/***************************************************************************
 *   Copyright (C) 2005 by Joris Guisson                                   *
 *   joris.guisson@gmail.com                                               *
 *                                                                         *
 *   This program is free software; you can redistribute it and/or modify  *
 *   it under the terms of the GNU General Public License as published by  *
 *   the Free Software Foundation; either version 2 of the License, or     *
 *   (at your option) any later version.                                   *
 *                                                                         *
 *   This program is distributed in the hope that it will be useful,       *
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of        *
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the         *
 *   GNU General Public License for more details.                          *
 *                                                                         *
 *   You should have received a copy of the GNU General Public License     *
 *   along with this program; if not, write to the                         *
 *   Free Software Foundation, Inc.,                                       *
 *   51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.             *
 ***************************************************************************/
#ifndef DHTKEY_H
#define DHTKEY_H

#include <QByteArray>
#include <ktorrent_export.h>
#include <util/sha1hash.h>

namespace dht
{
/**
 * @author Joris Guisson
 * @brief Key in the distributed hash table
 *
 * Key's in the distributed hash table are just SHA-1 hashes.
 * Key provides all necessary operators to be used as a value.
 */
class KTORRENT_EXPORT Key : public bt::SHA1Hash
{
public:
    /**
     * Constructor, sets key to 0.
     */
    Key();

    /**
     * Copy constructor. Seeing that Key doesn't add any data
     * we just pass a SHA1Hash, Key's are automatically covered by this
     * @param k Hash to copy
     */
    Key(const bt::SHA1Hash &k);

    /**
     * Make a key out of a bytearray
     * @param ba The QByteArray
     */
    Key(const QByteArray &ba);

    /**
     * Make a key out of a 20 byte array.
     * @param d The array
     */
    Key(const bt::Uint8 *d);

    /// Destructor.
    ~Key() override;

    /**
     * Create a random key.
     * @return A random Key
     */
    static Key random();

    /// Get the minimum key (all zeros)
    static Key min();

    /// Get the maximum key (all FF)
    static Key max();

    /**
     * Equality operator.
     * @param other The key to compare
     * @return true if this key is equal to other
     */
    bool operator==(const Key &other) const;

    /**
     * Inequality operator.
     * @param other The key to compare
     * @return true if this key is not equal to other
     */
    bool operator!=(const Key &other) const;

    /**
     * Smaller then operator.
     * @param other The key to compare
     * @return rue if this key is smaller then other
     */
    bool operator<(const Key &other) const;

    /**
     * Smaller then or equal operator.
     * @param other The key to compare
     * @return rue if this key is smaller then or equal to other
     */
    bool operator<=(const Key &other) const;

    /**
     * Greater then operator.
     * @param other The key to compare
     * @return rue if this key is greater then other
     */
    bool operator>(const Key &other) const;

    /**
     * Greater then or equal operator.
     * @param other The key to compare
     * @return rue if this key is greater then or equal to other
     */
    bool operator>=(const Key &other) const;

    /**
     * Divide by a number operator
     */
    Key operator/(int value) const;

    /**
     * Addition for keys
     * @param a The first key
     * @param b The second key
     */
    friend KTORRENT_EXPORT Key operator+(const Key &a, const Key &b);

    /**
     * Subtraction for keys
     * @param a The first key
     * @param b The second key
     */
    friend KTORRENT_EXPORT Key operator-(const Key &a, const Key &b);

    /**
     * Addition for key and a value
     * @param a The key
     * @param b The value
     */
    friend KTORRENT_EXPORT Key operator+(const Key &a, bt::Uint8 value);

    /**
     * The distance of two keys is the keys xor together.
     * @param a The first key
     * @param b The second key
     * @return a xor b
     */
    static Key distance(const Key &a, const Key &b);

    /**
     * Calculate the middle between two keys.
     * @param a The first key
     * @param b The second key
     * @return The middle
     */
    static Key mid(const Key &a, const Key &b);
};

}

#endif
