/*
    * 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.binder.context.statement.dml;
  
  import lombok.Getter;
  import org.apache.shardingsphere.infra.binder.context.segment.table.TablesContext;
  import org.apache.shardingsphere.infra.binder.context.statement.CommonSQLStatementContext;
  import org.apache.shardingsphere.infra.binder.context.type.TableAvailable;
  import org.apache.shardingsphere.infra.binder.context.type.WhereAvailable;
  import org.apache.shardingsphere.sql.parser.sql.common.extractor.TableExtractor;
  import org.apache.shardingsphere.sql.parser.sql.common.segment.dml.column.ColumnSegment;
  import org.apache.shardingsphere.sql.parser.sql.common.segment.dml.expr.BinaryOperationExpression;
  import org.apache.shardingsphere.sql.parser.sql.common.segment.dml.predicate.WhereSegment;
  import org.apache.shardingsphere.sql.parser.sql.common.segment.generic.table.SimpleTableSegment;
  import org.apache.shardingsphere.sql.parser.sql.common.statement.dml.DeleteStatement;
  import org.apache.shardingsphere.sql.parser.sql.common.util.ColumnExtractor;
  import org.apache.shardingsphere.sql.parser.sql.common.util.ExpressionExtractUtils;
  
  import java.util.Collection;
  import java.util.HashMap;
  import java.util.LinkedList;
  import java.util.Map;
  
  /**
   * Delete statement context.
   */
  @Getter
  public final class DeleteStatementContext extends CommonSQLStatementContext implements TableAvailable, WhereAvailable {
      
      private final TablesContext tablesContext;
      
      private final Collection<WhereSegment> whereSegments = new LinkedList<>();
      
      private final Collection<ColumnSegment> columnSegments = new LinkedList<>();
      
      private final Collection<BinaryOperationExpression> joinConditions = new LinkedList<>();
      
      public DeleteStatementContext(final DeleteStatement sqlStatement) {
          super(sqlStatement);
          tablesContext = new TablesContext(getAllSimpleTableSegments(), getDatabaseType());
          getSqlStatement().getWhere().ifPresent(whereSegments::add);
          ColumnExtractor.extractColumnSegments(columnSegments, whereSegments);
          ExpressionExtractUtils.extractJoinConditions(joinConditions, whereSegments);
      }
      
      private Collection<SimpleTableSegment> getAllSimpleTableSegments() {
          TableExtractor tableExtractor = new TableExtractor();
          tableExtractor.extractTablesFromDelete(getSqlStatement());
          return filterAliasDeleteTable(tableExtractor.getRewriteTables());
      }
      
      private Collection<SimpleTableSegment> filterAliasDeleteTable(final Collection<SimpleTableSegment> tableSegments) {
          Collection<SimpleTableSegment> result = new LinkedList<>();
          Map<String, SimpleTableSegment> aliasAndTableSegmentMap = getAliasAndTableSegmentMap(tableSegments);
          for (SimpleTableSegment each : tableSegments) {
              SimpleTableSegment aliasDeleteTable = aliasAndTableSegmentMap.get(each.getTableName().getIdentifier().getValue());
              if (null == aliasDeleteTable || aliasDeleteTable.equals(each)) {
                  result.add(each);
              }
          }
          return result;
      }
      
      private Map<String, SimpleTableSegment> getAliasAndTableSegmentMap(final Collection<SimpleTableSegment> tableSegments) {
          Map<String, SimpleTableSegment> result = new HashMap<>(tableSegments.size(), 1F);
          for (SimpleTableSegment each : tableSegments) {
              each.getAliasName().ifPresent(optional -> result.putIfAbsent(optional, each));
          }
          return result;
      }
      
      @Override
      public DeleteStatement getSqlStatement() {
          return (DeleteStatement) super.getSqlStatement();
      }
      
      @Override
      public Collection<SimpleTableSegment> getAllTables() {
          return tablesContext.getSimpleTableSegments();
      }
      
      @Override
      public Collection<WhereSegment> getWhereSegments() {
          return whereSegments;
     }
     
     @Override
     public Collection<ColumnSegment> getColumnSegments() {
         return columnSegments;
     }
     
     @Override
     public Collection<BinaryOperationExpression> getJoinConditions() {
         return joinConditions;
     }
 }