// 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/segment/binary_prefix_page.h"

#include <stddef.h>

#include <stdint.h>

#include <algorithm>

#include <vector>

#include "common/status.h"

#include "util/coding.h"

#include "util/faststring.h"

#include "util/slice.h"

namespace doris {

namespace segment_v2 {

Status BinaryPrefixPageBuilder::add(const uint8_t* vals, size_t* add_count) {

    DCHECK(!_finished);

    if (*add_count == 0) {

        return Status::OK();

    }

    const Slice* src = reinterpret_cast<const Slice*>(vals);

    int i = 0;

    for (; i < *add_count; ++i, ++src) {

        if (is_page_full()) {

            break;

        }

        const char* entry = src->data;

        size_t entry_len = src->size;

        size_t old_size = _buffer.size();

        size_t share_len;

        if (_count % RESTART_POINT_INTERVAL == 0) {

            share_len = 0;

            _restart_points_offset.push_back(cast_set<uint32_t>(old_size));

        } else {

            size_t max_share_len = std::min(_last_entry.size(), entry_len);

            share_len = max_share_len;

            for (int j = 0; j < max_share_len; ++j) {

                if (entry[j] != _last_entry[j]) {

                    share_len = j;

                    break;

                }

            }

        }

        size_t non_share_len = entry_len - share_len;

        // This may need a large memory, should return error if could not allocated

        // successfully, to avoid BE OOM.

        RETURN_IF_CATCH_EXCEPTION({

            put_varint32(&_buffer, cast_set<uint32_t>(share_len));

            put_varint32(&_buffer, cast_set<uint32_t>(non_share_len));

            _buffer.append(entry + share_len, non_share_len);

            _last_entry.clear();

            _last_entry.append(entry, entry_len);

        });

        _raw_data_size += entry_len;

        ++_count;

    }

    *add_count = i;

    return Status::OK();

}

Status BinaryPrefixPageBuilder::finish(OwnedSlice* slice) {

    DCHECK(!_finished);

    _finished = true;

    RETURN_IF_CATCH_EXCEPTION({

        put_fixed32_le(&_buffer, (uint32_t)_count);

        uint8_t restart_point_internal = RESTART_POINT_INTERVAL;

        _buffer.append(&restart_point_internal, 1);

        auto restart_point_size = _restart_points_offset.size();

        for (uint32_t i = 0; i < restart_point_size; ++i) {

            put_fixed32_le(&_buffer, _restart_points_offset[i]);

        }

        put_fixed32_le(&_buffer, cast_set<uint32_t>(restart_point_size));

        *slice = _buffer.build();

    });

    return Status::OK();

}

const uint8_t* BinaryPrefixPageDecoder::_decode_value_lengths(const uint8_t* ptr, uint32_t* shared,

                                                              uint32_t* non_shared) {

    if ((ptr = decode_varint32_ptr(ptr, _footer_start, shared)) == nullptr) {

        return nullptr;

    }

    if ((ptr = decode_varint32_ptr(ptr, _footer_start, non_shared)) == nullptr) {

        return nullptr;

    }

    if (_footer_start - ptr < *non_shared) {

        return nullptr;

    }

    return ptr;

}

Status BinaryPrefixPageDecoder::_read_next_value() {

    if (_cur_pos >= _num_values) {

        return Status::EndOfFile("no more value to read");

    }

    uint32_t shared_len;

    uint32_t non_shared_len;

    auto data_ptr = _decode_value_lengths(_next_ptr, &shared_len, &non_shared_len);

    if (data_ptr == nullptr) {

        DCHECK(false) << "[BinaryPrefixPageDecoder::_read_next_value] corruption!";

        return Status::Corruption("Failed to decode value at position {}", _cur_pos);

    }

    _current_value.resize(shared_len);

    _current_value.append(data_ptr, non_shared_len);

    _next_ptr = data_ptr + non_shared_len;

    return Status::OK();

}

Status BinaryPrefixPageDecoder::_seek_to_restart_point(size_t restart_point_index) {

    _cur_pos = cast_set<uint32_t>(restart_point_index * _restart_point_internal);

    _next_ptr = _get_restart_point(restart_point_index);

    return _read_next_value();

}

Status BinaryPrefixPageDecoder::init() {

    _cur_pos = 0;

    _next_ptr = reinterpret_cast<const uint8_t*>(_data.get_data());

    const uint8_t* end = _next_ptr + _data.get_size();

    _num_restarts = decode_fixed32_le(end - 4);

    _restarts_ptr = end - (_num_restarts + 1) * 4;

    _footer_start = _restarts_ptr - 4 - 1;

    _num_values = decode_fixed32_le(_footer_start);

    _restart_point_internal = decode_fixed8(_footer_start + 4);

    _parsed = true;

    return _read_next_value();

}

Status BinaryPrefixPageDecoder::seek_to_position_in_page(size_t pos) {

    DCHECK(_parsed);

    DCHECK_LE(pos, _num_values);

    if (_num_values == 0) [[unlikely]] {

        if (pos != 0) {

            return Status::Error<ErrorCode::INTERNAL_ERROR, false>(

                    "seek pos {} is larger than total elements  {}", pos, _num_values);

        }

    }

    // seek past the last value is valid

    if (pos == _num_values) {

        _cur_pos = cast_set<uint32_t>(_num_values);

        return Status::OK();

    }

    size_t restart_point_index = pos / _restart_point_internal;

    RETURN_IF_ERROR(_seek_to_restart_point(restart_point_index));

    while (_cur_pos < pos) {

        _cur_pos++;

        RETURN_IF_ERROR(_read_next_value());

    }

    return Status::OK();

}

Status BinaryPrefixPageDecoder::seek_at_or_after_value(const void* value, bool* exact_match) {

    DCHECK(_parsed);

    Slice target = *reinterpret_cast<const Slice*>(value);

    uint32_t left = 0;

    uint32_t right = _num_restarts;

    // find the first restart point >= target. after loop,

    // - left == index of first restart point >= target when found

    // - left == _num_restarts when not found (all restart points < target)

    while (left < right) {

        uint32_t mid = left + (right - left) / 2;

        // read first entry at restart point `mid`

        RETURN_IF_ERROR(_seek_to_restart_point(mid));

        Slice mid_entry(_current_value);

        if (mid_entry.compare(target) < 0) {

            left = mid + 1;

        } else {

            right = mid;

        }

    }

    // then linear search from the last restart pointer < target.

    // when left == 0, all restart points >= target, so search from first one.

    // otherwise search from the last restart point < target, which is left - 1

    uint32_t search_index = left > 0 ? left - 1 : 0;

    RETURN_IF_ERROR(_seek_to_restart_point(search_index));

    while (true) {

        int cmp = Slice(_current_value).compare(target);

        if (cmp >= 0) {

            *exact_match = cmp == 0;

            return Status::OK();

        }

        _cur_pos++;

        auto st = _read_next_value();

        if (st.is<ErrorCode::END_OF_FILE>()) {

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

                    "all value small than the value");

        }

        if (!st.ok()) {

            return st;

        }

    }

}

Status BinaryPrefixPageDecoder::next_batch(size_t* n, MutableColumnPtr& dst) {

    DCHECK(_parsed);

    if (*n == 0 || _cur_pos >= _num_values) [[unlikely]] {

        *n = 0;

        return Status::OK();

    }

    size_t max_fetch = std::min(*n, static_cast<size_t>(_num_values - _cur_pos));

    // read and copy values

    for (size_t i = 0; i < max_fetch; ++i) {

        dst->insert_data((char*)(_current_value.data()), _current_value.size());

        _cur_pos++;

        // reach the end of the page, should not read the next value

        if (_cur_pos < _num_values) {

            RETURN_IF_ERROR(_read_next_value());

        }

    }

    *n = max_fetch;

    return Status::OK();

}

} // namespace segment_v2

} // namespace doris