/*
    * 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.shardingsphere.infra.rewrite.sql.token.pojo.generic;
  
  import com.cedarsoftware.util.CaseInsensitiveMap;
  import lombok.EqualsAndHashCode;
  import lombok.Getter;
  import org.apache.shardingsphere.infra.binder.context.segment.select.projection.Projection;
  import org.apache.shardingsphere.infra.binder.context.segment.select.projection.impl.ColumnProjection;
  import org.apache.shardingsphere.infra.database.core.metadata.database.enums.QuoteCharacter;
  import org.apache.shardingsphere.infra.database.core.type.DatabaseType;
  import org.apache.shardingsphere.infra.database.core.type.DatabaseTypeRegistry;
  import org.apache.shardingsphere.infra.rewrite.sql.token.pojo.RouteUnitAware;
  import org.apache.shardingsphere.infra.rewrite.sql.token.pojo.SQLToken;
  import org.apache.shardingsphere.infra.rewrite.sql.token.pojo.Substitutable;
  import org.apache.shardingsphere.infra.route.context.RouteMapper;
  import org.apache.shardingsphere.infra.route.context.RouteUnit;
  import org.apache.shardingsphere.sql.parser.sql.common.value.identifier.IdentifierValue;
  
  import java.util.Collection;
  import java.util.Collections;
  import java.util.HashMap;
  import java.util.Map;
  
  /**
   * Substitutable column name token.
   */
  @EqualsAndHashCode(callSuper = false)
  public final class SubstitutableColumnNameToken extends SQLToken implements Substitutable, RouteUnitAware {
      
      private static final String COLUMN_NAME_SPLITTER = ", ";
      
      @Getter
      private final int stopIndex;
      
      private final Collection<Projection> projections;
      
      private final boolean lastColumn;
      
      private final QuoteCharacter quoteCharacter;
      
      public SubstitutableColumnNameToken(final int startIndex, final int stopIndex, final Collection<Projection> projections, final DatabaseType databaseType) {
          super(startIndex);
          this.stopIndex = stopIndex;
          this.lastColumn = false;
          this.quoteCharacter = new DatabaseTypeRegistry(databaseType).getDialectDatabaseMetaData().getQuoteCharacter();
          this.projections = projections;
      }
      
      @Override
      public String toString(final RouteUnit routeUnit) {
          Map<String, String> logicAndActualTables = new HashMap<>();
          if (null != routeUnit) {
              logicAndActualTables.putAll(getLogicAndActualTables(routeUnit));
          }
          StringBuilder result = new StringBuilder();
          int count = 0;
          for (Projection each : projections) {
              if (0 == count && !lastColumn) {
                  result.append(getColumnExpression(each, logicAndActualTables));
              } else {
                  result.append(COLUMN_NAME_SPLITTER).append(getColumnExpression(each, logicAndActualTables));
              }
              count++;
          }
          return result.toString();
      }
      
      private Map<String, String> getLogicAndActualTables(final RouteUnit routeUnit) {
          if (null == routeUnit) {
              return Collections.emptyMap();
          }
          Map<String, String> result = new CaseInsensitiveMap<>();
          for (RouteMapper each : routeUnit.getTableMappers()) {
              result.put(each.getLogicName().toLowerCase(), each.getActualName());
          }
          return result;
      }
      
      private String getColumnExpression(final Projection projection, final Map<String, String> logicActualTableNames) {
          StringBuilder builder = new StringBuilder();
          if (projection instanceof ColumnProjection) {
              appendColumnProjection((ColumnProjection) projection, logicActualTableNames, builder);
          } else {
             builder.append(quoteCharacter.wrap(projection.getColumnLabel()));
         }
         return builder.toString();
     }
     
     private void appendColumnProjection(final ColumnProjection columnProjection, final Map<String, String> logicActualTableNames, final StringBuilder builder) {
         if (columnProjection.getOwner().isPresent()) {
             IdentifierValue owner = columnProjection.getOwner().get();
             String actualTableOwner = logicActualTableNames.getOrDefault(owner.getValue(), owner.getValue());
             builder.append(getValueWithQuoteCharacters(new IdentifierValue(actualTableOwner, owner.getQuoteCharacter()))).append('.');
         }
         builder.append(getValueWithQuoteCharacters(columnProjection.getName()));
         if (columnProjection.getAlias().isPresent()) {
             builder.append(" AS ").append(getValueWithQuoteCharacters(columnProjection.getAlias().get()));
         }
     }
     
     private String getValueWithQuoteCharacters(final IdentifierValue identifierValue) {
         return QuoteCharacter.NONE == identifierValue.getQuoteCharacter() ? identifierValue.getValue() : quoteCharacter.wrap(identifierValue.getValue());
     }
 }