/* Copyright (c) 2005 Ricebridge. All Rights Reserved.
 *
 * This file is available under the terms and conditions of the
 * Ricebridge "Open Source API" policy; Ricebridge grants use of this
 * copyrighted work under the terms of a BSD-style license only. See
 * http://www.opensource.org/licenses/bsd-license.php for more
 * information.
 * 
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 
 *  - Redistributions of source code must retain the above copyright
 *  notice, this list of conditions and the following disclaimer.
 *
 *  - Redistributions in binary form must reproduce the above
 *  copyright notice, this list of conditions and the following
 *  disclaimer in the documentation and/or other materials provided
 *  with the distribution.
 *
 *  - Neither the name of the Ricebridge nor the names of its
 *  contributors may be used to endorse or promote products derived
 *  from this software without specific prior written permission.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
 * OF THE POSSIBILITY OF SUCH DAMAGE.  
 */

package com.ricebridge.xmlman;


import org.jostraca.util.Internal;
import org.jostraca.util.Standard;

import java.sql.ResultSet;
import java.sql.ResultSetMetaData;

import java.util.*;


/** An implementation of {@link RecordProvider} that provides data records for saving
 *  from a {@link java.sql.ResultSet} object.
 *    <p>This class is used to implement the 
 *  {@link XmlManager#saveResultSet(File,RecordSpec,ResultSet) saveResultSet(*,RecordSpec,ResultSet)} 
 *  methods in {@link XmlManager}.
 *  It simply reads the next data record from the specified <code>ResultSet</code>,
 *  maintaining an internal index of the current record.</p>
 *    <p><code>ResultSetRecordProvider</code> is designed to be subclassed. You can change the default implementation by calling the 
 *  {@link com.ricebridge.xmlman.in.XmlManagerStoreBase#setResultSetRecordProviderClass setResultSetRecordProviderClass} method of 
 *  {@link com.ricebridge.xmlman.in.XmlManagerStore}, and providing a subclass of <code>ResultSetRecordProvider</code>. 
 *  <code>XmlManagerStore</code> can be accessed using {@link XmlManager#getXmlManagerStore}.</p>
 *    <p>The <b><a href="ResultSetRecordProvider.java.html">Source Code</a></b> of this Java class 
 *    is available under a <a href="http://www.opensource.org/licenses/bsd-license.php">BSD-style license</a>.</p>
 */
public class ResultSetRecordProvider extends RecordProviderSupport {

  // public

  /** Output headers as first data record
   *  (name for {@link XmlSpec#setProperty XmlSpec.setProperty}: <code>ResultSet.saveHeaders</code>). */
  public static final String PROP_ResultSet_saveHeaders = "ResultSet.saveHeaders";

  /** Reset {@link ResultSet} after saving
   *  (name for {@link XmlSpec#setProperty XmlSpec.setProperty}: <code>ResultSet.resetBeforeFirst</code>). */
  public static final String PROP_ResultSet_resetBeforeFirst = "ResultSet.resetBeforeFirst";


  // protected instance

  /** {@link ResultSet} containing source data. */
  protected ResultSet iResultSet        = null;

  /** Save the column names as first data record. See {@link #setXmlSpecImpl setXmlSpecImpl}. */
  protected boolean   iSaveHeaders      = false;

  /** Column names. */
  protected String[] iHeaders = null;

  /** Indicate that internal state is at the first record. */ 
  protected boolean iFirstRecord = true;

  /** Number of data fields in record, determined by {@link ResultSetMetaData}. */
  protected int iFieldCount = 0;

  /** Type of {@link ResultSet}, determines if it can be reset. */
  protected int iResultSetType = ResultSet.TYPE_FORWARD_ONLY;

  /** Reset {@link ResultSet} to beginning after saving data. */
  protected boolean iResetBeforeFirst = false;



  // constructors

  /** Create uninitialised for use with {@link #setResultSet}. */
  public ResultSetRecordProvider() {
    // init with setResultSet
  }


  /** Create initialised. See {@link #setResultSet setResultSet} for details. 
   *  @param pResultSet  <code>ResultSet</code> providing data
   */
  public ResultSetRecordProvider( ResultSet pResultSet ) {
    setResultSet( pResultSet );
  }



  // public methods

  /** Set the <code>ResultSet</code> providing data to save. 
   *    <p>The default number of fields per record is taken from 
   *  {@link java.sql.ResultSetMetaData#getColumnCount()}
   *  and the headers (output as the first record when the property <code>ResultSet.saveHeaders</code> is true), 
   *  are taken from {@link java.sql.ResultSetMetaData#getColumnName(int)}.</p>
   *  @param pResultSet  <code>ResultSet</code> providing data
   */
  public void setResultSet( ResultSet pResultSet ) {
    iResultSet = (ResultSet) Internal.null_arg( pResultSet );

    ResultSetMetaData rsmd = null;
    try {
      rsmd = iResultSet.getMetaData();
    }
    catch( Exception e ) {
      throw new XmlManagerException( XmlManagerException.CODE_resultset_method, 
                                     new String[] { "resultset", String.valueOf(iResultSet),
                                                    "params", "",
                                                    "method", "getMetaData" }, e );
    }

    try {
      iFieldCount = rsmd.getColumnCount();
    }
    catch( Exception e ) {
      throw new XmlManagerException( XmlManagerException.CODE_rsmd_method, 
                                     new String[] { "resultset", String.valueOf(iResultSet), 
                                                    "resultsetmetadata", String.valueOf(rsmd),
                                                    "params", "",
                                                    "method", "getColumnCount"}, e );
    }


    try {
      iResultSetType = iResultSet.getType();
    }
    catch( Exception e ) {
      throw new XmlManagerException( XmlManagerException.CODE_resultset_method, 
                                     new String[] { "resultset", String.valueOf(iResultSet), 
                                                    "params", "",
                                                    "method", "getType"}, e );
    }


    if( iSaveHeaders && -1 < iFieldCount) {
      iHeaders = new String[ iFieldCount + 1 ];
      int cI = 1;
      try {
        for( ; cI <= iFieldCount; cI++ ) {
          iHeaders[cI] = rsmd.getColumnName( cI );
        }
      }
      catch( Exception e ) {
        throw new XmlManagerException( XmlManagerException.CODE_rsmd_method, 
                                       new String[] { "resultset", String.valueOf(iResultSet), 
                                                      "method", "getColumnName",
                                                      "params", ""+cI,
                                                      "resultsetmetadata", String.valueOf(rsmd)}, e );
      }
    }
    else {
      iSaveHeaders = false;
    }
  }



  // RecordProviderSupport methods

  /** Handle property settings for saving {@link ResultSet ResultSets}.
   *    <p>You can change these using {@link XmlSpec}.</p>
   *  @see RecordListener#setXmlSpec
   *  @see #PROP_ResultSet_saveHeaders
   *  @see #PROP_ResultSet_resetBeforeFirst
   */
  protected void setXmlSpecImpl( XmlSpec pXmlSpec ) {
    iSaveHeaders      = pXmlSpec.getBooleanProperty( PROP_ResultSet_saveHeaders );
    iResetBeforeFirst = pXmlSpec.getBooleanProperty( PROP_ResultSet_resetBeforeFirst );
  }


  /** Start the saving process. */
  protected void startProcessImpl() {
    iFirstRecord = true;
  }


  /** Check if there are any more records. */
  protected boolean hasNextRecordImpl() {
    if( iSaveHeaders && iFirstRecord ) {
      return true;
    }
    else {
      try {
        return iResultSet.next();
      }
      catch( Exception e ) {
        throw new XmlManagerException( XmlManagerException.CODE_resultset_method, 
                                       new String[] { "resultset", String.valueOf(iResultSet),
                                                      "params", "",
                                                      "method", "next" }, e );
      }
    }
  }


  /** Return next data record as a <code>String[]</code> array. */
  protected String[] nextRecordImpl() {
    String[] record = new String[iFieldCount];
 
    if( iSaveHeaders && iFirstRecord ) {
      for( int fI = 0; fI < iFieldCount; fI++ ) {
        record[fI] = iHeaders[ fI ];
      }
    }
    else {
      int fI = 0;
      try {
        for( ; fI < iFieldCount; fI++ ) {
          record[fI] = String.valueOf( iResultSet.getObject( fI+1 ) );
        }
      }
      catch( Exception e ) {
        throw new XmlManagerException( XmlManagerException.CODE_resultset_method, 
                                       new String[] { "resultset", String.valueOf(iResultSet), 
                                                      "method", "getObject",
                                                      "params", String.valueOf(fI+1) }, e );
      }
    }

    return record;
  }


  /** Reset {@link ResultSet} by calling the {@link ResultSet#beforeFirst beforeFirst} method 
   *  if {@link #PROP_ResultSet_resetBeforeFirst} option is <code>true</code> and <code>ResultSet</code> type supports it.  */
  protected void endProcessImpl() {
    if( iResetBeforeFirst && ResultSet.TYPE_FORWARD_ONLY != iResultSetType ) {
      try {
        iResultSet.beforeFirst();
      }
      catch( Exception e ) {
        throw new XmlManagerException( XmlManagerException.CODE_resultset_reset, 
                                       new String[] { "resultset", String.valueOf(iResultSet) }, e );
      }
    }
  }

}