WordClockESP/lib/framework/FSPersistence.h
rjwats 0e2124062f
Use references & flash strings where approperate (#110)
* pass originId as const reference
* store strings for serial logging in flash
* Use string references where approperate.
2020-05-21 08:42:21 +01:00

101 lines
2.9 KiB
C++

#ifndef FSPersistence_h
#define FSPersistence_h
#include <StatefulService.h>
#include <JsonSerializer.h>
#include <JsonDeserializer.h>
#include <FS.h>
#define MAX_FILE_SIZE 1024
template <class T>
class FSPersistence {
public:
FSPersistence(JsonSerializer<T> jsonSerializer,
JsonDeserializer<T> jsonDeserializer,
StatefulService<T>* statefulService,
FS* fs,
char const* filePath) :
_jsonSerializer(jsonSerializer),
_jsonDeserializer(jsonDeserializer),
_statefulService(statefulService),
_fs(fs),
_filePath(filePath) {
enableUpdateHandler();
}
void readFromFS() {
File settingsFile = _fs->open(_filePath, "r");
if (settingsFile) {
if (settingsFile.size() <= MAX_FILE_SIZE) {
DynamicJsonDocument jsonDocument = DynamicJsonDocument(MAX_FILE_SIZE);
DeserializationError error = deserializeJson(jsonDocument, settingsFile);
if (error == DeserializationError::Ok && jsonDocument.is<JsonObject>()) {
JsonObject jsonObject = jsonDocument.as<JsonObject>();
_statefulService->updateWithoutPropagation(jsonObject, _jsonDeserializer);
settingsFile.close();
return;
}
}
settingsFile.close();
}
// If we reach here we have not been successful in loading the config,
// hard-coded emergency defaults are now applied.
applyDefaults();
}
bool writeToFS() {
// create and populate a new json object
DynamicJsonDocument jsonDocument = DynamicJsonDocument(MAX_FILE_SIZE);
JsonObject jsonObject = jsonDocument.to<JsonObject>();
_statefulService->read(jsonObject, _jsonSerializer);
// serialize it to filesystem
File settingsFile = _fs->open(_filePath, "w");
// failed to open file, return false
if (!settingsFile) {
return false;
}
// serialize the data to the file
serializeJson(jsonDocument, settingsFile);
settingsFile.close();
return true;
}
void disableUpdateHandler() {
if (_updateHandlerId) {
_statefulService->removeUpdateHandler(_updateHandlerId);
_updateHandlerId = 0;
}
}
void enableUpdateHandler() {
if (!_updateHandlerId) {
_updateHandlerId = _statefulService->addUpdateHandler([&](const String& originId) { writeToFS(); });
}
}
private:
JsonSerializer<T> _jsonSerializer;
JsonDeserializer<T> _jsonDeserializer;
StatefulService<T>* _statefulService;
FS* _fs;
char const* _filePath;
update_handler_id_t _updateHandlerId = 0;
protected:
// We assume the deserializer supplies sensible defaults if an empty object
// is supplied, this virtual function allows that to be changed.
virtual void applyDefaults() {
DynamicJsonDocument jsonDocument = DynamicJsonDocument(MAX_FILE_SIZE);
JsonObject jsonObject = jsonDocument.as<JsonObject>();
_statefulService->updateWithoutPropagation(jsonObject, _jsonDeserializer);
}
};
#endif // end FSPersistence