/*
    * Copyright 2002,2004 The Apache Software Foundation.
    *
    * Licensed 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.commons.jelly.tags.sql;
  
  import java.sql.Connection;
  import java.sql.SQLException;
  
  import javax.sql.DataSource;
  
  import org.apache.commons.jelly.JellyTagException;
  import org.apache.commons.jelly.TagSupport;
  import org.apache.commons.jelly.XMLOutput;
  import org.apache.commons.jelly.tags.Resources;
  
  /***
   * <p>Tag handler for &lt;Transaction&gt; in JSTL.
   *
   * @author Hans Bergsten
   */
  
  public class TransactionTag extends TagSupport {
  
      //**********************************************************************
      // Private constants
  
      private static final String TRANSACTION_READ_COMMITTED = "read_committed";
      private static final String TRANSACTION_READ_UNCOMMITTED = "read_uncommitted";
      private static final String TRANSACTION_REPEATABLE_READ = "repeatable_read";
      private static final String TRANSACTION_SERIALIZABLE = "serializable";
  
      //*********************************************************************
      // Protected state
  
      protected Object rawDataSource;
      protected boolean dataSourceSpecified;
  
      //*********************************************************************
      // Private state
  
      private Connection conn;
      private int isolation = Connection.TRANSACTION_NONE;
      private int origIsolation;
  
      //*********************************************************************
      // Constructor and initialization
  
      public TransactionTag() {
      }
  
      /**
       * Sets the SQL DataSource. DataSource can be
       * a String or a DataSource object.
       */
      public void setDataSource(Object dataSource) {
          this.rawDataSource = dataSource;
          this.dataSourceSpecified = true;
      }
  
  
      //**********************************************************************
      // Tag logic
  
      /**
       * Prepares for execution by setting the initial state, such as
       * getting the <code>Connection</code> and preparing it for
       * the transaction.
       */
      public void doTag(XMLOutput output) throws JellyTagException {
  
          if ((rawDataSource == null) && dataSourceSpecified) {
              throw new JellyTagException(Resources.getMessage("SQL_DATASOURCE_NULL"));
          }
  
          DataSource dataSource = DataSourceUtil.getDataSource(rawDataSource, context);
  
          try {
              conn = dataSource.getConnection();
              origIsolation = conn.getTransactionIsolation();
              if (origIsolation == Connection.TRANSACTION_NONE) {
                  throw new JellyTagException(Resources.getMessage("TRANSACTION_NO_SUPPORT"));
              }
              if ((isolation != Connection.TRANSACTION_NONE)
                  && (isolation != origIsolation)) {
                  conn.setTransactionIsolation(isolation);
              }
             conn.setAutoCommit(false);
         }
         catch (SQLException e) {
             throw new JellyTagException(
                 Resources.getMessage("ERROR_GET_CONNECTION", e.getMessage()));
         }
 
         boolean finished = false;
         try {
             invokeBody(output);
             finished = true;
         }
         catch (Exception e) {
             if (conn != null) {
                 try {
                     conn.rollback();
                 }
                 catch (SQLException s) {
                     // Ignore to not hide orignal exception
                 }
                 doFinally();
             }
             throw new JellyTagException(e);
         }
 
         // lets commit
         try {
             conn.commit();
         }
         catch (SQLException e) {
             throw new JellyTagException(
                 Resources.getMessage("TRANSACTION_COMMIT_ERROR", e.getMessage()));
         }
         finally {
             doFinally();
         }
     }
 
     //**********************************************************************
     // Public utility methods
 
     /**
      * Sets the transaction isolation level.
      */
     public void setIsolation(String iso) throws JellyTagException {
 
         if (TRANSACTION_READ_COMMITTED.equals(iso)) {
             isolation = Connection.TRANSACTION_READ_COMMITTED;
         }
         else if (TRANSACTION_READ_UNCOMMITTED.equals(iso)) {
             isolation = Connection.TRANSACTION_READ_UNCOMMITTED;
         }
         else if (TRANSACTION_REPEATABLE_READ.equals(iso)) {
             isolation = Connection.TRANSACTION_REPEATABLE_READ;
         }
         else if (TRANSACTION_SERIALIZABLE.equals(iso)) {
             isolation = Connection.TRANSACTION_SERIALIZABLE;
         }
         else {
             throw new JellyTagException(Resources.getMessage("TRANSACTION_INVALID_ISOLATION"));
         }
     }
 
     /***
      * Called by nested parameter elements to get a reference to
      * the Connection.
      */
     public Connection getSharedConnection() {
         return conn;
     }
 
     //**********************************************************************
     // Implementation methods methods
 
     /**
      * Restores the <code>Connection</code> to its initial state and
      * closes it.
      */
     protected void doFinally() {
         if (conn != null) {
             try {
                 if ((isolation != Connection.TRANSACTION_NONE)
                     && (isolation != origIsolation)) {
                     conn.setTransactionIsolation(origIsolation);
                 }
                 conn.setAutoCommit(true);
                 conn.close();
             }
             catch (SQLException e) {
                 // Not much we can do
             }
         }
         conn = null;
     }
 
 }