// Dynamically manages a 4-way intersection based on real-time vehicle density
 
#include <Wire.h>
#include <LiquidCrystal_I2C.h>
 
// ----- IR Sensor Pins -----
const int irSensors[4] = {22, 23, 24, 25};
 
// ----- LED Pins: {Red, Yellow, Green} per lane -----
const int laneLEDs[4][3] = {
  {2, 3, 4},
  {5, 6, 7},
  {8, 9, 10},
  {11, 12, 13}
};
 
const int emergencyButton = 26;
 
LiquidCrystal_I2C lcd(0x27, 16, 2);
 
const int baseGreenTime = 5000;   // Minimum green light duration (ms)
const int extraTimePerVehicle = 2000; // Extra green time per detected vehicle
 
void setup() {
  for (int i = 0; i < 4; i++) {
	pinMode(irSensors[i], INPUT);
	for (int j = 0; j < 3; j++) {
  	pinMode(laneLEDs[i][j], OUTPUT);
	}
  }
  pinMode(emergencyButton, INPUT_PULLUP);
 
  lcd.init();
  lcd.backlight();
  lcd.print("Traffic Control");
 
  Serial1.begin(9600); // Hardware serial to ESP8266
  Serial.begin(9600);
  delay(1500);
  allRed();
}
 
void loop() {
  // Check for emergency override first
  if (digitalRead(emergencyButton) == LOW) {
	handleEmergency();
	return;
  }
 
  // Cycle through each lane based on detected density
  for (int lane = 0; lane < 4; lane++) {
	int density = readLaneDensity(lane);
	int greenDuration = baseGreenTime + (density * extraTimePerVehicle);
 
	runLaneCycle(lane, greenDuration);
	sendToCloud(lane, density);
  }
}
 
// Reads how many times the IR sensor detects a vehicle over a short sampling window
int readLaneDensity(int lane) {
  int count = 0;
  for (int i = 0; i < 5; i++) {
	if (digitalRead(irSensors[lane]) == LOW) count++;
	delay(100);
  }
  return count;
}
 
// Runs the full Red -> Green -> Yellow -> Red cycle for one lane
void runLaneCycle(int activeLane, int greenDuration) {
  allRed();
 
  digitalWrite(laneLEDs[activeLane][0], LOW);  // Turn off Red
  digitalWrite(laneLEDs[activeLane][2], HIGH); // Turn on Green
 
  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print("Lane " + String(activeLane + 1) + ": GREEN");
  delay(greenDuration);
 
  digitalWrite(laneLEDs[activeLane][2], LOW);  // Turn off Green
  digitalWrite(laneLEDs[activeLane][1], HIGH); // Turn on Yellow
  delay(2000);
  digitalWrite(laneLEDs[activeLane][1], LOW);  // Turn off Yellow
 
  allRed();
}
 
// Sets every lane's signal to Red as the default safe state
void allRed() {
  for (int i = 0; i < 4; i++) {
	digitalWrite(laneLEDs[i][0], HIGH); // Red ON
	digitalWrite(laneLEDs[i][1], LOW);  // Yellow OFF
	digitalWrite(laneLEDs[i][2], LOW);  // Green OFF
  }
}
 
// Immediately grants green to a manually selected emergency lane (Lane 1 as default)
void handleEmergency() {
  lcd.clear();
  lcd.print("EMERGENCY MODE");
  runLaneCycle(0, 8000); // Default emergency priority lane; customize as needed
}
 
// Sends the current lane and its detected density to the cloud dashboard
void sendToCloud(int lane, int density) {
  Serial1.print("Lane"); Serial1.print(lane + 1);
  Serial1.print(":"); Serial1.println(density); // ESP8266 forwards this to ThingSpeak/Blynk
}