/*------------------------------------------------------------------------------
* Copyright (C) 2003-2006 Ben van Klinken and the CLucene Team
* 
* Distributable under the terms of either the Apache License (Version 2.0) or 
* the GNU Lesser General Public License, as specified in the COPYING file.
------------------------------------------------------------------------------*/
#ifndef _lucene_index_IndexModifier_
#define _lucene_index_IndexModifier_

#if defined(_LUCENE_PRAGMA_ONCE)
# pragma once
#endif

#include "CLucene/store/Directory.h"
#include "CLucene/document/Document.h"
#include "CLucene/analysis/AnalysisHeader.h"
#include "Term.h"
#include "IndexWriter.h"
#include "IndexReader.h"

CL_NS_DEF(index)

/** 
* A class to modify an index, i.e. to delete and add documents. This
* class hides {@link IndexReader} and {@link IndexWriter} so that you
* do not need to care about implementation details such as that adding
* documents is done via IndexWriter and deletion is done via IndexReader.
* 
* <p>Note that you cannot create more than one <code>IndexModifier</code> object
* on the same directory at the same time.
* 
* <p>Example usage:
* 
* <div align="left" class="java">
* <table border="0" cellpadding="3" cellspacing="0" bgcolor="#ffffff">
* <tr>
* <td nowrap="nowrap" valign="top" align="left">
* <code>
*     //note this code will leak memory :)
*     Analyzer* analyzer = <b>new</b> StandardAnalyzer();<br/>
*     // create an index in /tmp/index, overwriting an existing one:<br/>
*     IndexModifier* indexModifier = <b>new</b> IndexModifier("/tmp/index", analyzer, <b>true</b>);<br/>
*     Document* doc = <b>new </b>Document*();<br/>
*     doc->add(*<b>new </b>Field("id", "1", Field::STORE_YES| Field::INDEX_UNTOKENIZED));<br/>
*     doc->add(*<b>new </b>Field("body", "a simple test", Field::STORE_YES, Field::INDEX_TOKENIZED));<br/>
*     indexModifier->addDocument(doc);<br/>
*     <b>int32_t </b>deleted = indexModifier->deleteDocuments(<b>new </b>Term("id", "1"));<br/>
*     printf("Deleted %d document", deleted);<br/>
*     indexModifier->flush();<br/>
*     printf( "$d docs in index", indexModifier->docCount() );<br/>
*     indexModifier->close();
* </code></td>
* </tr>
* </table>
* </div>
*
* <p>Not all methods of IndexReader and IndexWriter are offered by this 
* class. If you need access to additional methods, either use those classes 
* directly or implement your own class that extends <code>IndexModifier</code>.
* 
* <p>Although an instance of this class can be used from more than one
* thread, you will not get the best performance. You might want to use 
* IndexReader and IndexWriter directly for that (but you will need to 
* care about synchronization yourself then).
* 
* <p>While you can freely mix calls to add() and delete() using this class,
* you should batch you calls for best performance. For example, if you
* want to update 20 documents, you should first delete all those documents,
* then add all the new documents.
* 
*/
class IndexModifier :LUCENE_BASE{
protected:
	IndexWriter* indexWriter;
	IndexReader* indexReader;

	CL_NS(store)::Directory* directory;
	CL_NS(analysis)::Analyzer* analyzer;
	bool open;

	// Lucene defaults:
	bool useCompoundFile;
	int32_t maxBufferedDocs;
	int32_t maxFieldLength;
	int32_t mergeFactor;

public:

	/**
	* Open an index with write access.
	*
	* @param directory the index directory
	* @param analyzer the analyzer to use for adding new documents
	* @param create <code>true</code> to create the index or overwrite the existing one;
	* 	<code>false</code> to append to the existing index
	*/
	IndexModifier(CL_NS(store)::Directory* directory, CL_NS(analysis)::Analyzer* analyzer, bool create);
		
	~IndexModifier();

	/**
	* Open an index with write access.
	*
	* @param dirName the index directory
	* @param analyzer the analyzer to use for adding new documents
	* @param create <code>true</code> to create the index or overwrite the existing one;
	* 	<code>false</code> to append to the existing index
	*/
	IndexModifier(const char* dirName, CL_NS(analysis)::Analyzer* analyzer, bool create);

protected:

	/**
	* Initialize an IndexWriter.
	* @throws IOException
	*/
	void init(CL_NS(store)::Directory* directory, CL_NS(analysis)::Analyzer* analyzer, bool create);

	/**
	* Throw an IllegalStateException if the index is closed.
	* @throws IllegalStateException
	*/
	void assureOpen() const;

	/**
	* Close the IndexReader and open an IndexWriter.
	* @throws IOException
	*/
	void createIndexWriter();

	/**
	* Close the IndexWriter and open an IndexReader.
	* @throws IOException
	*/
	void createIndexReader();

public:
	/**
	* Make sure all changes are written to disk.
	* @throws IOException
	*/
	void flush();

	/**
	* Adds a document to this index, using the provided analyzer instead of the
	* one specific in the constructor.  If the document contains more than
	* {@link #setMaxFieldLength(int32_t)} terms for a given field, the remainder are
	* discarded.
	* @see IndexWriter#addDocument(Document*, Analyzer*)
	* @throws IllegalStateException if the index is closed
    */	
	void addDocument(CL_NS(document)::Document* doc,  CL_NS(analysis)::Analyzer* docAnalyzer=NULL);


	/**
	* Deletes all documents containing <code>term</code>.
	* This is useful if one uses a document field to hold a unique ID string for
	* the document.  Then to delete such a document, one merely constructs a
	* term with the appropriate field and the unique ID string as its text and
	* passes it to this method.  Returns the number of documents deleted.
	* @return the number of documents deleted
	* @see IndexReader#deleteDocuments(Term*)
	* @throws IllegalStateException if the index is closed
	*/
	int32_t deleteDocuments(Term* term);

	/**
	* Deletes the document numbered <code>docNum</code>.
	* @see IndexReader#deleteDocument(int32_t)
	* @throws IllegalStateException if the index is closed
	*/
	void deleteDocument(int32_t docNum);

	/**
	* Returns the number of documents currently in this index.
	* @see IndexWriter#docCount()
	* @see IndexReader#numDocs()
	* @throws IllegalStateException if the index is closed
	*/
	int32_t docCount();

	/**
	* Merges all segments together into a single segment, optimizing an index
	* for search.
	* @see IndexWriter#optimize()
	* @throws IllegalStateException if the index is closed
	*/
	void optimize();

	/**
	* Setting to turn on usage of a compound file. When on, multiple files
	* for each segment are merged into a single file once the segment creation
	* is finished. This is done regardless of what directory is in use.
	* @see IndexWriter#setUseCompoundFile(bool)
	* @throws IllegalStateException if the index is closed
	*/
	void setUseCompoundFile(bool useCompoundFile);

	/**
	* @throws IOException
	* @see IndexModifier#setUseCompoundFile(bool)
	*/
	bool getUseCompoundFile();

	/**
	* The maximum number of terms that will be indexed for a single field in a
	* document.  This limits the amount of memory required for indexing, so that
	* collections with very large files will not crash the indexing process by
	* running out of memory.<p/>
	* Note that this effectively truncates large documents, excluding from the
	* index terms that occur further in the document.  If you know your source
	* documents are large, be sure to set this value high enough to accomodate
	* the expected size.  If you set it to Integer.MAX_VALUE, then the only limit
	* is your memory, but you should anticipate an OutOfMemoryError.<p/>
	* By default, no more than 10,000 terms will be indexed for a field.
	* @see IndexWriter#setMaxFieldLength(int32_t)
	* @throws IllegalStateException if the index is closed
	*/
	void setMaxFieldLength(int32_t maxFieldLength);

	/**
	* @throws IOException
	* @see IndexModifier#setMaxFieldLength(int32_t)
	*/
	int32_t getMaxFieldLength();

	/**
	* The maximum number of terms that will be indexed for a single field in a
	* document.  This limits the amount of memory required for indexing, so that
	* collections with very large files will not crash the indexing process by
	* running out of memory.<p/>
	* Note that this effectively truncates large documents, excluding from the
	* index terms that occur further in the document.  If you know your source
	* documents are large, be sure to set this value high enough to accomodate
	* the expected size.  If you set it to Integer.MAX_VALUE, then the only limit
	* is your memory, but you should anticipate an OutOfMemoryError.<p/>
	* By default, no more than 10,000 terms will be indexed for a field.
	* @see IndexWriter#setMaxBufferedDocs(int32_t)
	* @throws IllegalStateException if the index is closed
	*/
	void setMaxBufferedDocs(int32_t maxBufferedDocs);

	/**
	* @throws IOException
	* @see IndexModifier#setMaxBufferedDocs(int32_t)
	*/
	int32_t getMaxBufferedDocs();

	/**
	* Determines how often segment indices are merged by addDocument().  With
	* smaller values, less RAM is used while indexing, and searches on
	* unoptimized indices are faster, but indexing speed is slower.  With larger
	* values, more RAM is used during indexing, and while searches on unoptimized
	* indices are slower, indexing is faster.  Thus larger values (&gt; 10) are best
	* for batch index creation, and smaller values (&lt; 10) for indices that are
	* interactively maintained.
	* <p>This must never be less than 2.  The default value is 10.
	*
	* @see IndexWriter#setMergeFactor(int32_t)
	* @throws IllegalStateException if the index is closed
	*/
	void setMergeFactor(int32_t mergeFactor);

	/**
	* @throws IOException
	* @see IndexModifier#setMergeFactor(int32_t)
	*/
	int32_t getMergeFactor();

	/**
	* Close this index, writing all pending changes to disk.
	*
	* @throws IllegalStateException if the index has been closed before already
	*/
	void close();

	TCHAR* toString() const;	
	
	/**
	* Gets the version number of the currently open index.
	*/
	int64_t getCurrentVersion() const;
	
	/**
	* Returns an enumeration of all the documents which contain term. 
	*
	* Warning: This is not threadsafe. Make sure you lock the modifier object
	* while using the TermDocs. If the IndexReader that the modifier manages
	* is closed, the TermDocs object will fail.
	*/
	TermDocs* termDocs(Term* term=NULL);

	/**
	* Returns an enumeration of all terms after a given term.
	* If no term is given, an enumeration of all the terms 
	* in the index is returned.
	* The enumeration is ordered by Term.compareTo().  Each term
	* is greater than all that precede it in the enumeration.
	*
	* Warning: This is not threadsafe. Make sure you lock the modifier object
	* while using the TermDocs. If the IndexReader that the modifier manages
	* is closed, the Document will be invalid
	*/
	TermEnum* terms(Term* term=NULL);

	/**
	* Returns the stored fields of the n-th Document in this index. 
	*
	* Warning: This is not threadsafe. Make sure you lock the modifier object
	* while using the TermDocs. If the IndexReader that the modifier manages
	* is closed, the Document will be invalid
	*/
	bool document(const int32_t n, CL_NS(document)::Document* doc);
	_CL_DEPRECATED( document(i, document) ) CL_NS(document)::Document* document(const int32_t n);

	/**
	* Returns the directory used by this index.
	*/
	CL_NS(store)::Directory* getDirectory();
};
CL_NS_END
#endif