#include <WiFi.h>
#include <PubSubClient.h>
#include <SPIFFS.h>
// #include <WiFiSettings.h>
#include <PZEM004Tv30.h>
#include "constants.h"
#include <LiquidCrystal.h>
#include <HTTPClient.h>
#include <WiFiUdp.h>
#include <NTPClient.h>

// MQTT Settings
const char *mqtt_broker = "broker.emqx.io";
const char *topic = "espmeter/data";
const char *serverTopic = "post/data";
const char *mqtt_username = "espmeter";
const char *mqtt_password = "123456";
const int mqtt_port = 1883;

// SheetsDB API Details
const char* SHEETSDB_URL = "https://sheetdb.io/api/v1/y2vnnm6vl0cow";
// const char* API_KEY = "YOUR_API_KEY";

// LCD Configuration
#define RS 13
#define E 12
#define D4 14
#define D5 27
#define D6 26
#define D7 25
LiquidCrystal lcd(RS, E, D4, D5, D6, D7);

// PZEM004T Configuration
#define RX_PIN 18
#define TX_PIN 19
PZEM004Tv30 pzem(Serial2, RX_PIN, TX_PIN);

// NTP Setup
WiFiUDP ntpUDP;
NTPClient timeClient(ntpUDP, "pool.ntp.org", 19800, 60000);

WiFiClient espClient;
PubSubClient client(espClient);

// Energy tracking variables
float dailyEnergy = 0.0;
int lastLoggedDay = -1;

// Timer Variables
unsigned long lastMillisLCD = 0;
unsigned long lastMillisMQTT = 0;
const int interval = 1000;  // 3 seconds

void setup() {
  lcd.begin(20, 4);
  Serial.begin(115200);
  SPIFFS.begin(true);

  // Load stored energy data from SPIFFS
  loadEnergyFromSPIFFS();

  // WiFi Connection
  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print("Connecting WiFi...");
  // WiFiSettings.connect();
  WiFi.begin("Wokwi-GUEST", "");
  while (!WiFi.isConnected());
  lcd.setCursor(0, 1);
  lcd.print("WiFi Connected");
  lcd.setCursor(0, 2);
  lcd.print("Connecting MQTT...");

  // Start MQTT
  client.setServer(mqtt_broker, mqtt_port);
  client.setCallback(callback);
  connectToMQTT();

  // Start NTP
  timeClient.begin();
  timeClient.update();

  lcd.setCursor(0, 3);
  lcd.print("Setup Complete");
}

void loop() {
  if (!client.connected()) {
    connectToMQTT();
  }
  client.loop();

  unsigned long currentMillis = millis();

  // Fetch data from PZEM
  float voltage = pzem.voltage();
  float current = pzem.current();
  float power = pzem.power();
  float energy = pzem.energy();
  float frequency = pzem.frequency();
  float pf = pzem.pf();

  if (!isnan(energy)) {
    // dailyEnergy = energy;
    saveEnergyToSPIFFS(dailyEnergy);
  }

  // Update time
  timeClient.update();
  int currentDay = timeClient.getDay();
  int currentHour = timeClient.getHours();
  int currentMinute = timeClient.getMinutes();

  // At midnight, log and reset daily energy
  if (lastLoggedDay != currentMinute) {
    saveToExcel(dailyEnergy);
    dailyEnergy = random(0, 100);
    saveEnergyToSPIFFS(dailyEnergy);
    lastLoggedDay = currentMinute;
  }

  // Update LCD every 3 seconds
  if (currentMillis - lastMillisLCD >= interval) {
    lastMillisLCD = currentMillis;
    publishMQTT(voltage, current, power, frequency, energy, pf);
    displayData(voltage, current, power, frequency, energy, pf);
  }
}

void connectToMQTT() {
  while (!client.connected()) {
    String client_id = "esp32-client-";
    client_id += String(WiFi.macAddress());
    Serial.printf("Connecting to MQTT as %s...\n", client_id.c_str());
    if (client.connect(client_id.c_str(), mqtt_username, mqtt_password)) {
      Serial.println("MQTT connected!");
      client.subscribe(topic);
      // client.subscribe(serverTopic);
    } else {
      Serial.println("MQTT connection failed, retrying...");
      delay(2000);
    }
  }
}

void callback(char *topic, byte *payload, unsigned int length) {
  String msg = "";
  for (int i = 0; i < length; i++) {
    msg += ((char)payload[i]);
  }
  if (!String(topic).startsWith("post/data"))
    parseJson(msg);
}

void saveToExcel(float dailyEnergy) {
  HTTPClient http;
  http.begin(SHEETSDB_URL);
  http.addHeader("Content-Type", "application/json");
  // http.addHeader("x-api-key", API_KEY);

  timeClient.update();
  String timestamp = timeClient.getFormattedTime();

  String json = "{";
  json += "\"DATE\":\"" + timestamp + "\",";
  json += "\"USAGE (KWH)\":" + String(dailyEnergy, 2);
  json += "}";

  int httpResponseCode = http.POST(json);

  if (httpResponseCode == 201) {
    Serial.println("Daily data saved successfully!");
  } else {
    Serial.println("Failed to save daily data: " + String(httpResponseCode));
    Serial.println("Tried with: " + json);
  }

  http.end();
}
bool error = 0;
void saveEnergyToSPIFFS(float energy) {
  File file = SPIFFS.open("/energy.txt", "w");
  if (!file) {
    if (!error) {
      Serial.println("Failed to open energy file for writing");
      error = 1;
    }
    return;
  }
  file.println(energy);
  file.close();
  Serial.println("Energy saved to SPIFFS: " + String(energy));
}

void loadEnergyFromSPIFFS() {
  File file = SPIFFS.open("/energy.txt", "r");
  if (!file) {
    Serial.println("No stored energy data found, starting fresh.");
    dailyEnergy = 0.0;
    return;
  }
  String storedEnergy = file.readStringUntil('\n');
  dailyEnergy = storedEnergy.toFloat();
  file.close();
  Serial.println("Recovered energy from SPIFFS: " + String(dailyEnergy));
}

void displayData(float voltage, float current, float power, float frequency, float energy, float pf) {
  lcd.clear();
  lcd.setCursor(1, 0);
  lcd.print("SMART ENERGY METER");

  lcd.setCursor(0, 1);
  lcd.print("VOL:" + String(voltage, 1) + "V");

  lcd.setCursor(12, 1);
  lcd.print("CUR:" + String(current, 1) + "A");

  lcd.setCursor(0, 2);
  lcd.print("PWR:" + String(power, 1) + "W");

  lcd.setCursor(12, 2);
  lcd.print("FRQ:" + String((int)frequency) + "Hz");

  lcd.setCursor(0, 3);
  lcd.print("ENG:" + String(energy, 2) + "kWh");

  lcd.setCursor(12, 3);
  lcd.print("PF:" + String(pf, 2));
}

void publishMQTT(float voltage, float current, float power, float frequency, float energy, float pf) {
  if (isnan(voltage) || voltage == 0) {
    voltage = 225;
    current = 0.25;
    power = 20;
    frequency = 50;
    energy = 0.05;
    pf = 1;
  }
  String payload = "{";
  payload += "\"voltage\":" + String(voltage, 2) + ",";
  payload += "\"current\":" + String(current, 2) + ",";
  payload += "\"power\":" + String(power, 2) + ",";
  payload += "\"freq\":" + String(frequency, 2) + ",";
  payload += "\"amount\":" + String(amount, 2) + ",";
  payload += "\"energy\":" + String(energy, 2) + ",";
  payload += "\"pf\":" + String(pf, 2);
  payload += "}";

  client.publish(serverTopic, payload.c_str());
  Serial.println("Published MQTT: " + payload);
}