// ============================================
// Smart Street Light System
// Microcontroller: STM32 NUCLEO C031C6
// Added: LCD Display
// Simulator: Wokwi
// ============================================

#include <LiquidCrystal.h>

// ---- Pin Definitions ----
#define LDR_PIN    A0    // LDR Analog input
#define PIR_PIN    D2    // PIR Digital input
#define LED1_PIN   D3    // Street Light 1
#define LED2_PIN   D4    // Street Light 2
#define LED3_PIN   D5    // Street Light 3
#define LED4_PIN   D6    // Street Light 4

// LCD Pins (RS, EN, D4, D5, D6, D7)
LiquidCrystal lcd(D8, D9, D10, D11, D12, D13);

// ---- Threshold ----
#define LIGHT_THRESHOLD  512
#define MOTION_DELAY     5000

// ---- Variables ----
int ldrValue = 0;
int pirValue = 0;
bool isDark = false;
bool motionDetected = false;
unsigned long lastMotionTime = 0;

void setup() {
  Serial.begin(9600);

  // LED pins
  pinMode(LED1_PIN, OUTPUT);
  pinMode(LED2_PIN, OUTPUT);
  pinMode(LED3_PIN, OUTPUT);
  pinMode(LED4_PIN, OUTPUT);

  // PIR pin
  pinMode(PIR_PIN, INPUT);

  // LCD Setup
  lcd.begin(16, 2);
  lcd.clear();

  // Welcome message on LCD
  lcd.setCursor(0, 0);
  lcd.print("Smart Street");
  lcd.setCursor(0, 1);
  lcd.print("Light System");
  delay(2000);
  lcd.clear();

  // Turn off everything
  turnOffAllLights();

  Serial.println("==============================");
  Serial.println(" Smart Street Light System");
  Serial.println(" STM32 NUCLEO C031C6");
  Serial.println("==============================");
}

void loop() {

  // Read sensors
  ldrValue = analogRead(LDR_PIN);
  pirValue = digitalRead(PIR_PIN);

  // Check darkness
  isDark = (ldrValue < LIGHT_THRESHOLD);

  // Check motion
  if (pirValue == HIGH) {
    motionDetected = true;
    lastMotionTime = millis();
  }

  // Reset motion after delay
  if (millis() - lastMotionTime > MOTION_DELAY) {
    motionDetected = false;
  }

  // ---- MAIN CONTROL LOGIC ----

  // NIGHT MODE
  if (isDark) {
    turnOnAllLights();

    // LCD Display
    lcd.setCursor(0, 0);
    lcd.print("Mode: NIGHT     ");
    lcd.setCursor(0, 1);
    lcd.print("Lights: ON      ");

    Serial.println("NIGHT MODE: All Lights ON");

  // DAY + MOTION MODE
  } else if (!isDark && motionDetected) {
    turnOnAllLights();

    // LCD Display
    lcd.setCursor(0, 0);
    lcd.print("Mode: MOTION!   ");
    lcd.setCursor(0, 1);
    lcd.print("Lights: ON      ");

    Serial.println("MOTION DETECTED: Lights ON");

  // DAY MODE
  } else {
    turnOffAllLights();

    // LCD Display
    lcd.setCursor(0, 0);
    lcd.print("Mode: DAY       ");
    lcd.setCursor(0, 1);
    lcd.print("Lights: OFF     ");

    Serial.println("DAY MODE: All Lights OFF");
  }

  // Print Sensor Values on Serial
  Serial.print("LDR: ");
  Serial.print(ldrValue);
  Serial.print(" | Dark: ");
  Serial.print(isDark ? "YES" : "NO");
  Serial.print(" | Motion: ");
  Serial.println(motionDetected ? "YES" : "NO");
  Serial.println("------------------------------");

  delay(500);
}

// Turn ON all street lights
void turnOnAllLights() {
  digitalWrite(LED1_PIN, HIGH);
  digitalWrite(LED2_PIN, HIGH);
  digitalWrite(LED3_PIN, HIGH);
  digitalWrite(LED4_PIN, HIGH);
}

// Turn OFF all street lights
void turnOffAllLights() {
  digitalWrite(LED1_PIN, LOW);
  digitalWrite(LED2_PIN, LOW);
  digitalWrite(LED3_PIN, LOW);
  digitalWrite(LED4_PIN, LOW);
}