#include <OneWire.h>
#include <DallasTemperature.h>
#include <math.h>

// === Pin Assignments ===
#define PIN_ABSORB   6   // LDR AO for Absorbance
#define PIN_FLUOR    5   // LDR AO for Fluorescence
#define PIN_TURBID   4   // LDR AO for Turbidity
#define PIN_PH       7   // Potentiometer simulating pH
#define PIN_SAL      15  // Potentiometer simulating Salinity
#define PIN_TEMP     16  // DS18B20 Data pin

// === LED Pins for Optical Sources ===
#define LED_ABSORB   21
#define LED_FLUOR    20
#define LED_TURBID   19

// === DS18B20 Setup ===
OneWire oneWire(PIN_TEMP);
DallasTemperature tempSensor(&oneWire);

// === Smoothing function (EMA) ===
float smooth(float prev, float sample, float alpha = 0.1) {
  return prev + alpha * (sample - prev);
}

// === Variables to hold smoothed readings ===
float absorbSm = 0, fluorSm = 0, turbidSm = 0, phSm = 0, salSm = 0;

// === Calibration constants ===
float baselineAbsorb = 3000; // Blank reference ADC for absorbance

void setup() {
  Serial.begin(115200);
  tempSensor.begin();

  // Setup LEDs as outputs
  pinMode(LED_ABSORB, OUTPUT);
  pinMode(LED_FLUOR, OUTPUT);
  pinMode(LED_TURBID, OUTPUT);

  // Turn LEDs ON (continuous light sources)
  digitalWrite(LED_ABSORB, HIGH);
  digitalWrite(LED_FLUOR, HIGH);
  digitalWrite(LED_TURBID, HIGH);
}

void loop() {
  // === Read Analog Sensors ===
  int rawAbsorb = analogRead(PIN_ABSORB);
  int rawFluor  = analogRead(PIN_FLUOR);
  int rawTurbid = analogRead(PIN_TURBID);
  int rawPH     = analogRead(PIN_PH);
  int rawSal    = analogRead(PIN_SAL);

  // === Apply smoothing ===
  absorbSm = smooth(absorbSm, rawAbsorb);
  fluorSm  = smooth(fluorSm,  rawFluor);
  turbidSm = smooth(turbidSm, rawTurbid);
  phSm     = smooth(phSm,     rawPH);
  salSm    = smooth(salSm,    rawSal);

  // === Convert to Engineering Units ===
  // Absorbance (A = -log10(I/I0))
  float T = (baselineAbsorb > 0) ? absorbSm / baselineAbsorb : 1;
  if (T <= 0) T = 1e-6;
  float absorbance = -log10(T);

  // Fluorescence (%)
  float fluorescence = map(fluorSm, 0, 4095, 0, 100);

  // Turbidity (mock NTU)
  float turbidity = map(turbidSm, 0, 4095, 0, 1000);

  // pH (mock 0–14)
  float pH = map(phSm, 0, 4095, 0, 140) / 10.0;

  // Salinity (mock PSU 0–50)
  float salinity = map(salSm, 0, 4095, 0, 50);

  // Temperature (real DS18B20)
  tempSensor.requestTemperatures();
  float tempC = tempSensor.getTempCByIndex(0);

  // === Print list with units ===
  Serial.println("---- Sensor Readings ----");
  Serial.print("Absorbance: "); Serial.print(absorbance, 3); Serial.println(" A (dimensionless)");
  Serial.print("Fluorescence: "); Serial.print(fluorescence, 1); Serial.println(" %");
  Serial.print("Turbidity: "); Serial.print(turbidity, 1); Serial.println(" NTU");
  Serial.print("pH: "); Serial.println(pH, 2);
  Serial.print("Salinity: "); Serial.print(salinity, 1); Serial.println(" PSU");
  Serial.print("Temperature: "); Serial.print(tempC, 2); Serial.println(" °C");
  Serial.println("-------------------------\n");

  delay(1000); // 1s update
}