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

// -------- Wi-Fi Settings --------
const char* ssid = "Wokwi-GUEST";
const char* password = "";

// -------- Pin Settings --------
#define LED_WIFI 19
#define SW_RESET 32
#define OLED_SDA 21
#define OLED_SCL 22

// -------- OLED Settings --------
#define SCREEN_WIDTH 128
#define SCREEN_HEIGHT 64
#define OLED_RESET -1
#define OLED_ADDR 0x3C

Adafruit_SSD1306 display(
  SCREEN_WIDTH, SCREEN_HEIGHT,
  &Wire, OLED_RESET
);

// -------- Timing --------
const unsigned long BLINK_INTERVAL = 250;
const unsigned long RETRY_INTERVAL = 10000;
const unsigned long OLED_INTERVAL = 500;
const unsigned long DEBOUNCE_INTERVAL = 50;

unsigned long previousBlink = 0;
unsigned long previousRetry = 0;
unsigned long previousOLED = 0;
unsigned long debounceStart = 0;

bool ledState = false;
bool wasConnected = false;
bool lastReading = HIGH;
bool stableButton = HIGH;
bool oledReady = false;

// เริ่มเชื่อมต่อ Wi-Fi
void connectWiFi() {
  Serial.println("Connecting to WiFi...");

  WiFi.disconnect();
  WiFi.begin(ssid, password);

  previousRetry = millis();
  wasConnected = false;
}

// แสดงข้อมูลบน OLED
void updateOLED() {
  if (!oledReady) return;

  display.clearDisplay();
  display.setTextColor(SSD1306_WHITE);

  display.setTextSize(1);
  display.setCursor(0, 0);
  display.println("ESP32 WIFI MONITOR");

  display.drawLine(0, 12, 127, 12, SSD1306_WHITE);

  if (WiFi.status() == WL_CONNECTED) {
    display.setCursor(0, 18);
    display.println("Status: CONNECTED");

    display.setCursor(0, 30);
    display.print("SSID: ");
    display.println(WiFi.SSID());

    display.setCursor(0, 42);
    display.print("IP: ");
    display.println(WiFi.localIP());

    display.setCursor(0, 54);
    display.print("RSSI: ");
    display.print(WiFi.RSSI());
    display.println(" dBm");
  }
  else {
    display.setCursor(0, 22);
    display.println("Status: CONNECTING");

    display.setCursor(0, 38);
    display.println("Please wait...");

    display.setCursor(0, 54);
    display.println("LED: BLINKING");
  }

  display.display();
}

// ตรวจจับสวิตช์พร้อม Debounce
void checkButton() {
  bool reading = digitalRead(SW_RESET);

  if (reading != lastReading) {
    debounceStart = millis();
  }

  if (millis() - debounceStart >= DEBOUNCE_INTERVAL) {
    if (reading != stableButton) {
      stableButton = reading;

      if (stableButton == LOW) {
        Serial.println("WiFi Reset Button Pressed");
        connectWiFi();
        updateOLED();
      }
    }
  }

  lastReading = reading;
}

// ควบคุม LED แสดงสถานะ
void updateLED() {
  unsigned long now = millis();

  if (WiFi.status() == WL_CONNECTED) {
    digitalWrite(LED_WIFI, HIGH);

    if (!wasConnected) {
      wasConnected = true;

      Serial.println("WiFi Connected!");
      Serial.print("IP: ");
      Serial.println(WiFi.localIP());
      Serial.print("RSSI: ");
      Serial.println(WiFi.RSSI());
    }
  }
  else {
    if (wasConnected) {
      wasConnected = false;
      Serial.println("WiFi Disconnected!");
    }

    if (now - previousBlink >= BLINK_INTERVAL) {
      previousBlink = now;
      ledState = !ledState;
      digitalWrite(LED_WIFI, ledState);
    }
  }
}

void setup() {
  Serial.begin(115200);

  pinMode(LED_WIFI, OUTPUT);
  pinMode(SW_RESET, INPUT_PULLUP);
  digitalWrite(LED_WIFI, LOW);

  Wire.begin(OLED_SDA, OLED_SCL);

  oledReady = display.begin(
    SSD1306_SWITCHCAPVCC, OLED_ADDR
  );

  if (!oledReady) {
    Serial.println("OLED initialization failed!");
  } else {
    display.clearDisplay();
    display.setTextColor(SSD1306_WHITE);
    display.setTextSize(1);
    display.setCursor(10, 20);
    display.println("ESP32 WIFI SYSTEM");
    display.setCursor(20, 35);
    display.println("Starting...");
    display.display();
  }

  WiFi.mode(WIFI_STA);
  WiFi.setAutoReconnect(true);

  connectWiFi();
}

void loop() {
  unsigned long now = millis();

  checkButton();
  updateLED();

  // เชื่อมต่อใหม่เมื่อ Wi-Fi ขาด
  if (WiFi.status() != WL_CONNECTED) {
    if (now - previousRetry >= RETRY_INTERVAL) {
      Serial.println("Retrying WiFi...");
      connectWiFi();
    }
  }

  // อัปเดตหน้าจอทุก 500 ms
  if (now - previousOLED >= OLED_INTERVAL) {
    previousOLED = now;
    updateOLED();
  }
}