#include <Wire.h>
#include <LiquidCrystal_I2C.h>

// LCD address 0x27, 16 columns, 2 rows
LiquidCrystal_I2C lcd(0x27, 16, 2);

// Photodiode analog pins
const int leftSensorPin = A0;
const int rightSensorPin = A1;
const int upSensorPin = A2;
const int downSensorPin = A3;

// Stepper pins
const int dirPinH = 2;
const int stepPinH = 3;
const int dirPinV = 4;
const int stepPinV = 5;

const int stepDelay = 800;  // microseconds
const int threshold = 50;   // sensor difference threshold

void setup() {
  pinMode(dirPinH, OUTPUT);
  pinMode(stepPinH, OUTPUT);
  pinMode(dirPinV, OUTPUT);
  pinMode(stepPinV, OUTPUT);

  lcd.init();
  lcd.backlight();
  lcd.print("Dual Axis Tracker");
  delay(2000);
  lcd.clear();
}

void loop() {
  // Inverted readings: higher light = higher value
  int leftVal = 1023 - analogRead(leftSensorPin);
  int rightVal = 1023 - analogRead(rightSensorPin);
  int upVal = 1023 - analogRead(upSensorPin);
  int downVal = 1023 - analogRead(downSensorPin);

  // Horizontal control (corrected direction)
  if (abs(leftVal - rightVal) > threshold) {
    if (leftVal > rightVal) {
      moveStepper(dirPinH, stepPinH, false);  // Move LEFT
    } else {
      moveStepper(dirPinH, stepPinH, true);   // Move RIGHT
    }
  }

  // Vertical control (corrected direction)
  if (abs(upVal - downVal) > threshold) {
    if (upVal > downVal) {
      moveStepper(dirPinV, stepPinV, false);  // Move UP
    } else {
      moveStepper(dirPinV, stepPinV, true);   // Move DOWN
    }
  }

  // Display sensor values
  lcd.setCursor(0, 0);
  lcd.print("L:");
  lcd.print(leftVal);
  lcd.print(" R:");
  lcd.print(rightVal);

  lcd.setCursor(0, 1);
  lcd.print("U:");
  lcd.print(upVal);
  lcd.print(" D:");
  lcd.print(downVal);

  delay(200);
}

void moveStepper(int dirPin, int stepPin, bool direction) {
  digitalWrite(dirPin, direction ? HIGH : LOW);
  digitalWrite(stepPin, HIGH);
  delayMicroseconds(stepDelay);
  digitalWrite(stepPin, LOW);
  delayMicroseconds(stepDelay);
}