package api.usage;

 import api.Writer;

 import java.io.IOException;

 /** Writer alters each char from 'A' to 'Z' range with next one just like

  * old Romans did.

  *

  * @author Jaroslav Tulach

  */

 public class CryptoWriter implements Writer.Impl {

     private Writer out;

     private CryptoWriter(Writer out) {

         this.out = out;

     }

     public static Writer create(Writer out) {

         return Writer.create(new CryptoWriter(out));

     }

     @Override

     public void write(char[] cbuf, int off, int len) throws IOException {

         char[] arr = new char[len];

         for (int i = 0; i < len; i++) {

             arr[i] = convertChar(cbuf[off + i]);

         }

         out.write(arr, 0, len);

     }

     @Override

     public void write(String str, int off, int len) throws IOException {

         StringBuffer sb = new StringBuffer();

         for (int i = 0; i < len; i++) {

             sb.append(convertChar(str.charAt(off + i)));

         }

         out.write(sb.toString(), 0, len);

     }

     private char convertChar(int c) {

         if (c == 'Z') {

             return 'A';

         }

         if (c == 'z') {

             return 'a';

         }

         return (char)(c + 1);

     }

     public void close() throws IOException {

         out.close();

     }

     public void flush() throws IOException {

         out.flush();

     }

 }