// Licensed to the Apache Software Foundation (ASF) under one

// or more contributor license agreements.  See the NOTICE file

// distributed with this work for additional information

// regarding copyright ownership.  The ASF licenses this file

// to you under the Apache License, Version 2.0 (the

// "License"); you may not use this file except in compliance

// with the License.  You may obtain a copy of the License at

//

//   http://www.apache.org/licenses/LICENSE-2.0

//

// Unless required by applicable law or agreed to in writing,

// software distributed under the License is distributed on an

// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY

// KIND, either express or implied.  See the License for the

// specific language governing permissions and limitations

// under the License.

#pragma once

#include <rapidjson/document.h>

#include <stdint.h>

#include <map>

#include <memory>

#include <string>

#include <unordered_map>

#include <vector>

#include "common/status.h"

#include "olap/olap_common.h"

#include "olap/rowset/rowset_meta.h"

namespace doris {

/// VersionGraph class which is implemented to build and maintain total versions of rowsets.

/// This class use adjacency-matrix represent rowsets version and links. A vertex is a version

/// and a link is the _version object of a rowset (from start version to end version + 1).

/// Use this class, when given a spec_version, we can get a version path which is the shortest path

/// in the graph.

class VersionGraph {

public:

    /// Use rs_metas to construct the graph including vertex and edges, and return the

    /// max_version in metas.

    void construct_version_graph(const std::vector<RowsetMetaSharedPtr>& rs_metas,

                                 int64_t* max_version);

    /// Reconstruct the graph, begin construction the vertex vec and edges list will be cleared.

    void reconstruct_version_graph(const std::vector<RowsetMetaSharedPtr>& rs_metas,

                                   int64_t* max_version);

    /// Add a version to this graph, graph will add the version and edge in version.

    void add_version_to_graph(const Version& version);

    /// Delete a version from graph. Notice that this del operation only remove this edges and

    /// remain the vertex.

    Status delete_version_from_graph(const Version& version);

    /// Given a spec_version, this method can find a version path which is the shortest path

    /// in the graph. The version paths are added to version_path as return info.

    Status capture_consistent_versions(const Version& spec_version,

                                       std::vector<Version>* version_path) const;

    // See comment of TimestampedVersionTracker's get_orphan_vertex_ratio();

    double get_orphan_vertex_ratio();

private:

    /// Private method add a version to graph.

    void _add_vertex_to_graph(int64_t vertex_value);

    // OLAP version contains two parts, [start_version, end_version]. In order

    // to construct graph, the OLAP version has two corresponding vertex, one

    // vertex's value is version.start_version, the other is

    // version.end_version + 1.

    // Use adjacency list to describe version graph.

    // In order to speed up the version capture, vertex's edges are sorted by version in descending order.

    std::vector<Vertex> _version_graph;

    // vertex value --> vertex_index of _version_graph

    // It is easy to find vertex index according to vertex value.

    std::unordered_map<int64_t, int64_t> _vertex_index_map;

};

/// TimestampedVersion class which is implemented to maintain multi-version path of rowsets.

/// This compaction info of a rowset includes start version, end version and the create time.

class TimestampedVersion {

public:

    /// TimestampedVersion construction function. Use rowset version and create time to build a TimestampedVersion.

    TimestampedVersion(const Version& version, int64_t create_time)

            : _version(version.first, version.second), _create_time(create_time) {}

    ~TimestampedVersion() {}

    /// Return the rowset version of TimestampedVersion record.

    Version version() const { return _version; }

    /// Return the rowset create_time of TimestampedVersion record.

    int64_t get_create_time() { return _create_time; }

    /// Compare two version trackers.

    bool operator!=(const TimestampedVersion& rhs) const { return _version != rhs._version; }

    /// Compare two version trackers.

    bool operator==(const TimestampedVersion& rhs) const { return _version == rhs._version; }

    /// Judge if a tracker contains the other.

    bool contains(const TimestampedVersion& other) const {

        return _version.contains(other._version);

    }

private:

    Version _version;

    int64_t _create_time;

};

using TimestampedVersionSharedPtr = std::shared_ptr<TimestampedVersion>;

/// TimestampedVersionPathContainer class is used to maintain a path timestamped version path

/// and record the max create time in a path version. Once a timestamped version is added, the max_create_time

/// will compare with the version timestamp and be refreshed.

class TimestampedVersionPathContainer {

public:

    /// TimestampedVersionPathContainer construction function, max_create_time is assigned to 0.

    TimestampedVersionPathContainer() : _max_create_time(0) {}

    /// Return the max create time in a path version.

    int64_t max_create_time() { return _max_create_time; }

    /// Add a timestamped version to timestamped_versions_container. Once a timestamped version is added,

    /// the max_create_time will compare with the version timestamp and be refreshed.

    void add_timestamped_version(TimestampedVersionSharedPtr version);

    /// Return the timestamped_versions_container as const type.

    std::vector<TimestampedVersionSharedPtr>& timestamped_versions();

private:

    std::vector<TimestampedVersionSharedPtr> _timestamped_versions_container;

    int64_t _max_create_time;

};

using PathVersionListSharedPtr = std::shared_ptr<TimestampedVersionPathContainer>;

/// TimestampedVersionTracker class is responsible to track all rowsets version links of a tablet.

/// This class not only records the graph of all versions, but also records the paths which will be removed

/// after the path is expired.

class TimestampedVersionTracker {

public:

    /// Construct rowsets version tracker by main path rowset meta.

    void construct_versioned_tracker(const std::vector<RowsetMetaSharedPtr>& rs_metas);

    /// Construct rowsets version tracker by main path rowset meta and stale rowset meta.

    void construct_versioned_tracker(const std::vector<RowsetMetaSharedPtr>& rs_metas,

                                     const std::vector<RowsetMetaSharedPtr>& stale_metas);

    /// Recover rowsets version tracker from stale version path map. When delete operation fails, the

    /// tracker can be recovered from deleted stale_version_path_map.

    void recover_versioned_tracker(

            const std::map<int64_t, PathVersionListSharedPtr>& stale_version_path_map);

    /// Add a version to tracker, this version is a new version rowset, not merged rowset.

    void add_version(const Version& version);

    void delete_version(const Version& version) {

        static_cast<void>(_version_graph.delete_version_from_graph(version));

    }

    /// Add a version path with stale_rs_metas, this versions in version path

    /// are merged rowsets.  These rowsets are tracked and removed after they are expired.

    /// TabletManager sweep these rowsets using tracker by timing.

    void add_stale_path_version(const std::vector<RowsetMetaSharedPtr>& stale_rs_metas);

    /// Given a spec_version, this method can find a version path which is the shortest path

    /// in the graph. The version paths are added to version_path as return info.

    /// If this version not in main version, version_path can be included expired rowset.

    Status capture_consistent_versions(const Version& spec_version,

                                       std::vector<Version>* version_path) const;

    /// Capture all expired path version.

    /// When the last rowset create time of a path greater than expired time  which can be expressed

    /// "now() - tablet_rowset_stale_sweep_time_sec" , this path will be remained.

    /// Otherwise, this path will be added to path_version.

    void capture_expired_paths(int64_t stale_sweep_endtime,

                               std::vector<int64_t>* path_version) const;

    /// Fetch all versions with a path_version.

    PathVersionListSharedPtr fetch_path_version_by_id(int64_t path_id);

    /// Fetch all versions with a path_version, at the same time remove this path from the tracker.

    /// Next time, fetch this path, it will return empty.

    PathVersionListSharedPtr fetch_and_delete_path_by_id(int64_t path_id);

    /// Print all expired version path in a tablet.

    std::string get_current_path_map_str();

    /// Get json document of _stale_version_path_map. Fill the path_id and version_path

    /// list in the document. The parameter path arr is used as return variable.

    void get_stale_version_path_json_doc(rapidjson::Document& path_arr);

    // Return proportion of orphan vertex in VersionGraph's _version_graph.

    // If a vertex is no longer the starting point of any edge, then this vertex is defined as orphan vertex

    double get_orphan_vertex_ratio();

private:

    /// Construct rowsets version tracker with main path rowset meta.

    void _construct_versioned_tracker(const std::vector<RowsetMetaSharedPtr>& rs_metas);

    /// init stale_version_path_map by main path rowset meta and stale rowset meta.

    void _init_stale_version_path_map(const std::vector<RowsetMetaSharedPtr>& rs_metas,

                                      const std::vector<RowsetMetaSharedPtr>& stale_metas);

    /// find a path in stale_map from first_version to second_version, stale_path is used as result.

    bool _find_path_from_stale_map(

            const std::unordered_map<int64_t, std::unordered_map<int64_t, RowsetMetaSharedPtr>>&

                    stale_map,

            int64_t first_version, int64_t second_version,

            std::vector<RowsetMetaSharedPtr>* stale_path);

private:

    // This variable records the id of path version which will be dispatched to next path version,

    // it is not persisted.

    int64_t _next_path_id = 1;

    // path_version -> list of path version,

    // This variable is used to maintain the map from path version and it's all version.

    std::map<int64_t, PathVersionListSharedPtr> _stale_version_path_map;

    VersionGraph _version_graph;

};

} // namespace doris