C and JS interface, untested

src/genericModel.cc

@@ -0,0 +1,69 @@
+#include "genericModel.h"
+
+bool GenericModel::first = true;
+GenericModel::GenericModel(const std::string &url, const std::string& storepath, const std::string &id, int index) : url(url), id(id), storepath(("opfs/" + storepath)), GenericObj(index) {
+  if(first) {
+    vosk_set_log_level(-1);
+    int res{};
+    std::thread t{[&res](){
+      res = wasmfs_create_directory("opfs",0777,wasmfs_create_opfs_backend());
+    }};
+    t.join();
+    if(res == 1){
+      fireEv("error", "Unable to create OPFS directory");
+      return;
+    }
+    first = false;
+  }
+}
+bool GenericModel::checkId(const std::string& path, const std::string& id) {
+  std::ifstream file {(path + "/id"), std::ifstream::binary}; 
+  if(!file.is_open()) {
+    return false;
+  };
+  long long size {file.seekg(0, std::ios::end).tellg()};
+  std::string oldid(size, ' ');
+  file.seekg(0);
+  file.read(&oldid[0], size);
+  return id.compare(oldid) == 0 ? true : false;
+}
+bool GenericModel::loadModel() {
+  if(!checkModel(storepath) || !checkId(storepath, id)) {
+    if(emscripten_wget(url.c_str(), "opfs/model.tzst") == 1) {
+      fireEv("error", "Unable to fetch model");
+      return false;
+    }
+    if(!extractModel("opfs/model.tzst", storepath)) {
+      fireEv("error", "Unable to extract model");
+    }
+    fs::remove("opfs/model.tzst");
+    if(!checkModel(storepath)) {
+      fireEv("error", "Model URL contains invalid model files");
+    }
+    std::ofstream idFile((storepath + "/id"));
+    if(!idFile.is_open()) {
+      fireEv("error", "Unable to write new id");
+      fs::remove_all(storepath);
+      return false;
+    }
+    idFile << id;
+  }
+  return true;
+}
+bool GenericModel::extractModel(const char* target, const std::string& dest) {
+  std::string path{};
+  archive* src {archive_read_new()};
+  archive_entry* entry {};
+  archive_read_support_filter_all(src);
+  archive_read_support_format_all(src);
+  archive_read_open_filename(src, target,22480);
+  if(archive_errno(src) != 0) return false;
+  while (archive_read_next_header(src, &entry) == ARCHIVE_OK) {
+    path = archive_entry_pathname(entry);
+    archive_entry_set_pathname(entry, (dest + path.substr(path.find("/"))).c_str());
+    if(archive_errno(src) != 0) return false;
+    archive_read_extract(src, entry, ARCHIVE_EXTRACT_UNLINK);
+  }
+  archive_read_free(src);
+  return true;
+}