// 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 <unicode/utf8.h>

#include <cstdint>

#include <span>

#include <string_view>

#include <vector>

#include "storage/index/inverted/char_filter/char_filter.h"

#include "storage/index/inverted/token_stream.h"

namespace doris::segment_v2::inverted_index {

class DorisTokenizer : public Tokenizer, public DorisTokenStream {

public:

    DorisTokenizer() = default;

    ~DorisTokenizer() override = default;

    void set_reader(const ReaderPtr& in) {

        if (in == nullptr) {

            throw Exception(ErrorCode::INVALID_ARGUMENT, "reader must not be null");

        }

        _in_pending = in;

    }

    using Tokenizer::reset;

    // Only use the parameterless reset method

    void reset() override { _in = _in_pending; };

    std::span<const int32_t> get_source_byte_offsets() const override {

        return _source_byte_offsets_enabled ? std::span<const int32_t> {_source_byte_offsets}

                                            : std::span<const int32_t> {};

    }

    void set_source_byte_offsets_enabled(bool enabled) override {

        _source_byte_offsets_enabled = enabled;

    }

protected:

    int32_t correct_source_offset(int32_t offset) const {

        const auto* char_filter = dynamic_cast<const DorisCharFilter*>(_in.get());

        return char_filter == nullptr ? offset : char_filter->correct_offset(offset);

    }

    void set_source_byte_offsets(std::string_view term, int32_t source_start) {

        _source_byte_offsets.clear();

        if (!_source_byte_offsets_enabled) {

            return;

        }

        const auto* char_filter = dynamic_cast<const DorisCharFilter*>(_in.get());

        const int32_t corrected_start =

                char_filter == nullptr ? source_start : char_filter->correct_offset(source_start);

        _source_byte_offsets.push_back(0);

        const char* data = term.data();

        const auto length = static_cast<int32_t>(term.size());

        int32_t offset = 0;

        while (offset < length) {

            UChar32 code_point;

            U8_NEXT(data, offset, length, code_point);

            if (code_point < 0) {

                _source_byte_offsets.clear();

                return;

            }

            _source_byte_offsets.push_back(

                    char_filter == nullptr

                            ? offset

                            : char_filter->correct_offset(source_start + offset) - corrected_start);

        }

    }

    ReaderPtr _in;

    ReaderPtr _in_pending;

    std::vector<int32_t> _source_byte_offsets;

    bool _source_byte_offsets_enabled {false};

};

using TokenizerPtr = std::shared_ptr<DorisTokenizer>;

} // namespace doris::segment_v2::inverted_index