/*
    * 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.sql.parser.postgresql.visitor.statement.type;
  
  import org.apache.shardingsphere.sql.parser.api.ASTNode;
  import org.apache.shardingsphere.sql.parser.api.visitor.statement.type.DALStatementVisitor;
  import org.apache.shardingsphere.sql.parser.autogen.PostgreSQLStatementParser.AnalyzeTableContext;
  import org.apache.shardingsphere.sql.parser.autogen.PostgreSQLStatementParser.CheckpointContext;
  import org.apache.shardingsphere.sql.parser.autogen.PostgreSQLStatementParser.ColIdContext;
  import org.apache.shardingsphere.sql.parser.autogen.PostgreSQLStatementParser.ConfigurationParameterClauseContext;
  import org.apache.shardingsphere.sql.parser.autogen.PostgreSQLStatementParser.EmptyStatementContext;
  import org.apache.shardingsphere.sql.parser.autogen.PostgreSQLStatementParser.ExplainContext;
  import org.apache.shardingsphere.sql.parser.autogen.PostgreSQLStatementParser.ExplainableStmtContext;
  import org.apache.shardingsphere.sql.parser.autogen.PostgreSQLStatementParser.LoadContext;
  import org.apache.shardingsphere.sql.parser.autogen.PostgreSQLStatementParser.ResetParameterContext;
  import org.apache.shardingsphere.sql.parser.autogen.PostgreSQLStatementParser.SetContext;
  import org.apache.shardingsphere.sql.parser.autogen.PostgreSQLStatementParser.ShowContext;
  import org.apache.shardingsphere.sql.parser.autogen.PostgreSQLStatementParser.VacuumContext;
  import org.apache.shardingsphere.sql.parser.autogen.PostgreSQLStatementParser.VacuumRelationContext;
  import org.apache.shardingsphere.sql.parser.autogen.PostgreSQLStatementParser.VacuumRelationListContext;
  import org.apache.shardingsphere.sql.parser.postgresql.visitor.statement.PostgreSQLStatementVisitor;
  import org.apache.shardingsphere.sql.parser.statement.core.segment.dal.VariableAssignSegment;
  import org.apache.shardingsphere.sql.parser.statement.core.segment.dal.VariableSegment;
  import org.apache.shardingsphere.sql.parser.statement.core.segment.generic.table.SimpleTableSegment;
  import org.apache.shardingsphere.sql.parser.statement.core.segment.generic.table.TableNameSegment;
  import org.apache.shardingsphere.sql.parser.statement.core.statement.SQLStatement;
  import org.apache.shardingsphere.sql.parser.statement.core.statement.type.dal.AnalyzeTableStatement;
  import org.apache.shardingsphere.sql.parser.statement.core.statement.type.dal.EmptyStatement;
  import org.apache.shardingsphere.sql.parser.statement.core.statement.type.dal.ExplainStatement;
  import org.apache.shardingsphere.sql.parser.statement.postgresql.dal.PostgreSQLLoadStatement;
  import org.apache.shardingsphere.sql.parser.statement.postgresql.dal.PostgreSQLResetParameterStatement;
  import org.apache.shardingsphere.sql.parser.statement.core.statement.type.dal.SetStatement;
  import org.apache.shardingsphere.sql.parser.statement.core.statement.type.dal.ShowStatement;
  import org.apache.shardingsphere.sql.parser.statement.postgresql.dal.PostgreSQLVacuumStatement;
  import org.apache.shardingsphere.sql.parser.statement.postgresql.dal.PostgreSQLCheckpointStatement;
  import org.apache.shardingsphere.sql.parser.statement.core.value.collection.CollectionValue;
  import org.apache.shardingsphere.sql.parser.statement.core.value.identifier.IdentifierValue;
  
  import java.util.Collections;
  import java.util.LinkedList;
  import java.util.List;
  
  /**
   * DAL statement visitor for PostgreSQL.
   */
  public final class PostgreSQLDALStatementVisitor extends PostgreSQLStatementVisitor implements DALStatementVisitor {
      
      @Override
      public ASTNode visitShow(final ShowContext ctx) {
          if (null != ctx.varName()) {
              return new ShowStatement(ctx.varName().getText());
          }
          if (null != ctx.ZONE()) {
              return new ShowStatement("timezone");
          }
          if (null != ctx.ISOLATION()) {
              return new ShowStatement("transaction_isolation");
          }
          if (null != ctx.AUTHORIZATION()) {
              return new ShowStatement("session_authorization");
          }
          return new ShowStatement("ALL");
      }
      
      @Override
      public ASTNode visitSet(final SetContext ctx) {
          List<VariableAssignSegment> variableAssigns = new LinkedList<>();
          if (null != ctx.configurationParameterClause()) {
              VariableAssignSegment variableAssignSegment = (VariableAssignSegment) visit(ctx.configurationParameterClause());
              if (null != ctx.runtimeScope()) {
                  variableAssignSegment.getVariable().setScope(ctx.runtimeScope().getText());
              }
              variableAssigns.add(variableAssignSegment);
          }
          if (null != ctx.encoding()) {
              VariableSegment variable = new VariableSegment(ctx.NAMES().getSymbol().getStartIndex(), ctx.NAMES().getSymbol().getStopIndex(), "client_encoding");
              VariableAssignSegment variableAssign = new VariableAssignSegment(ctx.encoding().start.getStartIndex(), ctx.encoding().stop.getStopIndex(), variable, ctx.encoding().getText());
              variableAssigns.add(variableAssign);
          }
          return new SetStatement(variableAssigns);
      }
      
      @Override
      public ASTNode visitConfigurationParameterClause(final ConfigurationParameterClauseContext ctx) {
         return new VariableAssignSegment(ctx.start.getStartIndex(), ctx.stop.getStopIndex(),
                 new VariableSegment(ctx.varName().start.getStartIndex(), ctx.varName().stop.getStopIndex(), ctx.varName().getText()), getAssignValue(ctx));
     }
     
     private String getAssignValue(final ConfigurationParameterClauseContext ctx) {
         if (null != ctx.varList()) {
             return ctx.varList().getText();
         }
         if (null != ctx.DEFAULT()) {
             return ctx.DEFAULT().getText();
         }
         return null;
     }
     
     @Override
     public ASTNode visitResetParameter(final ResetParameterContext ctx) {
         return new PostgreSQLResetParameterStatement(null != ctx.ALL() ? "ALL" : ctx.identifier().getText());
     }
     
     @SuppressWarnings("unchecked")
     @Override
     public ASTNode visitAnalyzeTable(final AnalyzeTableContext ctx) {
         return new AnalyzeTableStatement(null == ctx.vacuumRelationList() ? Collections.emptyList() : ((CollectionValue<SimpleTableSegment>) visit(ctx.vacuumRelationList())).getValue());
     }
     
     @Override
     public ASTNode visitVacuumRelationList(final VacuumRelationListContext ctx) {
         CollectionValue<SimpleTableSegment> result = new CollectionValue<>();
         for (VacuumRelationContext each : ctx.vacuumRelation()) {
             ColIdContext colId = each.qualifiedName().colId();
             TableNameSegment tableName = new TableNameSegment(colId.start.getStartIndex(), colId.stop.getStopIndex(), new IdentifierValue(colId.getText()));
             result.getValue().add(new SimpleTableSegment(tableName));
         }
         return result;
     }
     
     @Override
     public ASTNode visitLoad(final LoadContext ctx) {
         return new PostgreSQLLoadStatement();
     }
     
     @Override
     public ASTNode visitVacuum(final VacuumContext ctx) {
         return new PostgreSQLVacuumStatement();
     }
     
     @Override
     public ASTNode visitExplain(final ExplainContext ctx) {
         return new ExplainStatement((SQLStatement) visit(ctx.explainableStmt()));
     }
     
     @Override
     public ASTNode visitExplainableStmt(final ExplainableStmtContext ctx) {
         if (null != ctx.select()) {
             return visit(ctx.select());
         }
         if (null != ctx.insert()) {
             return visit(ctx.insert());
         }
         if (null != ctx.update()) {
             return visit(ctx.update());
         }
         if (null != ctx.delete()) {
             return visit(ctx.delete());
         }
         if (null != ctx.declare()) {
             // TODO visit declare statement
             return visit(ctx.declare());
         }
         if (null != ctx.executeStmt()) {
             return visit(ctx.executeStmt());
         }
         if (null != ctx.createMaterializedView()) {
             return visit(ctx.createMaterializedView());
         }
         // TODO visit refresh materialized view statement
         return visit(ctx.refreshMatViewStmt());
     }
     
     @Override
     public ASTNode visitCheckpoint(final CheckpointContext ctx) {
         return new PostgreSQLCheckpointStatement();
     }
     
     @Override
     public ASTNode visitEmptyStatement(final EmptyStatementContext ctx) {
         return new EmptyStatement();
     }
 }