#include <Wire.h>
#include <LiquidCrystal_I2C.h>

// ------------------- PINS ------------------------
#define ZONE_PIN     A0
#define BATT_PIN     A1

#define BUZZER_PIN   2

#define ARM_BTN      3
#define DISARM_BTN   4
#define SILENCE_BTN  5

#define LED_ARMED    6
#define LED_DISARMED 7
#define LED_ALARM    8

// ------------------- ADC THRESHOLDS ----------------
#define ZONE_OK_MIN  420
#define ZONE_OK_MAX  520

// ------------------- STATE ----------------------
bool armed = false;
bool alarmTriggered = false;
bool silenced = false;

unsigned long lastBtnTime = 0;
const unsigned long debounceDelay = 50;

unsigned long lastLedBlink = 0;
const unsigned long ledBlinkInterval = 500;

bool ledState = false;

// ------------------- BATTERY ----------------------
const float R1 = 10000.0;
const float R2 = 6800.0;
const float BAT_MIN = 6.0;
const float BAT_MAX = 8.4;
const int LOW_BATTERY_THRESHOLD = 20;
bool lowBatLedState = false;
unsigned long lastLowBatBlink = 0;
const unsigned long lowBatBlinkInterval = 500;

// ------------------- LCD ------------------------
LiquidCrystal_I2C lcd(0x27, 16, 2);
String lastLine1 = "";
String lastLine2 = "";
unsigned long lastLCDUpdate = 0;
const unsigned long LCD_UPDATE_INTERVAL = 300;

// ------------------- SIREN SETTINGS ----------------
const int FREQ_MIN = 800;
const int FREQ_MAX = 2000;
const int STEP_UP = 30;       // Increased from 15
const int STEP_DOWN = 10;     // Increased from 5
const int STEP_DELAY = 2;     // Decreased from 5
const int PAUSE_DELAY = 20;   // Decreased from 50

// Add these variables for non-blocking siren
unsigned long lastSirenUpdate = 0;
int sirenFreq = FREQ_MIN;
bool sirenRising = true;

void setup() {
  pinMode(ARM_BTN, INPUT_PULLUP);
  pinMode(DISARM_BTN, INPUT_PULLUP);
  pinMode(SILENCE_BTN, INPUT_PULLUP);

  pinMode(BUZZER_PIN, OUTPUT);

  pinMode(LED_ARMED, OUTPUT);
  pinMode(LED_DISARMED, OUTPUT);
  pinMode(LED_ALARM, OUTPUT);

  noTone(BUZZER_PIN);

  lcd.init();
  lcd.backlight();
  lcd.clear();
}

void loop() {
  handleButtons();
  monitorZone();
  updateSiren();  // Changed from alarmSound()
  updateLEDs();
  updateLCD();
  
  delay(10);  // Keep this for LCD stability
}

// ------------------- BUTTON HANDLING -----------------
void handleButtons() {
  if (millis() - lastBtnTime < debounceDelay) return;

  int armState = digitalRead(ARM_BTN);
  int disarmState = digitalRead(DISARM_BTN);
  int silenceState = digitalRead(SILENCE_BTN);

  if (armState == LOW && !armed) {
    armed = true;
    alarmTriggered = false;
    silenced = false;
    noTone(BUZZER_PIN);
    lastBtnTime = millis();
  }

  if (disarmState == LOW) {
    armed = false;
    alarmTriggered = false;
    silenced = false;
    noTone(BUZZER_PIN);
    sirenFreq = FREQ_MIN;  // Reset siren
    sirenRising = true;    // Reset direction
    lastBtnTime = millis();
  }

  if (silenceState == LOW && alarmTriggered) {
    silenced = true;
    noTone(BUZZER_PIN);
    sirenFreq = FREQ_MIN;  // Reset siren
    sirenRising = true;    // Reset direction
    lastBtnTime = millis();
  }
}

// ------------------- ZONE MONITOR -------------------
void monitorZone() {
  if (!armed || alarmTriggered) return;

  int zoneValue = analogRead(ZONE_PIN);
  if (zoneValue < ZONE_OK_MIN || zoneValue > ZONE_OK_MAX) {
    alarmTriggered = true;
    sirenFreq = FREQ_MIN;  // Start siren at minimum
    sirenRising = true;    // Start rising
  }
}

// ------------------- NON-BLOCKING SIREN --------------------
void updateSiren() {
  if (!alarmTriggered || silenced) {
    return;
  }

  // Check if it's time to update the siren
  if (millis() - lastSirenUpdate >= STEP_DELAY) {
    lastSirenUpdate = millis();
    
    if (sirenRising) {
      sirenFreq += STEP_UP;
      if (sirenFreq >= FREQ_MAX) {
        sirenFreq = FREQ_MAX;
        sirenRising = false;
        delayMicroseconds(PAUSE_DELAY * 1000);  // Short pause
      }
    } else {
      sirenFreq -= STEP_DOWN;
      if (sirenFreq <= FREQ_MIN) {
        sirenFreq = FREQ_MIN;
        sirenRising = true;
        delayMicroseconds(PAUSE_DELAY * 1000);  // Short pause
      }
    }
    
    tone(BUZZER_PIN, sirenFreq);
  }
}

// ------------------- LED CONTROL --------------------
void updateLEDs() {
  digitalWrite(LED_ARMED, LOW);
  digitalWrite(LED_DISARMED, LOW);
  digitalWrite(LED_ALARM, LOW);

  int adcBatt = analogRead(BATT_PIN);
  float vA1 = adcBatt * (5.0 / 1023.0);
  float vBat = vA1 * ((R1 + R2) / R2);
  int battPercent = constrain((vBat - BAT_MIN) / (BAT_MAX - BAT_MIN) * 100, 0, 100);

  if (battPercent < LOW_BATTERY_THRESHOLD) {
    if (millis() - lastLowBatBlink >= lowBatBlinkInterval) {
      lastLowBatBlink = millis();
      lowBatLedState = !lowBatLedState;
    }
    digitalWrite(LED_ALARM, lowBatLedState);
    return;
  }

  if (!armed) {
    digitalWrite(LED_DISARMED, HIGH);
    return;
  }

  if (armed && !alarmTriggered) {
    digitalWrite(LED_ARMED, HIGH);
    return;
  }

  if (alarmTriggered) {
    if (silenced) {
      digitalWrite(LED_ALARM, HIGH);
    } else {
      if (millis() - lastLedBlink >= ledBlinkInterval) {
        lastLedBlink = millis();
        ledState = !ledState;
      }
      digitalWrite(LED_ALARM, ledState);
    }
  }
}

// ------------------- LCD UPDATE ---------------------
void updateLCD() {
  if (millis() - lastLCDUpdate < LCD_UPDATE_INTERVAL) {
    return;
  }
  lastLCDUpdate = millis();
  
  int zoneValue = analogRead(ZONE_PIN);
  int adcBatt = analogRead(BATT_PIN);

  float vA1 = adcBatt * (5.0 / 1023.0);
  float vBat = vA1 * ((R1 + R2) / R2);
  int battPercent = constrain((vBat - BAT_MIN) / (BAT_MAX - BAT_MIN) * 100, 0, 100);

  String line1 = "";
  String line2 = "";

  if (!armed) line1 = "System: DISARMED";
  else if (armed && !alarmTriggered) line1 = "System: ARMED";
  else if (alarmTriggered) line1 = "System: ALARM!";

  if (battPercent < LOW_BATTERY_THRESHOLD) {
    line2 = "LOW BATTERY!    ";
  } else {
    line2 = "ADC:" + String(zoneValue);
    if (alarmTriggered) line2 += silenced ? " SIL" : " BUZ";
    line2 += " B:" + String(battPercent) + "%";
  }

  if (line1 != lastLine1) {
    lcd.setCursor(0, 0);
    lcd.print("                ");
    lcd.setCursor(0, 0);
    lcd.print(line1);
    lastLine1 = line1;
  }

  if (line2 != lastLine2) {
    lcd.setCursor(0, 1);
    lcd.print("                ");
    lcd.setCursor(0, 1);
    lcd.print(line2);
    lastLine2 = line2;
  }
}