/*
 * ESP32 Smart Energy Monitor with Manual Relay Control
 * Reconfigured with new requirements:
 * - ESP32 as main controller
 * - GSM module for SMS messaging (simulated)
 * - Relay module to control bulb/load
 * - Pushbuttons for manual relay ON/OFF control
 * - 16x2 LCD (I2C) for real-time display
 * - Potentiometers to simulate voltage & current sensors
 * - Real-time power calculation (P = V * I)
 *
 * HARDWARE CONFIGURATION:
 * - ESP32: Main microcontroller
 * - LCD 16x2 I2C: SDA=Pin21, SCL=Pin22
 * - Relay Module: Control=Pin2
 * - Button ON (Green): Pin4 (with pull-up)
 * - Button OFF (Red): Pin5 (with pull-up)
 * - Voltage Potentiometer: Pin36 (ADC1_CH0)
 * - Current Potentiometer: Pin39 (ADC1_CH3)
 * - GSM Module: TX0/RX0 (simulated with OLED)
 * - Bulb/Load: Connected through relay NO contact
 */

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

// Pin Definitions
#define RELAY_PIN 2         // Relay control pin
#define BUTTON_ON_PIN 4     // Green button for relay ON
#define BUTTON_OFF_PIN 5    // Red button for relay OFF
#define VOLTAGE_POT_PIN 36  // Potentiometer for voltage simulation
#define CURRENT_POT_PIN 39  // Potentiometer for current simulation

// LCD Configuration (I2C)
LiquidCrystal_I2C lcd(0x27, 16, 2);

// System Variables
bool relayState = false;
float voltage = 0.0;
float current = 0.0;
float power = 0.0;
float energy = 0.0;
unsigned long lastTime = 0;
unsigned long lastDisplayUpdate = 0;
unsigned long lastGsmUpdate = 0;
int gsmMessageCount = 0;

// Button states for debouncing
bool lastButtonOnState = HIGH;
bool lastButtonOffState = HIGH;
unsigned long lastDebounceTime = 0;
const unsigned long debounceDelay = 50;

void setup() {
  Serial.begin(115200);
  
  // Initialize pins
  pinMode(RELAY_PIN, OUTPUT);
  pinMode(BUTTON_ON_PIN, INPUT_PULLUP);
  pinMode(BUTTON_OFF_PIN, INPUT_PULLUP);
  
  // Initialize relay to OFF state
  digitalWrite(RELAY_PIN, LOW);
  relayState = false;
  
  // Initialize LCD
  lcd.init();
  lcd.backlight();
  lcd.clear();
  
  // Welcome message
  lcd.setCursor(0, 0);
  lcd.print("ESP32 Energy");
  lcd.setCursor(0, 1);
  lcd.print("Monitor v2.0");
  delay(2000);
  
  // Initialize GSM simulation
  Serial.println("=== ESP32 Smart Energy Monitor Started ===");
  Serial.println("Initializing GSM module...");
  Serial.println("AT");
  Serial.println("OK");
  Serial.println("AT+CPIN?");
  Serial.println("+CPIN: READY");
  Serial.println("GSM module initialized (simulated)");
  
  Serial.println("\n=== COMPONENT MAPPING ===");
  Serial.println("- ESP32: Main Controller");
  Serial.println("- LCD 16x2: SDA=21, SCL=22 (I2C)");
  Serial.println("- Relay Module: Control Pin 2");
  Serial.println("- Button ON (Green): Pin 4");
  Serial.println("- Button OFF (Red): Pin 5");
  Serial.println("- Voltage Sensor (Pot): Pin 36");
  Serial.println("- Current Sensor (Pot): Pin 39");
  Serial.println("- GSM Module: UART0 (Simulated)");
  Serial.println("- Bulb/Load: Through Relay NO contact");
  Serial.println("\n=== SYSTEM READY ===");
  
  lastTime = millis();
}

void loop() {
  unsigned long currentTime = millis();
  
  // Handle button presses with debouncing
  handleButtons();
  
  // Read sensor values (potentiometers simulate voltage and current sensors)
  readSensors();
  
  // Calculate power (P = V * I)
  power = voltage * current;
  
  // Calculate energy accumulation (simple integration)
  if (currentTime - lastTime >= 1000) { // Every second
    float timeHours = (currentTime - lastTime) / 3600000.0; // Convert ms to hours
    energy += power * timeHours; // kWh
    lastTime = currentTime;
  }
  
  // Update LCD display every 500ms
  if (currentTime - lastDisplayUpdate >= 500) {
    updateLCDDisplay();
    lastDisplayUpdate = currentTime;
  }
  
  // Send GSM messages every 30 seconds
  if (currentTime - lastGsmUpdate >= 30000) {
    sendGsmMessage();
    lastGsmUpdate = currentTime;
  }
  
  // Print serial data every 2 seconds
  static unsigned long lastSerialPrint = 0;
  if (currentTime - lastSerialPrint >= 2000) {
    printSerialData();
    lastSerialPrint = currentTime;
  }
}

void handleButtons() {
  bool currentButtonOnState = digitalRead(BUTTON_ON_PIN);
  bool currentButtonOffState = digitalRead(BUTTON_OFF_PIN);
  
  // Button ON pressed (LOW = pressed due to pull-up)
  if (currentButtonOnState == LOW && lastButtonOnState == HIGH) {
    if (millis() - lastDebounceTime > debounceDelay) {
      turnRelayOn();
      lastDebounceTime = millis();
    }
  }
  
  // Button OFF pressed
  if (currentButtonOffState == LOW && lastButtonOffState == HIGH) {
    if (millis() - lastDebounceTime > debounceDelay) {
      turnRelayOff();
      lastDebounceTime = millis();
    }
  }
  
  lastButtonOnState = currentButtonOnState;
  lastButtonOffState = currentButtonOffState;
}

void turnRelayOn() {
  digitalWrite(RELAY_PIN, HIGH);
  relayState = true;
  Serial.println(">>> RELAY ON - Load Connected <<<");
  
  // Send GSM notification
  Serial.println("\n=== GSM MESSAGE SENT ===");
  Serial.println("TO: +1234567890");
  Serial.println("MSG: Load turned ON manually. Power monitoring active.");
  Serial.println("STATUS: Message sent successfully");
  Serial.println("========================\n");
}

void turnRelayOff() {
  digitalWrite(RELAY_PIN, LOW);
  relayState = false;
  Serial.println(">>> RELAY OFF - Load Disconnected <<<");
  
  // Send GSM notification
  Serial.println("\n=== GSM MESSAGE SENT ===");
  Serial.println("TO: +1234567890");
  Serial.println("MSG: Load turned OFF manually. Standby mode active.");
  Serial.println("STATUS: Message sent successfully");
  Serial.println("========================\n");
}

void readSensors() {
  // Read potentiometer values (0-4095 for ESP32 ADC)
  int voltageRaw = analogRead(VOLTAGE_POT_PIN);
  int currentRaw = analogRead(CURRENT_POT_PIN);
  
  // Convert to realistic voltage values (180V to 250V)
  voltage = map(voltageRaw, 0, 4095, 180, 250);
  
  // Convert to realistic current values (0A to 20A)
  current = map(currentRaw, 0, 4095, 0, 2000) / 100.0;
  
  // If relay is OFF, current should be minimal
  if (!relayState) {
    current = current * 0.1; // 10% of reading for standby current
  }
}

void updateLCDDisplay() {
  lcd.clear();
  
  // First line: Voltage and Current
  lcd.setCursor(0, 0);
  lcd.print("V:");
  lcd.print(voltage, 0);
  lcd.print("V I:");
  lcd.print(current, 1);
  lcd.print("A");
  
  // Second line: Power and Relay status
  lcd.setCursor(0, 1);
  lcd.print("P:");
  lcd.print(power, 0);
  lcd.print("W ");
  
  if (relayState) {
    lcd.print("[ON]");
  } else {
    lcd.print("[OFF]");
  }
}

void sendGsmMessage() {
  gsmMessageCount++;
  
  Serial.println("\n=== GSM STATUS MESSAGE ===");
  Serial.println("AT+CMGS=\"+1234567890\"");
  Serial.print("MSG #");
  Serial.print(gsmMessageCount);
  Serial.print(": System Status - V:");
  Serial.print(voltage, 1);
  Serial.print("V, I:");
  Serial.print(current, 1);
  Serial.print("A, P:");
  Serial.print(power, 1);
  Serial.print("W, Load:");
  Serial.print(relayState ? "ON" : "OFF");
  Serial.print(", Energy:");
  Serial.print(energy, 3);
  Serial.println("kWh");
  Serial.println("+CMGS: OK");
  Serial.println("=========================\n");
}

void printSerialData() {
  Serial.print("Time: ");
  Serial.print(millis() / 1000);
  Serial.print("s | Voltage: ");
  Serial.print(voltage, 1);
  Serial.print("V | Current: ");
  Serial.print(current, 1);
  Serial.print("A | Power: ");
  Serial.print(power, 1);
  Serial.print("W | Energy: ");
  Serial.print(energy, 4);
  Serial.print("kWh | Relay: ");
  Serial.println(relayState ? "ON" : "OFF");
}