#include <Arduino.h>
// =====================================================
// ESP32 + MQ-135 + MQ-7 + OLED SSD1306 + GPS (BN-220)
// WiFi Version
// =====================================================

#include <WiFi.h>
#include <HTTPClient.h>
#include <Wire.h>
#include <MQUnifiedsensor.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>
#include <TinyGPSPlus.h>

// ================== WIFI ==================
const char* ssid = "KARAN";
const char* password = "12345679";

// Server
const char server[] = "http://leman.k-dummy.my.id";
const int port = 80;

// ================= OLED CONFIG =================
#define SCREEN_WIDTH 128
#define SCREEN_HEIGHT 64
#define OLED_RESET -1
#define OLED_ADDR 0x3C

Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, OLED_RESET);

// ================= GPS CONFIG ==================
static const int GPS_RX_PIN = 16;   // GPS TX -> ESP32 GPIO 16
static const int GPS_TX_PIN = 17;   // GPS RX -> ESP32 GPIO 17
static const uint32_t GPS_BAUD = 9600;

TinyGPSPlus gps;
HardwareSerial gpsSerial(2);

// ================= MQ CONFIG ===================
#define BOARD "ESP-32"
#define VOLTAGE 3.3
#define ADC_BITS 12

#define PIN_MQ135 34
#define PIN_MQ7 35

#define RATIO_CLEAN_MQ135 3.6
#define RATIO_CLEAN_MQ7 27.5

MQUnifiedsensor MQ135(BOARD, VOLTAGE, ADC_BITS, PIN_MQ135, "MQ-135");
MQUnifiedsensor MQ7(BOARD, VOLTAGE, ADC_BITS, PIN_MQ7, "MQ-7");

// ================== HELPER ==================
void oledWiFiStatus(const String &msg)
{
  display.clearDisplay();
  display.setTextSize(1);
  display.setTextColor(SSD1306_WHITE);
  display.setCursor(0, 0);

  display.println("STATUS WIFI:");
  display.println(msg);

  display.display();
  delay(500);
}

void oledMQStatus(
    const String &msg1,
    const String &msg2,
    const String &msg3,
    const String &msg4,
    String msg5 = "")
{
  display.clearDisplay();
  display.setTextSize(1);
  display.setTextColor(SSD1306_WHITE);
  display.setCursor(0, 0);

  display.println("MQ STATUS:");
  display.println(msg1);
  display.println(msg2);
  display.println(msg3);
  display.println(msg4);
  display.println(msg5);

  display.display();
  delay(500);
}

// =============== GPS HELPERS ===================

// Feed any pending GPS data to the library (non-blocking)
void updateGPS()
{
  while (gpsSerial.available() > 0)
  {
    gps.encode(gpsSerial.read());
  }
}

// Returns "lat,lng" if a valid fix exists, otherwise "-"
String getGPSCoordinates()
{
  updateGPS();

  if (gps.location.isValid() && gps.location.age() < 2000)
  {
    return String(gps.location.lat(), 6) + "," +
           String(gps.location.lng(), 6);
  }

  return "-";
}

// Returns a status string for the OLED
String getGPSStatus()
{
  if (gps.charsProcessed() < 10)
    return "NO DATA";

  if (gps.location.isValid() && gps.location.age() < 2000)
    return "FIX " + String(gps.satellites.value()) + " sats";

  return "NO FIX";
}

// ================= HELPER ======================
float readAverage(MQUnifiedsensor &sensor, int samples = 5)
{
  float sum = 0;

  for (int i = 0; i < samples; i++)
  {
    sensor.update();
    sum += sensor.readSensor();

    updateGPS();  // keep GPS buffer drained during sampling
    delay(50);
  }

  return sum / samples;
}

// =====================================================
// WIFI CONNECTION
// =====================================================
bool connectWiFi()
{
  Serial.println("[WiFi] Connecting...");
  Serial.print("[WiFi] SSID: ");
  Serial.println(ssid);

  oledWiFiStatus("Menghubungkan...");

  WiFi.mode(WIFI_STA);
  WiFi.begin(ssid, password);

  unsigned long startAttempt = millis();

  while (WiFi.status() != WL_CONNECTED &&
         millis() - startAttempt < 30000)
  {
    delay(500);
    Serial.print(".");
  }

  Serial.println();

  if (WiFi.status() == WL_CONNECTED)
  {
    Serial.println("[WiFi] CONNECTED");
    Serial.print("[WiFi] IP: ");
    Serial.println(WiFi.localIP());

    oledWiFiStatus("WIFI TERHUBUNG");

    delay(1000);

    return true;
  }

  Serial.println("[WiFi] Connection failed!");
  oledWiFiStatus("WIFI GAGAL");

  return false;
}

// =====================================================
// ENSURE WIFI
// =====================================================
bool ensureWiFi()
{
  if (WiFi.status() == WL_CONNECTED)
    return true;

  Serial.println("[WiFi] Connection lost!");
  oledWiFiStatus("WIFI PUTUS");

  WiFi.disconnect();
  delay(1000);

  return connectWiFi();
}

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

  // ================= GPS INIT ==================
  gpsSerial.begin(GPS_BAUD, SERIAL_8N1, GPS_RX_PIN, GPS_TX_PIN);
  Serial.println("[GPS] Serial initialized on GPIO16/17");

  // ================= OLED INIT =================

  Wire.begin(21, 22);

  if (!display.begin(SSD1306_SWITCHCAPVCC, OLED_ADDR))
  {
    Serial.println("OLED tidak ditemukan!");
    while (true) delay(1000);
  }

  // ================= WIFI INIT =================

  Serial.println("[WiFi] Init WiFi...");

  if (!connectWiFi())
  {
    Serial.println("[ERROR] WiFi gagal!");
    oledWiFiStatus("RESTART ESP32");
    delay(2000);
    ESP.restart();
  }

  // ================= MQ INIT =================

  Serial.println("[MQ] Init MQ135 & MQ7");

  oledMQStatus(
      "Init MQ135 & MQ7",
      "Mulai kalibrasi sensor...",
      "Pastikan udara bersih",
      "(±1-2 menit)");

  // ================= KALIBRASI =================

  Serial.println("Mulai kalibrasi sensor...");
  Serial.println("Pastikan udara bersih (±1-2 menit)");

  // ================= MQ135 =================

  MQ135.setRegressionMethod(1);
  MQ135.init();

  float r0_135 = 0;

  for (int i = 0; i < 10; i++)
  {
    MQ135.update();
    r0_135 += MQ135.calibrate(RATIO_CLEAN_MQ135);
    updateGPS();  // keep GPS data flowing
    delay(600);
  }

  r0_135 /= 10;
  MQ135.setR0(r0_135);

  // ================= MQ7 =================

  MQ7.setRegressionMethod(1);
  MQ7.init();

  float r0_7 = 0;

  for (int i = 0; i < 10; i++)
  {
    MQ7.update();
    r0_7 += MQ7.calibrate(RATIO_CLEAN_MQ7);
    updateGPS();
    delay(600);
  }

  r0_7 /= 10;
  MQ7.setR0(r0_7);

  // ================= CHECK CALIBRATION =================

  if (r0_135 <= 0 || r0_7 <= 0)
  {
    Serial.println("Kalibrasi gagal!");
    oledMQStatus("KALIBRASI GAGAL", "", "", "RESTART ESP32...");
    delay(2000);
    ESP.restart();
  }

  Serial.println("Kalibrasi selesai!");
  Serial.print("MQ135 R0 = ");
  Serial.println(r0_135);
  Serial.print("MQ7 R0 = ");
  Serial.println(r0_7);

  oledMQStatus("KALIBRASI OK", "...", "Mulai Monitoring", "...");
  delay(1000);
}

// =====================================================
// LOOP
// =====================================================
void loop()
{
  // ===================================================
  // CHECK WIFI
  // ===================================================

  if (!ensureWiFi())
  {
    Serial.println("[WiFi] Recover failed!");
    oledWiFiStatus("WIFI ERROR");
    delay(5000);
    return;
  }

  // =============== MQ135 =================

  MQ135.setA(110.47);
  MQ135.setB(-2.862);
  float co2 = readAverage(MQ135);
  if (co2 < 0) co2 = 0;

  MQ135.setA(605.18);
  MQ135.setB(-3.937);
  float benzene = readAverage(MQ135);
  if (benzene < 0) benzene = 0;

  // =============== MQ7 ===================

  MQ7.setA(99.042);
  MQ7.setB(-1.518);
  float co = readAverage(MQ7);
  if (co < 0) co = 0;

  // ========== AIR QUALITY ESTIMATION =====

  int aq = 100;

  if (co2 > 700)
    aq -= map(co2, 700, 2000, 0, 50);
  if (co2 > 2000)
    aq -= map(co2, 2000, 5000, 50, 80);
  if (co > 10)
    aq -= map(co, 10, 50, 0, 30);
  if (co > 50)
    aq -= 30;
  if (benzene > 5)
    aq -= map(benzene, 5, 50, 0, 40);

  aq = constrain(aq, 0, 100);

  // ================= STATUS =================

  String status;
  if (aq >= 90)      status = "Sangat Baik";
  else if (aq >= 70) status = "Baik";
  else if (aq >= 50) status = "Sedang";
  else if (aq >= 30) status = "Buruk";
  else               status = "Sangat Buruk";

  // =============== GPS READ ==================

  String gps_coords = getGPSCoordinates();
  String gps_status = getGPSStatus();

  // =============== OLED DISPLAY ==========
  // 6 lines fit on 128x64 with textSize(1)
  display.clearDisplay();
  display.setTextSize(1);
  display.setTextColor(SSD1306_WHITE);
  display.setCursor(0, 0);

  display.println("CO2:" + String(co2, 1) + " CO:" + String(co, 1));
  display.println("BZ :" + String(benzene, 1) + " AQ:" + String(aq) + "%");
  display.println(status);
  display.println("GPS: " + gps_status);

  String lat = "-3.9891687826423334";
  String lng = "119.65221465458342";

  if (gps_coords != "-")
  {
    // Split lat/lng to two lines for readability
    int commaIdx = gps_coords.indexOf(',');
    display.println("Lat:" + gps_coords.substring(0, commaIdx));
    display.println("Lng:" + gps_coords.substring(commaIdx + 1));

    lat = gps_coords.substring(0, commaIdx);
    lng = gps_coords.substring(commaIdx + 1);

  }
  else
  {
    display.println("Lat: -");
    display.println("Lng: -");
  }

  display.display();

  // =============== SERIAL =================

  Serial.println("===== STATUS UDARA =====");
  Serial.print("CO2 : ");
  Serial.print(co2);
  Serial.println(" ppm");
  Serial.print("CO  : ");
  Serial.print(co);
  Serial.println(" ppm");
  Serial.print("BZ  : ");
  Serial.print(benzene);
  Serial.println(" ppm");
  Serial.print("AQ  : ");
  Serial.print(aq);
  Serial.print("% ");
  Serial.println(status);
  Serial.print("GPS : ");
  Serial.println(gps_coords);
  Serial.print("GPS status: ");
  Serial.println(gps_status);
  Serial.println("========================\n");

  delay(5000);

  // =================================================
  // HTTP REQUEST
  // =================================================

  if (WiFi.status() == WL_CONNECTED)
  {
    HTTPClient http;

    String url = String(server) + "/api/update?";
    url += "co2=" + String(co2);
    url += "&co=" + String(co);
    url += "&bz=" + String(benzene);
    url += "&aq=" + String(aq);
    url += "&id=2";
    url += "&lat=" + lat;
    url += "&lng=" + lng;

    Serial.print("[HTTP] GET ");
    Serial.println(url);

    oledWiFiStatus("MENGIRIM DATA...");

    http.begin(url);
    int httpCode = http.GET();

    if (httpCode > 0)
    {
      Serial.print("[HTTP] Response code: ");
      Serial.println(httpCode);

      String response = http.getString();
      Serial.println("----- HTTP RESPONSE -----");
      Serial.println(response);
      Serial.println("-------------------------");

      int jsonStart = response.indexOf('{');
      if (jsonStart >= 0)
      {
        String json = response.substring(jsonStart);
        Serial.print("[JSON] ");
        Serial.println(json);
        oledWiFiStatus("RESP OK");
      }
      else
      {
        Serial.println("[ERROR] No JSON found!");
        oledWiFiStatus("RESP ERROR");
      }
    }
    else
    {
      Serial.print("[ERROR] HTTP failed: ");
      Serial.println(http.errorToString(httpCode));
      oledWiFiStatus("GAGAL KIRIM");
    }

    http.end();
  }
  else
  {
    Serial.println("[ERROR] WiFi disconnected!");
    oledWiFiStatus("WIFI PUTUS");
  }

  Serial.println("===== LOOP END =====");

  delay(10000);
}