/*
 * This file is a part of Winix
 * and is not publicly distributed
 * 
 * Copyright (c) 2008-2011, Tomasz Sowa
 * All rights reserved.
 * 
 */
 
#ifndef headerfile_winix_templates_patterncacher
#define headerfile_winix_templates_patterncacher

#include <vector>
#include <map>

#include "core/item.h"
#include "misc.h"
#include "ezc.h"





class PatternCacher
{
public:

	PatternCacher();

	// setting when we should delete patterns
	// we are deleting when we have more (or equal) patterns than 'when_delete'
	// and then we are deleting 'how_many_del' patterns
	void SetWhenDelete(size_t when_delete, size_t how_many_del);

	void SetEzcFunctions(TemplatesFunctions::EzcFun * fun);

	// returning a pattern corresponding to the 'item'
	Ezc::Pattern * GetPattern(const Item & item);

	// updating the pattern for the item
	// if there is no such a pattern the method does nothing
	void UpdatePattern(const Item & item);
	
	// deleting the pattern for the item
	// if there is no such a pattern the method does nothing
	void DeletePattern(const Item & item);

	// deleting some rarely used patters
	// call it at the end of a request (or at the beginning)
	void DeleteOldPatterns();

	// size of the current cache in use
	size_t Size();


private:

	struct PatternUsed
	{
		Ezc::Pattern pattern;
		int used;    // how many times used (incremented by GetPattern and UpdatePattern)
		int item_id;
	};

	typedef std::map<long, PatternUsed> PatternTab;
	PatternTab pattern_tab;

	
	// temporarily struct used during deleting some items from pattern_tab
	struct PatternErase
	{
		PatternTab::iterator iter;
		int used;
		
		bool operator<(const PatternErase & p) const { return used < p.used; }
	};
	
	// temporarily buffer used during deleting some items from pattern_tab
	std::vector<PatternErase> erase_tab;
	
	

	void CreatePattern(const Item & item, Ezc::Pattern & pattern);
	void AddIndexes(const Item & item, size_t pattern_index);
	Ezc::Pattern * AddPattern(const Item & item);


	// the size of pattern_tab when we are deleting some items
	size_t when_delete_patterns;
	
	// how many items to delete
	size_t how_many_delete;

	// can be null (not set directly)
	TemplatesFunctions::EzcFun * ezc_fun;

};

#endif