// ============================================
//   LINE FOLLOWING ROBOT — Arduino Uno
//   3 IR Sensors + L298N Motor Driver
//   Sensors: D2 (Left), D3 (Centre), D4 (Right)
//   Motor A (Left):  IN1=D5, IN2=D6,  ENA=D9
//   Motor B (Right): IN3=D7, IN4=D8,  ENB=D10
// ============================================

const int IR_LEFT   = 2;
const int IR_CENTRE = 3;
const int IR_RIGHT  = 4;

const int IN1 = 5;
const int IN2 = 6;
const int ENA = 9;

const int IN3 = 7;
const int IN4 = 8;
const int ENB = 10;

const int BASE_SPEED  = 150;
const int TURN_SPEED  = 100;
const int SHARP_SPEED = 60;

void setup() {
  pinMode(IR_LEFT,   INPUT);
  pinMode(IR_CENTRE, INPUT);
  pinMode(IR_RIGHT,  INPUT);
  pinMode(IN1, OUTPUT); pinMode(IN2, OUTPUT);
  pinMode(IN3, OUTPUT); pinMode(IN4, OUTPUT);
  pinMode(ENA, OUTPUT); pinMode(ENB, OUTPUT);
  Serial.begin(9600);
  delay(1000);
}

void loop() {
  bool L = (digitalRead(IR_LEFT)   == LOW);
  bool C = (digitalRead(IR_CENTRE) == LOW);
  bool R = (digitalRead(IR_RIGHT)  == LOW);

  if      (!L && C && !R) moveForward(BASE_SPEED,  BASE_SPEED);
  else if (!L && C &&  R) moveForward(BASE_SPEED,  TURN_SPEED);
  else if ( L && C && !R) moveForward(TURN_SPEED,  BASE_SPEED);
  else if (!L && !C && R) moveForward(BASE_SPEED,  SHARP_SPEED);
  else if ( L && !C && !R) moveForward(SHARP_SPEED, BASE_SPEED);
  else if ( L && C &&  R) moveForward(BASE_SPEED,  BASE_SPEED);
  else                     stopMotors();
}

void moveForward(int speedA, int speedB) {
  digitalWrite(IN1, HIGH); digitalWrite(IN2, LOW);
  analogWrite(ENA, speedA);
  digitalWrite(IN3, HIGH); digitalWrite(IN4, LOW);
  analogWrite(ENB, speedB);
}

void stopMotors() {
  digitalWrite(IN1, LOW); digitalWrite(IN2, LOW);
  digitalWrite(IN3, LOW); digitalWrite(IN4, LOW);
  analogWrite(ENA, 0);    analogWrite(ENB, 0);
}]
}