/*    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 <string>

#include "mongo/bson/bsonobj.h"

namespace mongo {

    /**
     * A BSONField holds the name and the type intended for a given BSON element. The
     * class helps documenting and enforcing that field's type.
     *
     * Example usages:
     *
     *     In a header file:
     *     // Determines the types for the fields used in a collection.
     *     static const std::string MyColl;
     *     struct MyCollFields {
     *         static BSONField<std::string> name;
     *         static BSONField<bool> draining;
     *         static BSONField<int> count;
     *     };
     *
     *     In a cpp file:
     *     const std::string MyColl = "my_collection_name";
     *
     *     // determines the names used for the fields
     *     BSONField<std::string> MyCollFields::name("_id");
     *     BSONField<bool> MyCollFields::draining("draining");
     *     BSONField<int> MyCollFields::count("count");
     *
     *     In an insert:
     *     conn->insert(myColl,
     *                  BSON(MyCollFields::name("id_for_this_doc") <<
     *                       MyCollFields::draining(true) <<
     *                       MyCollFields::count(0)));
     *
     *     In a query:
     *     conn->findOne(myColl, BSON(MyCollFields::count.gt(10))) ;
     *
     *     In a command:
     *     conn->ensureIndex(mycoll, BSON(MyCollFields::draining() << 1), true);
     */

    template<typename T>
    class BSONFieldValue {
    public:
        BSONFieldValue(const std::string& name, const T& t)
            : _name(name), _t(t) { }

        const T& value() const { return _t; }
        const std::string& name() const { return _name; }

    private:
        std::string _name;
        T _t;
    };

    template<typename T>
    class BSONField {
    public:
        BSONField(const std::string& name)
            : _name(name), _defaultSet(false) {}

        BSONField(const std::string& name, const T& defaultVal)
            : _name(name), _default(defaultVal) , _defaultSet(true) {}

        BSONFieldValue<T> make(const T& t) const {
            return BSONFieldValue<T>(_name, t);
        }

        BSONFieldValue<T> operator()(const T& t) const {
            return BSONFieldValue<T>(_name, t);
        }

        const std::string& name() const {
            return _name;
        }

        const T& getDefault() const {
            return _default;
        }

        bool hasDefault() const {
            return _defaultSet;
        }

        std::string operator()() const {
            return _name;
        }

        BSONFieldValue<BSONObj> query(const char * q, const T& t) const;

        BSONFieldValue<BSONObj> gt(const T& t) const {
            return query("$gt", t);
        }

        BSONFieldValue<BSONObj> lt(const T& t) const {
            return query("$lt", t);
        }

        BSONFieldValue<BSONObj> ne(const T& t) const {
            return query("$ne", t);
        }

    private:
        std::string _name;
        T _default;
        bool _defaultSet;
    };

} // namespace mongo
