#pragma once

class OpenSSL_Base64
{
public:
    static size_t calcDecodeLength(const char* b64input);
    static size_t Base64Decode(char* b64message, unsigned char** buffer, size_t* length);
    static char * Base64Encode(char *decoded_bytes, size_t decoded_length);
};

#include "OpenSSL_Base64.h"

#include <string.h>
#include <assert.h>
#include <openssl/bio.h>
#include <openssl/evp.h>
#include <openssl/buffer.h>

size_t OpenSSL_Base64::calcDecodeLength(const char* b64input) { //Calculates the length of a decoded string
    size_t len = strlen(b64input),
        padding = 0;

    if (b64input[len - 1] == '=' && b64input[len - 2] == '=') //last two chars are =
        padding = 2;
    else if (b64input[len - 1] == '=') //last char is =
        padding = 1;

    return (len * 3) / 4 - padding;
}

size_t OpenSSL_Base64::Base64Decode(char* b64message, unsigned char** buffer, size_t* length) { //Decodes a base64 encoded string
    BIO *bio, *b64;

    int decodeLen = calcDecodeLength(b64message);
    *buffer = (unsigned char*)malloc(decodeLen + 1);
    (*buffer)[decodeLen] = '\0';

    bio = BIO_new_mem_buf(b64message, -1);
    b64 = BIO_new(BIO_f_base64());
    bio = BIO_push(b64, bio);

    BIO_set_flags(bio, BIO_FLAGS_BASE64_NO_NL); //Do not use newlines to flush buffer
    *length = BIO_read(bio, *buffer, strlen(b64message));
    assert(*length == decodeLen); //length should equal decodeLen, else something went horribly wrong
    BIO_free_all(bio);

    return (0); //success
}

char * OpenSSL_Base64::Base64Encode(char *decoded_bytes, size_t decoded_length)
{
    int x;
    BIO *bioMem, *b64;
    BUF_MEM *bufPtr;
    char *buff;

    b64 = BIO_new(BIO_f_base64());
    BIO_set_flags(b64, BIO_FLAGS_BASE64_NO_NL);
    bioMem = BIO_new(BIO_s_mem());
    b64 = BIO_push(b64, bioMem);

    BIO_write(b64, decoded_bytes, decoded_length);
    x = BIO_flush(b64);
    if (x < 1) {
        BIO_free_all(b64);
        return NULL;
    }

    BIO_get_mem_ptr(b64, &bufPtr);

    buff = (char *)malloc(bufPtr->length + 1);
    memcpy(buff, bufPtr->data, bufPtr->length);
    buff[bufPtr->length] = 0;

    BIO_free_all(b64);
    return buff;
}