diff --git a/lib/main.dart b/lib/main.dart
index e016029..4ae32a1 100644
--- a/lib/main.dart
+++ b/lib/main.dart
@@ -1,6 +1,8 @@
 import 'package:flutter/material.dart';
+import 'package:sqflite_common_ffi/sqflite_ffi.dart';
 
 void main() {
+  sqfliteFfiInit();
   runApp(const MyApp());
 }
 
diff --git a/lib/repositories/common_models/message.dart b/lib/repositories/common_models/message.dart
index d49c1fc..4cd4c71 100644
--- a/lib/repositories/common_models/message.dart
+++ b/lib/repositories/common_models/message.dart
@@ -1,7 +1,7 @@
 /*
  * @Author       : Linloir
  * @Date         : 2022-10-11 10:30:05
- * @LastEditTime : 2022-10-11 15:36:23
+ * @LastEditTime : 2022-10-11 23:35:45
  * @Description  : 
  */
 
@@ -32,6 +32,7 @@ class Message extends JSONEncodable {
   final String _content;
   final int _timestamp;
   late final String _contentmd5;
+  late final String? _filemd5;
   final LocalFile? _payload;
 
   Message({
@@ -54,6 +55,7 @@ class Message extends JSONEncodable {
       ..addAll(Uint8List(4)..buffer.asInt32List()[0] = targetid)
       ..addAll(Uint8List(4)..buffer.asInt32List()[0] = _timestamp)
     ).toString();
+    _filemd5 = _payload?.filemd5;
   }
 
   Message.fromJSONObject({
@@ -66,6 +68,7 @@ class Message extends JSONEncodable {
     _content = jsonObject['content'] as String,
     _timestamp = jsonObject['timestamp'] as int,
     _contentmd5 = jsonObject['md5encoded'] as String,
+    _filemd5 = jsonObject['filemd5'] as String,
     _payload = payload;
 
   int get senderID => _userid;
@@ -75,6 +78,7 @@ class Message extends JSONEncodable {
   String get contentEncoded => _content;
   String get contentmd5 => _contentmd5;
   int get timeStamp => _timestamp;
+  String? get filemd5 => _filemd5;
   LocalFile? get payload => _payload;
 
   @override
diff --git a/lib/repositories/local_service_repository/local_service_repository.dart b/lib/repositories/local_service_repository/local_service_repository.dart
index b5af46f..a6f84ca 100644
--- a/lib/repositories/local_service_repository/local_service_repository.dart
+++ b/lib/repositories/local_service_repository/local_service_repository.dart
@@ -1,6 +1,250 @@
 /*
  * @Author       : Linloir
  * @Date         : 2022-10-11 10:56:02
- * @LastEditTime : 2022-10-11 10:56:03
- * @Description  : 
+ * @LastEditTime : 2022-10-11 23:49:16
+ * @Description  : Local Service Repository
  */
+
+import 'dart:async';
+import 'dart:io';
+
+import 'package:crypto/crypto.dart';
+import 'package:file_picker/file_picker.dart';
+import 'package:path_provider/path_provider.dart';
+import 'package:shared_preferences/shared_preferences.dart';
+import 'package:tcp_client/repositories/common_models/message.dart';
+import 'package:tcp_client/repositories/common_models/userinfo.dart';
+import 'package:tcp_client/repositories/local_service_repository/models/local_file.dart';
+import 'package:sqflite_common/sqlite_api.dart';
+import 'package:sqflite_common_ffi/sqflite_ffi.dart';
+
+class LocalServiceRepository {
+  late final Database _database;
+
+  LocalServiceRepository._internal({
+    required Database database
+  }): _database = database;
+
+  static FutureOr<void> _onDatabaseCreate(Database db, int version) async {
+    await db.execute(
+      '''
+        create table users (
+          userid    integer primary key,
+          username  text not null,
+          avatar    text
+        );
+        create table msgs (
+          userid      integer not null,
+          targetid    integer not null,
+          contenttype text not null,
+          content     text not null,
+          timestamp   int not null,
+          md5encoded  text primary key,
+          filemd5     text not null
+        );
+        create table files (
+          filemd5     text primary key,
+          dir         text not null
+        );
+      '''
+    );
+  }
+
+  static Future<LocalServiceRepository> create({
+    UserInfo? currentUser,
+    required String databaseFilePath
+  }) async {
+    var database = await databaseFactoryFfi.openDatabase(
+      databaseFilePath,
+      options: OpenDatabaseOptions(
+        version: 1,
+        onCreate: _onDatabaseCreate
+      )
+    );
+    return LocalServiceRepository._internal(database: database);
+  }
+
+  //Calls on the system to open the file
+  Future<LocalFile?> pickFile(FileType fileType) async {
+    var filePickResult = await FilePicker.platform.pickFiles(
+      type: fileType,
+      allowMultiple: false,
+    );
+    if (filePickResult == null) return null;
+    var file = File(filePickResult.files.single.path!);
+    return LocalFile(
+      file: file, 
+      filemd5: md5.convert(await file.readAsBytes()).toString(),
+      ext: file.path.substring(file.path.lastIndexOf('.'))
+    );
+  }
+
+  Future<void> storeMessages(List<Message> messages) async {
+    for(var message in messages) {
+      try {
+        await _database.insert(
+          'msgs',
+          message.jsonObject,
+          conflictAlgorithm: ConflictAlgorithm.replace
+        );
+      } catch (err) {
+        //TODO: do something
+      }
+    }
+  }
+
+  Future<List<Message>> findMessages({required String pattern}) async {
+    // Obtain shared preferences.
+    final pref = await SharedPreferences.getInstance();
+    // Get user info from preferences
+    var currentUserID = pref.getInt('userid');
+    var alikeMessages = await _database.query(
+      'msgs',
+      where: 'userid = ? or targetid = ?',
+      whereArgs: [
+        currentUserID, currentUserID
+      ],
+      orderBy: 'timestamp desc',
+      limit: 100
+    );
+    return alikeMessages.map((e) => Message.fromJSONObject(jsonObject: e)).toList();
+  }
+
+  //Find the most recent message of given users
+  Future<List<List<Message>>> fetchMessageList({required List<int> users}) async {
+    var pref = await SharedPreferences.getInstance();
+    var currentUserID = pref.getInt('userid');
+    var messages = <List<Message>>[];
+    for(var user in users) {
+      var queryResult = await _database.query(
+        'msgs',
+        where: '(userid = ? and targetid = ?) and (userid = ? and targetid = ?)',
+        whereArgs: [
+          currentUserID, user, user, currentUserID
+        ],
+        orderBy: 'timestamp desc',
+        limit: 1
+      );
+      if(queryResult.isEmpty) {
+        messages.add([]);
+      }
+      else {
+        messages.add([Message.fromJSONObject(jsonObject: queryResult[0])]);
+      }
+    }
+    return messages;
+  }
+
+  //Fetch chat history with another user, provided the user ID
+  Future<List<Message>> fetchMessageHistory({required int userID, required int position, int num = 20}) async {
+    //the histories with userID
+    var pref = await SharedPreferences.getInstance();
+    var currentUserID = pref.getInt('userid');
+    if(currentUserID == null) {
+      //TODO: do something
+      return [];
+    }
+    var queryResult = await _database.query(
+      'msgs',
+      where: '(userid = ? and targetid = ?) or (userid = ? and targetid = ?)',
+      whereArgs: [
+        currentUserID, userID, userID, currentUserID
+      ],
+      orderBy: 'timestamp desc',
+      limit: num,
+      offset: position
+    );
+    return queryResult.map((e) => Message.fromJSONObject(jsonObject: e)).toList();
+  }
+
+  Future<File?> findFile({required String filemd5}) async {
+    var directory = await _database.query(
+      'files',
+      where: 'filemd5 = ?',
+      whereArgs: [
+        filemd5
+      ]
+    );
+    if(directory.isEmpty) {
+      return null;
+    }
+    else {
+      var filePath = directory[0]['dir'] as String;
+      //Try if the file exists
+      var file = File(filePath);
+      if(await file.exists()) {
+        return file;
+      }
+      else {
+        //Delete all linked files
+        await _database.delete(
+          'files',
+          where: 'filemd5 = ?',
+          whereArgs: [
+            filemd5
+          ]
+        );
+        return null;
+      }
+    }
+  }
+  
+  Future<void> storeFile({
+    required LocalFile tempFile
+  }) async {
+    //Write to file library
+    var documentPath = (await getApplicationDocumentsDirectory()).path;
+    var permanentFilePath = '$documentPath/files/${tempFile.filemd5}${tempFile.ext}';
+    await tempFile.file.copy(permanentFilePath);
+    await _database.insert(
+      'files',
+      {
+        'filemd5': tempFile.filemd5,
+        'dir': permanentFilePath
+      }
+    );
+  }
+
+  final StreamController<UserInfo> _userInfoChangeStreamController = StreamController();
+  Stream<UserInfo> get userInfoChangedStream => _userInfoChangeStreamController.stream;
+
+  Future<void> storeUserInfo({
+    required UserInfo userInfo
+  }) async {
+    //check if exist
+    var queryResult = await _database.query(
+      'users',
+      where: 'userid = ?',
+      whereArgs: [userInfo.userID]
+    );
+    if(queryResult.isEmpty) {
+      _database.insert(
+        'users',
+        userInfo.jsonObject
+      );
+    }
+    else {
+      _database.update(
+        'users',
+        userInfo.jsonObject,
+        where: 'userid = ?',
+        whereArgs: [userInfo.userID]
+      );
+    }
+    _userInfoChangeStreamController.add(userInfo);
+  }
+
+  Future<UserInfo?> fetchUserInfo({required userid}) async {
+    var targetUser = await _database.query(
+      'users',
+      where: 'userid = ?',
+      whereArgs: [userid]
+    );
+    if(targetUser.isEmpty) {
+      return null;
+    }
+    else {
+      return UserInfo.fromJSONObject(jsonObject: targetUser[0]);
+    }
+  }
+}
diff --git a/lib/repositories/local_service_repository/models/local_file.dart b/lib/repositories/local_service_repository/models/local_file.dart
index 6400e30..7df6edb 100644
--- a/lib/repositories/local_service_repository/models/local_file.dart
+++ b/lib/repositories/local_service_repository/models/local_file.dart
@@ -1,7 +1,7 @@
 /*
  * @Author       : Linloir
  * @Date         : 2022-10-11 10:55:36
- * @LastEditTime : 2022-10-11 17:44:06
+ * @LastEditTime : 2022-10-11 22:54:59
  * @Description  : Local File Model
  */
 
@@ -12,8 +12,9 @@ import 'package:equatable/equatable.dart';
 class LocalFile extends Equatable {
   final File file;
   final String filemd5;
+  final String ext;
 
-  const LocalFile({required this.file, required this.filemd5});
+  const LocalFile({required this.file, required this.filemd5, required this.ext});
 
   @override
   List<Object> get props => [filemd5];
diff --git a/lib/repositories/tcp_repository/models/tcp_response.dart b/lib/repositories/tcp_repository/models/tcp_response.dart
index dbc27a4..9d92c0e 100644
--- a/lib/repositories/tcp_repository/models/tcp_response.dart
+++ b/lib/repositories/tcp_repository/models/tcp_response.dart
@@ -1,7 +1,7 @@
 /*
  * @Author       : Linloir
  * @Date         : 2022-10-11 11:02:19
- * @LastEditTime : 2022-10-11 16:00:53
+ * @LastEditTime : 2022-10-11 22:55:48
  * @Description  : 
  */
 
@@ -195,12 +195,18 @@ class FindFileResponse extends TCPResponse {
 }
 
 class FetchFileResponse extends TCPResponse {
-  final LocalFile _payload;
+  late final LocalFile _payload;
 
   FetchFileResponse({
     required Map<String, Object?> jsonObject,
     required LocalFile payload
-  }): _payload = payload, super(jsonObject: jsonObject);
+  }): super(jsonObject: jsonObject) {
+    _payload = LocalFile(
+      file: payload.file, 
+      filemd5: payload.filemd5, 
+      ext: (jsonObject['body'] as Map<String, Object?>)['ext'] as String
+    );
+  }
 
   LocalFile get payload => _payload;
 }
diff --git a/lib/repositories/tcp_repository/tcp_repository.dart b/lib/repositories/tcp_repository/tcp_repository.dart
index 520f0d2..c73a09f 100644
--- a/lib/repositories/tcp_repository/tcp_repository.dart
+++ b/lib/repositories/tcp_repository/tcp_repository.dart
@@ -1,7 +1,7 @@
 /*
  * @Author       : Linloir
  * @Date         : 2022-10-11 09:42:05
- * @LastEditTime : 2022-10-11 17:41:11
+ * @LastEditTime : 2022-10-11 22:55:28
  * @Description  : TCP repository
  */
 
@@ -11,12 +11,17 @@ import 'dart:io';
 
 import 'package:crypto/crypto.dart';
 import 'package:flutter/foundation.dart';
+import 'package:shared_preferences/shared_preferences.dart';
 import 'package:tcp_client/repositories/local_service_repository/models/local_file.dart';
 import 'package:tcp_client/repositories/tcp_repository/models/tcp_request.dart';
 import 'package:tcp_client/repositories/tcp_repository/models/tcp_response.dart';
 
 class TCPRepository {
-  TCPRepository(this._socket) {
+  TCPRepository({
+    required Socket socket,
+    required String remoteAddress,
+    required int remotePort
+  }): _socket = socket, _remoteAddress = remoteAddress, _remotePort = remotePort {
     _socket.listen(_pullResponse);
     //This future never ends, would that be bothersome?
     Future(() async {
@@ -33,6 +38,8 @@ class TCPRepository {
   }
 
   final Socket _socket;
+  final String _remoteAddress;
+  final int _remotePort;
 
   //Stores the incoming bytes of the TCP connection temporarily
   final List<int> buffer = [];
@@ -50,7 +57,12 @@ class TCPRepository {
 
   //Provide a response stream for blocs to listen on
   final StreamController<TCPResponse> _responseStreamController = StreamController();
+  Stream<TCPResponse>? _responseStreamBroadcast;
   Stream<TCPResponse> get responseStream => _responseStreamController.stream;
+  Stream<TCPResponse> get responseStreamBroadcast {
+    _responseStreamBroadcast ??= _responseStreamController.stream.asBroadcastStream();
+    return _responseStreamBroadcast!;
+  }
 
   //Provide a request stream for widgets to push to
   final StreamController<TCPRequest> _requestStreamController = StreamController();
@@ -213,7 +225,8 @@ class TCPRepository {
           jsonObject: responseObject,
           payload: LocalFile(
             file: tempFile,
-            filemd5: md5.convert(await tempFile.readAsBytes()).toString()
+            filemd5: md5.convert(await tempFile.readAsBytes()).toString(),
+            ext: ""
           )
         ));
         break;
@@ -239,4 +252,37 @@ class TCPRepository {
       }
     }
   }
+
+  Future<bool> checkFileExistence({
+    required LocalFile file
+  }) async {
+    //Duplicate current socket
+    Socket socket = await Socket.connect(_remoteAddress, _remotePort);
+    TCPRepository duplicatedRepository = TCPRepository(
+      socket: socket, 
+      remoteAddress: _remoteAddress, 
+      remotePort: _remotePort
+    );
+    var pref = await SharedPreferences.getInstance();
+    var request = FindFileRequest(file: file, token: pref.getInt('token')!);
+    duplicatedRepository.pushRequest(request);
+    var hasFile = false;
+    await for(var response in duplicatedRepository.responseStream) {
+      if(response.type == TCPResponseType.findFile) {
+        hasFile = response.status == TCPResponseStatus.ok;
+        break;
+      }
+    }
+    duplicatedRepository.dispose();
+    return hasFile;
+  }
+
+  void dispose() {
+    _responseRawStreamController.close();
+    _payloadPullStreamController.close();
+    _payloadRawStreamController.close();
+    _responseStreamController.close();
+    _requestStreamController.close();
+    _socket.close();
+  }
 }
\ No newline at end of file
diff --git a/macos/Flutter/GeneratedPluginRegistrant.swift b/macos/Flutter/GeneratedPluginRegistrant.swift
index cccf817..14e6964 100644
--- a/macos/Flutter/GeneratedPluginRegistrant.swift
+++ b/macos/Flutter/GeneratedPluginRegistrant.swift
@@ -5,6 +5,10 @@
 import FlutterMacOS
 import Foundation
 
+import path_provider_macos
+import shared_preferences_macos
 
 func RegisterGeneratedPlugins(registry: FlutterPluginRegistry) {
+  PathProviderPlugin.register(with: registry.registrar(forPlugin: "PathProviderPlugin"))
+  SharedPreferencesPlugin.register(with: registry.registrar(forPlugin: "SharedPreferencesPlugin"))
 }
diff --git a/pubspec.lock b/pubspec.lock
index 0494f98..5140352 100644
--- a/pubspec.lock
+++ b/pubspec.lock
@@ -85,6 +85,20 @@ packages:
       url: "https://pub.flutter-io.cn"
     source: hosted
     version: "2.0.1"
+  file:
+    dependency: transitive
+    description:
+      name: file
+      url: "https://pub.flutter-io.cn"
+    source: hosted
+    version: "6.1.4"
+  file_picker:
+    dependency: "direct main"
+    description:
+      name: file_picker
+      url: "https://pub.flutter-io.cn"
+    source: hosted
+    version: "5.2.1"
   flutter:
     dependency: "direct main"
     description: flutter
@@ -104,11 +118,23 @@ packages:
       url: "https://pub.flutter-io.cn"
     source: hosted
     version: "2.0.1"
+  flutter_plugin_android_lifecycle:
+    dependency: transitive
+    description:
+      name: flutter_plugin_android_lifecycle
+      url: "https://pub.flutter-io.cn"
+    source: hosted
+    version: "2.0.7"
   flutter_test:
     dependency: "direct dev"
     description: flutter
     source: sdk
     version: "0.0.0"
+  flutter_web_plugins:
+    dependency: transitive
+    description: flutter
+    source: sdk
+    version: "0.0.0"
   formz:
     dependency: "direct main"
     description:
@@ -158,6 +184,15 @@ packages:
       url: "https://pub.flutter-io.cn"
     source: hosted
     version: "1.0.0"
+  open_file:
+    dependency: "direct main"
+    description:
+      path: "."
+      ref: HEAD
+      resolved-ref: fbf68e4bb5cb3e262d8f8ebe10b2f8449ff8e030
+      url: "https://github.com/crazecoder/open_file"
+    source: git
+    version: "3.2.2"
   path:
     dependency: transitive
     description:
@@ -165,6 +200,76 @@ packages:
       url: "https://pub.flutter-io.cn"
     source: hosted
     version: "1.8.2"
+  path_provider:
+    dependency: "direct main"
+    description:
+      name: path_provider
+      url: "https://pub.flutter-io.cn"
+    source: hosted
+    version: "2.0.11"
+  path_provider_android:
+    dependency: transitive
+    description:
+      name: path_provider_android
+      url: "https://pub.flutter-io.cn"
+    source: hosted
+    version: "2.0.20"
+  path_provider_ios:
+    dependency: transitive
+    description:
+      name: path_provider_ios
+      url: "https://pub.flutter-io.cn"
+    source: hosted
+    version: "2.0.11"
+  path_provider_linux:
+    dependency: transitive
+    description:
+      name: path_provider_linux
+      url: "https://pub.flutter-io.cn"
+    source: hosted
+    version: "2.1.7"
+  path_provider_macos:
+    dependency: transitive
+    description:
+      name: path_provider_macos
+      url: "https://pub.flutter-io.cn"
+    source: hosted
+    version: "2.0.6"
+  path_provider_platform_interface:
+    dependency: transitive
+    description:
+      name: path_provider_platform_interface
+      url: "https://pub.flutter-io.cn"
+    source: hosted
+    version: "2.0.5"
+  path_provider_windows:
+    dependency: transitive
+    description:
+      name: path_provider_windows
+      url: "https://pub.flutter-io.cn"
+    source: hosted
+    version: "2.1.3"
+  platform:
+    dependency: transitive
+    description:
+      name: platform
+      url: "https://pub.flutter-io.cn"
+    source: hosted
+    version: "3.1.0"
+  plugin_platform_interface:
+    dependency: transitive
+    description:
+      name: plugin_platform_interface
+      url: "https://pub.flutter-io.cn"
+    source: hosted
+    version: "2.1.3"
+  process:
+    dependency: transitive
+    description:
+      name: process
+      url: "https://pub.flutter-io.cn"
+    source: hosted
+    version: "4.2.4"
   provider:
     dependency: transitive
     description:
@@ -172,6 +277,62 @@ packages:
       url: "https://pub.flutter-io.cn"
     source: hosted
     version: "6.0.3"
+  shared_preferences:
+    dependency: "direct main"
+    description:
+      name: shared_preferences
+      url: "https://pub.flutter-io.cn"
+    source: hosted
+    version: "2.0.15"
+  shared_preferences_android:
+    dependency: transitive
+    description:
+      name: shared_preferences_android
+      url: "https://pub.flutter-io.cn"
+    source: hosted
+    version: "2.0.13"
+  shared_preferences_ios:
+    dependency: transitive
+    description:
+      name: shared_preferences_ios
+      url: "https://pub.flutter-io.cn"
+    source: hosted
+    version: "2.1.1"
+  shared_preferences_linux:
+    dependency: transitive
+    description:
+      name: shared_preferences_linux
+      url: "https://pub.flutter-io.cn"
+    source: hosted
+    version: "2.1.1"
+  shared_preferences_macos:
+    dependency: transitive
+    description:
+      name: shared_preferences_macos
+      url: "https://pub.flutter-io.cn"
+    source: hosted
+    version: "2.0.4"
+  shared_preferences_platform_interface:
+    dependency: transitive
+    description:
+      name: shared_preferences_platform_interface
+      url: "https://pub.flutter-io.cn"
+    source: hosted
+    version: "2.1.0"
+  shared_preferences_web:
+    dependency: transitive
+    description:
+      name: shared_preferences_web
+      url: "https://pub.flutter-io.cn"
+    source: hosted
+    version: "2.0.4"
+  shared_preferences_windows:
+    dependency: transitive
+    description:
+      name: shared_preferences_windows
+      url: "https://pub.flutter-io.cn"
+    source: hosted
+    version: "2.1.1"
   sky_engine:
     dependency: transitive
     description: flutter
@@ -261,6 +422,20 @@ packages:
       url: "https://pub.flutter-io.cn"
     source: hosted
     version: "2.1.2"
+  win32:
+    dependency: transitive
+    description:
+      name: win32
+      url: "https://pub.flutter-io.cn"
+    source: hosted
+    version: "3.0.0"
+  xdg_directories:
+    dependency: transitive
+    description:
+      name: xdg_directories
+      url: "https://pub.flutter-io.cn"
+    source: hosted
+    version: "0.2.0+2"
 sdks:
   dart: ">=2.18.2 <3.0.0"
-  flutter: ">=1.16.0"
+  flutter: ">=3.0.0"
diff --git a/pubspec.yaml b/pubspec.yaml
index 5cb36b5..d9c52a2 100644
--- a/pubspec.yaml
+++ b/pubspec.yaml
@@ -32,6 +32,7 @@ dependencies:
   flutter:
     sdk: flutter
 
+  path_provider: ^2.0.11
   sqflite_common_ffi: ^2.1.1+1
   sqflite_common: ^2.3.0
   crypto: ^3.0.2
@@ -40,6 +41,11 @@ dependencies:
   formz: ^0.4.1
   bloc: ^8.1.0
   flutter_bloc: ^8.1.1
+  file_picker: ^5.2.1
+  open_file:
+    git:
+      url: https://github.com/crazecoder/open_file
+  shared_preferences: ^2.0.15
 
   # The following adds the Cupertino Icons font to your application.
   # Use with the CupertinoIcons class for iOS style icons.