/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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 org.apache.solr.update;

import java.util.ArrayList;
import java.util.Collection;
import java.util.List;

import org.apache.lucene.document.Document;
import org.apache.lucene.index.Term;
import org.apache.lucene.util.BytesRef;
import org.apache.lucene.util.BytesRefBuilder;
import org.apache.solr.common.SkyHook;
import org.apache.solr.common.SolrException;
import org.apache.solr.common.SolrInputDocument;
import org.apache.solr.common.SolrInputField;
import org.apache.solr.common.params.CommonParams;
import org.apache.solr.common.params.ShardParams;
import org.apache.solr.request.SolrQueryRequest;
import org.apache.solr.schema.IndexSchema;
import org.apache.solr.schema.SchemaField;

/**
 * An {@link UpdateCommand} for adding or updating one document.  Technically more than one Lucene documents
 * may be involved in the event of nested documents.
 */
public class AddUpdateCommand extends UpdateCommand {
  public final static ThreadLocal<AddUpdateCommand> THREAD_LOCAL_AddUpdateCommand = new ThreadLocal<>(){
    protected AddUpdateCommand initialValue() {
      return new AddUpdateCommand(null);
    }
  };

  public final static ThreadLocal<AddUpdateCommand> THREAD_LOCAL_AddUpdateCommand_TLOG = new ThreadLocal<>(){
    protected AddUpdateCommand initialValue() {
      return new AddUpdateCommand(null);
    }
  };


  /**
   * Higher level SolrInputDocument, normally used to construct the Lucene Document(s)
   * to index.
   */
  public volatile SolrInputDocument solrDoc;

  /**
   * This is the version of a document, previously indexed, on which the current
   * update depends on. This version could be that of a previous in-place update
   * or a full update. A negative value here, e.g. -1, indicates that this add
   * update does not depend on a previous update.
   */
  public volatile long prevVersion = -1;

  public volatile boolean overwrite = true;

  /**
   * The term to use to delete an existing document (for dedupe). (optional)
   */
  public volatile Term updateTerm;

  public volatile int commitWithin = -1;

  public volatile boolean isLastDocInBatch = false;

  /** Is this a nested update, null means not yet calculated. */
  public volatile Boolean isNested = null;

  // optional id in "internal" indexed form... if it is needed and not supplied,
  // it will be obtained from the doc.
  private volatile BytesRef indexedId;

  public AddUpdateCommand(SolrQueryRequest req) {
    super(req);
  }

  @Override
  public String name() {
    return "add";
  }

   /** Reset state to reuse this object with a different document in the same request */
   public void clear() {
     solrDoc = null;
     flags = 0;
     route = null;
     indexedId = null;
     isNested = false;
     updateTerm = null;
     isLastDocInBatch = false;
     version = 0;
     prevVersion = -1;
     overwrite = true;
     commitWithin = -1;
     req = null;
   }

   public SolrInputDocument getSolrInputDocument() {
     return solrDoc;
   }

  /**
   * Creates and returns a lucene Document to index.
   * Nested documents, if found, will cause an exception to be thrown.  Call {@link #getLuceneDocsIfNested()} for that.
   * Any changes made to the returned Document will not be reflected in the SolrInputDocument, or future calls to this
   * method.
   * Note that the behavior of this is sensitive to {@link #isInPlaceUpdate()}.*/
   public Document getLuceneDocument() {
     final boolean ignoreNestedDocs = false; // throw an exception if found
     SolrInputDocument solrInputDocument = solrDoc;
     if (!isInPlaceUpdate() && getReq().getSchema().isUsableForChildDocs()) {
       addRootField(solrInputDocument, getRootIdUsingRouteParam());
     }
     return DocumentBuilder.toDocument(solrInputDocument, req.getSchema(), isInPlaceUpdate(), ignoreNestedDocs);
   }

  /** Returns the indexed ID for this document.  The returned BytesRef is retained across multiple calls, and should not be modified. */
   public BytesRef getIndexedId() {
     if (indexedId == null && req != null) {
       IndexSchema schema = req.getSchema();
       SchemaField sf = schema.getUniqueKeyField();
       if (sf != null) {
         if (solrDoc != null) {
           SolrInputField field = solrDoc.getField(sf.getName());

           int count = field==null ? 0 : field.getValueCount();
           if (count == 0) {
             if (overwrite) {
               throw new SolrException( SolrException.ErrorCode.BAD_REQUEST, "Document is missing mandatory uniqueKey field: " + sf.getName());
             }
           } else if (count  > 1) {
             throw new SolrException( SolrException.ErrorCode.BAD_REQUEST, "Document contains multiple values for uniqueKey field: " + field);
           } else {
             BytesRefBuilder b = new BytesRefBuilder();
             sf.getType().readableToIndexed(field.getFirstValue().toString(), b);
             indexedId = b.get();

             if (SkyHook.skyHookDoc != null) {
               SkyHook.skyHookDoc.register(field.getFirstValue().toString());
             }
           }
         }
       }
     }
     return indexedId;
   }

   public void setIndexedId(BytesRef indexedId) {
     this.indexedId = indexedId;
   }

   public String getPrintableId() {
    if (req != null) {
      IndexSchema schema = req.getSchema();
      SchemaField sf = schema.getUniqueKeyField();
      if (solrDoc != null && sf != null) {
        SolrInputField field = solrDoc.getField(sf.getName());
        if (field != null) {
          return field.getFirstValue().toString();
        }
      }
    }
     return "(null)";
   }

  /**
   *
   * @return value of _route_ param({@link ShardParams#_ROUTE_}), otherwise doc id.
   */
  public String getRootIdUsingRouteParam() {
     return req.getParams().get(ShardParams._ROUTE_, getHashableId());
   }

  /**
   * @return String id to hash
   */
  public String getHashableId() {
    IndexSchema schema = req.getSchema();
    SchemaField sf = schema.getUniqueKeyField();
    if (sf != null) {
      if (solrDoc != null) {
        SolrInputField field = solrDoc.getField(sf.getName());

        int count = field == null ? 0 : field.getValueCount();
        if (count == 0) {
          if (overwrite) {
            throw new SolrException(SolrException.ErrorCode.BAD_REQUEST,
                "Document is missing mandatory uniqueKey field: "
                    + sf.getName());
          }
        } else if (count > 1) {
          throw new SolrException(SolrException.ErrorCode.BAD_REQUEST,
              "Document contains multiple values for uniqueKey field: " + field);
        } else {
          return field.getFirstValue().toString();
        }
      }
    }
    return null;
  }

  /**
   * Computes the final flattened Solr docs that are ready to be converted to Lucene docs.  If no flattening is
   * performed then we return null, and the caller ought to use {@link #getLuceneDocument()} instead.
   * This should only be called once.
   * Any changes made to the returned Document(s) will not be reflected in the SolrInputDocument,
   * or future calls to this method.
   */
  public Iterable<Document> getLuceneDocsIfNested() {
    assert ! isInPlaceUpdate() : "We don't expect this to happen."; // but should "work"?
    if (req.getSchema() != null && !req.getSchema().isUsableForChildDocs()) {
      // note if the doc is nested despite this, we'll throw an exception elsewhere
      return null;
    }

    List<SolrInputDocument> all = flatten(solrDoc);
    if (all.size() <= 1) {
      return null; // caller should call getLuceneDocument() instead
    }

    final String rootId = getRootIdUsingRouteParam();
    final SolrInputField versionSif = solrDoc.get(CommonParams.VERSION_FIELD);

    for (SolrInputDocument sdoc : all) {
      addRootField(sdoc, rootId);
      if (versionSif != null) {
        addVersionField(sdoc, versionSif);
      }
      // TODO: if possible concurrent modification exception (if SolrInputDocument not cloned and is being forwarded to replicas)
      // then we could add this field to the generated lucene document instead.
    }

    return () -> all.stream().map(sdoc -> DocumentBuilder.toDocument(sdoc, req.getSchema())).iterator();
  }

  private void addRootField(SolrInputDocument sdoc, String rootId) {
    sdoc.setField(IndexSchema.ROOT_FIELD_NAME, rootId);
  }

  private void addVersionField(SolrInputDocument sdoc, SolrInputField versionSif) {
    // Reordered delete-by-query assumes all documents have a version, see SOLR-10114
    // all docs in hierarchy should have the same version.
    // Either fetch the version from the root doc or compute it and propagate it.
    sdoc.put(CommonParams.VERSION_FIELD, versionSif);
  }

  private List<SolrInputDocument> flatten(SolrInputDocument root) {
    List<SolrInputDocument> unwrappedDocs = new ArrayList<>(16);
    flattenAnonymous(unwrappedDocs, root, true);
    flattenLabelled(unwrappedDocs, root, true);
    unwrappedDocs.add(root);

    return unwrappedDocs;
  }

  /** Extract all child documents from parent that are saved in fields */
  private void flattenLabelled(List<SolrInputDocument> unwrappedDocs, SolrInputDocument currentDoc, boolean isRoot) {
    for (SolrInputField field: currentDoc.values()) {
      Object value = field.getFirstValue();
      // check if value is a childDocument
      if (value instanceof SolrInputDocument) {
        Object val = field.getValue();
        if (!(val instanceof Collection)) {
          flattenLabelled(unwrappedDocs, ((SolrInputDocument) val));
          continue;
        }
        @SuppressWarnings({"unchecked"})
        Collection<SolrInputDocument> childrenList = ((Collection) val);
        for (SolrInputDocument child : childrenList) {
          flattenLabelled(unwrappedDocs, child);
        }
      }
    }

    if (!isRoot) unwrappedDocs.add(currentDoc);
  }

  private void flattenLabelled(List<SolrInputDocument> unwrappedDocs, SolrInputDocument currentDoc) {
    if(currentDoc.hasChildDocuments()) {
      throw new SolrException(SolrException.ErrorCode.BAD_REQUEST,
          "Anonymous child docs can only hang from others or the root: " + currentDoc);
    }
    flattenLabelled(unwrappedDocs, currentDoc, false);
  }

  /** Extract all anonymous child documents from parent. */
  private void flattenAnonymous(List<SolrInputDocument> unwrappedDocs, SolrInputDocument currentDoc, boolean isRoot) {
    List<SolrInputDocument> children = currentDoc.getChildDocuments();
    if (children != null) {
      for (SolrInputDocument child : children) {
        flattenAnonymous(unwrappedDocs, child);
      }
    }

    if(!isRoot) unwrappedDocs.add(currentDoc);
  }

  private void flattenAnonymous(List<SolrInputDocument> unwrappedDocs, SolrInputDocument currentDoc) {
    flattenAnonymous(unwrappedDocs, currentDoc, false);
  }

  @Override
  public String toString() {
     StringBuilder sb = new StringBuilder(super.toString());
     sb.append(",id=").append(getPrintableId());
     if (!overwrite) sb.append(",overwrite=").append(overwrite);
     if (commitWithin != -1) sb.append(",commitWithin=").append(commitWithin);
     sb.append('}');
     return sb.toString();
   }

  /**
   * Is this add update an in-place update? An in-place update is one where only docValues are
   * updated, and a new document is not indexed.
   */
  public boolean isInPlaceUpdate() {
    return (prevVersion >= 0);
  }
}