/*
 * ======================================================
 * SMART COLLAR FIRMWARE
 * ------------------------------------------------------
 * Kirim data sensor (suhu, gerak, GPS, sinyal) ke backend
 * tiap 1 detik. Prioritas kirim lewat SIM800L (GPRS),
 * fallback otomatis ke WiFi kalau SIM800L gagal.
 * ======================================================
 */

#define TINY_GSM_MODEM_SIM800

#include <Wire.h>
#include <Adafruit_MLX90614.h>
#include <Adafruit_MPU6050.h>
#include <Adafruit_Sensor.h>
#include <TinyGPS++.h>
#include <HardwareSerial.h>

#include <WiFi.h>
#include <WiFiClientSecure.h>
#include <HTTPClient.h>
#include <time.h>
#include <sys/time.h>

#include <TinyGsmClient.h>
#include <ArduinoHttpClient.h>

// Install lewat Library Manager: "ArduinoJson" by Benoit Blanchon
#include <ArduinoJson.h>

// ======================================================
// PIN CONFIG
// ======================================================
#define SDA_PIN   21
#define SCL_PIN   22

#define GPS_RX    16
#define GPS_TX    17

#define SIM_RX    13
#define SIM_TX    12

// ======================================================
// WIFI CONFIG
// ======================================================
const char* WIFI_SSID     = "oke";
const char* WIFI_PASSWORD = "12345678";

// ======================================================
// GPRS CONFIG
// ======================================================
const char APN[] = "internet";

// ======================================================
// IDENTITAS DEVICE
// Harus sama persis dengan yang terdaftar di backend.
// ======================================================
const char* SERIAL_NUMBER  = "SC001";
const char* DEVICE_SECRET  = "eefda1ae-ceb8-47da-b89e-c8be0d6543f2";
const char* FIRMWARE_VERSION = "1.0.0";
const char* HARDWARE_VERSION = "1.0.0";

// ======================================================
// BACKEND CONFIG
// ======================================================
const char* WIFI_BASE_URL   = "https://api.smartcollar.my.id";
const char* MONITORING_PATH = "/api/v1/monitoring";

// Host SIM800L TANPA "http://"/"https://".
// Domain KHUSUS untuk jalur SIM800L (backend terpisah dari WiFi),
// jadi harus support plain HTTP di port 80 -- SIM800L via
// TinyGsmClient/HttpClient tidak bisa TLS/HTTPS.
const char GSM_SERVER[] = "sim.smartcollar.my.id";
const int  GSM_PORT     = 80;

// ======================================================
// KALIBRASI SENSOR
// ======================================================
const float TEMP_OFFSET = 2.0;

// ======================================================
// NTP CONFIG (fallback kalau device sedang pakai WiFi)
// ======================================================
const char* NTP_SERVER_1 = "pool.ntp.org";
const char* NTP_SERVER_2 = "time.google.com";
const long  GMT_OFFSET_SEC = 7 * 3600; // WIB = UTC+7
const int   DAYLIGHT_OFFSET_SEC = 0;
const unsigned long NTP_SYNC_TIMEOUT_MS = 10000;

// ======================================================
// TIMING
// ======================================================
const unsigned long SEND_INTERVAL_MS       = 1000; // kirim tiap 1 detik
const unsigned long WIFI_CONNECT_TIMEOUT_MS = 15000;
const unsigned long WIFI_RECONNECT_COOLDOWN_MS = 5000;

// ======================================================
// GLOBAL OBJECTS
// ======================================================
Adafruit_MLX90614 mlx;
Adafruit_MPU6050  mpu;
TinyGPSPlus        gps;

HardwareSerial SerialGPS(2);
HardwareSerial SerialSIM(1);

TinyGsm        modem(SerialSIM);
TinyGsmClient  gsmClient(modem);
HttpClient     gsmHttp(gsmClient, GSM_SERVER, GSM_PORT);

const unsigned long WIFI_HTTP_TIMEOUT_MS = 10000;

// ======================================================
// GLOBAL STATE
// ======================================================
float baseAccelX   = 0;
bool  simConnected  = false;

unsigned long lastSendMillis           = 0;
unsigned long lastWifiReconnectAttempt = 0;

// ======================================================
// STRUCT DATA SENSOR (biar gampang dibaca & di-passing)
// ======================================================
struct SensorReading {
  float  temperature;
  float  accelX;
  double latitude;
  double longitude;
  String linkMaps;
  int    signalStrength;
};

// ======================================================
// WIFI
// ======================================================
void connectWiFi() {

  Serial.println();
  Serial.println("CONNECT WIFI");

  WiFi.mode(WIFI_STA);
  WiFi.setSleep(false); // cegah ESP32 disconnect random akibat modem-sleep
  WiFi.begin(WIFI_SSID, WIFI_PASSWORD);

  unsigned long startAttempt = millis();

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

  Serial.println();

  if (WiFi.status() == WL_CONNECTED) {
    Serial.print("WIFI CONNECTED, IP: ");
    Serial.println(WiFi.localIP());
  } else {
    Serial.println("WIFI FAILED");
  }
}

// Reconnect non-blocking, dipanggil tiap loop() supaya WiFi yang
// putus di tengah jalan langsung dicoba nyambung lagi di background
// tanpa nge-block pembacaan sensor/GPS.
void reconnectWiFiIfNeeded() {

  if (WiFi.status() == WL_CONNECTED) {
    return;
  }

  unsigned long now = millis();

  if (now - lastWifiReconnectAttempt < WIFI_RECONNECT_COOLDOWN_MS) {
    return;
  }

  lastWifiReconnectAttempt = now;

  Serial.println();
  Serial.println("WIFI DISCONNECTED -> RECONNECT (background)");

  WiFi.reconnect();
}

// ======================================================
// SIM800L / GPRS
// ======================================================
bool connectSIM800() {

  Serial.println();
  Serial.println("INIT SIM800L");

  SerialSIM.begin(9600, SERIAL_8N1, SIM_RX, SIM_TX);
  delay(3000);

  if (!modem.restart()) {
    Serial.println("SIM800 NOT RESPOND");
    return false;
  }
  Serial.println("SIM800 OK");

  if (!modem.waitForNetwork()) {
    Serial.println("NETWORK FAILED");
    return false;
  }
  Serial.println("NETWORK OK");

  if (!modem.gprsConnect(APN, "", "")) {
    Serial.println("GPRS FAILED");
    return false;
  }

  Serial.print("GPRS CONNECTED, IP: ");
  Serial.println(modem.localIP());

  return true;
}

void reconnectSIM800() {

  if (!modem.isNetworkConnected()) {

    Serial.println();
    Serial.println("NETWORK LOST");

    if (modem.waitForNetwork()) {

      Serial.println("NETWORK RECONNECTED");

    } else {

      Serial.println("NETWORK FAILED");
    }
  }

  if (!modem.isGprsConnected()) {

    Serial.println();
    Serial.println("GPRS LOST");

    if (modem.gprsConnect(APN, "", "")) {

      Serial.println("GPRS RECONNECTED");

      simConnected = true;

    } else {

      Serial.println("GPRS FAILED");

      simConnected = false;
    }
  }
}

// ======================================================
// SYNC WAKTU (biar field "uptime" isinya Unix timestamp asli,
// sama seperti Date.now() di simulator -- bukan sekadar detik
// sejak boot / millis())
//
// CATATAN: sync waktu dari modem (AT+CCLK) SEMENTARA DINONAKTIFKAN
// karena gak semua provider SIM support & berisiko bikin proses
// nyangkut kalau modem/network gak respon sesuai harapan. Uptime
// akan fallback ke millis() kalau device cuma pakai SIM800L tanpa
// WiFi sama sekali -- gak ideal, tapi jauh lebih aman/stabil dulu
// sampai koneksi SIM800L ke backend beres.
// ======================================================

// Sync lewat NTP (butuh WiFi aktif)
bool syncTimeFromNTP() {

  Serial.println();
  Serial.println("SYNC WAKTU (NTP)...");

  configTime(GMT_OFFSET_SEC, DAYLIGHT_OFFSET_SEC, NTP_SERVER_1, NTP_SERVER_2);

  unsigned long startAttempt = millis();
  time_t now = time(nullptr);

  while (now < 1700000000 && millis() - startAttempt < NTP_SYNC_TIMEOUT_MS) {
    delay(300);
    Serial.print(".");
    now = time(nullptr);
  }

  Serial.println();

  if (now >= 1700000000) {
    Serial.print("WAKTU TERSINKRON DARI NTP: ");
    Serial.println(now);
    return true;
  }

  Serial.println("NTP SYNC GAGAL");
  return false;
}

// Coba sync waktu lewat NTP kalau WiFi aktif. Kalau device murni
// pakai SIM800L tanpa WiFi, uptime fallback ke millis() (lihat
// getUnixTimestamp() di bawah).
void syncTimeIfPossible() {

  if (WiFi.status() == WL_CONNECTED) {
    syncTimeFromNTP();
  } else {
    Serial.println();
    Serial.println("WIFI TIDAK AKTIF -- uptime pakai fallback millis()");
  }
}

// Ambil Unix timestamp (detik sejak epoch), sama format dengan
// Math.floor(Date.now() / 1000) di simulator.
unsigned long getUnixTimestamp() {

  time_t now = time(nullptr);

  if (now >= 1700000000) {
    return (unsigned long)now;
  }

  // Fallback kalau waktu belum/gagal sync sama sekali
  return millis() / 1000;
}

// ======================================================
// SENSOR SETUP
// ======================================================
void setupMPU() {
  mpu.setAccelerometerRange(MPU6050_RANGE_2_G);
  mpu.setFilterBandwidth(MPU6050_BAND_21_HZ);
}

void calibrateMPU() {
  sensors_event_t a, g, t;
  mpu.getEvent(&a, &g, &t);
  baseAccelX = a.acceleration.x;
}

// ======================================================
// SIGNAL STRENGTH
// ======================================================
int getSignalStrength() {

  if (WiFi.status() == WL_CONNECTED) {
    return WiFi.RSSI();
  }

  if (simConnected) {
    int csq = modem.getSignalQuality();
    return (csq == 99) ? -113 : (-113 + csq * 2);
  }

  return 0;
}

// ======================================================
// BACA SEMUA SENSOR
// ======================================================
SensorReading readSensors() {

  SensorReading reading;

  // Suhu
  float rawTemp = mlx.readObjectTempC();
  reading.temperature = isnan(rawTemp) ? 0 : rawTemp + TEMP_OFFSET;

  // Gerak (accelX mentah, status dihitung di backend)
  sensors_event_t a, g, t;
  mpu.getEvent(&a, &g, &t);
  reading.accelX = a.acceleration.x - baseAccelX;

  // GPS
  reading.latitude  = 0;
  reading.longitude = 0;
  reading.linkMaps  = "-";

  if (gps.location.isValid()) {
    reading.latitude  = gps.location.lat();
    reading.longitude = gps.location.lng();
    reading.linkMaps  = "https://www.google.com/maps?q=" +
                        String(reading.latitude, 6) + "," +
                        String(reading.longitude, 6);
  }

  // Sinyal
  reading.signalStrength = getSignalStrength();

  return reading;
}

// ======================================================
// BANGUN PAYLOAD JSON
// Struktur & nama field disamakan persis dengan simulator.
// ======================================================
String buildPayload(const SensorReading& reading) {

  StaticJsonDocument<512> doc;

  doc["serialNumber"] = SERIAL_NUMBER;
  doc["deviceSecret"] = DEVICE_SECRET;

  JsonObject device = doc.createNestedObject("device");
  device["signal"]          = reading.signalStrength;
  device["firmwareVersion"] = FIRMWARE_VERSION;
  device["hardwareVersion"] = HARDWARE_VERSION;
  device["uptime"]          = getUnixTimestamp();

  JsonObject sensor = doc.createNestedObject("sensor");
  sensor["temperature"] = round(reading.temperature * 100) / 100.0;

  JsonObject gpsObj = sensor.createNestedObject("gps");
  gpsObj["latitude"]  = reading.latitude;
  gpsObj["longitude"] = reading.longitude;
  gpsObj["linkMaps"]  = reading.linkMaps;

  JsonObject movement = sensor.createNestedObject("movement");
  movement["accelX"] = round(reading.accelX * 100) / 100.0;

  String payload;
  serializeJson(doc, payload);

  if (doc.overflowed()) {
    Serial.println();
    Serial.println("WARNING: JSON BUFFER OVERFLOW! Payload mungkin kepotong, perbesar StaticJsonDocument.");
  }

  return payload;
}

// ======================================================
// KIRIM VIA SIM800L
// return true kalau berhasil (statusCode > 0)
// ======================================================
bool sendViaSIM800(const String& payload) {

  Serial.println();
  Serial.println("---- KIRIM VIA SIM800L ----");
  Serial.print("Host   : ");
  Serial.println(GSM_SERVER);
  Serial.print("Path   : ");
  Serial.println(MONITORING_PATH);
  Serial.print("Payload: ");
  Serial.println(payload);

  gsmHttp.beginRequest();
  gsmHttp.post(MONITORING_PATH);
  gsmHttp.sendHeader("Content-Type", "application/json");
  gsmHttp.sendHeader("Content-Length", payload.length());
  gsmHttp.beginBody();
  gsmHttp.print(payload);
  gsmHttp.endRequest();

  int statusCode = gsmHttp.responseStatusCode();
  String response = gsmHttp.responseBody();

  Serial.print("Status Code : ");
  Serial.println(statusCode);
  Serial.print("Response    : ");
  Serial.println(response.length() > 0 ? response : "(kosong)");

  return statusCode > 0;
}

// ======================================================
// KIRIM VIA WIFI (HTTPS)
// ======================================================
bool sendViaWiFi(const String& payload) {

  if (WiFi.status() != WL_CONNECTED) {
    connectWiFi();
  }

  if (WiFi.status() != WL_CONNECTED) {
    Serial.println();
    Serial.println("NO INTERNET (WiFi gagal connect)");
    return false;
  }

  String url = String(WIFI_BASE_URL) + String(MONITORING_PATH);

  Serial.println();
  Serial.println("---- KIRIM VIA WIFI ----");
  Serial.print("URL    : ");
  Serial.println(url);
  Serial.print("Payload: ");
  Serial.println(payload);

  // ESP32 HTTPClient wajib pakai WiFiClientSecure untuk https,
  // kalau tidak, request bisa gagal diam-diam (httpCode negatif).
  WiFiClientSecure secureClient;
  secureClient.setInsecure();
  secureClient.setTimeout(WIFI_HTTP_TIMEOUT_MS);

  HTTPClient http;
  http.setTimeout(WIFI_HTTP_TIMEOUT_MS);
  http.setConnectTimeout(WIFI_HTTP_TIMEOUT_MS);
  http.begin(secureClient, url);
  http.addHeader("Content-Type", "application/json");

  int httpCode = http.POST(payload);

  Serial.print("HTTP Code : ");
  Serial.println(httpCode);

  bool success = httpCode > 0 && httpCode < 400;

  if (httpCode > 0) {
    String body = http.getString();
    Serial.print("Response  : ");
    Serial.println(body.length() > 0 ? body : "(kosong)");
  } else {
    Serial.print("HTTP Error: ");
    Serial.println(http.errorToString(httpCode));
  }

  http.end();

  return success;
}

// ======================================================
// KIRIM DATA — PRIORITAS SIM800L, FALLBACK WIFI
// ======================================================
void sendToBackend(const String& payload) {

  bool success = false;

  if (simConnected) {
    success = sendViaSIM800(payload);

    if (!success) {
      Serial.println();
      Serial.println("SIM800L GAGAL -> COBA WIFI");
    }
  }

  if (!success) {
    success = sendViaWiFi(payload);
  }

  Serial.println();
  if (success) {
    Serial.println("===== DATA BERHASIL TERKIRIM =====");
  } else {
    Serial.println("===== DATA GAGAL TERKIRIM (cek koneksi/backend) =====");
  }
}

// ======================================================
// SETUP
// ======================================================
void setup() {

  Serial.begin(115200);
  delay(3000);

  Serial.println();
  Serial.println("SMART COLLAR START");
  Serial.print("Serial Number : ");
  Serial.println(SERIAL_NUMBER);

  // Koneksi: prioritas SIM800L, fallback WiFi
  simConnected = connectSIM800();

  if (!simConnected) {
    connectWiFi();
  }

  syncTimeIfPossible();

  // I2C + sensor
  Wire.begin(SDA_PIN, SCL_PIN);

  Serial.println(mlx.begin() ? "MLX OK" : "MLX FAILED");

  if (mpu.begin()) {
    Serial.println("MPU OK");
    setupMPU();
    calibrateMPU();
  } else {
    Serial.println("MPU FAILED");
  }

  // GPS
  SerialGPS.begin(9600, SERIAL_8N1, GPS_RX, GPS_TX);
  Serial.println("GPS READY");
}

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

  reconnectSIM800();

  if (!simConnected) {
    reconnectWiFiIfNeeded();
  }

  // Update data GPS terus-menerus (non-blocking)
  while (SerialGPS.available()) {
    gps.encode(SerialGPS.read());
  }

  unsigned long currentMillis = millis();

  if (currentMillis - lastSendMillis < SEND_INTERVAL_MS) {
    return;
  }

  lastSendMillis = currentMillis;

  SensorReading reading = readSensors();
  String payload = buildPayload(reading);

  Serial.println();
  Serial.println(payload);

  sendToBackend(payload);
}