/**
 *    Copyright (C) 2008 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 <boost/filesystem/path.hpp>
#include <memory>

#include "mongo/db/namespace_string.h"
#include "mongo/db/record_id.h"
#include "mongo/db/storage/data_protector.h"

namespace mongo {

class Collection;
class Database;
class DataProtector;
class OperationContext;
class QueryRequest;

/**
 * db helpers are helper functions and classes that let us easily manipulate the local
 * database instance in-proc.
 *
 * all helpers assume locking is handled above them
 */
struct Helpers {
    class RemoveSaver;

    /* fetch a single object from collection ns that matches query.
       set your db SavedContext first.

       @param query - the query to perform.  note this is the low level portion of query so
                      "orderby : ..." won't work.

       @param requireIndex if true, assert if no index for the query.  a way to guard against
       writing a slow query.

       @return true if object found
    */
    static bool findOne(OperationContext* opCtx,
                        Collection* collection,
                        const BSONObj& query,
                        BSONObj& result,
                        bool requireIndex = false);

    static RecordId findOne(OperationContext* opCtx,
                            Collection* collection,
                            const BSONObj& query,
                            bool requireIndex);

    static RecordId findOne(OperationContext* opCtx,
                            Collection* collection,
                            std::unique_ptr<QueryRequest> qr,
                            bool requireIndex);

    /**
     * @param foundIndex if passed in will be set to 1 if ns and index found
     * @return true if object found
     */
    static bool findById(OperationContext* opCtx,
                         Database* db,
                         StringData ns,
                         BSONObj query,
                         BSONObj& result,
                         bool* nsFound = 0,
                         bool* indexFound = 0);

    /* TODO: should this move into Collection?
     * uasserts if no _id index.
     * @return null loc if not found */
    static RecordId findById(OperationContext* opCtx, Collection* collection, const BSONObj& query);

    /**
     * Get the first object generated from a forward natural-order scan on "ns".  Callers do not
     * have to lock "ns".
     *
     * Returns true if there is such an object.  An owned copy of the object is placed into the
     * out-argument "result".
     *
     * Returns false if there is no such object.
     */
    static bool getSingleton(OperationContext* opCtx, const char* ns, BSONObj& result);

    /**
     * Same as getSingleton, but with a reverse natural-order scan on "ns".
     */
    static bool getLast(OperationContext* opCtx, const char* ns, BSONObj& result);

    /**
     * Performs an upsert of "obj" into the collection "ns", with an empty update predicate.
     * Callers must have "ns" locked.
     */
    static void putSingleton(OperationContext* opCtx, const char* ns, BSONObj obj);

    /**
     * you have to lock
     * you do not have to have Context set
     * o has to have an _id field or will assert
     */
    static void upsert(OperationContext* opCtx,
                       const std::string& ns,
                       const BSONObj& o,
                       bool fromMigrate = false);

    // TODO: this should be somewhere else probably
    /* Takes object o, and returns a new object with the
     * same field elements but the names stripped out.
     * Example:
     *    o = {a : 5 , b : 6} --> {"" : 5, "" : 6}
     */
    static BSONObj toKeyFormat(const BSONObj& o);

    /* Takes object o, and infers an ascending keyPattern with the same fields as o
     * Example:
     *    o = {a : 5 , b : 6} --> {a : 1 , b : 1 }
     */
    static BSONObj inferKeyPattern(const BSONObj& o);

    /**
     * Remove all documents from a collection.
     * You do not need to set the database before calling.
     * Does not oplog the operation.
     */
    static void emptyCollection(OperationContext* opCtx, const NamespaceString& nss);

    /**
     * for saving deleted bson objects to a flat file
     */
    class RemoveSaver {
        MONGO_DISALLOW_COPYING(RemoveSaver);

    public:
        RemoveSaver(const std::string& type, const std::string& ns, const std::string& why);
        ~RemoveSaver();

        /**
         * Writes document to file. File is created lazily before writing the first document.
         * Returns error status if the file could not be created or if there were errors writing
         * to the file.
         */
        Status goingToDelete(const BSONObj& o);

        /**
         * A path object describing the directory containing the file with deleted documents.
         */
        const auto& root() const& {
            return _root;
        }
        void root() && = delete;

        /**
         * A path object describing the actual file containing BSON documents.
         */
        const auto& file() const& {
            return _file;
        }
        void file() && = delete;

    private:
        boost::filesystem::path _root;
        boost::filesystem::path _file;
        std::unique_ptr<DataProtector> _protector;
        std::unique_ptr<std::ostream> _out;
    };
};

}  // namespace mongo