/*
 * Copyright 2010-2012 Luca Garulli (l.garulli--at--orientechnologies.com)
 *
 * 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.orientechnologies.orient.core.sql.operator;

import com.orientechnologies.common.collection.OMultiValue;
import com.orientechnologies.orient.core.command.OCommandContext;
import com.orientechnologies.orient.core.db.record.OIdentifiable;
import com.orientechnologies.orient.core.id.ORID;
import com.orientechnologies.orient.core.index.OCompositeIndexDefinition;
import com.orientechnologies.orient.core.index.OIndex;
import com.orientechnologies.orient.core.index.OIndexDefinition;
import com.orientechnologies.orient.core.index.OIndexDefinitionMultiValue;
import com.orientechnologies.orient.core.index.OIndexInternal;
import com.orientechnologies.orient.core.metadata.schema.OType;
import com.orientechnologies.orient.core.record.ORecord;
import com.orientechnologies.orient.core.record.impl.ODocument;
import com.orientechnologies.orient.core.record.impl.ODocumentHelper;
import com.orientechnologies.orient.core.sql.filter.OSQLFilterCondition;
import com.orientechnologies.orient.core.sql.filter.OSQLFilterItemField;
import com.orientechnologies.orient.core.sql.filter.OSQLFilterItemParameter;

import java.util.Collection;
import java.util.Collections;
import java.util.List;

/**
 * EQUALS operator.
 * 
 * @author Luca Garulli
 * 
 */
public class OQueryOperatorEquals extends OQueryOperatorEqualityNotNulls {

  public OQueryOperatorEquals() {
    super("=", 5, false);
  }

  @Override
  protected boolean evaluateExpression(final OIdentifiable iRecord, final OSQLFilterCondition iCondition, final Object iLeft,
      final Object iRight, OCommandContext iContext) {
    return equals(iLeft, iRight);
  }

  public static boolean equals(final Object iLeft, final Object iRight) {
    if (iLeft == null || iRight == null)
      return false;

    // RECORD & ORID
    if (iLeft instanceof ORecord<?>)
      return comparesValues(iRight, (ORecord<?>) iLeft, true);
    else if (iRight instanceof ORecord<?>)
      return comparesValues(iLeft, (ORecord<?>) iRight, true);

    // ALL OTHER CASES
    final Object right = OType.convert(iRight, iLeft.getClass());
    if (right == null)
      return false;
    return iLeft.equals(right);
  }

  protected static boolean comparesValues(final Object iValue, final ORecord<?> iRecord, final boolean iConsiderIn) {
    // ORID && RECORD
    final ORID other = ((ORecord<?>) iRecord).getIdentity();

    if (!other.isPersistent() && iRecord instanceof ODocument) {
      // ODOCUMENT AS RESULT OF SUB-QUERY: GET THE FIRST FIELD IF ANY
      final String[] firstFieldName = ((ODocument) iRecord).fieldNames();
      if (firstFieldName.length > 0) {
        Object fieldValue = ((ODocument) iRecord).field(firstFieldName[0]);
        if (fieldValue != null) {
          if (iConsiderIn && OMultiValue.isMultiValue(fieldValue)) {
            for (Object o : OMultiValue.getMultiValueIterable(fieldValue)) {
              if (o != null && o.equals(iValue))
                return true;
            }
          }

          return fieldValue.equals(iValue);
        }
      }
      return false;
    }
    return other.equals(iValue);
  }

  @Override
  public OIndexReuseType getIndexReuseType(final Object iLeft, final Object iRight) {
    if (iLeft instanceof OIdentifiable && iRight instanceof OIdentifiable)
      return OIndexReuseType.NO_INDEX;
    if (iRight == null || iLeft == null)
      return OIndexReuseType.NO_INDEX;

    return OIndexReuseType.INDEX_METHOD;
  }

  @Override
  public Object executeIndexQuery(OCommandContext iContext, OIndex<?> index, List<Object> keyParams,
																	boolean ascSortOrder, IndexResultListener resultListener, int fetchLimit) {
    final OIndexDefinition indexDefinition = index.getDefinition();

    final OIndexInternal<?> internalIndex = index.getInternal();
    if (!internalIndex.canBeUsedInEqualityOperators())
      return null;

    final Object result;

    if (indexDefinition.getParamCount() == 1) {
      final Object key;
      if (indexDefinition instanceof OIndexDefinitionMultiValue)
        key = ((OIndexDefinitionMultiValue) indexDefinition).createSingleValue(keyParams.get(0));
      else
        key = indexDefinition.createValue(keyParams);

      if (key == null)
        return null;

      final Object indexResult;
      indexResult = index.get(key);

      result = convertIndexResult(indexResult);
    } else {
      // in case of composite keys several items can be returned in case of we perform search
      // using part of composite key stored in index.

      final OCompositeIndexDefinition compositeIndexDefinition = (OCompositeIndexDefinition) indexDefinition;

      final Object keyOne = compositeIndexDefinition.createSingleValue(keyParams);

      if (keyOne == null)
        return null;

      final Object keyTwo = compositeIndexDefinition.createSingleValue(keyParams);

      if (internalIndex.hasRangeQuerySupport()) {
        if (resultListener != null) {
          index.getValuesBetween(keyOne, true, keyTwo, true, ascSortOrder, resultListener);
          result = resultListener.getResult();
        } else
          result = index.getValuesBetween(keyOne, true, keyTwo, true, ascSortOrder);
      } else {
        if (indexDefinition.getParamCount() == keyParams.size()) {
          final Object indexResult;
          indexResult = index.get(keyOne);

          result = convertIndexResult(indexResult);
        } else
          return null;
      }
    }

    updateProfiler(iContext, index, keyParams, indexDefinition);
    return result;
  }

  private Object convertIndexResult(Object indexResult) {
    Object result;
    if (indexResult instanceof Collection)
      result = (Collection<?>) indexResult;
    else if (indexResult == null)
      result = Collections.emptyList();
    else if (indexResult instanceof OIdentifiable)
      result = Collections.singletonList((OIdentifiable) indexResult);
    else
      result = indexResult;
    return result;
  }

  @Override
  public ORID getBeginRidRange(final Object iLeft, final Object iRight) {
    if (iLeft instanceof OSQLFilterItemField && ODocumentHelper.ATTRIBUTE_RID.equals(((OSQLFilterItemField) iLeft).getRoot()))
      if (iRight instanceof ORID)
        return (ORID) iRight;
      else {
        if (iRight instanceof OSQLFilterItemParameter
            && ((OSQLFilterItemParameter) iRight).getValue(null, null, null) instanceof ORID)
          return (ORID) ((OSQLFilterItemParameter) iRight).getValue(null, null, null);
      }

    if (iRight instanceof OSQLFilterItemField && ODocumentHelper.ATTRIBUTE_RID.equals(((OSQLFilterItemField) iRight).getRoot()))
      if (iLeft instanceof ORID)
        return (ORID) iLeft;
      else {
        if (iLeft instanceof OSQLFilterItemParameter
            && ((OSQLFilterItemParameter) iLeft).getValue(null, null, null) instanceof ORID)
          return (ORID) ((OSQLFilterItemParameter) iLeft).getValue(null, null, null);
      }

    return null;
  }

  @Override
  public ORID getEndRidRange(final Object iLeft, final Object iRight) {
    return getBeginRidRange(iLeft, iRight);
  }
}
