#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>
#include "DHT.h"

// ==================== PIN DEFINITIONS ====================
#define DHTPIN 15
#define DHTTYPE DHT22

#define TRIG_PIN 5
#define ECHO_PIN 18

#define PIR_PIN 19
#define LDR_PIN 34      // ADC pin - Light sensor
#define MQ2_PIN 35      // ADC pin - Gas sensor (simulated with potentiometer)

#define SCREEN_WIDTH 128
#define SCREEN_HEIGHT 64
#define OLED_RESET -1

// ==================== OBJECTS ====================
DHT dht(DHTPIN, DHTTYPE);
Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, OLED_RESET);

// ==================== VARIABLES ====================
float temperature = 0;
float humidity = 0;
long distance = 0;
bool motionDetected = false;
int lightValue = 0;
int gasValue = 0;

unsigned long lastUpdate = 0;
const int updateInterval = 2000;

// ==================== SETUP ====================
void setup() {
  Serial.begin(115200);
  delay(1000);
  
  Serial.println("\n╔══════════════════════════════════════╗");
  Serial.println("║   ESP32 5-SENSOR MONITORING SYSTEM   ║");
  Serial.println("║   DHT22 | HC-SR04 | PIR | LDR | MQ-2 ║");
  Serial.println("╚══════════════════════════════════════╝\n");
  
  // Initialize pins
  pinMode(TRIG_PIN, OUTPUT);
  pinMode(ECHO_PIN, INPUT);
  pinMode(PIR_PIN, INPUT);
  
  // Initialize DHT
  dht.begin();
  
  // Initialize OLED
  if(!display.begin(SSD1306_SWITCHCAPVCC, 0x3C)) {
    Serial.println(F("SSD1306 allocation failed"));
  } else {
    display.clearDisplay();
    display.setTextSize(1);
    display.setTextColor(SSD1306_WHITE);
    display.setCursor(0,0);
    display.println(F("Initializing..."));
    display.display();
  }
  
  delay(2000);
  Serial.println("✓ All sensors initialized successfully");
  Serial.println("Starting readings...\n");
}

// ==================== SENSOR FUNCTIONS ====================

float readUltrasonic() {
  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 400; // No echo received
  
  float dist = duration * 0.034 / 2;
  
  // Constrain to realistic range
  if (dist > 400) dist = 400;
  if (dist < 2) dist = 2;
  
  return dist;
}

void readDHT() {
  float newTemp = dht.readTemperature();
  float newHum = dht.readHumidity();
  
  if (!isnan(newTemp)) temperature = newTemp;
  if (!isnan(newHum)) humidity = newHum;
}

void readAnalogSensors() {
  // Read LDR (0-4095 for ESP32 12-bit ADC)
  lightValue = analogRead(LDR_PIN);
  
  // Read MQ-2 Gas Sensor (simulated with potentiometer)
  gasValue = analogRead(MQ2_PIN);
}

void readPIR() {
  motionDetected = digitalRead(PIR_PIN);
}

// ==================== DISPLAY FUNCTIONS ====================

void updateSerialMonitor() {
  Serial.println("┌────────────────────────────────────┐");
  Serial.println("│         SENSOR READINGS            │");
  Serial.println("├────────────────────────────────────┤");
  
  // Temperature & Humidity
  Serial.printf("│ 🌡️  Temperature: %.1f °C          │\n", temperature);
  Serial.printf("│ 💧 Humidity:    %.1f %%            │\n", humidity);
  
  // Distance
  Serial.printf("│ 📏 Distance:    %3ld cm            │\n", distance);
  
  // Motion
  Serial.print("│ 🚶 Motion:      ");
  if (motionDetected) {
    Serial.println("DETECTED! ⚠️        │");
  } else {
    Serial.println("None                │");
  }
  
  // Light percentage
  int lightPercent = map(lightValue, 0, 4095, 0, 100);
  Serial.printf("│ 💡 Light Level: %3d %%             │\n", lightPercent);
  
  // Gas with status
  Serial.printf("│ ☁️  Gas Level:  %4d ", gasValue);
  if (gasValue > 3000) Serial.print("DANGER! ");
  else if (gasValue > 2000) Serial.print("Warning ");
  else Serial.print("Safe    ");
  Serial.println(" │");
  
  Serial.println("└────────────────────────────────────┘");
  Serial.println();
}

void updateOLED() {
  display.clearDisplay();
  
  // Header
  display.setTextSize(1);
  display.setCursor(0,0);
  display.print(F("5-SENSOR SYSTEM"));
  display.drawLine(0, 10, 128, 10, SSD1306_WHITE);
  
  // Temperature & Humidity
  display.setCursor(0, 14);
  display.printf("T:%.1fC H:%.0f%%", temperature, humidity);
  
  // Distance
  display.setCursor(0, 24);
  display.printf("Dist:%3ldcm", distance);
  
  // Motion indicator
  display.setCursor(0, 34);
  display.print(F("Motion:"));
  if (motionDetected) {
    display.print(F("YES!"));
    display.fillCircle(110, 36, 4, SSD1306_WHITE);
  } else {
    display.print(F("No"));
  }
  
  // Light & Gas
  int lightPercent = map(lightValue, 0, 4095, 0, 100);
  display.setCursor(0, 44);
  display.printf("Light:%3d%%", lightPercent);
  
  display.setCursor(0, 54);
  display.printf("Gas:%4d", gasValue);
  
  // Alert indicator on OLED
  if (gasValue > 3000 || motionDetected) {
    display.setCursor(80, 54);
    display.print(F("ALERT!"));
  }
  
  display.display();
}

// ==================== MAIN LOOP ====================
void loop() {
  unsigned long currentMillis = millis();
  
  // Read all sensors
  readDHT();
  distance = readUltrasonic();
  readPIR();
  readAnalogSensors();
  
  // Update displays every interval
  if (currentMillis - lastUpdate >= updateInterval) {
    lastUpdate = currentMillis;
    
    updateSerialMonitor();
    updateOLED();
    checkAlerts();
  }
  
  delay(100);
}

void checkAlerts() {
  bool alert = false;
  
  if (motionDetected) {
    Serial.println("⚠️  ALERT: Motion detected in area!");
    alert = true;
  }
  
  if (gasValue > 3000) {
    Serial.println("🚨 DANGER: High gas concentration detected!");
    alert = true;
  }
  
  if (temperature > 50) {
    Serial.println("🔥 WARNING: Extreme temperature detected!");
    alert = true;
  }
  
  if (alert) {
    Serial.println("═══════════════════════════════════════\n");
  }
}