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

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

#define SCREEN_WIDTH 128
#define SCREEN_HEIGHT 64

const int buzzerPin = 4;                         // active buzzer, warns on colour change
const int redledPin = 5;                         // pedestrian LED (lit = safe to cross)
const int oledsdaPin = 8;                        // OLED I2C data pin
const int oledsclPin = 9;                        // OLED I2C clock pin
const int rgbPin_R = 14;                         // RGB LED - red channel
const int rgbPin_B = 17;                         // RGB LED - blue channel (unused, always LOW)
const int rgbPin_G = 18;                         // RGB LED - green channel

bool isRed = false;                              // global flag: true while the traffic light is red

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

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

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

  Wire.begin(oledsdaPin, oledsclPin);            // start I2C on custom pins
  display.begin(SSD1306_SWITCHCAPVCC, 0x3C);     // initialize OLED at I2C address 0x3C
  display.clearDisplay();                        // clear display buffer
  display.setTextColor(SSD1306_WHITE);           // set text color
  display.display();                             // apply initial blank screen
}

// ===== Function WITHOUT parameters =====
// Flashes the pedestrian LED and beeps the buzzer 4 times
void warnChange() {
  for (int i = 0; i < 4; i++) {
    digitalWrite(redledPin, HIGH);               // LED on
    tone(buzzerPin, 400);                        // beep on
    delay(200);
    digitalWrite(redledPin, LOW);                // LED off
    noTone(buzzerPin);                           // beep off
    delay(200);
  }
}

// ===== Function WITH parameters =====
// Turns on only the requested RGB colour(s) for onTime ms, then turns them off
void setTrafficLight(int redPin, int bluePin, int greenPin, int onTime) {
  isRed = redPin;                                // remember if red is on during this call
  digitalWrite(rgbPin_R, redPin);
  digitalWrite(rgbPin_B, bluePin);
  digitalWrite(rgbPin_G, greenPin);
  delay(onTime);                                 // keep the colour on for onTime ms
  digitalWrite(rgbPin_R, LOW);                   // turn everything off before returning
  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;                                  // reads the global flag set by setTrafficLight()
}

void loop() {
  // ---- GREEN (traffic) ----
  Serial.println("Phase: GREEN");
  display.clearDisplay();
  display.setTextSize(2);
  display.setCursor(0, 20);
  display.println("Stop!");                      // pedestrians must wait, cars are moving
  display.display();
  digitalWrite(redledPin, LOW);                  // pedestrian LED off (not safe yet)

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

  warnChange();                                  // warn: light is about to change

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

  warnChange();                                  // warn: about to turn red

  // ---- RED (traffic) ----
  Serial.println("Phase: RED");
  bool canCross = pedestrianCanCross();          // check if it's safe to cross
  display.clearDisplay();
  display.setTextSize(2);
  display.setCursor(0, 20);
  display.println(canCross ? "Go !" : "Stop!");  // show GO only when true
  display.display();
  digitalWrite(redledPin, canCross);             // pedestrian LED on (safe to cross)

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