/* 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.
 *
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 *  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
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 */

package com.ricebridge.xmlman;


import org.jostraca.util.Internal;

import java.util.*;


/** Helper class for implementing the {@link RecordProvider} interface.
 *    <p>Use of this class will help ensure future compatibility with any XML Manager API changes.
 *  Subclasses should implement the <code>*Impl</code> methods (for example, {@link  #hasNextRecordImpl hasNextRecordImpl})
 *  rather than the declared interface methods such as {@link #hasNextRecord hasNextRecord}.
 *  See the {@link RecordProvider} interface documentation for a description of the calling sequence of the methods
 *  in this class. </p>
 *    <p>The <b><a href="RecordProviderSupport.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 abstract class RecordProviderSupport implements RecordProvider {

  // protected instance

  /** Record specification field names, if specified in the {@link RecordSpec} object. 
   *  <b>NOTE: may be empty.</b> 
   */
  protected String[] iFieldNames = new String[]{};


  // public methods
  
  /** Helper implementation of {@link RecordProvider#setXmlSpec RecordProvider.setXmlSpec}. 
   *  Subclasses should implement {@link #setXmlSpecImpl setXmlSpecImpl}.
   */
  public void setXmlSpec( XmlSpec pXmlSpec ) {
    XmlSpec xs = (XmlSpec) Internal.null_arg( pXmlSpec );
    try {
      setXmlSpecImpl( xs );
    }
    catch( XmlManagerException xme ) { throw xme; }
    catch( Exception e ) {
      throw new XmlManagerException( XmlManagerException.CODE_recordprovider_set, 
                                     new String[] { "record-provider-class", this.getClass().getName(), 
                                                    "methodname", "setXmlSpecImpl", "setargument", String.valueOf(xs) }, e );
    }
  }


  /** Helper implementation of {@link RecordProvider#setFieldNames RecordProvider.setFieldNames}. 
   *  Subclasses should implement {@link #setFieldNamesImpl setFieldNamesImpl}.
   */
  public void setFieldNames( String[] pFieldNames ) {
    String[] fn = (String[]) Internal.null_array( pFieldNames );
    try {
      setFieldNamesImpl( fn );
    }
    catch( XmlManagerException xme ) { throw xme; }
    catch( Exception e ) {
      throw new XmlManagerException( XmlManagerException.CODE_recordprovider_set, 
                                     new String[] { "record-provider-class", this.getClass().getName(), 
                                                    "methodname", "setFieldNamesImpl", 
                                                    "setargument", Arrays.asList(fn).toString() }, e );
    }
  }


  /** Helper implementation of {@link RecordProvider#startProcess RecordProvider.startProcess}. 
   *  Subclasses should implement {@link #startProcessImpl startProcessImpl}.
   */
  public void startProcess() {
    try {
      startProcessImpl();
    }
    catch( XmlManagerException xme ) { throw xme; }
    catch( Exception e ) {
      throw new XmlManagerException( XmlManagerException.CODE_recordprovider_exception, 
                                     new String[] { "record-provider-class", this.getClass().getName(), 
                                                    "methodname", "startProcessImpl" }, e );
    }
  }


  /** Helper implementation of  {@link RecordProvider#hasNextRecord RecordProvider.hasNextRecord}. 
   *  Sub classes should implement {@link #hasNextRecordImpl hasNextRecordImpl}.
   */
  public boolean hasNextRecord() {
    try {
      return hasNextRecordImpl();
    }
    catch( XmlManagerException xme ) { throw xme; }
    catch( Exception e ) {
      throw new XmlManagerException( XmlManagerException.CODE_recordprovider_exception, 
                                     new String[] { "record-provider-class", this.getClass().getName(), 
                                                    "methodname", "hasNextRecordImpl" }, e );
    }
  }


  /** Helper implementation of  {@link RecordProvider#nextRecord RecordProvider.nextRecord}. 
   *  Sub classes should implement {@link #nextRecordImpl nextRecordImpl}.
   */
  public String[] nextRecord() {
    try {
      String[] record = nextRecordImpl();
      if( null == record ) {
        throw new XmlManagerException( XmlManagerException.CODE_null_record,
                                     new String[] { "record-provider-class", this.getClass().getName(), 
                                                    "methodname", "nextRecordImpl" } );
      }

      // check for nulls
      for( int fI = 0; fI < record.length; fI++ ) {
        if( null == record[fI] ) {
          record[fI] = "";
        }
      }
      
      return record;
    }
    catch( XmlManagerException xme ) { throw xme; }
    catch( Exception e ) {
      throw new XmlManagerException( XmlManagerException.CODE_recordprovider_exception, 
                                     new String[] { "record-provider-class", this.getClass().getName(), 
                                                    "methodname", "nextRecordImpl" }, e );
    }
  }


  /** Helper implementation of {@link RecordProvider#endProcess RecordProvider.endProcess}. 
   *  Subclasses should implement {@link #endProcessImpl endProcessImpl}.
   */
  public void endProcess() {
    try {
      endProcessImpl();
    }
    catch( XmlManagerException xme ) { throw xme; }
    catch( Exception e ) {
      throw new XmlManagerException( XmlManagerException.CODE_recordprovider_exception, 
                                     new String[] { "record-provider-class", this.getClass().getName(), 
                                                    "methodname", "endProcessImpl" }, e );
    }
  }



  // protected

  /** Implement this method to receive the current {@link XmlSpec} settings.
   *    <p>This method is optional for subclasses, as an empty implementation is provided here.</p>
   *  @param pXmlSpec XML specification
   *  @see #setXmlSpec
   *  @see RecordProvider#setXmlSpec
   */
  protected void setXmlSpecImpl( XmlSpec pXmlSpec ) {
    // empty implementation
  }


  /** Implement this method to obtain the record specification field names, if available.
   *    <p>The default implementation stores the field names in the {@link #iFieldNames} member variable.
   *  This method is optional for subclasses, as an implementation is provided here.</p>
   *  @param pFieldNames record field names
   *  @see #setFieldNames
   *  @see RecordProvider#setFieldNames
   */
  protected void setFieldNamesImpl( String[] pFieldNames ) {
    iFieldNames = (String[]) Internal.null_array( pFieldNames );
  }


  /** Implement this method to receive notification that the saving of XML data is about to start. 
   *    <p>This method is optional for subclasses, as an empty implementation is provided here.</p>
   *  @see #startProcess
   *  @see RecordProvider#startProcess
   */
  protected void startProcessImpl() {
    // empty implementation
  }


  /** Return <code>true</code> if there are more data records to save. 
   *    <p>This method must be implemented by subclasses.</p>
   *  @see #hasNextRecord
   *  @see RecordProvider#hasNextRecord
   */
  protected abstract boolean hasNextRecordImpl();


  /** Indicates that the next data record is to be saved.
   *    <p>This method must be implemented by subclasses.</p>
   *  @see #nextRecord
   *  @see RecordProvider#nextRecord
   */
  protected abstract String[] nextRecordImpl();


  /** Implement this method to receive notification that the saving of XML data has ended. 
   *    <p>This method is optional for subclasses, as an empty implementation is provided here.</p>
   *  @see #endProcess
   *  @see RecordProvider#endProcess
   */
  protected void endProcessImpl() {
    // empty implementation
  }

}