/*******************************************************************************
 * Copyright 2013 SAP AG
 * 
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * 
 *   http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 ******************************************************************************/
package com.sap.core.odata.testutil.helper;

import java.io.BufferedReader;
import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.UnsupportedEncodingException;
import java.nio.charset.Charset;
import java.util.Random;

import org.apache.http.HttpEntity;

import com.sap.core.odata.testutil.TestUtilRuntimeException;

/**
 * @author SAP AG
 */
public class StringHelper {

  public static String inputStreamToString(final InputStream in, final boolean preserveLineBreaks) throws IOException {
    final BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(in, Charset.forName("UTF-8")));
    final StringBuilder stringBuilder = new StringBuilder();
    String line = null;

    while ((line = bufferedReader.readLine()) != null) {
      stringBuilder.append(line);
      if (preserveLineBreaks) {
        stringBuilder.append("\n");
      }
    }

    bufferedReader.close();

    final String result = stringBuilder.toString();

    return result;
  }

  public static String inputStreamToString(final InputStream in) throws IOException {
    return inputStreamToString(in, false);
  }

  public static String httpEntityToString(final HttpEntity entity) throws IOException, IllegalStateException {
    return inputStreamToString(entity.getContent());
  }

  /**
   * Encapsulate given content in an {@link InputStream} with charset <code>UTF-8</code>.
   * 
   * @param content to encapsulate content
   * @return content as stream
   */
  public static InputStream encapsulate(final String content) {
    try {
      return encapsulate(content, "UTF-8");
    } catch (UnsupportedEncodingException e) {
      // we know that UTF-8 is supported
      throw new TestUtilRuntimeException("UTF-8 MUST be supported.", e);
    }
  }

  /**
   * Encapsulate given content in an {@link InputStream} with given charset.
   * 
   * @param content to encapsulate content
   * @param charset to be used charset
   * @return content as stream
   * @throws UnsupportedEncodingException if charset is not supported
   */
  public static InputStream encapsulate(final String content, final String charset) throws UnsupportedEncodingException {
    return new ByteArrayInputStream(content.getBytes(charset));
  }

  /**
   * Generate a string with given length containing random upper case characters ([A-Z]).
   * 
   * @param len length of to generated string
   * @return random upper case characters ([A-Z]).
   */
  public static InputStream generateDataStream(final int len) {
    return encapsulate(generateData(len));
  }

  /**
   * Generates a string with given length containing random upper case characters ([A-Z]).
   * @param len length of the generated string
   * @return random upper case characters ([A-Z])
   */
  public static String generateData(final int len) {
    Random random = new Random();
    StringBuilder b = new StringBuilder(len);
    for (int j = 0; j < len; j++) {
      final char c = (char) ('A' + random.nextInt('Z' - 'A' + 1));
      b.append(c);
    }
    return b.toString();
  }

}