esp8266_milight_hub/lib/MiLightState/GroupStatePersistence.cpp

#include <GroupStatePersistence.h>
#include <FS.h>

static const char FILE_PREFIX[] = "group_states/";

void GroupStatePersistence::get(const GroupId &id, GroupState& state) {
  char path[30];
  buildFilename(id, path);

  if (SPIFFS.exists(path)) {
    File f = SPIFFS.open(path, "r");
    state.load(f);
    f.close();
  }
}

void GroupStatePersistence::set(const GroupId &id, const GroupState& state) {
  char path[30];
  buildFilename(id, path);

  File f = SPIFFS.open(path, "w");
  state.dump(f);
  f.close();
}

void GroupStatePersistence::clear(const GroupId &id) {
  char path[30];
  buildFilename(id, path);

  if (SPIFFS.exists(path)) {
    SPIFFS.remove(path);
  }
}

char* GroupStatePersistence::buildFilename(const GroupId &id, char *buffer) {
  uint32_t compactId = (id.deviceId << 24) | (id.deviceType << 8) | id.groupId;
  return buffer + sprintf(buffer, "%s%x", FILE_PREFIX, compactId);
}