#include "csv.hh"

#include "line.hh"
#include "str.hh"

#include <cstdint>
#include <expected>
#include <memory>
#include <span>
#include <string_view>
#include <utility>
#include <vector>

namespace csv {

namespace {

class ReaderImpl : public Reader {
 public:
  ReaderImpl(std::unique_ptr<line::Reader> reader, char separator)
      : reader_(std::move(reader)), separator_(separator) {}

  [[nodiscard]]
  std::expected<std::span<std::string_view>, io::ReadError> read() override {
    while (true) {
      auto line = reader_->read();
      if (line.has_value()) {
        str::split(line.value(), line_, separator_, /* keep_empty */ true);
        if (line_.size() == 1 && line_[0].empty())
          continue;
        return line_;
      }
      if (line.error() == io::ReadError::Eof) {
        return {};
      }
      return std::unexpected(line.error());
    }
  }

  [[nodiscard]] uint64_t number() const override { return reader_->number(); }

 private:
  std::unique_ptr<line::Reader> reader_;
  char const separator_;
  std::vector<std::string_view> line_;
};

}  // namespace

std::unique_ptr<Reader> open(std::unique_ptr<line::Reader> reader,
                             char separator) {
  return std::make_unique<ReaderImpl>(std::move(reader), separator);
}

std::unique_ptr<Reader> open(std::unique_ptr<io::Reader> reader,
                             char separator) {
  return open(line::open(std::move(reader)), separator);
}

}  // namespace csv