/**
 *    Copyright (C) 2018-present MongoDB, Inc.
 *
 *    This program is free software: you can redistribute it and/or modify
 *    it under the terms of the Server Side Public License, version 1,
 *    as published by MongoDB, Inc.
 *
 *    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
 *    Server Side Public License for more details.
 *
 *    You should have received a copy of the Server Side Public License
 *    along with this program. If not, see
 *    <http://www.mongodb.com/licensing/server-side-public-license>.
 *
 *    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 Server Side 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 "mongo/db/concurrency/d_concurrency.h"
#include "mongo/db/namespace_string.h"
#include "mongo/db/s/collection_sharding_state.h"
#include "mongo/db/s/metadata_manager.h"
#include "mongo/platform/atomic_word.h"
#include "mongo/stdx/variant.h"
#include "mongo/util/decorable.h"

namespace mongo {

extern AtomicWord<int> migrationLockAcquisitionMaxWaitMS;

/**
 * See the comments for CollectionShardingState for more information on how this class fits in the
 * sharding architecture.
 */
class CollectionShardingRuntime final : public CollectionShardingState,
                                        public Decorable<CollectionShardingRuntime> {
    CollectionShardingRuntime(const CollectionShardingRuntime&) = delete;
    CollectionShardingRuntime& operator=(const CollectionShardingRuntime&) = delete;

public:
    CollectionShardingRuntime(ServiceContext* sc,
                              NamespaceString nss,
                              executor::TaskExecutor* rangeDeleterExecutor);

    /**
     * Obtains the sharding runtime state for the specified collection. If it does not exist, it
     * will be created and will remain active until the collection is dropped or unsharded.
     *
     * Must be called with some lock held on the specific collection being looked up and the
     * returned pointer should never be stored.
     */
    static CollectionShardingRuntime* get(OperationContext* opCtx, const NamespaceString& nss);

    /**
     * Updates the collection's filtering metadata based on changes received from the config server
     * and also resolves the pending receives map in case some of these pending receives have
     * committed on the config server or have been abandoned by the donor shard.
     *
     * This method must be called with an exclusive collection lock and it does not acquire any
     * locks itself.
     */
    void setFilteringMetadata(OperationContext* opCtx, CollectionMetadata newMetadata);

    /**
     * Marks the collection's filtering metadata as UNKNOWN, meaning that all attempts to check for
     * shard version match will fail with StaleConfig errors in order to trigger an update.
     *
     * It is safe to call this method with only an intent lock on the collection (as opposed to
     * setFilteringMetadata which requires exclusive), however note that clearing a collection's
     * filtering metadata will interrupt all in-progress orphan cleanups in which case orphaned data
     * will remain behind on disk.
     */
    void clearFilteringMetadata();

    /**
     * Schedules any documents in `range` for immediate cleanup iff no running queries can depend
     * on them, and adds the range to the list of pending ranges. Otherwise, returns a notification
     * that yields bad status immediately.  Does not block.  Call waitStatus(opCtx) on the result
     * to wait for the deletion to complete or fail.  After that, call waitForClean to ensure no
     * other deletions are pending for the range.
     */
    using CleanupNotification = CollectionRangeDeleter::DeleteNotification;
    CleanupNotification beginReceive(ChunkRange const& range);

    /*
     * Removes `range` from the list of pending ranges, and schedules any documents in the range for
     * immediate cleanup. Does not block.
     */
    void forgetReceive(const ChunkRange& range);

    /**
     * Schedules documents in `range` for cleanup after any running queries that may depend on them
     * have terminated. Does not block. Fails if range overlaps any current local shard chunk.
     * Passed kDelayed, an additional delay (configured via server parameter orphanCleanupDelaySecs)
     * is added to permit (most) dependent queries on secondaries to complete, too.
     *
     * Call result.waitStatus(opCtx) to wait for the deletion to complete or fail. If that succeeds,
     * waitForClean can be called to ensure no other deletions are pending for the range. Call
     * result.abandon(), instead of waitStatus, to ignore the outcome.
     */
    enum CleanWhen { kNow, kDelayed };
    CleanupNotification cleanUpRange(ChunkRange const& range, CleanWhen when);

    /**
     * Tracks deletion of any documents within the range, returning when deletion is complete.
     * Throws if the collection is dropped while it sleeps.
     */
    static Status waitForClean(OperationContext* opCtx,
                               const NamespaceString& nss,
                               OID const& epoch,
                               ChunkRange orphanRange);

    /**
     * Reports whether any range still scheduled for deletion overlaps the argument range. If so,
     * it returns a notification n such that n->get(opCtx) will wake when the newest overlapping
     * range's deletion (possibly the one of interest) completes or fails. This should be called
     * again after each wakeup until it returns boost::none, because there can be more than one
     * range scheduled for deletion that overlaps its argument.
     */
    auto trackOrphanedDataCleanup(ChunkRange const& range) -> boost::optional<CleanupNotification>;

    /**
     * Returns a range _not_ owned by this shard that starts no lower than the specified
     * startingFrom key value, if any, or boost::none if there is no such range.
     */
    boost::optional<ChunkRange> getNextOrphanRange(BSONObj const& startingFrom);

    /**
     * BSON output of the pending metadata into a BSONArray
     */
    void toBSONPending(BSONArrayBuilder& bb) const {
        _metadataManager->toBSONPending(bb);
    }

private:
    friend boost::optional<Date_t> CollectionRangeDeleter::cleanUpNextRange(
        OperationContext*, NamespaceString const&, OID const&, int, CollectionRangeDeleter*);

    // Namespace this state belongs to.
    const NamespaceString _nss;

    // Contains all the metadata associated with this collection.
    std::shared_ptr<MetadataManager> _metadataManager;

    boost::optional<ScopedCollectionMetadata> _getMetadata(
        const boost::optional<mongo::LogicalTime>& atClusterTime) override;
};

/**
 * RAII-style class, which obtains a reference to the critical section for the specified collection.
 */
class CollectionCriticalSection {
    CollectionCriticalSection(const CollectionCriticalSection&) = delete;
    CollectionCriticalSection& operator=(const CollectionCriticalSection&) = delete;

public:
    CollectionCriticalSection(OperationContext* opCtx, NamespaceString ns);
    ~CollectionCriticalSection();

    /**
     * Enters the commit phase of the critical section and blocks reads.
     */
    void enterCommitPhase();

private:
    NamespaceString _nss;

    OperationContext* _opCtx;
};

}  // namespace mongo