/*
  Drifting Water Quality Monitor - Wokwi Test Version
  Board: ESP32 DevKit
  Fungsi simulasi:
  - Baca pH, turbidity, TDS dari potensiometer analog
  - Baca suhu dari DS18B20
  - Baca GPS dari NEO-6M/Wokwi GPS melalui Serial2
  - Simpan data CSV ke microSD
  - Simulasi kirim LoRa melalui Serial Monitor

  Catatan:
  Modul LoRa RA-02 SX1278 tidak selalu tersedia sebagai simulasi penuh di Wokwi.
  Karena itu, transmisi LoRa disimulasikan dengan Serial.println("[LoRa TX] ...").
*/

#include <Arduino.h>
#include <SPI.h>
#include <SD.h>
#include <OneWire.h>
#include <DallasTemperature.h>
#include <TinyGPS++.h>

// ======================= PIN SETUP =======================
// Sensor analog disimulasikan memakai potentiometer/slider
#define PH_PIN        34
#define TURB_PIN      35
#define TDS_PIN       32

// DS18B20
#define ONE_WIRE_BUS  4

// GPS UART2
#define GPS_RX_PIN    16   // ESP32 RX2, sambung ke TX GPS
#define GPS_TX_PIN    17   // ESP32 TX2, sambung ke RX GPS
#define GPS_BAUD      9600

// microSD SPI
#define SD_CS         5
#define SD_SCK        18
#define SD_MISO       19
#define SD_MOSI       23

// LoRa RA-02 SX1278, wiring fisik asli
// Catatan: pada simulasi ini belum dipakai karena LoRa disimulasikan via Serial.
#define LORA_SCK      18
#define LORA_MISO     19
#define LORA_MOSI     23
#define LORA_NSS      15
#define LORA_RST      14
#define LORA_DIO0     26

// ======================= OBJECTS =======================
OneWire oneWire(ONE_WIRE_BUS);
DallasTemperature ds18b20(&oneWire);
TinyGPSPlus gps;

// ======================= VARIABLES =======================
unsigned long lastSample = 0;
const unsigned long sampleIntervalMs = 1000;

uint32_t recordId = 0;
const char* logFile = "/waterlog.csv";

// ======================= HELPER FUNCTIONS =======================
float readVoltage(int pin) {
  int adc = analogRead(pin);             // 0 - 4095
  return (adc / 4095.0) * 3.3;           // simulasi 0 - 3.3 V
}

float simulatePH(float voltage) {
  // Simulasi rentang pH 0 - 14 dari tegangan 0 - 3.3 V.
  // Untuk alat asli, harus diganti persamaan kalibrasi sensor pH.
  return (voltage / 3.3) * 14.0;
}

float simulateTurbidity(float voltage) {
  // Simulasi NTU: makin tinggi tegangan, makin tinggi kekeruhan.
  // Untuk alat asli, perlu kalibrasi terhadap standar NTU.
  return (voltage / 3.3) * 1000.0;
}

float simulateTDS(float voltage) {
  // Simulasi ppm.
  // Untuk alat asli, pakai formula sensor TDS dan kompensasi suhu.
  return (voltage / 3.3) * 1000.0;
}

float readTemperatureC() {
  ds18b20.requestTemperatures();
  float t = ds18b20.getTempCByIndex(0);
  if (t == DEVICE_DISCONNECTED_C) return NAN;
  return t;
}

String gpsTimestamp() {
  if (gps.date.isValid() && gps.time.isValid()) {
    char buf[25];
    snprintf(
      buf, sizeof(buf),
      "%04d-%02d-%02d %02d:%02d:%02d",
      gps.date.year(), gps.date.month(), gps.date.day(),
      gps.time.hour(), gps.time.minute(), gps.time.second()
    );
    return String(buf);
  }
  // fallback jika GPS belum fix
  return String(millis() / 1000);
}

void feedGPS() {
  while (Serial2.available() > 0) {
    gps.encode(Serial2.read());
  }
}

void initSD() {
  SPI.begin(SD_SCK, SD_MISO, SD_MOSI, SD_CS);

  if (!SD.begin(SD_CS)) {
    Serial.println("ERROR: microSD gagal diinisialisasi.");
    return;
  }

  if (!SD.exists(logFile)) {
    File f = SD.open(logFile, FILE_WRITE);
    if (f) {
      f.println("id,timestamp,lat,lon,sat,ph,temp_c,turbidity_ntu,tds_ppm,battery_percent,upload_status");
      f.close();
    }
  }

  Serial.println("microSD siap.");
}

bool appendLog(const String& line) {
  File f = SD.open(logFile, FILE_APPEND);
  if (!f) {
    Serial.println("ERROR: gagal membuka file log.");
    return false;
  }
  f.println(line);
  f.close();
  return true;
}

void simulateLoRaSend(const String& payload) {
  // Ganti fungsi ini dengan LoRa.beginPacket(), LoRa.print(), LoRa.endPacket()
  // ketika memakai modul RA-02 asli.
  Serial.print("[LoRa TX] ");
  Serial.println(payload);
}

void setup() {
  Serial.begin(115200);
  delay(1000);

  Serial.println();
  Serial.println("=== Drifting Water Quality Monitor - Wokwi Test ===");

  analogReadResolution(12);
  ds18b20.begin();

  Serial2.begin(GPS_BAUD, SERIAL_8N1, GPS_RX_PIN, GPS_TX_PIN);

  initSD();

  Serial.println("Sistem mulai. Data dibaca setiap 1 detik.");
}

void loop() {
  feedGPS();

  if (millis() - lastSample >= sampleIntervalMs) {
    lastSample = millis();
    recordId++;

    float phV = readVoltage(PH_PIN);
    float turbV = readVoltage(TURB_PIN);
    float tdsV = readVoltage(TDS_PIN);

    float ph = simulatePH(phV);
    float turbidity = simulateTurbidity(turbV);
    float tds = simulateTDS(tdsV);
    float tempC = readTemperatureC();

    double lat = gps.location.isValid() ? gps.location.lat() : 0.0;
    double lon = gps.location.isValid() ? gps.location.lng() : 0.0;
    int sat = gps.satellites.isValid() ? gps.satellites.value() : 0;

    // Simulasi baterai tetap 85%.
    int battery = 85;

    String timestamp = gpsTimestamp();

    char csv[240];
    snprintf(
      csv, sizeof(csv),
      "%lu,%s,%.6f,%.6f,%d,%.2f,%.2f,%.1f,%.1f,%d,pending",
      (unsigned long)recordId,
      timestamp.c_str(),
      lat,
      lon,
      sat,
      ph,
      tempC,
      turbidity,
      tds,
      battery
    );

    String line = String(csv);

    appendLog(line);

    // Payload LoRa dibuat pendek.
    char payload[180];
    snprintf(
      payload, sizeof(payload),
      "%lu,%s,%.6f,%.6f,%.2f,%.1f,%.0f,%.0f,%d",
      (unsigned long)recordId,
      timestamp.c_str(),
      lat,
      lon,
      ph,
      tempC,
      turbidity,
      tds,
      battery
    );

    simulateLoRaSend(String(payload));
  }
}