// motors
#define MOT_A_ENB  5 // motor A enable and PWM/speed control ~
#define MOT_B_ENB  6 // motor B enable and PWM/speed control ~
#define MOT_A_FWD 10 // motor A forward ->
#define MOT_A_REV 11 // motor A <- reverse
#define MOT_B_FWD 12 // motor B forward ->
#define MOT_B_REV 13 // motor B <- reverse

#define LOW_SPEED  63 // PWM speed 0 - 255 ___
#define MED_SPEED 127 // PWM speed 0 - 255 ---
#define HI_SPEED  255 // PWM speed 0 - 255 ^^^
#define SPEED LOW_SPEED // set to low, med, hi

// line detectors
int Line_Detect_Right = 2; // Digital I/O pin means 1 or 0
int Line_Detect_Left = 3;
int val_Right  = 0;
int val_Center = 0;
int val_Left   = 0;

void setup() {
  Serial.begin(9600); // configure Serial Monitor for output

  pinMode(Line_Detect_Right, INPUT); // line detect right
  pinMode(Line_Detect_Left, INPUT); // line detect left

  pinMode(MOT_A_FWD, OUTPUT); // pin 10, motor A (usually IN3 with DC motors)
  pinMode(MOT_A_REV, OUTPUT); // pin 11, motor A (usually IN4 with DC motors)
  pinMode(MOT_B_FWD, OUTPUT); // pin 12, motor B (usually IN1 with DC motors)
  pinMode(MOT_B_REV, OUTPUT); // pin 13, motor B (usually IN2 with DC motors)

  pinMode(MOT_A_ENB, OUTPUT); // pin 4, motor A enable
  pinMode(MOT_B_ENB, OUTPUT); // pin 5, motro B enable
  digitalWrite(MOT_A_ENB, HIGH); // HIGH might be OFF
  digitalWrite(MOT_B_ENB, HIGH); // HIGH might be OFF

  Serial.println("########################################");
  Serial.println("# #");
  Serial.println("# Arduino Run #");
  Serial.println("# #");
  Serial.println("########################################");
  Serial.println(" --> Initial Pins");
}

void loop() {
  val_Right = digitalRead(Line_Detect_Right); // changed to digitalRead()
  val_Left  = digitalRead(Line_Detect_Left); // changed to digitalRead()

  Serial.print("Center = ");
  Serial.print(val_Center);
  Serial.print(" --> R = ");
  Serial.print(val_Right);
  Serial.print(" --> L = ");
  Serial.print(val_Left);

  if (val_Right == 1 && val_Left == 1) { // BOTH sensors detect black line
    Serial.print(" - Detect = L & R");
    Stop();
    delay(100);
  }

  else if (val_Right == 0 && val_Left == 0) { // BOTH sensors DO NOT detect a line
    Serial.print(" - Detect = CENTER");
    Forward();
    delay(100);
  }

  else if (val_Right == 1 && val_Left == 0) { // RIGHT sensor detects black line
    Serial.print(" - Detect = Right");
    Turn_Right();
    delay(100);
  }

  else if (val_Right == 0 && val_Left == 1) { // LEFT sensor detects black line
    Serial.print(" - Detect = Left");
    Turn_Left();
    delay(100);
  }

  Serial.println("\n");
  delay(160);
}

void Stop() {
  Serial.print(" --> Direction: STOP");
  digitalWrite(MOT_A_FWD, LOW); // motor A
  digitalWrite(MOT_A_REV, LOW);
  digitalWrite(MOT_B_FWD, LOW); // motor B is 180 degrees from motor A
  digitalWrite(MOT_B_REV, LOW);
  digitalWrite(MOT_A_ENB, LOW); // DISABLE motor A
  digitalWrite(MOT_B_ENB, LOW); // DISABLE motor B
}

void Forward() {
  Serial.print(" --> Direction: Forward");
  digitalWrite(MOT_A_FWD, HIGH); // motor A
  digitalWrite(MOT_A_REV, LOW);
  digitalWrite(MOT_B_FWD, HIGH); // motor B is 180 degrees from motor A
  digitalWrite(MOT_B_REV, LOW);
  analogWrite(MOT_A_ENB, SPEED); // PWM/speed for motor A
  analogWrite(MOT_B_ENB, SPEED); // PWM/speed for motor B
}

void Backward() {
  Serial.print(" --> Direction: Backward");
  digitalWrite(MOT_A_FWD, HIGH);
  digitalWrite(MOT_A_REV, LOW);
  digitalWrite(MOT_B_FWD, LOW);
  digitalWrite(MOT_B_REV, HIGH);
  analogWrite(MOT_A_ENB, SPEED);
  analogWrite(MOT_B_ENB, SPEED);
}

void Turn_Right() {
  Serial.print(" --> Direction: Turn Left");
  digitalWrite(MOT_A_FWD, LOW); // motor A fowrward
  digitalWrite(MOT_A_REV, HIGH);
  digitalWrite(MOT_B_FWD, HIGH); // motor B reverse
  digitalWrite(MOT_B_REV, LOW);
  analogWrite(MOT_A_ENB, SPEED);
  analogWrite(MOT_B_ENB, SPEED);
}

void Turn_Left() {
  Serial.print(" --> Direction: Turn Right");
  digitalWrite(MOT_A_FWD, HIGH); // motor A reverse
  digitalWrite(MOT_A_REV, LOW);
  digitalWrite(MOT_B_FWD, LOW); // motor B forward
  digitalWrite(MOT_B_REV, HIGH);
  analogWrite(MOT_A_ENB, SPEED);
  analogWrite(MOT_B_ENB, SPEED);
}