fix: edge cases of tags editing

src/input_ncm.cpp

@@ -32,7 +32,7 @@ inline bool fb2k_ncm::input_ncm::g_is_our_content_type(const char *p_content_typ
 /// The former is stored in the audio content, while the latter is stored in the ncm header.
 /// @note
 /// - See also: `ncm_file::overwrite_meta()`
-inline void fb2k_ncm::input_ncm::retag(const file_info &p_info, abort_callback &p_abort) {
+void fb2k_ncm::input_ncm::retag(const file_info &p_info, abort_callback &p_abort) {
  DEBUG_LOG("input_ncm::retag()");
  // Replay Gain
  file_info_impl cur_file_info;
@@ -45,21 +45,50 @@ inline void fb2k_ncm::input_ncm::retag(const file_info &p_info, abort_callback &
  // NOTE: Always do differential update, to maximally avoid appending "overwrite" key,
  // which will change the "163 key xxxx" content.
  auto target_json = meta_processor(p_info).dump();
+ if (target_json.empty()) { // fallback case: clear all fields
+ return this->remove_tags(p_abort);
+ }
  this->get_info(cur_file_info, p_abort);
  auto current_json = meta_processor(cur_file_info).dump();
 
- if (current_json.contains(overwrite_key)) {
- current_json.erase(overwrite_key);
+ auto overwrite = json_t::object();
+
+ if (ncm_file_->meta_info().contains(overwrite_key)) {
+ // overwrite is guaranteed to be suitable with current_meta
+ // because this->get_info() will call parse() and reset meta_info()
+ overwrite = ncm_file_->meta_info()[overwrite_key];
  }
 
  auto diff = json_t::diff(current_json, target_json);
- ncm_file_->overwrite_meta(json_t::object().patch(diff), p_abort);
+ auto to_merge = json_t::object();
+ for (const auto &op : diff) {
+ json_t::json_pointer pt(op["path"]);
+ for (; !pt.parent_pointer().empty(); pt = pt.parent_pointer()) {
+ continue;
+ }
+ if (op["op"] == "remove") {
+ if (!overwrite.contains(pt.back())) {
+ overwrite.emplace(pt.back(), nullptr);
+ } else {
+ overwrite[pt.back()] = nullptr;
+ }
+ } else {
+ if (overwrite.contains(pt.back())) {
+ overwrite.erase(pt.back());
+ }
+ overwrite.emplace(pt.back(), target_json.at(pt)); // copy the top level
+ }
+ }
+
+ overwrite.merge_patch(to_merge);
+
+ ncm_file_->overwrite_meta(overwrite, p_abort);
 }
 
 /// @brief "Clear tags" => restore the meta field (163 key) to its original state
 /// @attention ReplayGain and embedded tags in the audio content are left untouched.
 /// @note ReplayGain can be wiped by retagging, since the meta diff would be empty then.
-inline void fb2k_ncm::input_ncm::remove_tags(abort_callback &p_abort) {
+void fb2k_ncm::input_ncm::remove_tags(abort_callback &p_abort) {
  DEBUG_LOG("input_ncm::remove_tags()");
  // source_info_writer_->remove_tags_fallback(p_abort);
  ncm_file_->overwrite_meta(nlohmann::json(), p_abort);

src/meta_process.cpp

@@ -99,13 +99,17 @@ void meta_processor::update_by_json(const nlohmann::json &json, bool overwriting
  using refl_f_t = void(const nlohmann::json &);
  auto reflection = std::unordered_map<std::string_view, std::function<refl_f_t>>{}; // UPPERCASE keys
  reflection["artist"] = [&](const json_t &j) {
+ if (j.is_null()) {
+ artist.reset();
+ return;
+ }
  if (!artist.has_value()) {
  artist.emplace();
+ } else if (overwriting) {
+ artist.reset();
+ artist.emplace();
  }
  for (const auto &val : j.get_ref<const json_t::array_t &>()) {
- if (!val.is_array()) {
- continue;
- }
  if (val.size() != 2) {
  continue;
  }
@@ -121,6 +125,10 @@ void meta_processor::update_by_json(const nlohmann::json &json, bool overwriting
 
 #define reflect_single(field, TYPE) \
  [&](const json_t &j) { \
+ if (j.is_null()) { \
+ field.reset(); \
+ return; \
+ } \
  try { \
  update_v(field, j.get<TYPE>()); \
  } catch (const json_t::type_error &) { \
@@ -133,6 +141,10 @@ void meta_processor::update_by_json(const nlohmann::json &json, bool overwriting
  }
 #define reflect_multi_string(field) \
  [&](const json_t &j) { \
+ if (j.is_null()) { \
+ field.reset(); \
+ return; \
+ } \
  if (!j.is_array()) { \
  return; \
  } \

src/ncm_file.cpp

@@ -314,7 +314,7 @@ bool ncm_file::save_raw_audio(const char *to_dir, abort_callback &p_abort) {
  return false;
 }
 
-void ncm_file::overwrite_meta(const nlohmann::json &meta, abort_callback &p_abort) {
+void ncm_file::overwrite_meta(const nlohmann::json &overwrite, abort_callback &p_abort) {
  if (!meta_parsed()) {
  this->parse(parse_targets::NCM_PARSE_META);
  }
@@ -329,15 +329,20 @@ void ncm_file::overwrite_meta(const nlohmann::json &meta, abort_callback &p_abor
  // embed overwriting meta into the source
 
  auto meta_str_to_write = std::string("music:");
- nlohmann::ordered_json live_meta = nlohmann::ordered_json::parse(meta_str_); // NOTE: use unmodified raw json string to keep stricted order
+ nlohmann::ordered_json live_meta =
+ nlohmann::ordered_json::parse(meta_str_); // NOTE: use unmodified raw json string to keep stricted order
  if (live_meta.contains(overwrite_key)) {
  live_meta.erase(overwrite_key); // replace the old key
  }
 
- if (meta.size()) {
- live_meta[overwrite_key] = meta;
- live_meta[overwrite_key].emplace(foo_input_ncm_comment_key, foo_input_ncm_comment);
- }
+ if (auto size = overwrite.size(); size > 0)
+ do {
+ if (size == 1 && overwrite.contains(foo_input_ncm_comment_key)) {
+ break;
+ }
+ live_meta[overwrite_key] = overwrite;
+ live_meta[overwrite_key].emplace(foo_input_ncm_comment_key, foo_input_ncm_comment);
+ } while (false);
  meta_str_to_write += live_meta.dump();
 
  DEBUG_LOG_F("Overwriting meta (to {}): {}", this->path(), meta_str_to_write);

src/ncm_file.hpp

@@ -64,7 +64,7 @@ namespace fb2k_ncm
  }
  void parse(uint16_t to_parse = 0xffff);
  bool save_raw_audio(const char *to_dir, abort_callback &p_abort = fb2k::noAbort);
- void overwrite_meta(const nlohmann::json &meta, abort_callback &p_abort = fb2k::noAbort);
+ void overwrite_meta(const nlohmann::json &overwrite, abort_callback &p_abort = fb2k::noAbort);
  void reset_album_image(album_art_data_ptr image, abort_callback &p_abort = fb2k::noAbort);
 
  private: