldown after a buzz to avoid spamming

// ---- Internal State ----
bool eventActive = false;
unsigned long eventStartMs = 0;
unsigned long lastPirChangeMs = 0;
unsigned long lastBuzzEndMs = 0;

void setup() {
  Serial.begin(115200);
  delay(100);
  Serial.println(F("=== Smart Security Light (ESP32 + LDR + PIR) ==="));
  Serial.println(F("Tips: Put hand over LDR to simulate darkness in Wokwi; toggle PIR by moving the green 'motion' ring."));

  pinMode(PIN_PIR, INPUT);
  pinMode(PIN_BUZZ, OUTPUT);
  pinMode(PIN_LED, OUTPUT);
  digitalWrite(PIN_BUZZ, LOW);
  digitalWrite(PIN_LED, LOW);

  // Optional: quick auto-scan to suggest threshold (simple baseline sampling at start)
  int baseline = 0;
  const int samples = 20;
  for (int i=0; i<samples; i++) {
    baseline += analogRead(PIN_LDR);
    delay(10);
  }
  baseline /= samples;
  // Suggest a threshold: 75% of baseline for "dark" if starting under normal light in Wokwi
  int suggested = (int)(baseline * 0.75);
  Serial.print(F("[Calib] Baseline ADC=")); Serial.print(baseline);
  Serial.print(F(", suggested LDR_THRESHOLD≈")); Serial.println(suggested);
  Serial.println(F("You can change LDR_THRESHOLD in code if needed."));
}

void loop() {
  // Read sensors
  int ldrRaw = analogRead(PIN_LDR); // 0..4095
  bool pirRaw = digitalRead(PIN_PIR) == HIGH;

  // Map LDR to pseudo 'light %' (cosmetic only)
  float lightPct = (ldrRaw / 4095.0) * 100.0;
  if (lightPct > LIGHT_PERCENT_CEIL) lightPct = LIGHT_PERCENT_CEIL; // clamp cosmetic ceiling

  // Simple PIR debounce (ignore rapid toggles)
  unsigned long now = millis();
  static bool pirStable = false;
  static bool pirPrev   = false;
  if (pirRaw != pirPrev) {
    lastPirChangeMs = now;
    pirPrev = pirRaw;
  }
  if (now - lastPirChangeMs > DEBOUNCE_MS) {
    pirStable = pirRaw;
  }

  // Event Detection: DARK AND MOTION AND not in cooldown
  bool isDark = (ldrRaw < LDR_THRESHOLD);
  bool inCooldown = (now - lastBuzzEndMs < COOLDOWN_MS);

  if (!eventActive && isDark && pirStable && !inCooldown) {
    eventActive = true;
    eventStartMs = now;
    digitalWrite(PIN_BUZZ, HIGH);
    digitalWrite(PIN_LED, HIGH);
    Serial.println(F("[EVENT] DARK+MOTION detected → BUZZER ON, LED ON"));
  }

  // End event after BUZZ_MS
  if (eventActive && (now - eventStartMs >= BUZZ_MS)) {
    eventActive = false;
    digitalWrite(PIN_BUZZ, LOW);
    digitalWrite(PIN_LED, LOW);
    lastBuzzEndMs = now;
    Serial.println(F("[EVENT] Completed → BUZZER OFF, LED OFF (cooldown)"));
  }

  // Telemetry
  static unsigned long lastPrint = 0;
  if (now - lastPrint > 500) {
    lastPrint = now;
    Serial.print("LDR_ADC="); Serial.print(ldrRaw);
    Serial.print(" (~"); Serial.print((int)lightPct); Serial.print("%)");
    Serial.print(" | PIR="); Serial.print(pirStable ? "HIGH" : "LOW");
    Serial.print(" | isDark="); Serial.print(isDark ? "1" : "0");
    Serial.print(" | event="); Serial.print(eventActive ? "ON " : "OFF");
    Serial.print(" | cooldown="); Serial.println(inCooldown ? "YES" : "NO");
  }
}