/*
 * This file is part of the Meeds project (https://meeds.io/).
 * Copyright (C) 2020 Meeds Association
 * contact@meeds.io
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 3 of the License, or (at your option) any later version.
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 * You should have received a copy of the GNU Lesser General Public License
 * along with this program; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 */
package org.exoplatform.services.rest.impl.provider;

import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.io.Reader;
import java.io.Writer;
import java.nio.charset.Charset;
import java.nio.charset.IllegalCharsetNameException;
import java.nio.charset.UnsupportedCharsetException;

/**
 * @author <a href="mailto:andrew00x@gmail.com">Andrey Parfonov</a>
 * @version $Id: $
 */
public final class IOHelper
{

   /**
    * Default character set name.
    */
   static final String DEFAULT_CHARSET_NAME = "UTF-8";

   /**
    * If character set was not specified then this will be used.
    */
   static final Charset DEFAULT_CHARSET = Charset.forName(DEFAULT_CHARSET_NAME);

   /**
    * Constructor.
    */
   private IOHelper()
   {
   }

   /**
    * Write data from {@link InputStream} to {@link OutputStream}.
    * 
    * @param in See {@link InputStream}
    * @param out See {@link OutputStream}
    * @throws IOException if i/o errors occurs
    */
   static void write(InputStream in, OutputStream out) throws IOException
   {
      byte[] buf = new byte[1024];
      int rd = -1;
      while ((rd = in.read(buf)) != -1)
         out.write(buf, 0, rd);
   }

   /**
    * Write data from {@link Reader} to {@link Writer}.
    * 
    * @param in See {@link Reader}
    * @param out See {@link Writer}
    * @throws IOException if i/o errors occurs
    */
   static void write(Reader in, Writer out) throws IOException
   {
      char[] buf = new char[1024];
      int rd = -1;
      while ((rd = in.read(buf)) != -1)
         out.write(buf, 0, rd);
   }

   /**
    * Read String from given {@link InputStream}.
    * 
    * @param in source stream for reading
    * @param cs character set, if null then {@link #DEFAULT_CHARSET} will be used
    * @return resulting String
    * @throws IOException if i/o errors occurs
    */
   static String readString(InputStream in, String cs) throws IOException
   {
      Charset charset;
      // Must respect application specified character set.
      // For output if specified character set is not supported then UTF-8 should
      // be used instead.
      try
      {
         charset = cs != null ? Charset.forName(cs) : DEFAULT_CHARSET;
      }
      catch (Exception e)
      {
         charset = DEFAULT_CHARSET;
      }
      Reader r = new InputStreamReader(in, charset);
      char[] buf = new char[1024];
      StringBuffer sb = new StringBuffer();
      int rd = -1;
      while ((rd = r.read(buf)) != -1)
         sb.append(buf, 0, rd);

      return sb.toString();
   }

   /**
    * Write String to {@link OutputStream}.
    * 
    * @param s String
    * @param out See {@link OutputStream}
    * @param cs character set, if null then {@link #DEFAULT_CHARSET} will be used
    * @throws IOException if i/o errors occurs
    */
   static void writeString(String s, OutputStream out, String cs) throws IOException
   {
      Charset charset;
      // Must respect application specified character set.
      // For output if specified character set is not supported then UTF-8 should
      // be used instead.
      try
      {
         charset = cs != null ? Charset.forName(cs) : DEFAULT_CHARSET;
      }
      catch (IllegalCharsetNameException e)
      {
         charset = DEFAULT_CHARSET;
      }
      catch (UnsupportedCharsetException e)
      {
         charset = DEFAULT_CHARSET;
      }
      catch (IllegalArgumentException e)
      {
         charset = DEFAULT_CHARSET;
      }
      Writer w = new OutputStreamWriter(out, charset);
      try
      {
         w.write(s);
      }
      finally
      {
         w.flush();
         w.close();
      }
   }

}
