// ================================================================
//  SmartLoo — IoT Autonomous Toilet Maintenance System
//  Wokwi Simulation Version
//  Board  : ESP32 Dev Module
//  Author : SmartLoo Project
// ================================================================
//
//  PIN MAP
//  -------
//  GPIO 14  → PIR #1  (Entry sensor)
//  GPIO 27  → PIR #2  (Exit sensor)
//  GPIO 34  → MQ-135  (Gas / Odor — Analog)
//  GPIO 26  → DHT22   (Temp & Humidity)   ← Wokwi uses DHT22
//  GPIO 5   → HC-SR04 TRIG (Water level)
//  GPIO 18  → HC-SR04 ECHO (Water level)
//  GPIO 13  → Servo   (Freshener spray)
//  GPIO 21  → LCD SDA (I2C)
//  GPIO 22  → LCD SCL (I2C)
//  GPIO 25  → LED Red   (simulates Relay→Pump)
//  GPIO 33  → LED Green (simulates Relay→Fan)
//  GPIO 32  → LED Blue  (simulates Relay→Spare)
// ================================================================

#include <Wire.h>
#include <LiquidCrystal_I2C.h>
#include <DHT.h>
#include <ESP32Servo.h>

// ── PIN DEFINITIONS ─────────────────────────────────────────────
#define PIR_ENTRY     14
#define PIR_EXIT      27
#define MQ135_PIN     34
#define DHT_PIN       26
#define TRIG_PIN       5
#define ECHO_PIN      18
#define SERVO_PIN     13
#define LED_PUMP      25    // Simulates water pump relay
#define LED_FAN       33    // Simulates exhaust fan relay
#define LED_SPARE     32    // Simulates occupied indicator

// ── THRESHOLDS ──────────────────────────────────────────────────
#define GAS_THRESHOLD     400    // Above this = bad odor detected
#define WATER_LOW_CM       15    // Distance > 15cm = tank is low
#define FLUSH_DELAY_MS  10000    // 10 sec after exit → auto flush
#define FLUSH_DURATION   5000    // Pump runs 5 seconds
#define MAX_DAILY_USES     50    // Alert at 50 uses per day

// ── DHT TYPE (Wokwi uses DHT22 component for simulation) ────────
#define DHT_TYPE DHT22

// ── OBJECTS ─────────────────────────────────────────────────────
LiquidCrystal_I2C lcd(0x27, 16, 2);
DHT               dht(DHT_PIN, DHT_TYPE);
Servo             sprayServo;

// ── STATE VARIABLES ─────────────────────────────────────────────
int           usageCount    = 0;
bool          isOccupied    = false;
bool          flushPending  = false;
unsigned long exitTimestamp = 0;
unsigned long lastLCDUpdate = 0;
unsigned long lastSerialLog = 0;

// ════════════════════════════════════════════════════════════════
//  HELPER FUNCTIONS
// ════════════════════════════════════════════════════════════════

// Read distance from HC-SR04 ultrasonic sensor (returns cm)
float getDistance() {
  digitalWrite(TRIG_PIN, LOW);
  delayMicroseconds(2);
  digitalWrite(TRIG_PIN, HIGH);
  delayMicroseconds(10);
  digitalWrite(TRIG_PIN, LOW);
  long duration = pulseIn(ECHO_PIN, HIGH, 30000); // 30ms timeout
  if (duration == 0) return 999; // No echo = error
  return (duration * 0.034) / 2.0;
}

// Trigger auto-flush (pump runs for 5 seconds)
void triggerFlush() {
  Serial.println("╔══════════════════════════════╗");
  Serial.println("║  AUTO FLUSH TRIGGERED!       ║");
  Serial.println("╚══════════════════════════════╝");

  lcd.clear();
  lcd.setCursor(0, 0); lcd.print("AUTO CLEANING...");
  lcd.setCursor(0, 1); lcd.print("Flushing: 5 sec ");

  digitalWrite(LED_PUMP, HIGH);   // Pump ON (relay LOW in real)
  Serial.println("[PUMP] Water pump ON — GPIO25 → Relay IN1 LOW");

  delay(FLUSH_DURATION);          // Run for 5 seconds

  digitalWrite(LED_PUMP, LOW);    // Pump OFF
  Serial.println("[PUMP] Water pump OFF — flush complete!");
  Serial.println("-------------------------------");
}

// Trigger freshener spray (servo sweeps 0° → 90° → 0°)
void triggerSpray() {
  Serial.println("[SERVO] GPIO13 PWM → 90° (spray press)");
  sprayServo.write(90);
  delay(800);
  sprayServo.write(0);
  Serial.println("[SERVO] GPIO13 PWM → 0° (released)");
}

// Update the 16×2 LCD display
void updateLCD(int gasLevel, float temp, float humidity) {
  lcd.clear();
  lcd.setCursor(0, 0);
  if (isOccupied) {
    lcd.print("Status:OCCUPIED ");
  } else if (flushPending) {
    lcd.print("Status:CLEANING ");
  } else {
    lcd.print("Status: VACANT  ");
  }

  lcd.setCursor(0, 1);
  lcd.print("U:");
  lcd.print(usageCount);
  lcd.print(" G:");
  lcd.print(gasLevel);
  lcd.print(" T:");
  lcd.print((int)temp);
  lcd.print("C");
}

// ════════════════════════════════════════════════════════════════
//  SETUP
// ════════════════════════════════════════════════════════════════
void setup() {
  Serial.begin(115200);
  delay(500);

  // Welcome banner
  Serial.println("");
  Serial.println("╔════════════════════════════════════╗");
  Serial.println("║   SmartLoo IoT System v1.0         ║");
  Serial.println("║   Autonomous Toilet Maintenance    ║");
  Serial.println("╚════════════════════════════════════╝");
  Serial.println("[BOOT] Initializing all pins...");

  // Input pins
  pinMode(PIR_ENTRY, INPUT);
  pinMode(PIR_EXIT,  INPUT);
  pinMode(TRIG_PIN,  OUTPUT);
  pinMode(ECHO_PIN,  INPUT);

  // Output pins (simulate relays with LEDs)
  pinMode(LED_PUMP,  OUTPUT);
  pinMode(LED_FAN,   OUTPUT);
  pinMode(LED_SPARE, OUTPUT);

  // All outputs OFF at start
  digitalWrite(LED_PUMP,  LOW);
  digitalWrite(LED_FAN,   LOW);
  digitalWrite(LED_SPARE, LOW);

  // Initialize DHT sensor
  dht.begin();
  Serial.println("[DHT]  DHT22 sensor initialized on GPIO26");

  // Initialize LCD
  Wire.begin(21, 22);
  lcd.init();
  lcd.backlight();
  lcd.setCursor(0, 0); lcd.print(" SmartLoo v1.0  ");
  lcd.setCursor(0, 1); lcd.print("  Initializing  ");
  Serial.println("[LCD]  16x2 I2C display initialized (0x27)");

  // Initialize servo
  sprayServo.attach(SERVO_PIN);
  sprayServo.write(0);
  Serial.println("[SERVO] SG90 servo attached to GPIO13");

  Serial.println("[BOOT] All systems ready!");
  Serial.println("-------------------------------");
  Serial.println("  PIR Entry  → GPIO 14");
  Serial.println("  PIR Exit   → GPIO 27");
  Serial.println("  MQ-135     → GPIO 34 (Analog)");
  Serial.println("  DHT22      → GPIO 26");
  Serial.println("  Ultrasonic → TRIG:5 ECHO:18");
  Serial.println("  Servo      → GPIO 13");
  Serial.println("  Pump LED   → GPIO 25 (Relay IN1)");
  Serial.println("  Fan  LED   → GPIO 33 (Relay IN2)");
  Serial.println("-------------------------------");

  delay(2000);
  lcd.clear();
  lcd.setCursor(0, 0); lcd.print("Status: VACANT  ");
  lcd.setCursor(0, 1); lcd.print("Uses:0  Gas:--- ");
}

// ════════════════════════════════════════════════════════════════
//  MAIN LOOP
// ════════════════════════════════════════════════════════════════
void loop() {

  // ── Read all sensors ────────────────────────────────────────
  int   entryDetected = digitalRead(PIR_ENTRY);
  int   exitDetected  = digitalRead(PIR_EXIT);
  int   gasLevel      = analogRead(MQ135_PIN);
  float temperature   = dht.readTemperature();
  float humidity      = dht.readHumidity();
  float waterDist     = getDistance();

  // Protect against NaN from DHT
  if (isnan(temperature)) temperature = 0;
  if (isnan(humidity))    humidity    = 0;

  // ── ENTRY DETECTION ─────────────────────────────────────────
  if (entryDetected == HIGH && !isOccupied) {
    isOccupied    = true;
    flushPending  = false;
    usageCount++;

    digitalWrite(LED_SPARE, HIGH);   // Occupied indicator ON

    Serial.println("");
    Serial.println(">>> PIR #1 HIGH — GPIO14 — PERSON ENTERED!");
    Serial.print  ("    Usage count today: ");
    Serial.println(usageCount);

    if (usageCount >= MAX_DAILY_USES) {
      Serial.println("!!! ALERT: 50 uses reached — manual cleaning needed!");
    }
  }

  // ── EXIT DETECTION ──────────────────────────────────────────
  if (exitDetected == HIGH && isOccupied) {
    isOccupied    = false;
    flushPending  = true;
    exitTimestamp = millis();

    digitalWrite(LED_SPARE, LOW);    // Occupied indicator OFF

    Serial.println("");
    Serial.println(">>> PIR #2 HIGH — GPIO27 — PERSON EXITED!");
    Serial.println("    Auto-flush scheduled in 10 seconds...");
  }

  // ── AUTO FLUSH after 10 seconds ─────────────────────────────
  if (flushPending && (millis() - exitTimestamp >= FLUSH_DELAY_MS)) {
    flushPending = false;
    triggerFlush();
  }

  // ── ODOR CONTROL ────────────────────────────────────────────
  if (gasLevel > GAS_THRESHOLD) {
    digitalWrite(LED_FAN, HIGH);      // Fan ON

    // Only spray if fan was previously off (avoid repeated sprays)
    static bool sprayCooldown = false;
    if (!sprayCooldown) {
      Serial.print("[MQ135] Gas level HIGH: ");
      Serial.println(gasLevel);
      Serial.println("[FAN]  GPIO33 → Relay IN2 LOW — FAN ON");
      triggerSpray();
      sprayCooldown = true;
    }
  } else {
    if (digitalRead(LED_FAN) == HIGH) {
      Serial.print("[MQ135] Gas cleared: ");
      Serial.println(gasLevel);
      Serial.println("[FAN]  GPIO33 → Relay IN2 HIGH — FAN OFF");
    }
    digitalWrite(LED_FAN, LOW);       // Fan OFF

    // Reset spray cooldown when air is clean
    static bool sprayCooldown = false;
    sprayCooldown = false;
  }

  // ── WATER LEVEL CHECK ───────────────────────────────────────
  static bool waterAlerted = false;
  if (waterDist > WATER_LOW_CM && waterDist < 500) {
    if (!waterAlerted) {
      Serial.print("[WATER] Tank LOW! Distance: ");
      Serial.print(waterDist);
      Serial.println("cm — refill needed!");
      waterAlerted = true;
    }
  } else {
    waterAlerted = false;
  }

  // ── SERIAL LOG every 3 seconds ──────────────────────────────
  if (millis() - lastSerialLog >= 3000) {
    lastSerialLog = millis();

    Serial.println("─────────── SENSOR READINGS ───────────");
    Serial.print  ("  MQ-135  gas    : "); Serial.print(gasLevel);
    Serial.println(gasLevel > GAS_THRESHOLD ? "  [ODOR!]" : "  [GOOD]");

    Serial.print  ("  DHT22   temp   : "); Serial.print(temperature, 1);
    Serial.println(" C");

    Serial.print  ("  DHT22   humid  : "); Serial.print(humidity, 1);
    Serial.println(" %");

    Serial.print  ("  HC-SR04 water  : "); Serial.print(waterDist, 1);
    Serial.println(" cm");

    Serial.print  ("  Status         : ");
    Serial.println(isOccupied ? "OCCUPIED" : flushPending ? "CLEANING" : "VACANT");

    Serial.print  ("  Usage count    : "); Serial.println(usageCount);
    Serial.println("────────────────────────────────────────");
  }

  // ── UPDATE LCD every 2 seconds ──────────────────────────────
  if (millis() - lastLCDUpdate >= 2000) {
    lastLCDUpdate = millis();
    updateLCD(gasLevel, temperature, humidity);
  }

  delay(300);   // Loop runs every 300ms
}