/*
    * 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.data.pipeline.core.sqlbuilder.sql;
  
  import com.github.benmanes.caffeine.cache.Cache;
  import com.github.benmanes.caffeine.cache.Caffeine;
  import org.apache.shardingsphere.data.pipeline.core.ingest.record.Column;
  import org.apache.shardingsphere.data.pipeline.core.ingest.record.DataRecord;
  import org.apache.shardingsphere.data.pipeline.core.sqlbuilder.dialect.DialectPipelineSQLBuilder;
  import org.apache.shardingsphere.data.pipeline.core.sqlbuilder.segment.PipelineSQLSegmentBuilder;
  import org.apache.shardingsphere.infra.database.core.type.DatabaseType;
  import org.apache.shardingsphere.infra.database.core.spi.DatabaseTypedSPILoader;
  
  import java.util.Collection;
  import java.util.Objects;
  import java.util.Optional;
  import java.util.stream.Collectors;
  
  /**
   * Pipeline import SQL builder engine.
   */
  public final class PipelineImportSQLBuilder {
      
      private static final String INSERT_SQL_CACHE_KEY_PREFIX = "INSERT_";
      
      private static final String UPDATE_SQL_CACHE_KEY_PREFIX = "UPDATE_";
      
      private static final String DELETE_SQL_CACHE_KEY_PREFIX = "DELETE_";
      
      private final DialectPipelineSQLBuilder dialectSQLBuilder;
      
      private final PipelineSQLSegmentBuilder sqlSegmentBuilder;
      
      private final Cache<String, String> sqlCache;
      
      public PipelineImportSQLBuilder(final DatabaseType databaseType) {
          dialectSQLBuilder = DatabaseTypedSPILoader.getService(DialectPipelineSQLBuilder.class, databaseType);
          sqlSegmentBuilder = new PipelineSQLSegmentBuilder(databaseType);
          sqlCache = Caffeine.newBuilder().initialCapacity(16).maximumSize(1024L).build();
      }
      
      /**
       * Build insert SQL.
       *
       * @param schemaName schema name
       * @param dataRecord data record
       * @return insert SQL
       */
      public String buildInsertSQL(final String schemaName, final DataRecord dataRecord) {
          String sqlCacheKey = INSERT_SQL_CACHE_KEY_PREFIX + dataRecord.getTableName();
          if (null == sqlCache.getIfPresent(sqlCacheKey)) {
              String insertMainClause = buildInsertMainClause(schemaName, dataRecord);
              sqlCache.put(sqlCacheKey, dialectSQLBuilder.buildInsertOnDuplicateClause(dataRecord).map(optional -> insertMainClause + " " + optional).orElse(insertMainClause));
          }
          return sqlCache.getIfPresent(sqlCacheKey);
      }
      
      private String buildInsertMainClause(final String schemaName, final DataRecord dataRecord) {
          String columnsLiteral = dataRecord.getColumns().stream().map(each -> sqlSegmentBuilder.getEscapedIdentifier(each.getName())).collect(Collectors.joining(","));
          String valuesLiteral = dataRecord.getColumns().stream().map(each -> "?").collect(Collectors.joining(","));
          return String.format("INSERT INTO %s(%s) VALUES(%s)", sqlSegmentBuilder.getQualifiedTableName(schemaName, dataRecord.getTableName()), columnsLiteral, valuesLiteral);
      }
      
      /**
       * Build update SQL.
       *
       * @param schemaName schema name
       * @param dataRecord data record
       * @param conditionColumns condition columns
       * @return update SQL
       */
      public String buildUpdateSQL(final String schemaName, final DataRecord dataRecord, final Collection<Column> conditionColumns) {
          String sqlCacheKey = UPDATE_SQL_CACHE_KEY_PREFIX + dataRecord.getTableName();
          if (null == sqlCache.getIfPresent(sqlCacheKey)) {
              String updateMainClause = String.format("UPDATE %s SET %%s", sqlSegmentBuilder.getQualifiedTableName(schemaName, dataRecord.getTableName()));
              sqlCache.put(sqlCacheKey, buildWhereClause(conditionColumns).map(optional -> updateMainClause + optional).orElse(updateMainClause));
          }
          Collection<Column> setColumns = dataRecord.getColumns().stream().filter(Column::isUpdated).collect(Collectors.toList());
          String updateSetClause = setColumns.stream().map(each -> sqlSegmentBuilder.getEscapedIdentifier(each.getName()) + " = ?").collect(Collectors.joining(","));
          return String.format(Objects.requireNonNull(sqlCache.getIfPresent(sqlCacheKey)), updateSetClause);
      }
      
      /**
       * Build delete SQL.
      *
      * @param schemaName schema name
      * @param dataRecord data record
      * @param conditionColumns condition columns
      * @return delete SQL
      */
     public String buildDeleteSQL(final String schemaName, final DataRecord dataRecord, final Collection<Column> conditionColumns) {
         String sqlCacheKey = DELETE_SQL_CACHE_KEY_PREFIX + dataRecord.getTableName();
         if (null == sqlCache.getIfPresent(sqlCacheKey)) {
             String deleteMainClause = buildDeleteMainClause(schemaName, dataRecord);
             sqlCache.put(sqlCacheKey, buildWhereClause(conditionColumns).map(optional -> deleteMainClause + optional).orElse(deleteMainClause));
         }
         return sqlCache.getIfPresent(sqlCacheKey);
     }
     
     private String buildDeleteMainClause(final String schemaName, final DataRecord dataRecord) {
         return String.format("DELETE FROM %s", sqlSegmentBuilder.getQualifiedTableName(schemaName, dataRecord.getTableName()));
     }
     
     private Optional<String> buildWhereClause(final Collection<Column> conditionColumns) {
         return conditionColumns.isEmpty()
                 ? Optional.empty()
                 : Optional.of(" WHERE " + conditionColumns.stream().map(each -> sqlSegmentBuilder.getEscapedIdentifier(each.getName()) + " = ?").collect(Collectors.joining(" AND ")));
     }
 }