// Copyright 2024 The Pigweed Authors

//

// Licensed 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

//

//     https://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 <optional>

#include <string>

#include <vector>

namespace pw::tokenizer {

namespace internal {

class CsvParser {

 public:

  CsvParser() : state_(kNewEntry), line_(1u) {}

  [[nodiscard]] std::optional<std::vector<std::string>> ParseCharacter(

      char ch) {

    return ParseCharacterOrEof(ch);

  }

  [[nodiscard]] std::optional<std::vector<std::string>> Flush() {

    return ParseCharacterOrEof(kEndOfFile);

  }

 private:

  static constexpr int kEndOfFile = -1;

  std::optional<std::vector<std::string>> FinishLine();

  std::optional<std::vector<std::string>> ParseCharacterOrEof(int ch);

  enum {

    kNewEntry,

    kUnquotedEntry,

    kQuotedEntry,

    kQuotedEntryQuote,

    kError,

  } state_;

  std::vector<std::string> line_;

};

}  // namespace internal

/// Parses a CSV file, calling the provided function for each line.

///

/// Errors are logged and the involved lines are skipped.

template <typename Function>

void ParseCsv(std::string_view csv, Function handle_line) {

  internal::CsvParser parser;

  for (char ch : csv) {

    if (auto line = parser.ParseCharacter(ch); line.has_value()) {

      handle_line(std::move(*line));

    }

  }

  auto line = parser.Flush();

  if (line.has_value()) {

    handle_line(std::move(*line));

  }

}

/// Parses a CSV file. Returns the results as a single nested std::vector of

/// std::string.

[[nodiscard]] inline std::vector<std::vector<std::string>> ParseCsv(

    std::string_view csv) {

  std::vector<std::vector<std::string>> result;

  ParseCsv(csv, [&result](std::vector<std::string>&& line) {

    result.push_back(std::move(line));

  });

  return result;

}

}  // namespace pw::tokenizer