/**
 * @file
 * Copyright 2014 (c) Anna Schumaker.
 */
#ifndef OCARINA_CORE_INDEX_H
#define OCARINA_CORE_INDEX_H

#include <core/database.h>

#include <set>
#include <string>


/**
 * The IndexEntry class is used to associate a specific key with a set of
 * integer identifiers.  This lets us use a Database as an inverted index.
 */
class IndexEntry : public DatabaseEntry {
public:
	std::string		_key;    /**< The term stored by this IndexEntry. */
	std::set<unsigned int>	_values; /**< Integers representing strings that
					      contain this term. */

	IndexEntry(); /**< Create an empty IndexEntry. */

	/**
	 * Create an IndexEntry with a specific key.
	 *
	 * @param  key  The key associated with this IndexEntry.
	 */
	IndexEntry(const std::string &);


	/**
	 * Access the key stored by this IndexEntry.
	 *
	 * @return IndexEntry::_key.
	 */
	const std::string primary_key() const;

	/**
	 * Add a new value to this IndexEntry.
	 *
	 * @param  value  The new value to add.
	 */
	void insert(unsigned int);

	/**
	 * Remove a value from this IndexEntry.
	 *
	 * @param  value  The value to remove.
	 */
	void remove(unsigned int);


	/**
	 * Write an IndexEntry to file.
	 *
	 * @param  file  The file to use when writing data.
	 */
	void write(File &);

	/**
	 * Read an IndexEntry from file.
	 *
	 * @param  file  The file read from.
	 */
	void read(File &);
};


/**
 * A special Database for index access.
 */
class Index : public Database<IndexEntry> {
public:
	/**
	 * Index constructor.
	 * @param  filepath  Where to store the file on disk.
	 * @param  autosave  True if changes should automatically be saved.
	 */
	Index(const std::string &, bool);

	/**
	 * Add a new (key, value) pair to the index.
	 * @param  key  String to store in the index.
	 * @param  value  Integer value associated with the key.
	 */
	void insert(const std::string &, unsigned int);

	/**
	 * Remove a (key, value) pair from the index.
	 * @param  key  Key associated with the value to be removed.
	 * @param  value  Value to remove from the index.
	 */
	void remove(const std::string &, unsigned int);
};

#endif /* OCARINA_CORE_DATABASE_H */