#include <DHT.h>
#include <U8g2lib.h>
#include <Wire.h>
#include <ESP32Servo.h>

#define DHTPIN    D2
#define DHTTYPE   DHT11
#define SERVO_PIN D9

DHT dht(DHTPIN, DHTTYPE);
Servo myServo;

U8G2_SH1106_128X64_NONAME_F_HW_I2C u8g2(U8G2_R0, U8X8_PIN_NONE);
// U8G2_SSD1306_128X64_NONAME_F_HW_I2C u8g2(U8G2_R0, U8X8_PIN_NONE);

int  currentMode  = 0;
int  servoAngle   = 0;
bool sweeping     = true;
bool servoEnabled = true;

unsigned long lastSensorRead = 0;
unsigned long lastServoMove  = 0;
const unsigned long SENSOR_INTERVAL = 2000;
const unsigned long SERVO_INTERVAL  = 15;

// ──────────────────────────────────────────
// OLED display functions
// ──────────────────────────────────────────

void showFabLab() {
  u8g2.clearBuffer();
  u8g2.setFont(u8g2_font_ncenB14_tr);
  u8g2.drawStr(18, 24, "Hello");
  u8g2.setFont(u8g2_font_ncenB18_tr);
  u8g2.drawStr(8, 54, "Fab Lab!");
  u8g2.sendBuffer();
}

void showHumidity(float h) {
  char valStr[10];
  dtostrf(h, 4, 1, valStr);
  strcat(valStr, " %");
  u8g2.clearBuffer();
  u8g2.setFont(u8g2_font_ncenB10_tr);
  u8g2.drawStr(28, 14, "Humidity");
  u8g2.drawHLine(0, 18, 128);
  u8g2.setFont(u8g2_font_ncenB24_tr);
  u8g2.drawStr(14, 52, valStr);
  u8g2.sendBuffer();
}

void showTempC(float t) {
  char valStr[10];
  dtostrf(t, 4, 1, valStr);
  strcat(valStr, " C");
  u8g2.clearBuffer();
  u8g2.setFont(u8g2_font_ncenB10_tr);
  u8g2.drawStr(18, 14, "Temperature");
  u8g2.drawHLine(0, 18, 128);
  u8g2.setFont(u8g2_font_ncenB08_tr);
  u8g2.drawStr(44, 32, "Celsius");
  u8g2.setFont(u8g2_font_ncenB24_tr);
  u8g2.drawStr(14, 62, valStr);
  u8g2.sendBuffer();
}

void showTempF(float t) {
  float f = (t * 9.0 / 5.0) + 32.0;
  char valStr[10];
  dtostrf(f, 4, 1, valStr);
  strcat(valStr, " F");
  u8g2.clearBuffer();
  u8g2.setFont(u8g2_font_ncenB10_tr);
  u8g2.drawStr(18, 14, "Temperature");
  u8g2.drawHLine(0, 18, 128);
  u8g2.setFont(u8g2_font_ncenB08_tr);
  u8g2.drawStr(30, 32, "Fahrenheit");
  u8g2.setFont(u8g2_font_ncenB24_tr);
  u8g2.drawStr(14, 62, valStr);
  u8g2.sendBuffer();
}

void showServoOff() {
  u8g2.clearBuffer();
  u8g2.setFont(u8g2_font_ncenB10_tr);
  u8g2.drawStr(28, 14, "Servo Status");
  u8g2.drawHLine(0, 18, 128);
  u8g2.setFont(u8g2_font_ncenB18_tr);
  u8g2.drawStr(22, 48, "STOPPED");
  u8g2.sendBuffer();
}

void showServoOn() {
  u8g2.clearBuffer();
  u8g2.setFont(u8g2_font_ncenB10_tr);
  u8g2.drawStr(28, 14, "Servo Status");
  u8g2.drawHLine(0, 18, 128);
  u8g2.setFont(u8g2_font_ncenB18_tr);
  u8g2.drawStr(18, 48, "RUNNING");
  u8g2.sendBuffer();
}

// ──────────────────────────────────────────
// Sensor read + display
// ──────────────────────────────────────────

void readAndDisplay() {
  float humidity    = dht.readHumidity();
  float temperature = dht.readTemperature();

  if (isnan(humidity) || isnan(temperature)) {
    Serial.println("DHT11 read error!");
    u8g2.clearBuffer();
    u8g2.setFont(u8g2_font_ncenB08_tr);
    u8g2.drawStr(10, 35, "Sensor error!");
    u8g2.sendBuffer();
    return;
  }

  if (currentMode == 1) {
    showHumidity(humidity);
    Serial.print("Humidity: ");
    Serial.print(humidity, 1);
    Serial.println(" %");
  } else if (currentMode == 2) {
    showTempC(temperature);
    Serial.print("Temperature: ");
    Serial.print(temperature, 1);
    Serial.println(" C");
  } else if (currentMode == 3) {
    showTempF(temperature);
    float f = (temperature * 9.0 / 5.0) + 32.0;
    Serial.print("Temperature: ");
    Serial.print(f, 1);
    Serial.println(" F");
  }
}

// ──────────────────────────────────────────
// Servo sweep
// ──────────────────────────────────────────

void updateServo() {
  if (!servoEnabled) return;
  if (millis() - lastServoMove < SERVO_INTERVAL) return;
  lastServoMove = millis();

  myServo.write(servoAngle);

  if (sweeping) {
    servoAngle++;
    if (servoAngle >= 180) sweeping = false;
  } else {
    servoAngle--;
    if (servoAngle <= 0) sweeping = true;
  }
}

// ──────────────────────────────────────────
// Setup
// ──────────────────────────────────────────

void setup() {
  Serial.begin(115200);
  dht.begin();
  u8g2.begin();

  myServo.setPeriodHertz(50);
  myServo.attach(SERVO_PIN, 500, 2400);
  myServo.write(0);

  showFabLab();
  Serial.println("DHT11 Monitor ready.");
  Serial.println("0 = Hello Fab Lab | 1 = Humidity | 2 = Temp C | 3 = Temp F");
  Serial.println("5 = Servo OFF      | 6 = Servo ON");
}

// ──────────────────────────────────────────
// Loop
// ──────────────────────────────────────────

void loop() {
  updateServo();

  if (Serial.available() > 0) {
    char input = Serial.read();

    if (input == '0') {
      currentMode = 0;
      showFabLab();
      Serial.println("Mode: Hello Fab Lab");

    } else if (input == '1') {
      currentMode = 1;
      Serial.println("Mode: Humidity");
      readAndDisplay();
      lastSensorRead = millis();

    } else if (input == '2') {
      currentMode = 2;
      Serial.println("Mode: Temperature (Celsius)");
      readAndDisplay();
      lastSensorRead = millis();

    } else if (input == '3') {
      currentMode = 3;
      Serial.println("Mode: Temperature (Fahrenheit)");
      readAndDisplay();
      lastSensorRead = millis();

    } else if (input == '5') {
      servoEnabled = false;
      myServo.write(0);        // return to rest
      delay(500);              // wait to reach position
      myServo.detach();        // cut signal — no jitter
      servoAngle = 0;
      sweeping   = true;
      showServoOff();
      Serial.println("Servo: OFF");

    } else if (input == '6') {
      servoEnabled = true;
      servoAngle   = 0;
      sweeping     = true;
      myServo.attach(SERVO_PIN, 500, 2400);
      myServo.write(0);
      delay(300);
      showServoOn();
      Serial.println("Servo: ON");

    } else if (input != '\n' && input != '\r') {
      Serial.println("Invalid. Send 0, 1, 2, 3, 5 or 6.");
    }
  }

  // Auto-refresh sensor display every 2 seconds
  if (currentMode >= 1 && currentMode <= 3 &&
      millis() - lastSensorRead >= SENSOR_INTERVAL) {
    lastSensorRead = millis();
    readAndDisplay();
  }
}