// 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 <butil/macros.h>

#include <gen_cpp/olap_file.pb.h>

#include <gen_cpp/segment_v2.pb.h>

#include <glog/logging.h>

#include <cstdint>

#include <map>

#include <memory> // for unique_ptr

#include <string>

#include <unordered_map>

#include "agent/be_exec_version_manager.h"

#include "common/status.h" // Status

#include "core/column/column.h"

#include "core/data_type/data_type.h"

#include "io/fs/file_reader.h"

#include "io/fs/file_reader_writer_fwd.h"

#include "io/fs/file_system.h"

#include "runtime/descriptors.h"

#include "storage/cache/page_cache.h"

#include "storage/field.h"

#include "storage/olap_common.h"

#include "storage/schema.h"

#include "storage/segment/page_handle.h"

#include "storage/tablet/tablet_schema.h"

#include "util/once.h"

#include "util/slice.h"

namespace doris {

class IDataType;

class ShortKeyIndexDecoder;

class Schema;

class StorageReadOptions;

class PrimaryKeyIndexReader;

class RowwiseIterator;

struct RowLocation;

namespace segment_v2 {

class Segment;

class InvertedIndexIterator;

class IndexFileReader;

class IndexIterator;

class ColumnReader;

class ColumnIterator;

class ColumnReaderCache;

class ColumnMetaAccessor;

using SegmentSharedPtr = std::shared_ptr<Segment>;

struct SparseColumnCache;

using SparseColumnCacheSPtr = std::shared_ptr<SparseColumnCache>;

// key is column path, value is the sparse column cache

// now column path is only SPARSE_COLUMN_PATH, in the future, we can add more sparse column paths

using PathToSparseColumnCache = std::unordered_map<std::string, SparseColumnCacheSPtr>;

using PathToSparseColumnCacheUPtr = std::unique_ptr<PathToSparseColumnCache>;

struct BinaryColumnCache;

using BinaryColumnCacheSPtr = std::shared_ptr<BinaryColumnCache>;

using PathToBinaryColumnCache = std::unordered_map<std::string, BinaryColumnCacheSPtr>;

using PathToBinaryColumnCacheUPtr = std::unique_ptr<PathToBinaryColumnCache>;

// A Segment is used to represent a segment in memory format. When segment is

// generated, it won't be modified, so this struct aimed to help read operation.

// It will prepare all ColumnReader to create ColumnIterator as needed.

// And user can create a RowwiseIterator through new_iterator function.

//

// NOTE: This segment is used to a specified TabletSchema, when TabletSchema

// is changed, this segment can not be used any more. For example, after a schema

// change finished, client should disable all cached Segment for old TabletSchema.

class Segment : public std::enable_shared_from_this<Segment>, public MetadataAdder<Segment> {

public:

    static Status open(io::FileSystemSPtr fs, const std::string& path, int64_t tablet_id,

                       uint32_t segment_id, RowsetId rowset_id, TabletSchemaSPtr tablet_schema,

                       const io::FileReaderOptions& reader_options,

                       std::shared_ptr<Segment>* output, InvertedIndexFileInfo idx_file_info = {},

                       OlapReaderStatistics* stats = nullptr);

    static io::UInt128Wrapper file_cache_key(std::string_view rowset_id, uint32_t seg_id);

    io::UInt128Wrapper file_cache_key() const {

        return file_cache_key(_rowset_id.to_string(), _segment_id);

    }

    ~Segment() override;

    int64_t get_metadata_size() const override;

    void update_metadata_size();

    Status new_iterator(SchemaSPtr schema, const StorageReadOptions& read_options,

                        std::unique_ptr<RowwiseIterator>* iter);

    static Status new_default_iterator(const TabletColumn& tablet_column,

                                       std::unique_ptr<ColumnIterator>* iter);

    uint32_t id() const { return _segment_id; }

    RowsetId rowset_id() const { return _rowset_id; }

    uint32_t num_rows() const { return _num_rows; }

    // if variant_sparse_column_cache is nullptr, means the sparse column cache is not used

    Status new_column_iterator(const TabletColumn& tablet_column,

                               std::unique_ptr<ColumnIterator>* iter, const StorageReadOptions* opt,

                               const std::unordered_map<int32_t, PathToBinaryColumnCacheUPtr>*

                                       variant_sparse_column_cache = nullptr);

    Status new_index_iterator(const TabletColumn& tablet_column, const TabletIndex* index_meta,

                              const StorageReadOptions& read_options,

                              std::unique_ptr<IndexIterator>* iter);

    const ShortKeyIndexDecoder* get_short_key_index() const {

        DCHECK(_load_index_once.has_called() && _load_index_once.stored_result().ok());

        return _sk_index_decoder.get();

    }

    const PrimaryKeyIndexReader* get_primary_key_index() const {

        DCHECK(_load_index_once.has_called() && _load_index_once.stored_result().ok());

        return _pk_index_reader.get();

    }

    Status lookup_row_key(const Slice& key, const TabletSchema* latest_schema, bool with_seq_col,

                          bool with_rowid, RowLocation* row_location, OlapReaderStatistics* stats,

                          std::string* encoded_seq_value = nullptr);

    Status read_key_by_rowid(uint32_t row_id, std::string* key);

    Status seek_and_read_by_rowid(const TabletSchema& schema, SlotDescriptor* slot, uint32_t row_id,

                                  MutableColumnPtr& result,

                                  StorageReadOptions& storage_read_options,

                                  std::unique_ptr<ColumnIterator>& iterator_hint);

    Status load_index(OlapReaderStatistics* stats);

    Status load_pk_index_and_bf(OlapReaderStatistics* stats);

    void update_healthy_status(Status new_status) { _healthy_status.update(new_status); }

    // The segment is loaded into SegmentCache and then will load indices, if there are something wrong

    // during loading indices, should remove it from SegmentCache. If not, it will always report error during

    // query. So we add a healthy status API, the caller should check the healhty status before using the segment.

    Status healthy_status();

    std::string min_key() {

        DCHECK(_tablet_schema->keys_type() == UNIQUE_KEYS && _pk_index_meta != nullptr);

        return _pk_index_meta->min_key();

    }

    std::string max_key() {

        DCHECK(_tablet_schema->keys_type() == UNIQUE_KEYS && _pk_index_meta != nullptr);

        return _pk_index_meta->max_key();

    }

    io::FileReaderSPtr file_reader() { return _file_reader; }

    // Including the column reader memory.

    // another method `get_metadata_size` not include the column reader, only the segment object itself.

    int64_t meta_mem_usage() const { return _meta_mem_usage; }

    // Get the inner file column's data type.

    // When `read_options` is provided, the decision (e.g. flat-leaf vs hierarchical) can depend

    // on the reader type and tablet schema; when it is nullptr, we treat it as a query reader.

    // nullptr will be returned if storage type does not contain such column.

    std::shared_ptr<const IDataType> get_data_type_of(const TabletColumn& column,

                                                      const StorageReadOptions& read_options);

    // If column in segment is the same type in schema, then it is safe to apply predicate.

    bool can_apply_predicate_safely(

            int cid, const Schema& schema,

            const std::map<std::string, DataTypePtr>& target_cast_type_for_variants,

            const StorageReadOptions& read_options) {

        const doris::StorageField* col = schema.column(cid);

        DCHECK(col != nullptr) << "Column not found in schema for cid=" << cid;

        DataTypePtr storage_column_type = get_data_type_of(col->get_desc(), read_options);

        if (storage_column_type == nullptr || col->type() != FieldType::OLAP_FIELD_TYPE_VARIANT ||

            !target_cast_type_for_variants.contains(col->name())) {

            // Default column iterator or not variant column

            return true;

        }

        if (storage_column_type->equals(*target_cast_type_for_variants.at(col->name()))) {

            return true;

        } else {

            return false;

        }

    }

    const TabletSchemaSPtr& tablet_schema() { return _tablet_schema; }

    // get the column reader by tablet column, return NOT_FOUND if not found reader in this segment

    Status get_column_reader(const TabletColumn& col, std::shared_ptr<ColumnReader>* column_reader,

                             OlapReaderStatistics* stats);

    // get the column reader by column unique id, return NOT_FOUND if not found reader in this segment

    Status get_column_reader(int32_t col_uid, std::shared_ptr<ColumnReader>* column_reader,

                             OlapReaderStatistics* stats);

    Status traverse_column_meta_pbs(const std::function<void(const ColumnMetaPB&)>& visitor);

    static StoragePageCache::CacheKey get_segment_footer_cache_key(

            const io::FileReaderSPtr& file_reader);

private:

    DISALLOW_COPY_AND_ASSIGN(Segment);

    Segment(uint32_t segment_id, RowsetId rowset_id, TabletSchemaSPtr tablet_schema,

            InvertedIndexFileInfo idx_file_info = InvertedIndexFileInfo());

    static Status _open(io::FileSystemSPtr fs, const std::string& path, uint32_t segment_id,

                        RowsetId rowset_id, TabletSchemaSPtr tablet_schema,

                        const io::FileReaderOptions& reader_options,

                        std::shared_ptr<Segment>* output, InvertedIndexFileInfo idx_file_info,

                        OlapReaderStatistics* stats);

    // open segment file and read the minimum amount of necessary information (footer)

    Status _open(OlapReaderStatistics* stats);

    Status _parse_footer(std::shared_ptr<SegmentFooterPB>& footer,

                         OlapReaderStatistics* stats = nullptr);

    Status _create_column_meta(const SegmentFooterPB& footer);

    Status _load_pk_bloom_filter(OlapReaderStatistics* stats);

    // Must ensure _create_column_readers_once has been called before calling this function.

    ColumnReader* _get_column_reader(const TabletColumn& col);

    Status _write_error_file(size_t file_size, size_t offset, size_t bytes_read, char* data,

                             io::IOContext& io_ctx);

    Status _open_index_file_reader();

    Status _create_column_meta_once(OlapReaderStatistics* stats);

    virtual Status _get_segment_footer(std::shared_ptr<SegmentFooterPB>&,

                                       OlapReaderStatistics* stats);

    StoragePageCache::CacheKey get_segment_footer_cache_key() const;

    friend class SegmentIterator;

    friend class ColumnReaderCache;

    friend class MockSegment;

    io::FileSystemSPtr _fs;

    io::FileReaderSPtr _file_reader;

    uint32_t _segment_id;

    uint32_t _num_rows;

    AtomicStatus _healthy_status;

    // 1. Tracking memory use by segment meta data such as footer or index page.

    // 2. Tracking memory use by segment column reader

    // The memory consumed by querying is tracked in segment iterator.

    int64_t _meta_mem_usage;

    int64_t _tracked_meta_mem_usage = 0;

    RowsetId _rowset_id;

    TabletSchemaSPtr _tablet_schema;

    std::unique_ptr<PrimaryKeyIndexMetaPB> _pk_index_meta;

    PagePointerPB _sk_index_page;

    // Limited cache for column readers

    std::unique_ptr<ColumnReaderCache> _column_reader_cache;

    // Centralized accessor for column metadata layout and uid->column_ordinal mapping.

    std::unique_ptr<ColumnMetaAccessor> _column_meta_accessor;

    // Init from ColumnMetaPB in SegmentFooterPB

    // map column unique id ---> it's inner data type

    std::map<int32_t, std::shared_ptr<const IDataType>> _file_column_types;

    // used to guarantee that short key index will be loaded at most once in a thread-safe way

    DorisCallOnce<Status> _load_index_once;

    // used to guarantee that primary key bloom filter will be loaded at most once in a thread-safe way

    DorisCallOnce<Status> _load_pk_bf_once;

    DorisCallOnce<Status> _create_column_meta_once_call;

    std::weak_ptr<SegmentFooterPB> _footer_pb;

    // used to hold short key index page in memory

    PageHandle _sk_index_handle;

    // short key index decoder

    // all content is in memory

    std::unique_ptr<ShortKeyIndexDecoder> _sk_index_decoder;

    // primary key index reader

    std::unique_ptr<PrimaryKeyIndexReader> _pk_index_reader;

    std::mutex _open_lock;

    // inverted index file reader

    std::shared_ptr<IndexFileReader> _index_file_reader;

    DorisCallOnce<Status> _index_file_reader_open;

    InvertedIndexFileInfo _idx_file_info;

    int _be_exec_version = BeExecVersionManager::get_newest_version();

};

} // namespace segment_v2

} // namespace doris