#include <stdio.h>
#include <string.h>
#include "base64.h"

static const char base64_tab[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";

extern "C" size_t base64_encode( FILE *fin, FILE *fout )
{
    size_t nBytesRead = 0;
    size_t nLineLength = 0;
    size_t nBytesWritten = 0;

    size_t nBytes = 0;

    do
    {
        unsigned char in_buffer[3];

        memset( in_buffer, 0, sizeof(in_buffer) );
        nBytes = fread( in_buffer, 1, sizeof(in_buffer), fin );
        nBytesRead += nBytes;

        if ( nBytes )
        {
            unsigned long value =
                ((unsigned long)in_buffer[0]) << 16 |
                ((unsigned long)in_buffer[1]) << 8 |
                ((unsigned long)in_buffer[2]) << 0;

            unsigned char out_buffer[4];

            memset( out_buffer, '=', sizeof(out_buffer) );

            out_buffer[0] = base64_tab[(value >> 18) & 0x3F];
            out_buffer[1] = base64_tab[(value >> 12) & 0x3F];

            if ( nBytes > 1 )
            {
                out_buffer[2] = base64_tab[(value >> 6) & 0x3F];
                if ( nBytes > 2 )
                    out_buffer[3] = base64_tab[(value >> 0) & 0x3F];
            }

            if ( nLineLength >= 76 )
            {
                fputs( "\n", fout );
                nLineLength = 0;
            }

            nBytesWritten += fwrite( out_buffer, 1, sizeof(out_buffer), fout );
            nLineLength += sizeof(out_buffer);
        }
    } while ( nBytes );

    return nBytesWritten;
}