#define PIN_CAR_RED     12
#define PIN_CAR_YELLOW  13
#define PIN_CAR_GREEN   14
#define PIN_PED_RED     25
#define PIN_PED_GREEN   26
#define PIN_BUTTON      0
#define PIN_TRIG        17
#define PIN_ECHO        16

const unsigned long TIME_CAR_GREEN_NORMAL  = 10000;
const unsigned long TIME_CAR_GREEN_HEAVY   = 20000;
const unsigned long TIME_CAR_YELLOW        = 2000;
const unsigned long TIME_CAR_RED           = 8000;
const unsigned long TIME_PED_GREEN_NORMAL  = 8000;
const unsigned long TIME_PED_GREEN_HEAVY   = 4000;
const unsigned long TIME_ALL_RED           = 1000;

const int DISTANCE_HEAVY_TRAFFIC = 50;  // см

bool pedestrianRequest = false;
bool heavyTraffic = false;
String currentMode = "NORMAL";

enum State { ST_CAR_GREEN, ST_CAR_YELLOW, ST_CAR_RED_PED_GREEN, ST_CAR_RED_PED_RED };
State currentState = ST_CAR_GREEN;

void setup() {
  Serial.begin(115200);
  
  pinMode(PIN_CAR_RED, OUTPUT);
  pinMode(PIN_CAR_YELLOW, OUTPUT);
  pinMode(PIN_CAR_GREEN, OUTPUT);
  pinMode(PIN_PED_RED, OUTPUT);
  pinMode(PIN_PED_GREEN, OUTPUT);
  pinMode(PIN_BUTTON, INPUT_PULLUP);
  pinMode(PIN_TRIG, OUTPUT);
  pinMode(PIN_ECHO, INPUT);
  
  setCarLights(LOW, LOW, HIGH);
  setPedLights(HIGH, LOW);
  
  Serial.println(" Светофор запущен!");
  printStatus();
}

void loop() {
  checkButton();
  checkTraffic();
  runStateMachine();
  delay(100);
}


void checkButton() {
  if (digitalRead(PIN_BUTTON) == LOW) {
    delay(50);
    if (digitalRead(PIN_BUTTON) == LOW && !pedestrianRequest) {
      pedestrianRequest = true;
      Serial.println(" Pedestrian button: PRESSED");
      while (digitalRead(PIN_BUTTON) == LOW) delay(10);
    }
  }
}

int measureDistance() {
  digitalWrite(PIN_TRIG, LOW);
  delayMicroseconds(2);
  digitalWrite(PIN_TRIG, HIGH);
  delayMicroseconds(10);
  digitalWrite(PIN_TRIG, LOW);
  
  long duration = pulseIn(PIN_ECHO, HIGH, 30000);
  if (duration == 0) return 999;
  return duration * 0.034 / 2;
}

void checkTraffic() {
  int d = measureDistance();
  bool newHeavy = (d < DISTANCE_HEAVY_TRAFFIC);
  if (newHeavy != heavyTraffic) {
    heavyTraffic = newHeavy;
    Serial.println(String(" Cars: ") + (heavyTraffic ? "HEAVY TRAFFIC" : "LIGHT TRAFFIC"));
    currentMode = heavyTraffic ? "EXTENDED GREEN" : "NORMAL";
    printStatus();
  }
}

void runStateMachine() {
  unsigned long tGreen = heavyTraffic ? TIME_CAR_GREEN_HEAVY : TIME_CAR_GREEN_NORMAL;
  unsigned long tPed = heavyTraffic ? TIME_PED_GREEN_HEAVY : TIME_PED_GREEN_NORMAL;
  
  switch (currentState) {
    
    case ST_CAR_GREEN: {  
      setCarLights(LOW, LOW, HIGH);
      setPedLights(HIGH, LOW);
      
      unsigned long startGreen = millis();
      while (millis() - startGreen < tGreen) {
        checkButton();
        delay(100);
      }
      
      Serial.println(" Car: YELLOW");
      currentState = ST_CAR_YELLOW;
      break;
    }  
    
    case ST_CAR_YELLOW: {
      setCarLights(LOW, HIGH, LOW);
      setPedLights(HIGH, LOW);
      delay(TIME_CAR_YELLOW);
      
      Serial.println(" Car: RED /  Ped: GREEN");
      currentState = ST_CAR_RED_PED_GREEN;
      break;
    }
    
    case ST_CAR_RED_PED_GREEN: {
      setCarLights(HIGH, LOW, LOW);
      
      if (pedestrianRequest || heavyTraffic) {
        setPedLights(LOW, HIGH);
        delay(tPed);
        pedestrianRequest = false;
        Serial.println(" Pedestrian: GREEN (served)");
      } else {
        setPedLights(HIGH, LOW);
        Serial.println(" Pedestrian: skipped");
      }
      
      currentState = ST_CAR_RED_PED_RED;
      break;
    }
    
    case ST_CAR_RED_PED_RED: {
      setCarLights(HIGH, LOW, LOW);
      setPedLights(HIGH, LOW);
      delay(TIME_ALL_RED);
      
      Serial.println(" Cycle restart: Car GREEN");
      printStatus();
      currentState = ST_CAR_GREEN;
      break;
    }
  }
}

void setCarLights(bool r, bool y, bool g) {
  digitalWrite(PIN_CAR_RED, r ? HIGH : LOW);
  digitalWrite(PIN_CAR_YELLOW, y ? HIGH : LOW);
  digitalWrite(PIN_CAR_GREEN, g ? HIGH : LOW);
}

void setPedLights(bool r, bool g) {
  digitalWrite(PIN_PED_RED, r ? HIGH : LOW);
  digitalWrite(PIN_PED_GREEN, g ? HIGH : LOW);
}

void printStatus() {
  Serial.println("═══════════════════════════");
  Serial.print("Cars: ");
  Serial.println(heavyTraffic ? "HEAVY TRAFFIC" : "LIGHT TRAFFIC");
  Serial.print("Pedestrian button: ");
  Serial.println(pedestrianRequest ? "PRESSED" : "NOT PRESSED");
  Serial.print("Mode: ");
  Serial.println(currentMode);
  Serial.println("═══════════════════════════");
}