/*    Copyright 2012 10gen Inc.
 *
 *    This program is free software: you can redistribute it and/or  modify
 *    it under the terms of the GNU Affero General Public License, version 3,
 *    as published by the Free Software Foundation.
 *
 *    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 Affero General Public License for more details.
 *
 *    You should have received a copy of the GNU Affero General Public License
 *    along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 *    As a special exception, the copyright holders give permission to link the
 *    code of portions of this program with the OpenSSL library under certain
 *    conditions as described in each individual source file and distribute
 *    linked combinations including the program with the OpenSSL library. You
 *    must comply with the GNU Affero General Public License in all respects
 *    for all of the code used other than as permitted herein. If you modify
 *    file(s) with this exception, you may extend this exception to your
 *    version of the file(s), but you are not obligated to do so. If you do not
 *    wish to do so, delete this exception statement from your version. If you
 *    delete this exception statement from all source files in the program,
 *    then also delete it in the license file.
 */

#pragma once

#include <iosfwd>
#include <memory>
#include <string>


#include "mongo/base/disallow_copying.h"
#include "mongo/base/string_data.h"

namespace mongo {

/**
 * Representation of a name of a principal (authenticatable user) in a MongoDB system.
 *
 * Consists of a "user name" part, and a "database name" part.
 */
class UserName {
public:
    UserName() : _splitPoint(0) {}
    UserName(StringData user, StringData dbname);

    /**
     * Gets the user part of a UserName.
     */
    StringData getUser() const {
        return StringData(_fullName).substr(0, _splitPoint);
    }

    /**
     * Gets the database name part of a UserName.
     */
    StringData getDB() const {
        return StringData(_fullName).substr(_splitPoint + 1);
    }

    /**
     * Gets the full unique name of a user as a string, formatted as "user@db".
     */
    const std::string& getFullName() const {
        return _fullName;
    }

    /**
     * Stringifies the object, for logging/debugging.
     */
    std::string toString() const {
        return getFullName();
    }

    bool operator==(const UserName& rhs) const {
        return _splitPoint == rhs._splitPoint && getFullName() == rhs.getFullName();
    }

    bool operator!=(const UserName& rhs) const {
        return _splitPoint != rhs._splitPoint || getFullName() != rhs.getFullName();
    }

    bool operator<(const UserName& rhs) const {
        return getUser() < rhs.getUser() || (getUser() == rhs.getUser() && getDB() < rhs.getDB());
    }

private:
    std::string _fullName;  // The full name, stored as a string.  "user@db".
    size_t _splitPoint;     // The index of the "@" separating the user and db name parts.
};

std::ostream& operator<<(std::ostream& os, const UserName& name);

/**
 * Iterator over an unspecified container of UserName objects.
 */
class UserNameIterator {
public:
    class Impl {
        MONGO_DISALLOW_COPYING(Impl);

    public:
        Impl(){};
        virtual ~Impl(){};
        static Impl* clone(Impl* orig) {
            return orig ? orig->doClone() : NULL;
        }
        virtual bool more() const = 0;
        virtual const UserName& get() const = 0;

        virtual const UserName& next() = 0;

    private:
        virtual Impl* doClone() const = 0;
    };

    UserNameIterator() : _impl(nullptr) {}
    UserNameIterator(const UserNameIterator& other) : _impl(Impl::clone(other._impl.get())) {}
    explicit UserNameIterator(Impl* impl) : _impl(impl) {}

    UserNameIterator& operator=(const UserNameIterator& other) {
        _impl.reset(Impl::clone(other._impl.get()));
        return *this;
    }

    bool more() const {
        return _impl.get() && _impl->more();
    }
    const UserName& get() const {
        return _impl->get();
    }

    const UserName& next() {
        return _impl->next();
    }

    const UserName& operator*() const {
        return get();
    }
    const UserName* operator->() const {
        return &get();
    }

private:
    std::unique_ptr<Impl> _impl;
};


template <typename ContainerIterator>
class UserNameContainerIteratorImpl : public UserNameIterator::Impl {
    MONGO_DISALLOW_COPYING(UserNameContainerIteratorImpl);

public:
    UserNameContainerIteratorImpl(const ContainerIterator& begin, const ContainerIterator& end)
        : _curr(begin), _end(end) {}
    virtual ~UserNameContainerIteratorImpl() {}
    virtual bool more() const {
        return _curr != _end;
    }
    virtual const UserName& next() {
        return *(_curr++);
    }
    virtual const UserName& get() const {
        return *_curr;
    }
    virtual UserNameIterator::Impl* doClone() const {
        return new UserNameContainerIteratorImpl(_curr, _end);
    }

private:
    ContainerIterator _curr;
    ContainerIterator _end;
};

template <typename ContainerIterator>
UserNameIterator makeUserNameIterator(const ContainerIterator& begin,
                                      const ContainerIterator& end) {
    return UserNameIterator(new UserNameContainerIteratorImpl<ContainerIterator>(begin, end));
}

template <typename Container>
UserNameIterator makeUserNameIteratorForContainer(const Container& container) {
    return makeUserNameIterator(container.begin(), container.end());
}

}  // namespace mongo