include/ylt/standalone/iguana/prettify.hpp

#pragma once

// https://github.com/stephenberry/glaze/blob/main/include/glaze/json/prettify.hpp

namespace iguana {
namespace detail {
enum class general_state : uint32_t {
  NORMAL,
  ESCAPED,
  STRING,
  BEFORE_ASTERISK,
  COMMENT,
  BEFORE_FSLASH
};

template <typename Out, typename NL>
inline void prettify_normal_state(const char c, Out &out, uint32_t &indent,
                                  NL nl, general_state &state) noexcept {
  switch (c) {
    case ',':
      out += c;
      nl();
      break;
    case '[':
      out += c;
      ++indent;
      nl();
      break;
    case ']':
      --indent;
      nl();
      out += c;
      break;
    case '{':
      out += c;
      ++indent;
      nl();
      break;
    case '}':
      --indent;
      nl();
      out += c;
      break;
    case '\\':
      out += c;
      state = general_state::ESCAPED;
      break;
    case '\"':
      out += c;
      state = general_state::STRING;
      break;
    case '/':
      out += " /";
      state = general_state::BEFORE_ASTERISK;
      break;
    case ':':
      out += ": ";
      break;
    case ' ':
    case '\n':
    case '\r':
    case '\t':
      break;
    default:
      out += c;
      break;
  }
}

inline void prettify_other_states(const char c, general_state &state) noexcept {
  switch (state) {
    case general_state::ESCAPED:
      state = general_state::NORMAL;
      break;
    case general_state::STRING:
      if (c == '"') {
        state = general_state::NORMAL;
      }
      break;
    case general_state::BEFORE_ASTERISK:
      state = general_state::COMMENT;
      break;
    case general_state::COMMENT:
      if (c == '*') {
        state = general_state::BEFORE_FSLASH;
      }
      break;
    case general_state::BEFORE_FSLASH:
      if (c == '/') {
        state = general_state::NORMAL;
      }
      else {
        state = general_state::COMMENT;
      }
      break;
    default:
      break;
  }
}
}  // namespace detail

/// <summary>
/// pretty print a JSON string
/// </summary>
template <typename In, typename Out>
inline void prettify(const In &in, Out &out, const bool tabs = false,
                     const uint32_t indent_size = 3) noexcept {
  out.reserve(in.size());
  uint32_t indent{};

  auto nl = [&]() {
    out += "\n";

    for (uint32_t i = 0; i < indent * (tabs ? 1 : indent_size); i++) {
      out += tabs ? "\t" : " ";
    }
  };

  using namespace detail;
  general_state state{general_state::NORMAL};

  for (auto c : in) {
    if (state == general_state::NORMAL) {
      prettify_normal_state(c, out, indent, nl, state);
      continue;
    }
    else {
      out += c;
      prettify_other_states(c, state);
    }
  }
}

/// <summary>
/// allocating version of prettify
/// </summary>
template <typename In>
inline std::string prettify(const In &in, const bool tabs = false,
                            const uint32_t indent_size = 3) noexcept {
  std::string out{};
  prettify(in, out, tabs, indent_size);
  return out;
}
}  // namespace iguana