/*
    * 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.opencastproject.list.api.ListProviderException;
  import org.opencastproject.list.api.ListProvidersService;
  import org.opencastproject.list.api.ResourceListQuery;
  import org.opencastproject.list.impl.ResourceListQueryImpl;
  
  import com.google.common.collect.Iterables;
  
  import org.apache.commons.lang3.StringUtils;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  import java.util.ArrayList;
  import java.util.Arrays;
  import java.util.Collections;
  import java.util.Comparator;
  import java.util.HashMap;
  import java.util.List;
  import java.util.Map;
  import java.util.Optional;
  import java.util.stream.Collectors;
  
  public class DublinCoreMetadataCollection {
    private static final Logger logger = LoggerFactory.getLogger(DublinCoreMetadataCollection.class);
  
    /** The list containing all the metadata */
    private List<MetadataField> fieldsInOrder = new ArrayList<>();
    private final Map<String, MetadataField> outputFields = new HashMap<>();
  
    public DublinCoreMetadataCollection() {
      this(Collections.emptyList());
    }
  
    public DublinCoreMetadataCollection(final Iterable<MetadataField> fields) {
      for (final MetadataField field : fields) {
        addField(field);
      }
    }
  
    public DublinCoreMetadataCollection(final DublinCoreMetadataCollection c) {
      this(c.fieldsInOrder);
    }
  
    public DublinCoreMetadataCollection readOnlyCopy() {
      return new DublinCoreMetadataCollection(this.fieldsInOrder.stream().map(MetadataField::readOnlyCopy)
              .collect(Collectors.toList()));
    }
  
    public Map<String, MetadataField> getOutputFields() {
      return outputFields;
    }
  
    public void addField(final MetadataField metadata) {
      if (metadata == null)
        throw new IllegalArgumentException("The metadata must not be null.");
      addFieldInOrder(metadata);
      this.outputFields.put(metadata.getOutputID(), metadata);
    }
  
    /**
     * Adds a field in ui order to the collection. If no order is specified it will be added to the end.
     *
     * @param metadata
     *          The metadata to add to the collection.
     */
    private void addFieldInOrder(final MetadataField metadata) {
      removeFieldIfExists(metadata);
  
      // Find all of the ordered or unordered elements.
      final ArrayList<MetadataField> orderedFields = new ArrayList<>();
      final ArrayList<MetadataField> unorderedFields = new ArrayList<>();
      for (final MetadataField field : fieldsInOrder) {
        if (field.getOrder() != null) {
          orderedFields.add(field);
        } else {
          unorderedFields.add(field);
        }
     }
 
     // Add the new field to either the ordered fields or the unordered fields.
     if (metadata.getOrder() != null) {
       orderedFields.add(metadata);
     } else {
       unorderedFields.add(metadata);
     }
 
     // Sort the ordered elements so that early entries don't push later entries to the right
     orderedFields.sort(Comparator.comparingInt(MetadataField::getOrder));
 
     // Add all the non-ordered elements to the collection
     fieldsInOrder = new ArrayList<>(unorderedFields);
 
     // Add all of the fields that have an index to their location starting at the lowest value.
     for (final MetadataField orderedField : orderedFields) {
       final int index = orderedField.getOrder() < fieldsInOrder.size() ? orderedField.getOrder()
               : fieldsInOrder.size();
       fieldsInOrder.add(index, orderedField);
     }
   }
 
   public void addEmptyField(final MetadataField metadataField, final ListProvidersService listProvidersService) {
     addField(metadataField, Collections.emptyList(), Optional.empty(), listProvidersService);
   }
 
   public void addField(final MetadataField metadataField, final String value, final ListProvidersService
           listProvidersService) {
     addField(metadataField, Collections.singletonList(value), Optional.empty(), listProvidersService);
   }
 
   public void addField(final MetadataField metadataField, final Optional<String> valueOpt, final
     Optional<ResourceListQuery> collectionQueryOverrideOpt, final ListProvidersService listProvidersService) {
     if (valueOpt.isPresent()) {
       addField(metadataField, Collections.singletonList(valueOpt.get()), collectionQueryOverrideOpt,
               listProvidersService);
     } else {
       addField(metadataField, Collections.emptyList(), collectionQueryOverrideOpt, listProvidersService);
     }
   }
 
   /**
    * Set value to a metadata field of unknown type
    */
   private static void setValueFromDCCatalog(
           final List<String> filteredValues,
           final MetadataField metadataField) {
     if (filteredValues.isEmpty()) {
       throw new IllegalArgumentException("Values cannot be empty");
     }
 
     if (filteredValues.size() > 1
             && metadataField.getType() != MetadataField.Type.MIXED_TEXT
             && metadataField.getType() != MetadataField.Type.ITERABLE_TEXT) {
       logger.warn("Cannot put multiple values into a single-value field, only the last value is used. {}",
               Arrays.toString(filteredValues.toArray()));
     }
 
     switch (metadataField.getType()) {
       case BOOLEAN:
         metadataField.setValue(Boolean.parseBoolean(Iterables.getLast(filteredValues)), false);
         break;
       case DATE:
         if (metadataField.getPattern() == null) {
           metadataField.setPattern("yyyy-MM-dd'T'HH:mm:ss.SSS'Z'");
         }
         metadataField.setValue(EncodingSchemeUtils.decodeDate(Iterables.getLast(filteredValues)), false);
         break;
       case DURATION:
         final String value = Iterables.getLast(filteredValues);
         final DCMIPeriod period = EncodingSchemeUtils.decodePeriod(value);
         if (period == null)
           throw new IllegalArgumentException("period couldn't be parsed: " + value);
         final long longValue = period.getEnd().getTime() - period.getStart().getTime();
         metadataField.setValue(Long.toString(longValue), false);
         break;
       case ITERABLE_TEXT:
       case MIXED_TEXT:
         metadataField.setValue(filteredValues, false);
         break;
       case LONG:
         metadataField.setValue(Long.parseLong(Iterables.getLast(filteredValues)), false);
         break;
       case START_DATE:
         if (metadataField.getPattern() == null) {
           metadataField.setPattern("yyyy-MM-dd'T'HH:mm:ss.SSS'Z'");
         }
         metadataField.setValue(Iterables.getLast(filteredValues), false);
         break;
       case TEXT:
       case ORDERED_TEXT:
       case TEXT_LONG:
         metadataField.setValue(Iterables.getLast(filteredValues), false);
         break;
       default:
         throw new IllegalArgumentException("Unknown metadata type! " + metadataField.getType());
     }
   }
 
   public void addField(final MetadataField metadataField, final List<String> values, final ListProvidersService
           listProvidersService) {
     addField(metadataField, values, Optional.empty(), listProvidersService);
   }
 
   public void addField(final MetadataField metadataField, final List<String> values, final Optional<ResourceListQuery>
           collectionQueryOverrideOpt, final ListProvidersService listProvidersService) {
     final List<String> filteredValues = values.stream().filter(StringUtils::isNotBlank).collect(Collectors.toList());
 
     if (!filteredValues.isEmpty()) {
       setValueFromDCCatalog(filteredValues, metadataField);
     }
 
     metadataField.setIsTranslatable(getCollectionIsTranslatable(metadataField, listProvidersService));
     metadataField.setCollection(getCollection(metadataField, listProvidersService, collectionQueryOverrideOpt));
 
     addField(metadataField);
   }
 
   private static Boolean getCollectionIsTranslatable(
           final MetadataField metadataField,
           final ListProvidersService listProvidersService) {
     if (listProvidersService != null && metadataField.getListprovider() != null) {
       try {
         return listProvidersService.isTranslatable(metadataField.getListprovider());
       } catch (final ListProviderException ex) {
         // failed to get is-translatable property on list-provider-service
         // as this field is optional, it is fine to pass here
       }
     }
     return null;
   }
 
   private static Map<String, String> getCollection(final MetadataField metadataField, final ListProvidersService
           listProvidersService, final Optional<ResourceListQuery> collectionQueryOverrideOpt) {
     try {
       if (listProvidersService != null && metadataField.getListprovider() != null) {
 
         // use collection query override?
         ResourceListQuery resourceListQuery;
         if (collectionQueryOverrideOpt.isPresent()) {
           resourceListQuery = collectionQueryOverrideOpt.get();
 
           // shortcut: don't query list provider if limit is set to 0
           Optional<Integer> limit = resourceListQuery.getLimit();
           if (limit.isPresent() && limit.get() == 0) {
             return Collections.emptyMap();
           }
         } else {
           resourceListQuery = new ResourceListQueryImpl();
         }
 
         return listProvidersService.getList(metadataField.getListprovider(), resourceListQuery, true);
       }
       return null;
     } catch (final ListProviderException e) {
       logger.warn("Unable to set collection on metadata because", e);
       return null;
     }
   }
 
   /**
    * Removes a {@link MetadataField} if it already exists in the ordered collection.
    *
    * @param metadata
    *          The field to remove.
    */
   private void removeFieldIfExists(final MetadataField metadata) {
     int index = -1;
     for (final MetadataField field : fieldsInOrder) {
       if (field.getInputID().equalsIgnoreCase(metadata.getInputID())
               && field.getOutputID().equalsIgnoreCase(metadata.getOutputID())) {
         index = fieldsInOrder.indexOf(field);
       }
     }
 
     if (index >= 0) {
       fieldsInOrder.remove(index);
     }
   }
 
   public void removeField(final MetadataField metadata) {
     if (metadata == null)
       throw new IllegalArgumentException("The metadata must not be null.");
     this.fieldsInOrder.remove(metadata);
     this.outputFields.remove(metadata.getOutputID());
   }
 
   public List<MetadataField> getFields() {
     return this.fieldsInOrder;
   }
 
   public void updateStringField(final MetadataField current, final String value) {
     if (current.getValue() != null && !(current.getValue() instanceof String)) {
       throw new IllegalArgumentException("Unable to update a field to a different type than String with this method!");
     }
     removeField(current);
     final MetadataField field = new MetadataField(current);
     field.setValue(value);
     addField(field);
   }
 
   public boolean isUpdated() {
     for (final MetadataField field : fieldsInOrder) {
       if (field.isUpdated()) {
         return true;
       }
     }
     return false;
   }
 
 }