int cathode[] = {10, 11, 13, 12};
int anode[] = {6, 7, 8, 9};
int button[] = {2, 3, 4, 5};

#define WHT 0
#define RED 1
#define YEL 2
#define GRN 3

#define E 0
#define N 1
#define W 2
#define S 3

unsigned long normalTimer, normalTimeout = 1000;
unsigned long buttonTimer[4], buttonTimeout = 50;
int trafficState, buttonRead, buttonState[4], buttonStateOld[4];

unsigned long walkTimer, walkTimeout = 500;
bool walkPressed = false;

void setup() {
  Serial.begin(115200);
  pinMode(LED_BUILTIN, OUTPUT);

  for (int i = 0; i < 4; i++) {
    pinMode(anode[i], OUTPUT);
    digitalWrite(anode[i], LOW); // reverse bias
    pinMode(cathode[i], OUTPUT);
    digitalWrite(cathode[i], HIGH); // reverse bias
    pinMode(button[i], INPUT_PULLUP);
  }
}

void loop() {
  // testLEDs();
  // testButtons();
  //===============

  int direction = readButtons();
  if (walkPressed) {
    walk(direction);
  }
}

void walk(int dir) {
  // yel ON
  for (int i = 0; i < 4; i++) {
    ledON(YEL, i); // anode, cathode
  }

  delay(1000);

  // grn OFF
  ledOFF(GRN, E);
  ledOFF(GRN, N);
  ledOFF(GRN, W);
  ledOFF(GRN, S);

  delay(1000);

  // red ON
  ledON(RED, E);
  ledON(RED, N);
  ledON(RED, W);
  ledON(RED, S);

  while (1);

  // yel OFF
  ledOFF(YEL, E);
  ledOFF(YEL, N);
  ledOFF(YEL, W);
  ledOFF(YEL, S);

  if (dir == 1 || dir == 3) {
    // walk ON
    ledON(WHT, N);
    ledON(WHT, S);
  } else {
    // walk OFF
    ledON(WHT, E);
    ledON(WHT, W);
  }
}

void ledON (int an, int ca) {
  digitalWrite(anode[an], HIGH);
  digitalWrite(cathode[ca], LOW);
}

void ledOFF (int an, int ca) {
  digitalWrite(cathode[ca], HIGH);
  digitalWrite(anode[an], HIGH);
}

int readButtons() {
  for (int b = 0; b < 4; b++) {
    buttonRead = digitalRead(button[b]);
    if (buttonRead != buttonStateOld[b]) {
      buttonTimer[b] = millis();
    }
    if (millis() - buttonTimer[b] > buttonTimeout) {
      if (buttonRead != buttonState[b]) {
        buttonState[b] = buttonRead;
        if (buttonState[b] == LOW)  // button pressed
          walkPressed = true;
      }
    }
    buttonStateOld[b] = buttonRead;
  }
}

void normalflow() {
  // RED (3) >> RED/YEL (1) >> GRN (3) >> GRN/YEL (1) >>
  if (millis() - normalTimer > normalTimeout) {
    trafficState++;
    if (trafficState > 5)
      trafficState = 0;
  }

  switch (trafficState) {
    case 0: {
        digitalWrite(cathode[0], HIGH);
        digitalWrite(anode[0], LOW);
        digitalWrite(cathode[0], HIGH);
        digitalWrite(anode[0], LOW);
      }
  }
}

void testButtons() {
  for (int b = 0; b < 4; b++) {
    if (digitalRead(button[b]) == 0) {
      for (int i = 0; i < 4; i++) { // LEDs ON
        digitalWrite(anode[i], HIGH); // all anodes forward bias
        digitalWrite(cathode[b], LOW); // only button cathodes forward bias
      }
    } else {
      for (int i = 0; i < 4; i++) { // LEDs OFF
        digitalWrite(anode[i], LOW); // all anodes reverse bias
        digitalWrite(cathode[b], HIGH); // only button cathode reverse bias
      }
    }
  }
}

void testLEDs() {
  int dly = 100;
  for (int a = 0; a < 4; a++) {
    delay(dly);
    digitalWrite(anode[a], HIGH); // forward bias anodes
    for (int c = 0; c < 4; c++) {
      delay(dly);
      digitalWrite(cathode[c], LOW); // LED ON - forward bias cathode
      delay(dly);
      digitalWrite(cathode[c], HIGH); // LED OFF - reverse bias cathode
    }
    digitalWrite(anode[a], LOW); // reverse bias anodes
  }
}