// SHA-256 (FIPS 180-4), dependency-free, for provenance hashes of inputs/artifacts.
#pragma once
#include <string>
#include <string_view>
#include <span>
#include <array>
#include <cstdint>

namespace raid {

class Sha256 {
 public:
  Sha256();
  void update(const void* data, std::size_t len);
  void update(std::string_view s) { update(s.data(), s.size()); }
  std::array<std::uint8_t, 32> digest();
  std::string hex();
  static std::string of(std::string_view s) { Sha256 h; h.update(s); return h.hex(); }
  static std::string of_file(const std::string& path);
  template <class T> static std::string of_span(std::span<const T> x) { Sha256 h; h.update(x.data(), x.size_bytes()); return h.hex(); }
 private:
  void transform(const std::uint8_t* chunk);
  std::array<std::uint32_t, 8> h_;
  std::array<std::uint8_t, 64> buf_{};
  std::size_t buf_len_{0};
  std::uint64_t total_{0};
};

}  // namespace raid