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

#define DHTPIN  D2
#define DHTTYPE DHT11

DHT dht(DHTPIN, DHTTYPE);

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;  // 0 = Hello, 1 = humidity, 2 = temp C, 3 = temp F

void showHello() {
  u8g2.clearBuffer();
  u8g2.setFont(u8g2_font_ncenB10_tr);
  u8g2.drawStr(22, 20, "DHT11 Ready");
  u8g2.drawHLine(0, 25, 128);
  u8g2.setFont(u8g2_font_ncenB08_tr);
  u8g2.drawStr(10, 40, "0 - Hello Fab Lab");
  u8g2.drawStr(10, 52, "1 - Humidity");
  u8g2.drawStr(10, 64, "2 - Temp (C)  3 - Temp (F)");
  u8g2.sendBuffer();
}

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

  showHello();

  Serial.println("DHT11 Monitor ready.");
  Serial.println("Send 0 = Hello Fab Lab | 1 = Humidity | 2 = Temp C | 3 = Temp F");
}

void loop() {
  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");
    } else if (input == '2') {
      currentMode = 2;
      Serial.println("Mode: Temperature (Celsius)");
    } else if (input == '3') {
      currentMode = 3;
      Serial.println("Mode: Temperature (Fahrenheit)");
    } else if (input != '\n' && input != '\r') {
      Serial.println("Invalid. Send 0, 1, 2 or 3.");
    }
  }

  // Sensor modes refresh every 2 seconds
  if (currentMode == 1 || currentMode == 2 || currentMode == 3) {
    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();
      delay(2000);
      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");
    }

    delay(2000);
  }
}