/*
    * Licensed to The Apereo Foundation under one or more contributor license
    * agreements. See the NOTICE file distributed with this work for additional
    * information regarding copyright ownership.
    *
    *
    * The Apereo Foundation licenses this file to you under the Educational
    * Community 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://opensource.org/licenses/ecl2.txt
   *
   * 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 org.opencastproject.metadata.dublincore;
  
  import org.joda.time.Duration;
  import org.joda.time.format.ISODateTimeFormat;
  import org.joda.time.format.ISOPeriodFormat;
  
  import java.text.SimpleDateFormat;
  import java.util.Date;
  import java.util.HashMap;
  import java.util.Map;
  import java.util.Optional;
  import java.util.TimeZone;
  import java.util.regex.Matcher;
  import java.util.regex.Pattern;
  
  /**
   * Utility class to facilitate the work with DCMI encoding schemes.
   */
  public final class EncodingSchemeUtils {
  
    private static final Map<Precision, String> formats = new HashMap<Precision, String>();
  
    static {
      formats.put(Precision.Year, "yyyy");
      formats.put(Precision.Month, "yyyy-MM");
      formats.put(Precision.Day, "yyyy-MM-dd");
      formats.put(Precision.Minute, "yyyy-MM-dd'T'HH:mm'Z'");
      formats.put(Precision.Second, "yyyy-MM-dd'T'HH:mm:ss'Z'");
      formats.put(Precision.Fraction, "yyyy-MM-dd'T'HH:mm:ss.SSS'Z'");
    }
  
    /** Disable construction of this utility class */
    private EncodingSchemeUtils() {
    }
  
    /**
     * Encode a date with the given precision into a Dublin Core string value, using the recommended W3C-DTF scheme. The
     * UTC timezone is used for all precisions from {@link Precision#Minute} to {@link Precision#Fraction}. For years,
     * months and days the local timezone is used instead to ensure that the given date enters the DublinCore as is. If
     * UTC was used it may happen that you get the previous or next day, month or year respectively
     * <p>
     * The language of the returned value is {@link DublinCore#LANGUAGE_UNDEFINED}.
     * <p>
     * See <a href="http://www.w3.org/TR/NOTE-datetime">http://www.w3.org/TR/NOTE-datetime</a> for more information about
     * W3C-DTF.
     *
     * @param date
     *          the date to encode
     * @param precision
     *          the precision to use
     */
    public static DublinCoreValue encodeDate(Date date, Precision precision) {
      if (date == null) {
        throw new IllegalArgumentException("The date must not be null");
      }
      if (precision == null) {
        throw new IllegalArgumentException("The precision must not be null");
      }
  
      return DublinCoreValue.mk(formatDate(date, precision), DublinCore.LANGUAGE_UNDEFINED,
          Optional.of(DublinCore.ENC_SCHEME_W3CDTF));
    }
  
    public static String formatDate(Date date, Precision precision) {
      SimpleDateFormat f = new SimpleDateFormat(formats.get(precision));
      if (precision == Precision.Minute || precision == Precision.Second || precision == Precision.Fraction) {
        f.setTimeZone(TimeZone.getTimeZone("UTC"));
      }
      return f.format(date);
    }
  
    /**
     * Encode a period with the given precision into a Dublin Core string value using the recommended DCMI Period scheme.
     * For the usage of the UTC timezone please refer to {@link #encodeDate(Date, Precision)} for further information.
     * <p>
     * One of the dates may be null to create an open interval.
     * <p>
    * The language of the returned value is {@link DublinCore#LANGUAGE_UNDEFINED}.
    * <p>
    * See <a href="http://dublincore.org/documents/dcmi-period/">http://dublincore.org/documents/dcmi-period/</a> for
    * more information about DCMI Period.
    *
    * @param period
    *          the period
    * @param precision
    *          the precision
    */
   public static DublinCoreValue encodePeriod(DCMIPeriod period, Precision precision) {
     if (period == null) {
       throw new IllegalArgumentException("The period must not be null");
     }
     if (precision == null) {
       throw new IllegalArgumentException("The precision must not be null");
     }
 
     StringBuilder b = new StringBuilder();
     if (period.hasStart()) {
       b.append("start=").append(formatDate(period.getStart(), precision)).append(";");
     }
     if (period.hasEnd()) {
       if (b.length() > 0) {
         b.append(" ");
       }
       b.append("end=").append(formatDate(period.getEnd(), precision)).append(";");
     }
     if (period.hasName()) {
       b.append(" ").append("name=").append(period.getName().replace(";", "")).append(";");
     }
     b.append(" ").append("scheme=W3C-DTF;");
     return DublinCoreValue.mk(b.toString(), DublinCore.LANGUAGE_UNDEFINED, Optional.of(DublinCore.ENC_SCHEME_PERIOD));
   }
 
   /**
    * Encode a duration measured in milliseconds into a Dublin Core string using the
    * {@link DublinCore#ENC_SCHEME_ISO8601} encoding scheme <code>PTnHnMnS</code>.
    * <p>
    * The language of the returned value is {@link DublinCore#LANGUAGE_UNDEFINED}.
    * <p>
    * See <a href="http://en.wikipedia.org/wiki/ISO_8601#Durations"> ISO8601 Durations</a> for details.
    *
    * @param duration
    *          the duration in milliseconds
    */
   public static DublinCoreValue encodeDuration(long duration) {
     return DublinCoreValue.mk(ISOPeriodFormat.standard().print(new Duration(duration).toPeriod()),
             DublinCore.LANGUAGE_UNDEFINED, Optional.of(DublinCore.ENC_SCHEME_ISO8601));
   }
 
   /**
    * Decode a string encoded in the ISO8601 encoding scheme.
    * <p>
    * Also supports the REPLAY legacy format <code>hh:mm:ss</code>.
    * <p>
    * See <a href="http://en.wikipedia.org/wiki/ISO_8601#Durations"> ISO8601 Durations</a> for details.
    *
    * @param value
    *          the ISO encoded string
    * @return the duration in milliseconds or null, if the value cannot be parsed
    */
   public static Long decodeDuration(String value) {
     try {
       return ISOPeriodFormat.standard().parsePeriod(value).toStandardDuration().getMillis();
     } catch (IllegalArgumentException ignore) {
     }
     // also support the legacy format hh:mm:ss
     String[] parts = value.split(":");
     try {
       if (parts.length == 1) {
         return Long.parseLong(parts[0]) * 1000;
       }
       if (parts.length == 2) {
         return Long.parseLong(parts[0]) * 1000 * 60 + Long.parseLong(parts[1]) * 1000;
       }
       if (parts.length == 3) {
         return Long.parseLong(parts[0]) * 1000 * 60 * 60
             + Long.parseLong(parts[1]) * 1000 * 60
             + Long.parseLong(parts[2]) * 1000;
       }
     } catch (NumberFormatException ignore) {
     }
     return null;
   }
 
   /**
    * Decode a string encoded in the ISO8601 encoding scheme.
    *
    * @param value
    *          the Dublin Core value
    * @return the duration in milliseconds or null, if the value cannot be parsed or is in a different encoding scheme
    */
   public static Long decodeDuration(DublinCoreValue value) {
     if (!value.hasEncodingScheme() || value.getEncodingScheme().get().equals(DublinCore.ENC_SCHEME_ISO8601)) {
       return decodeDuration(value.getValue());
     }
     return null;
   }
 
   public static Long decodeMandatoryDuration(String value) {
     Long l = decodeDuration(value);
     if (l == null) {
       throw new IllegalArgumentException("Cannot decode duration: " + value);
     }
     return l;
   }
 
   /**
    * Tries to decode the given value as a W3C-DTF encoded date. If decoding fails, null is returned.
    *
    * @return the date or null if decoding fails
    */
   public static Date decodeDate(DublinCoreValue value) {
     if (!value.hasEncodingScheme() || value.getEncodingScheme().get().equals(DublinCore.ENC_SCHEME_W3CDTF)) {
       try {
         return parseW3CDTF(value.getValue());
       } catch (IllegalArgumentException ignore) {
       }
     }
 
     // Try unixtime in milliseconds (backwards-compatibility with older mediapackages)
     try {
       long timestamp = Long.parseLong(value.getValue());
       Date decoded = new java.util.Date(timestamp);
       return decoded;
     } catch (NumberFormatException nfe) {
     }
 
     return null;
   }
 
   /**
    * Tries to decode the given value as a W3C-DTF encoded date. If decoding fails, null is returned.
    *
    * @return the date or null if decoding fails
    */
   public static Date decodeDate(String value) {
     try {
       return parseW3CDTF(value);
     } catch (IllegalArgumentException ignore) {
     }
 
     // Try unixtime in milliseconds (backwards-compatibility with older mediapackages)
     try {
       long timestamp = Long.parseLong(value);
       Date decoded = new java.util.Date(timestamp);
       return decoded;
     } catch (NumberFormatException nfe) {
     }
 
     return null;
   }
 
   /**
    * Like {@link #decodeDate(String)}, but throws an {@link IllegalArgumentException} if the value cannot be decoded.
    *
    * @param value
    *          the value
    * @return the date
    * @throws IllegalArgumentException
    *           if the value cannot be decoded
    */
   public static Date decodeMandatoryDate(DublinCoreValue value) {
     Date date = decodeDate(value);
     if (date == null) {
       throw new IllegalArgumentException("Cannot decode to Date: " + value);
     }
     return date;
   }
 
   /**
    * Like {@link #decodeDate(String)}, but throws an {@link IllegalArgumentException} if the value cannot be decoded.
    *
    * @return the date
    * @throws IllegalArgumentException
    *           if the value cannot be decoded
    */
   public static Date decodeMandatoryDate(String value) {
     Date date = decodeDate(value);
     if (date == null) {
       throw new IllegalArgumentException("Cannot decode to Date: " + value);
     }
     return date;
   }
 
   private static final Pattern DCMI_PERIOD = Pattern.compile("(start|end|name)\\s*=\\s*(.*?)(?:;|\\s*$)");
   private static final Pattern DCMI_PERIOD_SCHEME = Pattern.compile("scheme\\s*=\\s*(.*?)(?:;|\\s*$)");
 
   /**
    * Tries to decode a string in the DCMI period format, using W3C-DTF for the encoding of the individual dates. If
    * parsing fails at any point, null will be returned.
    *
    * @return the period or null if decoding fails
    */
   public static DCMIPeriod decodePeriod(DublinCoreValue value) {
     return decodePeriod(value.getValue());
   }
 
   /**
    * Tries to decode a string in the DCMI period format, using W3C-DTF for the encoding of the individual dates. If
    * parsing fails at any point, null will be returned.
    *
    * @return the period or null if decoding fails
    */
   public static DCMIPeriod decodePeriod(String value) {
     // Parse value
     Matcher schemeMatcher = DCMI_PERIOD_SCHEME.matcher(value);
     boolean mayBeW3CDTFEncoded = true;
     if (schemeMatcher.find()) {
       String schemeString = schemeMatcher.group(1);
       if (!"W3C-DTF".equalsIgnoreCase(schemeString) && !"W3CDTF".equalsIgnoreCase(schemeString)) {
         mayBeW3CDTFEncoded = false;
       }
     }
     try {
       if (mayBeW3CDTFEncoded) {
         // Declare fields
         Date start = null;
         Date end = null;
         String name = null;
         // Parse
         Matcher m = DCMI_PERIOD.matcher(value);
         while (m.find()) {
           String field = m.group(1);
           String fieldValue = m.group(2);
           if ("start".equals(field)) {
             if (start != null) {
               return null;
             }
             start = parseW3CDTF(fieldValue);
           } else if ("end".equals(field)) {
             if (end != null) {
               return null;
             }
             end = parseW3CDTF(fieldValue);
           } else if ("name".equals(field)) {
             if (name != null) {
               return null;
             }
             name = fieldValue;
           }
         }
         if (start == null && end == null) {
           return null;
         }
         return new DCMIPeriod(start, end, name);
       }
     } catch (IllegalArgumentException ignore) {
       // Parse error
     }
     return null;
   }
 
   /**
    * Like {@link #decodePeriod(String)}, but throws an {@link IllegalArgumentException} if the value cannot be decoded.
    *
    * @return the period
    * @throws IllegalArgumentException
    *           if the value cannot be decoded
    */
   public static DCMIPeriod decodeMandatoryPeriod(DublinCoreValue value) {
     return decodeMandatoryPeriod(value.getValue());
   }
 
   /**
    * Like {@link #decodePeriod(DublinCoreValue)}, but throws an {@link IllegalArgumentException} if the value cannot be
    * decoded.
    *
    * @return the period
    * @throws IllegalArgumentException
    *           if the value cannot be decoded
    */
   public static DCMIPeriod decodeMandatoryPeriod(String value) {
     DCMIPeriod period = decodePeriod(value);
     if (period == null) {
       throw new IllegalArgumentException("Cannot decode to DCMIPeriod: " + value);
     }
 
     return period;
   }
 
   /**
    * Tries to decode the value to a temporal object. For now, supported types are {@link java.util.Date},
    * {@link DCMIPeriod} and Long for a duration.
    *
    * @param value
    *          the value to decode
    * @return a temporal object of the said types or null if decoding fails
    */
   public static Temporal decodeTemporal(DublinCoreValue value) {
     // First try Date
     Date instant = decodeDate(value);
     if (instant != null) {
       return Temporal.instant(instant);
     }
     DCMIPeriod period = decodePeriod(value);
     if (period != null) {
       return Temporal.period(period);
     }
     Long duration = decodeDuration(value);
     if (duration != null) {
       return Temporal.duration(duration);
     }
     return null;
   }
 
   /**
    * Like {@link #decodeTemporal(DublinCoreValue)}, but throws an {@link IllegalArgumentException} if the value cannot
    * be decoded.
    *
    * @return the temporal object of type {@link java.util.Date} or {@link DCMIPeriod}
    * @throws IllegalArgumentException
    *           if the value cannot be decoded
    */
   public static Temporal decodeMandatoryTemporal(DublinCoreValue value) {
     Temporal temporal = decodeTemporal(value);
     if (value == null) {
       throw new IllegalArgumentException("Cannot decode to either Date or DCMIPeriod: " + value);
     }
 
     return temporal;
   }
 
   /**
    * @throws IllegalArgumentException
    *           if the value cannot be parsed
    */
   private static Date parseW3CDTF(String value) {
     return ISODateTimeFormat.dateTimeParser().parseDateTime(value).toDate();
   }
 
 }