cached_json.dart

import 'dart:convert';
import 'dart:io';
import 'package:flutter/cupertino.dart';
import 'package:path_provider/path_provider.dart';

class CacheJson {
static var tempDirectory;

  ///Loads json file from cache(temp directory) with with given name
 static  Future<String> saveFile({
     @required
     Map<String, dynamic> file,
     @required
     String cachedFileName
   }) async{
    File jsonFile;
    var tempDir = await getApplicationDocumentsDirectory();
  String _filePath = tempDir.path + '/$cachedFileName.json';
    jsonFile = new File(_filePath);
    jsonFile.writeAsStringSync(json.encode(file));
    return "Done";
  }
///loads json cached file with a name
 static  Future<Map<String, dynamic>> loadFile({@required String cachedFileName}) async {
    File jsonFile;
    Map<String, dynamic> _file;
    var tempDir = await getApplicationDocumentsDirectory();
    String _filePath = tempDir.path + '/$cachedFileName.json';

    jsonFile = new File(_filePath);

    if (jsonFile.existsSync()) {
      _file = json.decode(jsonFile.readAsStringSync());
      return _file;
    }
  }
  /// deletes the created file
 static  Future<String> deleteFile({String cachedFileName}) async{
    File jsonFile;
    var tempDir = await getApplicationDocumentsDirectory();
    String _filePath = tempDir.path + '/$cachedFileName.json';
    jsonFile.writeAsStringSync(json.encode({}));
    return "Deleted";
  }



  /// now that all basic functionality is done ..but we still need some optimization and we can see that
/// our static functions are async and due to that reason it would be hard to load data quickly while calling them




///Future method for App document local directory

 Future setTempDirectory() async{
  var tempDir = await getApplicationDocumentsDirectory();
  tempDirectory = tempDir;
  }


  ///Once instantiated, Than this return object can be used to quickly store and load data
static Future<CacheJson> getInstance() async{
   CacheJson cacheJson = CacheJson();
   await cacheJson.setTempDirectory();
   return cacheJson;
}

///save json file in cache(temp directory) with with given name using instance member
  bool setFile({
  @required
  Map<String, dynamic> file,
  @required
  String cachedFileName})

  {
  File jsonFile;
  String _filePath = tempDirectory.path + '/$cachedFileName.json';
  jsonFile = new File(_filePath);
  jsonFile.writeAsStringSync(json.encode(file));
  return true;
 }

///loads json cached file with a name
  Map<String, dynamic> getFile({@required String cachedFileName}){
  File jsonFile;
  Map<String, dynamic> _file;
  String _filePath = tempDirectory.path + '/$cachedFileName.json';
  jsonFile = new File(_filePath);

  if (jsonFile.existsSync()) {
    _file = json.decode(jsonFile.readAsStringSync());
    return _file;
  }
}


/// deletes the created file
  bool removeFile({@required String cachedFileName}) {
  File jsonFile;
  String _filePath = tempDirectory.path + '/$cachedFileName.json';
  jsonFile.writeAsStringSync(json.encode({}));
  return true;
}

}