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();

    }

}