#include <Arduino.h>

char *originalString = "Привет, ESP32!";
char encodedString[128];
char decodedString[128];

// Таблица символов Base64
const char base64Table[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";

void base64Encode(const char *input, char *output) {
  int inputLength = strlen(input);
  int i = 0, j = 0;

  while (i < inputLength) {
    uint32_t octet_a = i < inputLength ? (unsigned char)input[i++] : 0;
    uint32_t octet_b = i < inputLength ? (unsigned char)input[i++] : 0;
    uint32_t octet_c = i < inputLength ? (unsigned char)input[i++] : 0;

    uint32_t triple = (octet_a << 16) | (octet_b << 8) | octet_c;

    output[j++] = base64Table[(triple >> 18) & 0x3F];
    output[j++] = base64Table[(triple >> 12) & 0x3F];
    output[j++] = i > inputLength + 1 ? '=' : base64Table[(triple >> 6) & 0x3F];
    output[j++] = i > inputLength ? '=' : base64Table[triple & 0x3F];
  }
  output[j] = '\0';
}

void base64Decode(const char *input, char *output) {
  int inputLength = strlen(input);
  int i = 0, j = 0;

  uint8_t base64ReverseTable[256] = {0};
  for (int k = 0; k < 64; k++) {
    base64ReverseTable[(uint8_t)base64Table[k]] = k;
  }

  while (i < inputLength) {
    uint32_t sextet_a = input[i] == '=' ? 0 & i++ : base64ReverseTable[(uint8_t)input[i++]];
    uint32_t sextet_b = input[i] == '=' ? 0 & i++ : base64ReverseTable[(uint8_t)input[i++]];
    uint32_t sextet_c = input[i] == '=' ? 0 & i++ : base64ReverseTable[(uint8_t)input[i++]];
    uint32_t sextet_d = input[i] == '=' ? 0 & i++ : base64ReverseTable[(uint8_t)input[i++]];

    uint32_t triple = (sextet_a << 18) | (sextet_b << 12) | (sextet_c << 6) | sextet_d;

    if (j < inputLength) output[j++] = (triple >> 16) & 0xFF;
    if (j < inputLength) output[j++] = (triple >> 8) & 0xFF;
    if (j < inputLength) output[j++] = triple & 0xFF;
  }
  output[j] = '\0';
}

void setup() {
  Serial.begin(115200);
  delay(1000); // Ждём, пока Serial откроется

  Serial.println("ESP32 Manual Base64 Encoding and Decoding Example");

  // Кодирование
  base64Encode(originalString, encodedString);
  Serial.print("Encoded: ");
  Serial.println(encodedString);

  // Декодирование
  base64Decode(encodedString, decodedString);
  Serial.print("Decoded: ");
  Serial.println(decodedString);
}

void loop() {
  delay(1000); // Повторяем каждую секунду, если требуется
}