Gemini on display using Xiao ESP32 C3 by Seeed Studio

/*Basic code for using Gemini AI on mini display with the help of tiny powerful devlopment board- Xiao ESP32 C3 by Seeed Studio.
You can also make this by uploading this code to you Xiao ESP32 C3 board and by following the other steps on mentioned hackster.io*/

//Devloped exclusively by IoT HUB

#include <WiFi.h>
#include <HTTPClient.h>
#include <ArduinoJson.h>
#include <U8g2lib.h>
#include <vector>

#define SCROLL_DOWN_PIN 9 
#define SCROLL_UP_PIN   8

const char *ssid = "YOUR WIFI SSID";
const char *password = "YOUR SSID PASSWORD";

const String apiKey = "Your Gemini API";
const String geminiUrl = "https://generativelanguage.googleapis.com/v1beta/models/gemini-1.5-flash-latest:generateContent?key=" + apiKey;

// OLED (SDA=6, SCL=7 for Xiao ESP32-C3)
U8G2_SSD1306_128X64_NONAME_F_HW_I2C u8g2(U8G2_R0, /* reset=*/U8X8_PIN_NONE, /* clock=*/7, /* data=*/6);

std::vector<String> wrappedAnswerLines;
std::vector<String> wrappedQuestionLines;
String displayedQuestion = "";
int currentPage = 0;
bool lastUpState = HIGH, lastDownState = HIGH;

// Clean intro animation with top and bottom line bouncing
void showStartupAnimation() {
  unsigned long startTime = millis();
  u8g2.setFont(u8g2_font_6x10_tr);

  while (millis() - startTime < 2000) {
    int offset = 10 * sin((millis() - startTime) / 300.0);
    u8g2.clearBuffer();
    u8g2.drawStr(25 + offset, 18, "Developed By -");
    u8g2.drawStr(35 - offset, 48, "IoT HUB");
    u8g2.sendBuffer();
    delay(50);
  }
}

// Loading animation: blinking dots
void showLoadingAnimationWhileWaiting() {
  int dotState = 0;
  unsigned long lastUpdate = 0;

  while (WiFi.status() == WL_CONNECTED && !Serial.available()) {
    if (millis() - lastUpdate > 300) {
      lastUpdate = millis();
      dotState = (dotState + 1) % 4;
      u8g2.clearBuffer();
      u8g2.setFont(u8g2_font_6x10_tr);
      String loadingText = "Loading";
      for (int i = 0; i < dotState; i++) loadingText += ".";
      u8g2.drawStr(40, 32, loadingText.c_str());
      u8g2.sendBuffer();
    }
    delay(10);
  }
}

void setup() {
  Serial.begin(115200);
  delay(1000);

  pinMode(SCROLL_DOWN_PIN, INPUT_PULLUP);
  pinMode(SCROLL_UP_PIN, INPUT_PULLUP);

  u8g2.begin();
  u8g2.setFont(u8g2_font_6x10_tr);

  showStartupAnimation();

  u8g2.clearBuffer();
  u8g2.drawStr(0, 15, "Connecting to WiFi...");
  u8g2.sendBuffer();

  WiFi.begin(ssid, password);
  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
  }

  Serial.println("\nConnected to WiFi");
  u8g2.clearBuffer();
  u8g2.drawStr(0, 15, "Connected to WiFi!");
  u8g2.drawStr(0, 30, "ASK A QUESTION:");
  u8g2.sendBuffer();

  Serial.println("Ask a question:");
}

void loop() {
  bool downState = digitalRead(SCROLL_DOWN_PIN);
  bool upState = digitalRead(SCROLL_UP_PIN);

  if (downState == LOW && lastDownState == HIGH) {
    scrollAnswerDown(); delay(200);
  }
  if (upState == LOW && lastUpState == HIGH) {
    scrollAnswerUp(); delay(200);
  }
  lastDownState = downState;
  lastUpState = upState;

  if (Serial.available()) {
    String userInput = Serial.readStringUntil('\n');
    userInput.trim();

    if (userInput.length() > 0) {
      displayedQuestion = userInput;
      displayedQuestion.toUpperCase();  // Force ALL CAPS

      showLoadingAnimationWhileWaiting();

      String answer = askGemini(userInput);

      if (answer.length() > 0) {
        Serial.println("Answer: " + answer);
        prepareAnswerLines(answer);
        prepareQuestionLines(displayedQuestion);
      } else {
        Serial.println("Failed to get an answer.");
        prepareAnswerLines("Error: No answer.");
        prepareQuestionLines(displayedQuestion);
      }

      currentPage = 0;
      displayCurrentPage();
      Serial.println("\nAsk another question:");
    }
  }
}

void scrollAnswerDown() {
  if (wrappedAnswerLines.empty()) return;
  int totalPages = (wrappedAnswerLines.size() + 2) / 3;
  currentPage = (currentPage + 1) % totalPages;
  displayCurrentPage();
}

void scrollAnswerUp() {
  if (wrappedAnswerLines.empty()) return;
  int totalPages = (wrappedAnswerLines.size() + 2) / 3;
  currentPage = (currentPage - 1 + totalPages) % totalPages;
  displayCurrentPage();
}

void wrapTextToLines(String text, std::vector<String>& linesOut, int maxLen = 22) {
  linesOut.clear();
  String word, line;

  for (int i = 0; i < text.length(); i++) {
    char c = text[i];
    if (c == ' ' || c == '\n') {
      if (line.length() + word.length() > maxLen) {
        linesOut.push_back(line);
        line = word + " ";
      } else {
        line += word + " ";
      }
      word = "";
      if (c == '\n' && line.length() > 0) {
        linesOut.push_back(line);
        line = "";
      }
    } else {
      word += c;
    }
  }
  if (word.length()) {
    if (line.length() + word.length() > maxLen) {
      linesOut.push_back(line);
      line = word;
    } else {
      line += word;
    }
  }
  if (line.length()) linesOut.push_back(line);
}

void prepareAnswerLines(String text) {
  wrapTextToLines(text, wrappedAnswerLines, 22);
}

void prepareQuestionLines(String text) {
  wrapTextToLines(text, wrappedQuestionLines, 22);
}

void displayCurrentPage() {
  u8g2.clearBuffer();
  u8g2.setFont(u8g2_font_6x10_tr);

  // Show question (up to 2 lines)
  if (wrappedQuestionLines.size() > 0)
    u8g2.drawStr(0, 10, wrappedQuestionLines[0].c_str());
  if (wrappedQuestionLines.size() > 1)
    u8g2.drawStr(0, 20, wrappedQuestionLines[1].c_str());

  // Show answer (3 lines)
  int startLine = currentPage * 3;
  for (int i = 0; i < 3; i++) {
    int idx = startLine + i;
    if (idx < wrappedAnswerLines.size()) {
      u8g2.drawStr(0, 35 + i * 10, wrappedAnswerLines[idx].c_str());
    }
  }

  u8g2.sendBuffer();
}

String askGemini(String question) {
  HTTPClient http;
  http.begin(geminiUrl);
  http.addHeader("Content-Type", "application/json");

  String payload = "{\"contents\":[{\"parts\":[{\"text\":\"" + question + "\"}]}]}";
  int httpCode = http.POST(payload);
  String response = http.getString();
  String result = "";

  if (httpCode == 200) {
    DynamicJsonDocument doc(4096);
    if (!deserializeJson(doc, response)) {
      JsonArray candidates = doc["candidates"];
      if (candidates.size() > 0) {
        result = candidates[0]["content"]["parts"][0]["text"].as<String>();
      } else {
        result = "No response.";
      }
    } else {
      result = "JSON parse error.";
    }
  } else {
    Serial.print("Request error: ");
    Serial.println(httpCode);
  }

  http.end();
  return result;
}


//An original *IoT HUB* creation