/**
 *    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.
 */

#include "mongo/platform/basic.h"

#include "mongo/base/error_codes.h"
#include "mongo/db/auth/authorization_session.h"
#include "mongo/db/client.h"
#include "mongo/db/commands.h"
#include "mongo/db/query/collation/collation_spec.h"
#include "mongo/s/commands/strategy.h"

namespace mongo {

using std::string;
using std::stringstream;
using std::vector;

namespace {

/**
 * Base class for mongos index filter commands.
 * Cluster index filter commands don't do much more than
 * forwarding the commands to all shards and combining the results.
 */
class ClusterIndexFilterCmd : public Command {
    MONGO_DISALLOW_COPYING(ClusterIndexFilterCmd);

public:
    /**
     * Instantiates a command that can be invoked by "name", which will be described by
     * "helpText", and will require privilege "actionType" to run.
     */
    ClusterIndexFilterCmd(const std::string& name, const std::string& helpText)
        : Command(name), _helpText(helpText) {}

    virtual ~ClusterIndexFilterCmd() {}

    bool slaveOk() const {
        return false;
    }

    bool slaveOverrideOk() const {
        return true;
    }


    virtual bool supportsWriteConcern(const BSONObj& cmd) const override {
        return false;
    }

    void help(stringstream& ss) const {
        ss << _helpText;
    }

    Status checkAuthForCommand(Client* client, const std::string& dbname, const BSONObj& cmdObj) {
        AuthorizationSession* authzSession = AuthorizationSession::get(client);
        ResourcePattern pattern = parseResourcePattern(dbname, cmdObj);

        if (authzSession->isAuthorizedForActionsOnResource(pattern,
                                                           ActionType::planCacheIndexFilter)) {
            return Status::OK();
        }

        return Status(ErrorCodes::Unauthorized, "unauthorized");
    }

    // Cluster plan cache command entry point.
    bool run(OperationContext* txn,
             const std::string& dbname,
             BSONObj& cmdObj,
             int options,
             std::string& errmsg,
             BSONObjBuilder& result) {
        const NamespaceString nss(parseNs(dbname, cmdObj));
        uassert(ErrorCodes::InvalidNamespace,
                str::stream() << nss.ns() << " is not a valid namespace",
                nss.isValid());

        // Dispatch command to all the shards.
        // Targeted shard commands are generally data-dependent but index filter
        // commands are tied to query shape (data has no effect on query shape).
        vector<Strategy::CommandResult> results;
        const BSONObj query;
        const BSONObj collation =
            BSON(CollationSpec::kLocaleField << CollationSpec::kSimpleBinaryComparison);
        Strategy::commandOp(txn, dbname, cmdObj, options, nss.ns(), query, collation, &results);

        // Set value of first shard result's "ok" field.
        bool clusterCmdResult = true;

        for (vector<Strategy::CommandResult>::const_iterator i = results.begin();
             i != results.end();
             ++i) {
            const Strategy::CommandResult& cmdResult = *i;

            // XXX: In absence of sensible aggregation strategy,
            //      promote first shard's result to top level.
            if (i == results.begin()) {
                result.appendElements(cmdResult.result);
                clusterCmdResult = cmdResult.result["ok"].trueValue();
            }

            // Append shard result as a sub object.
            // Name the field after the shard.
            result.append(cmdResult.shardTargetId.toString(), cmdResult.result);
        }

        return clusterCmdResult;
    }

private:
    const std::string _helpText;
};

// Register index filter commands at startup
ClusterIndexFilterCmd clusterPlanCacheListFiltersCmd(
    "planCacheListFilters", "Displays index filters for all query shapes in a collection.");

ClusterIndexFilterCmd clusterPlanCacheClearFiltersCmd(
    "planCacheClearFilters",
    "Clears index filter for a single query shape or, "
    "if the query shape is omitted, all filters for the collection.");

ClusterIndexFilterCmd clusterPlanCacheSetFilterCmd(
    "planCacheSetFilter", "Sets index filter for a query shape. Overrides existing index filter.");


}  // namespace
}  // namespace mongo