// 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 "storage/compaction/collection_similarity.h"

#include "storage/index/inverted/similarity/collection_statistics.h"

namespace doris::segment_v2 {

struct IndexQueryContext {

    io::IOContext* io_ctx = nullptr;

    OlapReaderStatistics* stats = nullptr;

    RuntimeState* runtime_state = nullptr;

    CollectionStatisticsPtr collection_statistics;

    CollectionSimilarityPtr collection_similarity;

    size_t query_limit = 0;

    bool is_asc = false;

    // G02 count-only fast-path handshake. Set by SegmentIterator ONLY while it

    // evaluates the single pushed-down MATCH predicate of a COUNT_ON_INDEX scan

    // whose row space is provably unfiltered (no deletes, no other conjuncts,

    // full row bitmap, no row-id consumers -- see count_on_index_fastpath.h),

    // and reset immediately after. When set, an index reader MAY answer the

    // query with a bitmap whose CARDINALITY equals the match count without the

    // row ids being real (SNII returns [0, df) straight from dict-entry df,

    // skipping the posting decode). Readers must never cache such a bitmap

    // under a key a row-accurate query could hit.

    bool count_on_index_fastpath = false;

    // ---- Reply direction: fields a READER writes and the CALLER reads back ----

    //

    // A caller that hands a reader a COPY of this context rather than the context itself must

    // fold the copy back with merge_reader_outputs(), or the reader's reply is dropped in

    // silence: nothing fails to compile, no test goes red, the query simply takes the wrong plan.

    // FunctionSearch's SNII leaf builder is such a caller -- it copies the context so the reader

    // publishes its BM25 into a throwaway CollectionSimilarity instead of the query's own.

    //

    // Every field added below this line must also be merged in merge_reader_outputs().

    // G03 reply direction of the same handshake. Set by a reader iff it DID

    // answer with such a fabricated count bitmap (never on a query-cache hit,

    // a single-flight shared result, or any row-accurate decode). Read and

    // reset by SegmentIterator right after the index apply; a true value is

    // the precondition for the count-emission shortcut that materializes the

    // remaining count as default rows without iterating the row bitmap.

    bool count_on_index_fastpath_hit = false;

    // Folds the reply-direction fields a reader wrote on a copy of this context back into it.

    // Latching (never clearing) is what makes this safe to call for each of several readers.

    void merge_reader_outputs(const IndexQueryContext& reader_context) {

        count_on_index_fastpath_hit |= reader_context.count_on_index_fastpath_hit;

    }

};

using IndexQueryContextPtr = std::shared_ptr<IndexQueryContext>;

} // namespace doris::segment_v2