/*
    * 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.executor.sql.process;
  
  import com.google.common.base.Strings;
  import org.apache.shardingsphere.infra.annotation.HighFrequencyInvocation;
  import org.apache.shardingsphere.infra.executor.kernel.model.ExecutionGroupContext;
  import org.apache.shardingsphere.infra.executor.kernel.model.ExecutionGroupReportContext;
  import org.apache.shardingsphere.infra.executor.sql.execute.engine.SQLExecutionUnit;
  import org.apache.shardingsphere.infra.metadata.user.Grantee;
  import org.apache.shardingsphere.infra.session.query.QueryContext;
  
  import java.util.Collections;
  import java.util.UUID;
  import java.util.concurrent.ThreadLocalRandom;
  
  /**
   * Process engine.
   */
  @HighFrequencyInvocation
  public final class ProcessEngine {
      
      /**
       * Connect.
       *
       * @param databaseName database name
       * @return process ID
       */
      public String connect(final String databaseName) {
          return connect(new ExecutionGroupReportContext(getProcessId(), databaseName));
      }
      
      /**
       * Connect.
       *
       * @param databaseName database name
       * @param grantee grantee
       * @return process ID
       */
      public String connect(final String databaseName, final Grantee grantee) {
          return connect(new ExecutionGroupReportContext(getProcessId(), databaseName, grantee));
      }
      
      private String connect(final ExecutionGroupReportContext reportContext) {
          ExecutionGroupContext<? extends SQLExecutionUnit> executionGroupContext = new ExecutionGroupContext<>(Collections.emptyList(), reportContext);
          ProcessRegistry.getInstance().add(new Process(executionGroupContext));
          return executionGroupContext.getReportContext().getProcessId();
      }
      
      private String getProcessId() {
          return new UUID(ThreadLocalRandom.current().nextLong(), ThreadLocalRandom.current().nextLong()).toString().replace("-", "");
      }
      
      /**
       * Disconnect.
       *
       * @param processId process ID
       */
      public void disconnect(final String processId) {
          ProcessRegistry.getInstance().remove(processId);
      }
      
      /**
       * Execute SQL.
       *
       * @param executionGroupContext execution group context
       * @param queryContext query context
       */
      public void executeSQL(final ExecutionGroupContext<? extends SQLExecutionUnit> executionGroupContext, final QueryContext queryContext) {
          ProcessRegistry.getInstance().add(new Process(queryContext.getSql(), executionGroupContext));
      }
      
      /**
       * Complete SQL unit execution.
       *
       * @param executionUnit execution unit
       * @param processId process ID
       */
      public void completeSQLUnitExecution(final SQLExecutionUnit executionUnit, final String processId) {
          if (Strings.isNullOrEmpty(processId)) {
              return;
          }
          Process process = ProcessRegistry.getInstance().get(processId);
          if (null == process) {
             return;
         }
         process.completeExecutionUnit();
         process.removeProcessStatement(executionUnit.getExecutionUnit());
     }
     
     /**
      * Complete SQL execution.
      *
      * @param processId process ID
      */
     public void completeSQLExecution(final String processId) {
         if (Strings.isNullOrEmpty(processId)) {
             return;
         }
         Process process = ProcessRegistry.getInstance().get(processId);
         if (null == process) {
             return;
         }
         ExecutionGroupContext<? extends SQLExecutionUnit> executionGroupContext = new ExecutionGroupContext<>(
                 Collections.emptyList(), new ExecutionGroupReportContext(processId, process.getDatabaseName(), new Grantee(process.getUsername(), process.getHostname())));
         ProcessRegistry.getInstance().add(new Process(executionGroupContext));
     }
 }