#include <WiFi.h>
#include <PubSubClient.h>
#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>
#include <ArduinoJson.h>

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

// MQTT Broker
const char* mqttServer = "test.mosquitto.org";
const int mqttPort = 1883;
const char* mqttTopic = "accident detected";

// PIR Sensor
#define PIR_PIN 35

// OLED Display
#define SCREEN_WIDTH 128
#define SCREEN_HEIGHT 64
#define OLED_RESET -1
Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, OLED_RESET);

WiFiClient espClient;
PubSubClient client(espClient);

unsigned long lastMotionTime = 0;
const unsigned long alertCooldown = 10000; // 10 seconds cooldown between alerts

// MQTT Callback to handle received alerts
void callback(char* topic, byte* payload, unsigned int length) {
  String msg = "";
  for (int i = 0; i < length; i++) {
    msg += (char)payload[i];
  }
  Serial.println("Received MQTT: " + msg);

  // Parse JSON
  StaticJsonDocument<200> doc;
  DeserializationError error = deserializeJson(doc, msg);
  if (error) {
    Serial.println("Failed to parse MQTT JSON");
    return;
  }

  if (doc["accident"] == true) {
    Serial.println("🚨 MQTT Accident Detected!");
    showAccidentAlert();
  }
}

void showAccidentAlert() {
  display.clearDisplay();
  display.setTextSize(1);
  display.setCursor(0, 0);
  display.println("Accident Alert!");
  display.setTextSize(2);
  display.setCursor(0, 20);
  display.println("Detected");
  display.display();

  delay(10000);

  display.clearDisplay();
  display.setCursor(0, 0);
  display.setTextSize(1);
  display.println("Monitoring...");
  display.display();
}

void setup() {
  Serial.begin(115200);
  pinMode(PIR_PIN, INPUT);

  // Initialize OLED
  if(!display.begin(SSD1306_SWITCHCAPVCC, 0x3C)) {
    Serial.println("OLED init failed");
    while(true);
  }

  display.clearDisplay();
  display.setTextSize(2);
  display.setCursor(0, 0);
  display.println("Booting...");
  display.display();

  // Connect WiFi
  WiFi.begin(ssid, password);
  while (WiFi.status() != WL_CONNECTED) {
    delay(1000);
    Serial.println("Connecting to WiFi...");
  }
  Serial.println("WiFi connected");

  // Connect MQTT
  client.setServer(mqttServer, mqttPort);
  client.setCallback(callback);

  while (!client.connected()) {
    Serial.println("Connecting to MQTT...");
    
    if (client.connect("userid")) {      //user id must be unique in case of many users under one topic to avoid conflict/crosstalk information
      Serial.println("Connected to MQTT");
      client.subscribe(mqttTopic);            //SUBSCRIBE TOPIC
    } else {
      Serial.print("Failed with state ");
      Serial.print(client.state());
      delay(2000);
    }
  }
  display.clearDisplay();
  display.setCursor(0, 0);
  display.setTextSize(1);
  display.println("Monitoring...");
  display.display();
}

void loop() {
  client.loop();

  int motion = digitalRead(PIR_PIN);
  unsigned long currentTime = millis();

  if (motion == HIGH && currentTime - lastMotionTime > alertCooldown) {
    Serial.println("🚨 PIR Motion Detected!");

    // Publish MQTT accident message
    StaticJsonDocument<100> doc;
    doc["accident"] = true;
    char buffer[100];
    serializeJson(doc, buffer);
    client.publish(mqttTopic, buffer);

    // Show on OLED
    showAccidentAlert();

    lastMotionTime = currentTime;
  }

  delay(200); // Small delay to reduce CPU usage
}