/** Copyright (c) 2007 Ricebridge. BSD License. */

package com.ricebridge.example.updown;

import java.io.OutputStream;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.util.ArrayList;
import java.util.Properties;

import com.ricebridge.csvman.CsvManager;
import com.ricebridge.csvman.CsvSaver;
import com.ricebridge.csvman.CsvSpec;


/** Extract data from database, convert it to CSV, and send the CSV to an 
 *  OutputStream. */
public class CsvDownloader extends DownloaderSupport {

  public void process( OutputStream pOutputStream, Properties pProperties ) 
  throws Exception 
  {
    mDatabaseErrors = new ArrayList();
    
    // use CSV Manager to create the CSV file
    CsvSpec    csvspec = makeCsvSpec( pProperties );
    CsvManager csvman  = new CsvManager( csvspec );
    CsvSaver   csvsvr  = csvman.makeSaver( pOutputStream );

    // select all database table columns
    PreparedStatement selectsql = mConnection.prepareStatement( 
        "SELECT * FROM "+mTableName+";" );
    ResultSet rs = null;
    
    try {
      rs = selectsql.executeQuery();
      Converter conv = new Converter(mTableName,rs);
      
      csvsvr.begin();

      // the first line is the column names so that uploading will also work
      csvsvr.next( conv.getColumnNames() );

      // get each row and output it as a CSV line
      while( rs.next() ) {
        String[] data = conv.getData(rs);
        csvsvr.next(data);
      }
      
    }
    catch( Exception e ) {
      mDatabaseErrors.add(e);
    }
    finally {
      csvsvr.end();
      close( rs, selectsql, mConnection );
    }
  }


  /** The particular CSV format to use is specified by a set of properties. */
  public CsvSpec makeCsvSpec( Properties pProperties ) {
    CsvSpec csvspec = CsvSpecHandler.makeCsvSpec(pProperties);
    return csvspec;
  }

}