/**
*    Copyright (C) 2013 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>

namespace mongo {

    using std::string;

    class BSONObj;

    /**
     * We need to know what 'type' an index is in order to plan correctly.  We can't entirely rely
     * on the key pattern to tell us what kind of index we have.
     *
     * An example of the Bad Thing That We Must Avoid:
     * 1. Create a 2dsphere index in 2.4, insert some docs.
     * 2. Downgrade to 2.2.  Insert some more docs into the collection w/the 2dsphere
     *    index.  2.2 treats the index as a normal btree index and creates keys accordingly.
     * 3. Using the 2dsphere index in 2.4 gives wrong results or assert-fails or crashes as
     *    the data isn't what we expect.
     */
    enum IndexType {
        INDEX_BTREE,
        INDEX_2D,
        INDEX_HAYSTACK,
        INDEX_2DSPHERE,
        INDEX_TEXT,
        INDEX_HASHED,
    };

    /**
     * We use the string representation of index names all over the place, so we declare them all
     * once here.
     */
    class IndexNames {
    public:
        static const string GEO_2D;
        static const string GEO_HAYSTACK;
        static const string GEO_2DSPHERE;
        static const string TEXT;
        static const string HASHED;
        static const string BTREE;

        /**
         * True if is a regular (non-plugin) index or uses a plugin that existed before 2.4.
         * These plugins are grandfathered in and allowed to exist in DBs with
         * PDFILE_MINOR_VERSION_22_AND_OLDER
         */
        static bool existedBefore24(const string& name);

        /**
         * Return the first string value in the provided object.  For an index key pattern,
         * a field with a non-string value indicates a "special" (not straight Btree) index.
         */
        static string findPluginName(const BSONObj& keyPattern);

        /**
         * Is the provided access method name one we recognize?
         */
        static bool isKnownName(const string& name);

        /**
         * Convert an index name to an IndexType.
         */
        static IndexType nameToType(const string& accessMethod);
    };

}  // namespace mongo
