/*
    * 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.metadata.statistics.builder.dialect;
  
  import org.apache.shardingsphere.infra.autogen.version.ShardingSphereVersion;
  import org.apache.shardingsphere.infra.metadata.ShardingSphereMetaData;
  import org.apache.shardingsphere.infra.metadata.database.ShardingSphereDatabase;
  import org.apache.shardingsphere.infra.metadata.database.schema.model.ShardingSphereSchema;
  import org.apache.shardingsphere.infra.metadata.database.schema.model.ShardingSphereTable;
  import org.apache.shardingsphere.infra.metadata.statistics.ShardingSphereDatabaseData;
  import org.apache.shardingsphere.infra.metadata.statistics.ShardingSphereRowData;
  import org.apache.shardingsphere.infra.metadata.statistics.ShardingSphereSchemaData;
  import org.apache.shardingsphere.infra.metadata.statistics.ShardingSphereStatistics;
  import org.apache.shardingsphere.infra.metadata.statistics.ShardingSphereTableData;
  import org.apache.shardingsphere.infra.metadata.statistics.builder.ShardingSphereStatisticsBuilder;
  
  import java.util.Arrays;
  import java.util.Collection;
  import java.util.Collections;
  import java.util.LinkedHashMap;
  import java.util.Map;
  import java.util.Map.Entry;
  
  /**
   * ShardingSphere statistics builder for PostgreSQL.
   */
  
  public final class PostgreSQLShardingSphereStatisticsBuilder implements ShardingSphereStatisticsBuilder {
      
      private static final String SHARDING_SPHERE = "shardingsphere";
      
      private static final String CLUSTER_INFORMATION = "cluster_information";
      
      private static final String SHARDING_TABLE_STATISTICS = "sharding_table_statistics";
      
      private static final Map<String, Collection<String>> INIT_DATA_SCHEMA_TABLES = new LinkedHashMap<>();
      
      static {
          INIT_DATA_SCHEMA_TABLES.put("pg_catalog", Arrays.asList("pg_class", "pg_namespace"));
      }
      
      @Override
      public ShardingSphereStatistics build(final ShardingSphereMetaData metaData) {
          ShardingSphereStatistics result = new ShardingSphereStatistics();
          for (Entry<String, ShardingSphereDatabase> entry : metaData.getDatabases().entrySet()) {
              ShardingSphereDatabaseData databaseData = new ShardingSphereDatabaseData();
              initSchemas(entry.getValue(), databaseData);
              if (!databaseData.getSchemaData().isEmpty()) {
                  result.putDatabase(entry.getKey(), databaseData);
              }
          }
          return result;
      }
      
      private void initSchemas(final ShardingSphereDatabase database, final ShardingSphereDatabaseData databaseData) {
          for (Entry<String, ShardingSphereSchema> entry : database.getSchemas().entrySet()) {
              if (SHARDING_SPHERE.equals(entry.getKey())) {
                  ShardingSphereSchemaData schemaData = new ShardingSphereSchemaData();
                  initClusterInformationTable(schemaData);
                  initShardingTableStatisticsTable(schemaData);
                  databaseData.putSchema(SHARDING_SPHERE, schemaData);
              }
              if (INIT_DATA_SCHEMA_TABLES.containsKey(entry.getKey())) {
                  ShardingSphereSchemaData schemaData = new ShardingSphereSchemaData();
                  initTables(entry.getValue(), INIT_DATA_SCHEMA_TABLES.get(entry.getKey()), schemaData);
                  databaseData.putSchema(entry.getKey(), schemaData);
              }
          }
      }
      
      private void initClusterInformationTable(final ShardingSphereSchemaData schemaData) {
          ShardingSphereTableData tableData = new ShardingSphereTableData(CLUSTER_INFORMATION);
          tableData.getRows().add(new ShardingSphereRowData(Collections.singletonList(ShardingSphereVersion.VERSION)));
          schemaData.putTable(CLUSTER_INFORMATION, tableData);
      }
      
      private void initShardingTableStatisticsTable(final ShardingSphereSchemaData schemaData) {
          schemaData.putTable(SHARDING_TABLE_STATISTICS, new ShardingSphereTableData(SHARDING_TABLE_STATISTICS));
      }
      
      private void initTables(final ShardingSphereSchema schema, final Collection<String> tables, final ShardingSphereSchemaData schemaData) {
          for (Entry<String, ShardingSphereTable> entry : schema.getTables().entrySet()) {
              if (tables.contains(entry.getValue().getName())) {
                  ShardingSphereTableData tableData = new ShardingSphereTableData(entry.getValue().getName());
                 schemaData.putTable(entry.getKey(), tableData);
             }
         }
     }
     
     @Override
     public String getDatabaseType() {
         return "PostgreSQL";
     }
 }