/**
 *    Copyright (C) 2014 MongoDB 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 <vector>
#include <boost/thread/mutex.hpp>
#include "mongo/base/disallow_copying.h"
#include "mongo/bson/bsonobj.h"
#include "mongo/db/query/canonical_query.h"
#include "mongo/db/query/index_entry.h"
#include "mongo/platform/unordered_map.h"

namespace mongo {

    /**
     * Holds allowed indices.
     */
    class AllowedIndices {
    private:
        MONGO_DISALLOW_COPYING(AllowedIndices);
    public:
        AllowedIndices(const std::vector<BSONObj>& indexKeyPatterns);
        ~AllowedIndices();

        // These are the index key patterns that
        // we will use to override the indexes retrieved from
        // the index catalog.
        std::vector<BSONObj> indexKeyPatterns;
    };

    /**
     * Value type for query settings.
     * Holds:
     *     query shape (query, sort, projection)
     *     vector of index specs
     */
    class AllowedIndexEntry {
    private:
        MONGO_DISALLOW_COPYING(AllowedIndexEntry);
    public:
        AllowedIndexEntry(const BSONObj& query, const BSONObj& sort,
                          const BSONObj& projection,
                          const std::vector<BSONObj>& indexKeyPatterns);
        ~AllowedIndexEntry();
        AllowedIndexEntry* clone() const;

        // _query, _sort and _projection collectively
        // represent the query shape that we are storing hint overrides for.
        BSONObj query;
        BSONObj sort;
        BSONObj projection;

        // These are the index key patterns that
        // we will use to override the indexes retrieved from
        // the index catalog.
        std::vector<BSONObj> indexKeyPatterns;
    };

    /**
     * Holds the index filters in a collection.
     */
    class QuerySettings {
    private:
        MONGO_DISALLOW_COPYING(QuerySettings);
    public:
        QuerySettings();

        ~QuerySettings();

        /**
         * Returns true and fills out allowedIndicesOut if a hint is set in the query settings
         * for the query.
         * Returns false and sets allowedIndicesOut to NULL otherwise.
         * Caller owns AllowedIndices.
         */
        bool getAllowedIndices(const CanonicalQuery& query,
                               AllowedIndices** allowedIndicesOut) const;

        /**
         * Returns copies all overrides for the collection..
         * Caller owns overrides in vector.
         */
        std::vector<AllowedIndexEntry*> getAllAllowedIndices() const;

        /**
         * Adds or replaces entry in query settings.
         * If existing entry is found for the same key,
         * frees resources for existing entry before replacing.
         */
        void setAllowedIndices(const CanonicalQuery& canonicalQuery,
                               const std::vector<BSONObj>& indexes);

        /**
         * Removes single entry from query settings. No effect if query shape is not found.
         */
        void removeAllowedIndices(const CanonicalQuery& canonicalQuery);

        /**
         * Clears all allowed indices from query settings.
         */
        void clearAllowedIndices();

    private:
        /**
         * Clears entries without acquiring mutex.
         */
        void _clear();

        typedef unordered_map<PlanCacheKey, AllowedIndexEntry*> AllowedIndexEntryMap;
        AllowedIndexEntryMap _allowedIndexEntryMap;

        /**
         * Protects data in query settings.
         */
        mutable boost::mutex _mutex;
    };

}  // namespace mongo