#ifndef CSV_HH
#define CSV_HH

#include "io.hh" // IWYU pragma: export
#include "line.hh"

#include <expected>
#include <memory>
#include <span>
#include <string_view>

namespace csv {

// Note that this reader is very simple, no quotes or escapes.
// Empty lines are ignored.
class Reader {
 public:
  virtual ~Reader() = default;

  // Returned span is only valid until next call to read.
  // Returns empty span at end-of-file and only then.
  [[nodiscard]]
  virtual std::expected<std::span<std::string_view>, io::ReadError> read() = 0;

  // Starts at zero. Returns next line.
  // So, before first read it is zero, after first read it is one.
  [[nodiscard]] virtual uint64_t number() const = 0;

 protected:
  Reader() = default;

  Reader(Reader const&) = delete;
  Reader& operator=(Reader const&) = delete;
};

[[nodiscard]] std::unique_ptr<Reader> open(std::unique_ptr<line::Reader> reader,
                                           char separator = ',');

[[nodiscard]] std::unique_ptr<Reader> open(std::unique_ptr<io::Reader> reader,
                                           char separator = ',');

}  // namespace csv

#endif  // CSV_HH