public int read()

in core/src/main/java/org/apache/calcite/avatica/util/Base64.java [1741:1834]
68 lines of code
18 McCabe index (conditional complexity)

    public int read() throws java.io.IOException  {

      // Do we need to get data?
      if( position < 0 ) {
        if( encode ) {
          byte[] b3 = new byte[3];
          int numBinaryBytes = 0;
          for( int i = 0; i < 3; i++ ) {
            int b = in.read();

            // If end of stream, b is -1.
            if( b >= 0 ) {
              b3[i] = (byte)b;
              numBinaryBytes++;
            } else {
              break; // out of for loop
            }   // end else: end of stream

          }   // end for: each needed input byte

          if( numBinaryBytes > 0 ) {
            encode3to4( b3, 0, numBinaryBytes, buffer, 0, options );
            position = 0;
            numSigBytes = 4;
          }   // end if: got data
          else {
            return -1;  // Must be end of stream
          }   // end else
        }   // end if: encoding

        // Else decoding
        else {
          byte[] b4 = new byte[4];
          int i = 0;
          for( i = 0; i < 4; i++ ) {
            // Read four "meaningful" bytes:
            int b = 0;
            do{ b = in.read(); }
            while( b >= 0 && decodabet[ b & 0x7f ] <= WHITE_SPACE_ENC );

            if( b < 0 ) {
              break; // Reads a -1 if end of stream
            }   // end if: end of stream

            b4[i] = (byte)b;
          }   // end for: each needed input byte

          if( i == 4 ) {
            numSigBytes = decode4to3( b4, 0, buffer, 0, options );
            position = 0;
          }   // end if: got four characters
          else if( i == 0 ){
            return -1;
          }   // end else if: also padded correctly
          else {
            // Must have broken out from above.
            throw new java.io.IOException( "Improperly padded Base64 input." );
          }   // end

        }   // end else: decode
      }   // end else: get data

      // Got data?
      if( position >= 0 ) {
        // End of relevant data?
        if( /*!encode &&*/ position >= numSigBytes ){
          return -1;
        }   // end if: got data

        if( encode && breakLines && lineLength >= MAX_LINE_LENGTH ) {
          lineLength = 0;
          return '\n';
        }   // end if
        else {
          lineLength++;   // This isn't important when decoding
          // but throwing an extra "if" seems
          // just as wasteful.

          int b = buffer[ position++ ];

          if( position >= bufferLength ) {
            position = -1;
          }   // end if: end

          return b & 0xFF; // This is how you "cast" a byte that's
          // intended to be unsigned.
        }   // end else
      }   // end if: position >= 0

      // Else error
      else {
        throw new java.io.IOException( "Error in Base64 code reading stream." );
      }   // end else
    }   // end read