/**
 * Copyright 2014 Tampere University of Technology, Pori Department
 * 
 * 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 core.tut.pori.utils;

import java.text.ParseException;
import java.util.Date;

import org.apache.commons.lang3.ArrayUtils;
import org.apache.commons.lang3.time.FastDateFormat;
import org.apache.log4j.Logger;


/**
 * A thread-safe utility class for processing Strings.
 */
public final class StringUtils {
  private static final FastDateFormat ISO_DATE = FastDateFormat.getInstance("yyyy-MM-dd'T'HH:mm:ssZ");
  private static final Logger LOGGER = Logger.getLogger(StringUtils.class);
  private static final String ZULU = "Z";

  /**
   * 
   */
  private StringUtils(){
    // nothing needed
  }

  /**
   * 
   * @param started
   * @param finished
   * @return string representation of the time interval between the given dates
   */
  public static String getDurationString(Date started, Date finished){    
    long duration_ms = finished.getTime() - started.getTime();
    long ms = ((duration_ms % 86400000) % 3600000) % 1000;
    long s = (((duration_ms % 86400000) % 3600000) % 60000) /1000;
    long min = ((duration_ms % 86400000) % 3600000)/60000;
    long h = (duration_ms % 86400000)/3600000;
    StringBuilder sb = new StringBuilder();
    if(h > 0){
      sb.append(String.valueOf(h));
      sb.append(" h");
    }
    if(min > 0){
      if(sb.length() > 0)
        sb.append(" ");
      sb.append(String.valueOf(min));
      sb.append(" min");
    }
    if(s > 0){
      if(sb.length() > 0)
        sb.append(" ");
      sb.append(String.valueOf(s));
      sb.append(" s");
    }
    if(ms > 0){
      if(sb.length() > 0)
        sb.append(" ");
      sb.append(String.valueOf(ms));
      sb.append(" ms");
    }
    if(sb.length() < 1){
      sb.append(" less than 1 ms");
    }
    return sb.toString();
  }

  /**
   * This method is synchronized for the conversion
   * 
   * @param date
   * @return null if null passed, otherwise the passed string in format yyyy-MM-dd'T'HH:mm:ssZ
   */
  public static String dateToISOString(Date date){
    return (date == null ? null : ISO_DATE.format(date));
  }
  
  /**
   * Note: this method will accept microseconds, but the actual microsecond values will be ignored,
   * passing 2012-05-23T10:32:20.000000Z equals to passing 2012-05-23T10:32:20Z. 
   * 
   * Both Z and +XXXX are accepted timezone formats.
   * 
   * @param date the passed string in format yyyy-MM-dd'T'HH:mm:ssZ
   * @return the given string as ISODate or null if the string does not contain a valid date
   */
  public static Date ISOStringToDate(String date){
    try {
      int pointIndex = date.indexOf('.');
      if(pointIndex > 0){ // strip milliseconds 2012-05-23T10:32:20.XXXXXXZ
        if(date.endsWith(ZULU)){ // strip the tailing Z as it creates issues with simple date format
          date = date.substring(0, pointIndex)+"+0000";
        }else{
          int plusIndex = date.indexOf('+', pointIndex);
          if(plusIndex < 0){
            LOGGER.error("Invalid date string.");
            return null;
          }
          date = date.substring(0, pointIndex) + date.substring(plusIndex);
        }
      }else if(date.endsWith(ZULU)){ // strip the tailing Z as it creates issues with simple date format
        date = date.substring(0, date.length()-1)+"+0000";
      }
      return ISO_DATE.parse(date);  
    } catch (ParseException ex) {//+0300
      LOGGER.error(ex, ex);
      return null;
    }
  }
  
  /**
   * Uses DataTypeConverter to parse arbitrary date string to Date.
   * @see javax.xml.bind.DatatypeConverter#parseDateTime(String)
   * @param date
   * @return the parsed date or null if null or empty date was passed
   */
  public static Date stringToDate(String date){
    if(org.apache.commons.lang3.StringUtils.isBlank(date)){
      return null;
    }
    return javax.xml.bind.DatatypeConverter.parseDateTime(date).getTime();
  }
  
  /**
   * 
   * @param sb
   * @param array array of items to append, if empty or null, this is a no-op
   * @param separator separator used for the join operation, if empty or null the values will appended without separator
   * @return the passed builder
   * @throws IllegalArgumentException on bad data
   */
  public static StringBuilder append(StringBuilder sb, int[] array, String separator) throws IllegalArgumentException{
    if(sb == null){
      throw new IllegalArgumentException("null builder.");
    }
    if(ArrayUtils.isEmpty(array)){
      LOGGER.debug("Ignored empty array.");
      return sb;
    }
    
    boolean hasSeparator = !org.apache.commons.lang3.StringUtils.isBlank(separator);
    
    sb.append(array[0]);
    for(int i=1;i<array.length;++i){
      if(hasSeparator){
        sb.append(separator);
      }
      sb.append(array[i]);
    }
    return sb;
  }
  
  /**
   * 
   * @param sb
   * @param array array of items to append, if empty or null, this is a no-op
   * @param separator separator used for the join operation, if empty or null the values will appended without separator
   * @return the passed builder
   * @throws IllegalArgumentException on bad data
   */
  public static StringBuilder append(StringBuilder sb, long[] array, String separator) throws IllegalArgumentException{
    if(sb == null){
      throw new IllegalArgumentException("null builder.");
    }
    if(ArrayUtils.isEmpty(array)){
      LOGGER.debug("Ignored empty array.");
      return sb;
    }
    
    boolean hasSeparator = !org.apache.commons.lang3.StringUtils.isBlank(separator);
    
    sb.append(array[0]);
    for(int i=1;i<array.length;++i){
      if(hasSeparator){
        sb.append(separator);
      }
      sb.append(array[i]);
    }
    return sb;
  }
}