#include <WiFi.h>
#include <ThingSpeak.h>
#include <Wire.h>
#include <LiquidCrystal_I2C.h>

// ================= WIFI =================
const char* ssid = "Wokwi-GUEST";
const char* password = "";

WiFiClient client;

// ================= THINGSPEAK =================
unsigned long channelID = 3375446;
const char* writeAPI = "HB0HNJHYJR55UR0G";

// ================= LCD =================
LiquidCrystal_I2C lcd(0x27, 16, 2);

// ================= NORTH SIGNAL =================
#define N_RED     27
#define N_YELLOW  26
#define N_GREEN   25
#define N_TRIG    14
#define N_ECHO    12

// ================= SOUTH SIGNAL =================
#define S_RED     4
#define S_YELLOW  19
#define S_GREEN   17
#define S_TRIG    18
#define S_ECHO    5

// ================= BUZZER =================
#define BUZZER 33

// ================= DISTANCE FUNCTION =================
long getDistance(int trigPin, int echoPin) {

  digitalWrite(trigPin, LOW);
  delayMicroseconds(2);

  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);

  digitalWrite(trigPin, LOW);

  long duration = pulseIn(echoPin, HIGH);

  long distance = duration * 0.034 / 2;

  return distance;
}

void setup() {

  Serial.begin(115200);

  // LED Setup
  pinMode(N_RED, OUTPUT);
  pinMode(N_YELLOW, OUTPUT);
  pinMode(N_GREEN, OUTPUT);

  pinMode(S_RED, OUTPUT);
  pinMode(S_YELLOW, OUTPUT);
  pinMode(S_GREEN, OUTPUT);

  // Ultrasonic
  pinMode(N_TRIG, OUTPUT);
  pinMode(N_ECHO, INPUT);

  pinMode(S_TRIG, OUTPUT);
  pinMode(S_ECHO, INPUT);

  // Buzzer
  pinMode(BUZZER, OUTPUT);

  // LCD
  Wire.begin(21, 22);

  lcd.init();
  lcd.backlight();

  lcd.setCursor(0,0);
  lcd.print("Connecting WiFi");

  // WiFi Connect
  WiFi.begin(ssid, password);

  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
  }

  Serial.println("WiFi Connected");

  lcd.clear();
  lcd.setCursor(0,0);
  lcd.print("WiFi Connected");

  delay(2000);

  // ThingSpeak
  ThingSpeak.begin(client);
}

void loop() {

  // Distance Read
  long northDistance = getDistance(N_TRIG, N_ECHO);
  long southDistance = getDistance(S_TRIG, S_ECHO);

  String trafficStatus = "NORMAL";
  String buzzerStatus = "OFF";

  // Object Detection
  if (northDistance < 20 || southDistance < 20) {

    digitalWrite(BUZZER, HIGH);

    trafficStatus = "OBJECT DETECT";
    buzzerStatus = "ON";

    lcd.clear();

    lcd.setCursor(0,0);
    lcd.print("OBJECT DETECT");

    lcd.setCursor(0,1);
    lcd.print("BUZZER ON");

    delay(2000);
  }
  else {

    digitalWrite(BUZZER, LOW);
  }

  // ================= NORTH GREEN =================
  digitalWrite(N_GREEN, HIGH);
  digitalWrite(N_RED, LOW);

  digitalWrite(S_RED, HIGH);
  digitalWrite(S_GREEN, LOW);

  lcd.clear();

  lcd.setCursor(0,0);
  lcd.print("North Green");

  // Countdown
  for (int i = 20; i >= 1; i--) {

    lcd.setCursor(0,1);
    lcd.print("Timer: ");
    lcd.print(i);
    lcd.print("   ");

    delay(1000);
  }

  // NORTH YELLOW
  digitalWrite(N_GREEN, LOW);
  digitalWrite(N_YELLOW, HIGH);

  digitalWrite(BUZZER, HIGH);

  delay(2000);

  digitalWrite(BUZZER, LOW);

  digitalWrite(N_YELLOW, LOW);
  digitalWrite(N_RED, HIGH);

  // ================= SOUTH GREEN =================
  digitalWrite(S_RED, LOW);
  digitalWrite(S_GREEN, HIGH);

  lcd.clear();

  lcd.setCursor(0,0);
  lcd.print("South Green");

  // Countdown
  for (int i = 20; i >= 1; i--) {

    lcd.setCursor(0,1);
    lcd.print("Timer: ");
    lcd.print(i);
    lcd.print("   ");

    delay(1000);
  }

  // SOUTH YELLOW
  digitalWrite(S_GREEN, LOW);
  digitalWrite(S_YELLOW, HIGH);

  digitalWrite(BUZZER, HIGH);

  delay(2000);

  digitalWrite(BUZZER, LOW);

  digitalWrite(S_YELLOW, LOW);
  digitalWrite(S_RED, HIGH);

  // ================= SEND DATA TO THINGSPEAK =================

  ThingSpeak.setField(1, northDistance);
  ThingSpeak.setField(2, southDistance);
  ThingSpeak.setField(3, trafficStatus);
  ThingSpeak.setField(4, buzzerStatus);
  ThingSpeak.setField(5, "North Green");
  ThingSpeak.setField(6, "South Red");
  ThingSpeak.setField(7, "Vehicle Check");
  ThingSpeak.setField(8, "20 Sec Timer");

  int response = ThingSpeak.writeFields(channelID, writeAPI);

  if(response == 200) {
    Serial.println("Data Sent to ThingSpeak");
  }
  else {
    Serial.println("ThingSpeak Error");
  }

  delay(15000);
}