/*
==== Task 6 - Miniature Traffic-Light System ====
                 Author: AI
*/

#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>

#define SCREEN_WIDTH 128
#define SCREEN_HEIGHT 64

const int buzzerPin = 4;
const int redledPin = 5;     // pedestrian LED - RED (stop)
const int greenledPin = 7;   // pedestrian LED - GREEN (go)
const int oledsdaPin = 8;
const int oledsclPin = 9;
const int rgbPin_R = 14;
const int rgbPin_B = 17;
const int rgbPin_G = 18;

bool isRed = false;   // global: remembers whether the traffic light is currently red

Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, -1);

void setup() {
  Serial.begin(115200);
  Serial.println("Hello, ESP32-S3!");

  pinMode(buzzerPin, OUTPUT);
  pinMode(redledPin, OUTPUT);
  pinMode(greenledPin, OUTPUT);
  pinMode(rgbPin_R, OUTPUT);
  pinMode(rgbPin_B, OUTPUT);
  pinMode(rgbPin_G, OUTPUT);

  Wire.begin(oledsdaPin, oledsclPin);
  display.begin(SSD1306_SWITCHCAPVCC, 0x3C);
  display.clearDisplay();
  display.setTextColor(SSD1306_WHITE);
  display.display();
}

// ===== Function WITHOUT parameters =====
// Beeps the buzzer once and briefly flashes the pedestrian RED LED
void warnChange() {
  for (int i = 0; i < 4; i++) {
    digitalWrite(redledPin, HIGH);
    delay(200);
    digitalWrite(redledPin, LOW);
    delay(200);
  }
  tone(buzzerPin, 400);
  delay(1000);
  noTone(buzzerPin);
}

// ===== New function WITHOUT parameters =====
// Blinks the pedestrian RED LED and shows "WARNING" on the OLED,
// used once at the start of each cycle before the traffic light turns green
void warningAlert() {
  for (int i = 0; i < 4; i++) {
    digitalWrite(redledPin, HIGH);
    display.clearDisplay();
    display.setTextSize(2);
    display.setCursor(20, 20);
    display.println("Warning!");
    display.display();
    delay(200);

    digitalWrite(redledPin, LOW);
    display.clearDisplay();
    display.display();
    delay(200);
  }
}

// ===== Function WITH parameters =====
// Turns on only the correct RGB pin(s) for onTime ms, then turns them off
void setTrafficLight(int redPin, int bluePin, int greenPin, int onTime) {
  digitalWrite(rgbPin_R, redPin);
  digitalWrite(rgbPin_B, bluePin);
  digitalWrite(rgbPin_G, greenPin);
  delay(onTime);
  digitalWrite(rgbPin_R, LOW);
  digitalWrite(rgbPin_B, LOW);
  digitalWrite(rgbPin_G, LOW);
}

// ===== Function WITH a return value (no parameters) =====
// Returns true while the traffic light is red (safe to cross)
bool pedestrianCanCross() {
  return isRed;
}

void loop() {
  // ---- WARNING (once, before the cycle starts) ----
  warningAlert();

  // ---- GREEN (traffic) ----
  isRed = false;
  digitalWrite(redledPin, HIGH);     // pedestrian: STOP
  digitalWrite(greenledPin, LOW);
  display.clearDisplay();
  display.setTextSize(2);
  display.setCursor(25, 20);
  display.println("STOP!");
  display.display();

  setTrafficLight(LOW, LOW, HIGH, 5000);   // green on for 5s
  delay(10);

  // ---- YELLOW (traffic) ----
  setTrafficLight(HIGH, LOW, HIGH, 1500);  // red+green (yellow) for 1.5s
  delay(10);

  digitalWrite(rgbPin_R, HIGH);       // keep yellow visible during the warning
  digitalWrite(rgbPin_G, HIGH);
  warnChange();
  digitalWrite(rgbPin_R, LOW);
  digitalWrite(rgbPin_G, LOW);
  digitalWrite(redledPin, HIGH);

  // ---- RED (traffic) ----
  isRed = true;                        // set BEFORE turning the light red
  bool canCross = pedestrianCanCross();

  digitalWrite(redledPin, !canCross);   // red pedestrian LED off (safe to cross)
  digitalWrite(greenledPin, canCross);  // green pedestrian LED on

  display.clearDisplay();
  display.setTextSize(2);
  display.setCursor(20, 20);
  display.println(canCross ? "Go!" : "STOP!");
  display.display();

  setTrafficLight(HIGH, LOW, LOW, 5000);   // red on for 5s (pedestrian green + "GO" already showing)
  delay(10);
}