// 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.

#include "storage/index/index_page.h"

#include <gen_cpp/segment_v2.pb.h>

#include <algorithm>

#include <ostream>

#include "util/coding.h"

namespace doris {

namespace segment_v2 {

void IndexPageBuilder::add(const Slice& key, const PagePointer& ptr) {

    DCHECK(!_finished) << "must reset() after finish() to add new entry";

    put_length_prefixed_slice(&_buffer, key);

    ptr.encode_to(&_buffer);

    _count++;

}

bool IndexPageBuilder::is_full() const {

    // estimate size of IndexPageFooterPB to be 16

    return _buffer.size() + 16 > _index_page_size;

}

void IndexPageBuilder::finish(OwnedSlice* body, PageFooterPB* footer) {

    DCHECK(!_finished) << "already called finish()";

    *body = _buffer.build();

    footer->set_type(INDEX_PAGE);

    footer->set_uncompressed_size(cast_set<uint32_t>(body->slice().get_size()));

    footer->mutable_index_page_footer()->set_num_entries(_count);

    footer->mutable_index_page_footer()->set_type(_is_leaf ? IndexPageFooterPB::LEAF

                                                           : IndexPageFooterPB::INTERNAL);

}

Status IndexPageBuilder::get_first_key(Slice* key) const {

    if (_count == 0) {

        return Status::Error<ErrorCode::ENTRY_NOT_FOUND>("index page is empty");

    }

    Slice input(_buffer);

    if (get_length_prefixed_slice(&input, key)) {

        return Status::OK();

    } else {

        return Status::Corruption("can't decode first key");

    }

}

///////////////////////////////////////////////////////////////////////////////

int64_t IndexPageReader::get_metadata_size() const {

    return sizeof(IndexPageReader) + _footer.ByteSizeLong();

}

Status IndexPageReader::parse(const Slice& body, const IndexPageFooterPB& footer) {

    _footer = footer;

    size_t num_entries = _footer.num_entries();

    Slice input(body);

    for (int i = 0; i < num_entries; ++i) {

        Slice key;

        PagePointer value;

        if (!get_length_prefixed_slice(&input, &key)) {

            return Status::InternalError("Data corruption");

        }

        if (!value.decode_from(&input)) {

            return Status::InternalError("Data corruption");

        }

        _keys.push_back(key);

        _values.push_back(value);

    }

    update_metadata_size();

    _parsed = true;

    return Status::OK();

}

///////////////////////////////////////////////////////////////////////////////

Status IndexPageIterator::seek_at_or_before(const Slice& search_key) {

    int32_t left = 0;

    auto right = cast_set<int32_t>(_reader->count() - 1);

    while (left <= right) {

        int32_t mid = left + (right - left) / 2;

        int cmp = search_key.compare(_reader->get_key(mid));

        if (cmp < 0) {

            right = mid - 1;

        } else if (cmp > 0) {

            left = mid + 1;

        } else {

            _pos = mid;

            return Status::OK();

        }

    }

    // no exact match, the insertion point is `left`

    if (left == 0) {

        // search key is smaller than all keys

        return Status::Error<ErrorCode::ENTRY_NOT_FOUND>(

                "given key is smaller than all keys in page");

    }

    // index entry records the first key of the indexed page,

    // therefore the first page with keys >= searched key is the one before the insertion point

    _pos = left - 1;

    return Status::OK();

}

} // namespace segment_v2

} // namespace doris