# Dart (Flutter)

**URL:** https://heroiclabs.com/docs/nakama/client-libraries/dart/
**Summary:** The official Dart client handles all communication in real-time with the server. It implements all features in the server. This guide will show you how to use the core Nakama features in Dart by showing you how to develop the Nakama specific parts of a game.
**Keywords:** dart client guide, flutter client, nakama flutter, authentication, user accounts, persistence, storage, wallet, status, groups, chat, dynamic chat, real-world example dart
**Categories:** nakama, dart, client-libraries

---


# Nakama Dart Client Guide

This client library guide will show you how to use the core Nakama features in **Dart (Flutter)** by showing you how to develop the Nakama specific parts (without full game logic or UI) of an [Among Us (external)](https://www.innersloth.com/games/among-us/) inspired game called Sagi-shi (Japanese for "Imposter").

<figure>
  <img src={{< fingerprint_image "/images/pages/nakama/client-libraries/gameplay.png" >}} alt="Sagi-shi gameplay screen">
  <figcaption>Sagi-shi gameplay</figcaption>
</figure>


## Prerequisites

Before proceeding ensure that you have:

* [Installed Nakama server](../../getting-started/install/docker/)
* [Downloaded and installed Flutter](https://docs.flutter.dev/get-started/install)

### Full API documentation

For the full API documentation please visit the [API docs](https://pub.dev/documentation/nakama/latest/).

### Installation

The client is available from the [GitHub Releases page](https://github.com/heroiclabs/nakama-dart/releases) and [pub.dev](https://pub.dev/packages/nakama).

To install the package in your project run:

```bash
# For flutter projects:
flutter pub add nakama

# For dart only projects
dart pub add nakama
```

#### Updates

New versions of the Nakama Dart Client and the corresponding improvements are documented in the [Changelog](https://github.com/heroiclabs/nakama-dart/blob/main/nakama/CHANGELOG.md).

#### Nakama Socket

The Nakama Socket is used for gameplay and real-time latency-sensitive features such as chat, parties, matches and RPCs.

```dart
final socket = NakamaWebsocketClient(
    host: '127.0.0.1',
    ssl: false,
    token: _session.token,
);
```

### Handling exceptions

Network programming requires additional safeguarding against connection and payload issues.

API calls in Sagi-shi are surrounded with a try block and a catch clause:

```dart
try {
    await client.authenticateDevice("<DeviceId>");
} catch (e) {
    print('Error authenticating device');
}
```

<!-- ### Handling retries

Nakama has a global or per-request `RetryConfiguration` object to control how failed API calls are retried. The retry pattern can be useful for authentication or background service related tasks.

Sagi-shi uses a global retry configuration to try failed API calls up to five times before outputting an error to the console.

Passing a `RetryConfiguration` object to an individual request will override any globally set configuration.

```csharp
var retryConfiguration = new Nakama.RetryConfiguration(baseDelay: 1, maxRetries: 5, delegate { System.Console.Writeline("about to retry."); });

// Configure the retry configuration globally.
client.GlobalRetryConfiguration = retryConfiguration;
var account = await client.GetAccount(session);

// Alternatively, pass the retry configuration to an individual request.
var account = await client.GetAccount(session, retryConfiguration);
```

Sometimes it can be useful to stagger the retry requests by a particular amount of time. For this purpose you can pass a delegate to the `jitter` argument when creating a new `RetryConfiguration`. For a fully random retry jitter you can use the `RetryJitter.FullJitter` delegate that comes as part of the SDK.

```csharp
// Retry configuration with random jitter intervals
var retryConfiguration = new RetryConfiguration(500, 5, RetryListener, RetryJitter.FullJitter);
```

If you need more control over the delay between requests you can provide your own jitter delegate.

```csharp
// Retry configuration with custom retry jitter
var retryConfigurationCustomJitter = new RetryConfiguration(500, 5, RetryListener, (history, baseDelay, random) =>
    {
        // Use the "Decorrelated Jitter" algorithm (https://aws.amazon.com/blogs/architecture/exponential-backoff-and-jitter/)
        const int delayCap = 20000;
        var lastAttempt = history.Last();
        var jitter = Mathf.Min(delayCap, random.Next(baseDelay, lastAttempt.JitterBackoff * 3));
        return jitter;
    });
```

Nakama APIs can take an optional `CancellationTokenSource` object which can be used to cancel requests:

```csharp
// Part of System.Threading namespace
var canceller = new CancellationTokenSource();
var account = await client.GetAccount(session, retryConfiguration: null, canceller);

canceller.Cancel();
``` -->


## Getting started

Learn how to get started using the Nakama Client and Socket objects to start building Sagi-shi and your own game.


### Nakama Client

The Nakama Client connects to a Nakama Server and is the entry point to access Nakama features. It is recommended to have one client per server per game.

To create a client for Sagi-shi pass in your server connection details:

```dart
final client = getNakamaClient(
  host: '127.0.0.1',
  ssl: false,
  serverKey: 'defaultkey',
  grpcPort: 7349, // optional
  httpPort: 7350, // optional
);
```


<!-- ### Configuring the Request Timeout Length

Each request to Nakama from the client must complete in a certain period of time before it is considered to have timed out. You can configure how long this period is (in seconds) by setting the `Timeout` value on the client:

```csharp
client.Timeout = 10;
```


### Configuring a Custom Logger

When working with Nakama you can configure the client to use a custom logger. This logger will then be passed down to the HTTP adapter where it will be used to log errors received from API calls.

To use a custom logger you must first create a class that implements the `Nakama.ILogger` interface and then assign it to the client's `Logger` property:

```csharp
var logger = new MyCustomLogger(); // Implements Nakama.ILogger
client.Logger = logger;
```

You can also use the provided `Nakama.UnityLogger` which will log to the Unity console. -->


### Nakama Socket

The Nakama Socket is used for gameplay and real-time latency-sensitive features such as chat, parties, matches and RPCs. You need to initialize this once after authentication. Then you establish a connection until the user closes the app:

```dart
NakamaWebsocketClient.init(
    host: '127.0.0.1',
    ssl: false,
    token: _session.token,
);
```

Remember to close the connection after disposing of the app widget:

```dart
NakamaWebsocketClient.instance.close();
```

## Authentication

Nakama has many [authentication methods](../../concepts/authentication/) and supports creating [custom authentication](../../concepts/authentication/#custom) on the server.

Sagi-shi will use device and Facebook authentication, linked to the same user account so that players can play from multiple devices.

<figure>
  <img src={{< fingerprint_image "/images/pages/nakama/client-libraries/login.png" >}} alt="Sagi-shi login screen">
  <figcaption>Login screen and Authentication options</figcaption>
</figure>


### Device authentication

Nakama [Device Authentication](../../concepts/authentication/#device) uses the physical device's unique identifier to easily authenticate a user and create an account if one does not exist.

When using only device authentication, you don't need a login UI as the player can automatically authenticate when the game launches.

Authentication is an example of a Nakama feature accessed from a Nakama Client instance.

```dart
Future<void> authenticateWithDevice() async {
    String deviceId;
    DeviceInfoPlugin deviceInfo = DeviceInfoPlugin();

    // Grabbing device id from device_info_plus package for iOS & Android
    if (Platform.isIOS) {
        deviceId = (await deviceInfo.iosInfo).identifierForVendor;
    } else if (Platform.isAndroid) {
        deviceId = (await deviceInfo.androidInfo).androidId;
    } else {
        // On web you could e.g. generate a UUID and store it into local storage
        final uuid = Uuid();
        deviceId = uuid.v4();
    }

    try {
        // Authenticate against Nakama with our device token.
        final session = await client.authenticateDevice(
            deviceId: deviceId,
        );
    } catch(e) {
        print('Authentication failed');
    }
}
```


### Facebook authentication

Nakama [Facebook Authentication](../../concepts/authentication/#facebook) is an easy to use authentication method which lets you optionally import the player's Facebook friends and add them to their Nakama Friends list.

To use Nakama Facebook Authentication, you need a facebook token that you can get for example with the [flutter_facebook_login (external)](https://pub.dev/packages/flutter_facebook_login/) package.

```dart
Future<void> authenticateWithFacebook() async {
    try {
        final session = await client.authenticateFacebook(
            token: facebookToken,
        );
    } catch(e) {
        print('Error authenticating with facebook');
    }
}
```


### Custom authentication

Nakama supports [Custom Authentication](../../concepts/authentication/#custom) methods to integrate with additional identity services.

See the [Itch.io custom authentication](../snippets/custom-authentication/) recipe for an example.

The following code shows how you would authenticate from the client side:

```dart
Future<void> authenticationWithCustom() async {
    try {
        final session = await client.authenticateCustom(
            id: 'custom-user-id',
        );
    } catch(e) {
        print('Error authenticating with custom token');
    }
}
```

### Linking authentication

Nakama allows players to [Link Authentication](../../concepts/authentication/#link-or-unlink) methods to their account once they have authenticated.


**Linking Device ID authentication**

```dart
Future<void> linkDeviceAuthentication() async {
    String deviceId;
    DeviceInfoPlugin deviceInfo = DeviceInfoPlugin();

    // Grabbing device id from device_info_plus package for iOS & Android
    if (Platform.isIOS) {
        deviceId = (await deviceInfo.iosInfo).identifierForVendor;
    } else if (Platform.isAndroid) {
        deviceId = (await deviceInfo.androidInfo).androidId;
    } else {
        // On web you could e.g. generate a UUID and store it into local storage
        final uuid = Uuid();
        deviceId = uuid.v4();
    }

    try {
        // Authenticate against Nakama with our device token.
        final session = await client.linkDevice(
            deviceId: deviceId,
        );
    } catch(e) {
        print('Linking device failed');
    }
}
```


**Linking Facebook authentication**

```dart
Future<void> linkFacebookAuthentication({
    required bool importFriends = true,
}) async {
    try {
        final session = await client.linkFacebook(
            token: facebookToken,
        );
    } catch(e) {
        print('Error linking account with facebook');
    }
}
```


### Session variables

Nakama [Session Variables](../../concepts/session/#session-variables) can be stored when authenticating and will be available on the client and server as long as the session is active.

Sagi-shi uses session variables to implement analytics, referral and rewards programs and more. We are using [package_info_plus (external)](https://pub.dev/packages/package_info_plus) to fetch the application version.

Store session variables by passing them as an argument when authenticating:

```dart
PackageInfo packageInfo = await PackageInfo.fromPlatform();

final vars = {
    'inviterUserId': '<someUserId>',
    'gameVersion': packageInfo.version,
};

var session = await client.authenticateDevice(
    deviceId: '<someDeviceId'>,
    vars: vars,
);

```
To access session variables on the Client use the `vars` property on the `Session` object:

```dart
final inviterUserId = session.vars['inviterUserId'];
```


### Session lifecycle

Nakama [Sessions](../../concepts/session/) expire after a time set in your server [configuration](../../getting-started/configuration/#session). Expiring inactive sessions is a good security practice.

Nakama provides ways to restore sessions, for example when Sagi-shi players re-launch the game, or refresh tokens to keep the session active while the game is being played.

Use the auth and refresh tokens on the session object to restore or refresh sessions.

To restore a session without having to re-authenticate just pass the session which is about to expire to `sessionRefresh` method and you'll receive a new one:

```dart
try {
    final session = await client.sessionRefresh(
        session: expiringSession,
    );
} catch(e) {
    print('Error refreshing the session');
}
```

Check if a session has expired or is close to expiring and refresh it to keep it alive:

```dart
final inOneHour = DateTime.now().add(Duration(hours: 1));

// Check whether a session has expired or is close to expiry.
if (session.isExpired || session.hasExpired(inOneHour)) {
    try {
        // Attempt to refresh the existing session.
        session = await client.sessionRefresh(session);
    } catch (e) {
        // Couldn't refresh the session so reauthenticate.
        session = await client.authenticateDevice(deviceId: deviceId);
    }
}
```

<!-- #### Automatic session refresh

The Unity client library includes a feature where sessions close to expiration are automatically refreshed.

This is enabled by default but can be configured when first creating the [Nakama client](#nakama-client) using the following parameters:

* `AutoRefreshSession` - Boolean value indicating if this feature is enabled, `true` by default
* `DefaultExpiredTimespan` - The time prior to session expiry when auto-refresh will occur, set to 5 minutes be default -->

### Ending sessions

Logout and end the current session:

```dart
await client.sessionLogout(session: session);
```


## User accounts

Nakama [User Accounts](../../concepts/user-accounts/) store user information defined by Nakama and custom developer metadata.

Sagi-shi allows players to edit their accounts and stores metadata for things like game progression and in-game items.

<figure>
  <img src={{< fingerprint_image "/images/pages/nakama/client-libraries/profile.png" >}} alt="Sagi-shi player profile screen">
  <figcaption>Player profile</figcaption>
</figure>


### Get the user account

Many of Nakama's features are accessible with an authenticated session, like [fetching a user account](../../concepts/user-accounts/#fetch-account).

Get a Sagi-shi player's full user account with their basic [user information](../../concepts/user-accounts/#fetch-account) and user id:

```dart
final account = await client.getAccount(session);
final username = account.user.username;
final avatarUrl = account.user.avatarUrl;
final userId = account.user.id;
```


### Update the user account

Nakama provides easy methods to update server stored resources like user accounts.

Sagi-shi players need to be able to update their public profiles:

```dart
final newUsername = "NotTheImp0ster";
final newDisplayName = "Innocent Dave";
final newAvatarUrl = "https://example.com/imposter.png";
final newLangTag = "en";
final newLocation = "Edinburgh";
final newTimezone = "BST";
await client.updateAccount(
    session: session,
    username: newUsername,
    displayName: newDisplayName,
    avatarUrl: newAvatarUrl,
    langTag: newLangTag,
    location: newLocation,
    timezone: newTimezone,
);
```


### Getting users

In addition to getting the current authenticated player's user account, Nakama has a convenient way to get a list of other players' public profiles from their ids or usernames.

Sagi-shi uses this method to display player profiles when engaging with other Nakama features:

```dart
final users = await client.getUsers(
    session: session,
    ids: ['<anotherId>'],
);
```


### Storing metadata

Nakama [User Metadata](../../concepts/user-accounts/#user-metadata) allows developers to extend user accounts with public user fields.

User metadata can only be updated on the server. See the [updating user metadata](../snippets/user-metadata/) recipe for an example.

Sagi-shi will use metadata to store what in-game items players have equipped:


### Reading metadata

Define a class that describes the metadata and parse the JSON metadata:

```dart
// Get the updated account object.
final account = await client.getAccount(session);

// Parse the account user metadata into Map<String, dynamic>
// Metadata is just stored as string, so you can store whatever you want
final metadata = jsonDecode(account.metadata);

print('Title: ${metadata['title']}');
print('Hat: ${metadata['hat']}');
print('Skin: ${metadata['skin']}');
```


### Wallets

Nakama [User Wallets](../../concepts/user-accounts/#virtual-wallet) can store multiple digital currencies as key/value pairs of strings/integers.

Players in Sagi-shi can unlock or purchase titles, skins and hats with a virtual in-game currency.


#### Accessing wallets

Parse the JSON wallet data from the user account:

```dart
final account = await client.getAccount(session);
final wallet = jsonDecode(account.wallet);

foreach (var currency in wallet.entries) {
    // Print out e.g. EUR: 2.50
    print('${currency.key}: ${currency.value}');
}
```


#### Updating wallets

Wallets can only be updated on the server. See the [user account virtual wallet](../../concepts/user-accounts/#virtual-wallet) documentation for an example.


#### Validating in-app purchases

Sagi-shi players can purchase the virtual in-game currency through in-app purchases that are authorized and validated to be legitimate on the server.

See the [In-app Purchase Validation](../../concepts/iap-validation/) documentation for examples.


## Storage Engine

The Nakama [Storage Engine](../../concepts/storage/collections/) is a distributed and scalable document-based storage solution for your game.

The Storage Engine gives you more control over how data can be [accessed](../../concepts/storage/permissions/#object-permissions) and [structured](../../concepts/storage/collections/#collections) in collections.

Collections are named, and store JSON data under a unique key and the user id.

By default, the player has full permission to create, read, update and delete their own storage objects.

Sagi-shi players can unlock or purchase many items, which are stored in the Storage Engine.

<figure>
  <img src={{< fingerprint_image "/images/pages/nakama/client-libraries/player-items.png" >}} alt="Sagi-shi player items screen">
  <figcaption>Player items</figcaption>
</figure>


### Reading storage objects

Define a class that describes the storage object and create a new storage object id with the collection name, key and user id. Finally, read the storage objects and parse the JSON data:

```dart
final result = await client.readStorageObject(
    session: session,
    collection: 'Unlocks',
    key: 'Hats',
    userId: session.UserId
);

if (result != null) {
    final hats = jsonDecode(result.value);

    print('Unlocked hats: ${hats}');
}
```

To read other players' public storage objects use their `userId` instead. Remember that players can only read storage objects they own or that are public (`PermissionRead` value of `2`).

### Writing storage objects

Nakama allows developers to write to the Storage Engine from the client and server.

Consider what adverse effects a malicious user can have on your game and economy when deciding where to put your write logic, for example data that should only be written authoritatively (i.e. game unlocks or progress).

Sagi-shi allows players to favorite items for easier access in the UI and it is safe to write this data from the client.

Create a write storage object with the collection name, key and JSON encoded data. Finally, write the storage objects to the Storage Engine:

```dart
await client.writeStorageObject(
    session: session,
    collection: 'favorites',
    key: 'hats',
    value: jsonEncode(['cowboy', 'alien']),
    readPermission: StorageReadPermission.ownerRead,
    writePermission: StorageWritePermission.ownerWrite,
);
```

### Conditional writes

Storage Engine [Conditional Writes](../../concepts/storage/collections/#conditional-writes) ensure that write operations only happen if the object hasn't changed since you accessed it.

This gives you protection from overwriting data, for example the Sagi-shi server could have updated an object since the player last accessed it.

To perform a conditional write, add a version to the write storage object with the most recent object version:

```dart
// Assuming we already have a storage object (storageObject)
try {
    await client.writeStorageObject(
        session: session,
        collection: 'favorites',
        key: 'hats',
        value: jsonEncode(['cowboy', 'alien']),
        readPermission: StorageReadPermission.ownerRead,
        writePermission: StorageWritePermission.ownerWrite,
        version: storageObject.version,
    );
} catch(e) {
    print(e);
}
```


### Listing storage objects

Instead of doing multiple read requests with separate keys you can list all the storage objects the player has access to in a collection.

Sagi-shi lists all the player's unlocked or purchased titles, hats and skins:

```dart
const limit = 3;
final unlocksObjectList = await client.listStorageObjects(
    session: session, 
    collection: 'unlocks',
    userId: session.userId,
    limit: limit,
);

for (var unlockStorageObject in unlocksObjectList.objects) {
    switch(unlockStorageObject.key) {
        case "titles":
            var unlockedTitles = jsonDecode(unlockStorageObject.value);
            // Display the unlocked titles
            break;
        case "hats":
            var unlockedHats = jsonDecode(unlockStorageObject.value);
            // Display the unlocked hats
            break;
        case "skins":
            var unlockedSkins = jsonDecode(unlockStorageObject.value);
            // Display the unlocked skins
            break;
    }
}
```


### Paginating results

Nakama methods that list results return a cursor which can be passed to subsequent calls to Nakama to indicate where to start retrieving objects from in the collection.

For example:
- If the cursor has a value of 5, you will get results from the fifth object.
- If the cursor is `null`, you will get results from the first object.

```dart
final objectList = await client.listStorageObjects(
    session: session,
    collection: "<CollectionName>",
    limit: limit,
    cursor: objectList.Cursor,
);
```

### Protecting storage operations on the server

Nakama Storage Engine operations can be protected on the server to protect data the player shouldn't be able to modify (i.e.  game unlocks or progress). See the [writing to the Storage Engine authoritatively](../snippets/authoritative-write/) recipe.

## Remote Procedure Calls

The Nakama [Server](../../server-framework/) allows developers to write custom logic and expose it to the client as [RPCs](../../server-framework/introduction/#functionality).

Sagi-shi contains various logic that needs to be protected on the server, like checking if the player owns equipment before equipping it.

### Creating server logic

See the [handling player equipment authoritatively](../snippets/authoritative-read/) recipe for an example of creating a remote procedure to check if the player owns equipment before equipping it.


### Client RPCs

Nakama Remote Procedures can be called from the client and take optional JSON payloads.

The Sagi-shi client makes an RPC to securely equip a hat:

```dart
try {
    final payload = { 'item': 'cowboy' };
    final response = await client.rpc(
        session: session,
        id: 'EquipHat',
        payload: jsonEncode(payload),
    );
    print('New hat equipped successfully: $response');
} catch (e) {
    print(e);
}
```


### Socket RPCs

Nakama Remote Procedures can also be called from the socket when you need to interface with Nakama's real-time functionality.

```dart
final response = await socket.rpc(
    id: '<RpcId>',
    payload: '<PayloadString>',
);
```


## Friends

Nakama [Friends](../../concepts/friends/) offers a complete social graph system to manage friendships amongst players.

Sagi-shi allows players to add friends, manage their relationships and play together.

<figure>
  <img src={{< fingerprint_image "/images/pages/nakama/client-libraries/friends.png" >}} alt="Sagi-shi Friends screen">
  <figcaption>Friends screen</figcaption>
</figure>


### Adding friends

Adding a friend in Nakama does not immediately add a mutual friend relationship. An outgoing friend request is created to each user, which they will need to accept.

Sagi-shi allows players to add friends by their usernames or user ids:


```dart
// Add friends by Username.
await client.addFriends(
    session: session,
    usernames: [ 'AlwaysTheImposter21', 'SneakyBoi' ],
);

// Add friends by User ID.
await client.addFriends(
    session: session,
    ids: [ '<SomeUserId>', '<AnotherUserId>' ],
);
```


### Friendship states

Nakama friendships are categorized with the following [states](../../concepts/friends/#friend-state):

| Value | State |
| 
----- | ----- |
| 0 | Mutual friends |
| 1 | An outgoing friend request pending acceptance |
| 2 | An incoming friend request pending acceptance |
| 3 | Blocked by the user |


### Listing friends

Nakama allows developers to list the player's friends based on their friendship state.

Sagi-shi lists the 20 most recent mutual friends:

```dart
final limit = 20; // Limit is capped at 1000
final frienshipState = FriendshipState.mutual;
final result = await client.listFriends(
    session: session,
    friendshipState: frienshipState,
    limit: limit,
);

for (var friend in result.friends) {
    print('ID: ${friend.user.id}');
}
```


### Accepting friend requests

When accepting a friend request in Nakama the player adds a [bi-directional friend relationship](../../concepts/friends/best-practices/#modeling-relationships).

Nakama takes care of changing the state from pending to mutual for both.

In a complete game you would allow players to accept individual requests.

Sagi-shi just fetches and accepts all the incoming friend requests:

```dart
final limit = 1000;
final result = await client.listFriends(
    session: session,
    friendshipState: FriendshipState.incomingRequest,
    limit: limit,
);

for (var friend in result.friends) {
    await client.addFriends(
        session: session,
        ids: friend.user.id,
    );
}
```


### Deleting friends

Sagi-shi players can decline friend requests and remove friends by their username or user id:

```dart
// Delete friends by User ID.
await client.deleteFriends(
    session: session,
    ids: [ '<SomeUserId>', '<AnotherUserId>' ],
);

// Delete friends by Username.
await client.deleteFriends(
    session: session,
    usernames: [ '<SomeUsername>', '<AnotherUsername>' ],
);
```


### Blocking users

Sagi-shi players can block others by their username or user id:


```dart
// Block friends by User ID.0
await client.blockFriends(
    session: session,
    ids: [ '<SomeUserId>', '<AnotherUserId>' ],
);

// Block friends by Username.
await client.blockFriends(
    session: session,
    usernames: [ '<SomeUsername>', '<AnotherUsername>' ],
);
```


## Status & Presence

Nakama [Status](../../concepts/status/) is a real-time status and presence service that allows users to set their online presence, update their status message and follow other user's updates.

Players don't have to be friends with others they want to follow.

Sagi-shi uses status messages and online presences to notify players when their friends are online and share matches.

<figure>
  <img src={{< fingerprint_image "/images/pages/nakama/client-libraries/status.png" >}} alt="Sagi-shi status update screen">
  <figcaption>Updating player status</figcaption>
</figure>


### Follow users

The Nakama real-time APIs allow developers to subscribe to events on the socket, like a status presence change, and receive them in real-time.

The method to follow users also returns the current online users, known as presences, and their status.

Sagi-shi follows a player's friends and notifies them when they are online:

```dart
a.onStatusPresence.listen((event) {
    for (final presence in event.joins) {
        print('${presence.username} is online with status ${presence.status}');
    }

    for (final presence in event.leaves) {
        print('${presence.username} went offline');
    }
});

// Follow mutual friends and get the initial Status of any that are currently online.
final friendsResult = await client.listFriends(
    session: session,
    friendshipState: FriendshipState.mutual,
);
final friendIds = friends.friends.map((f) => f.user.id).toList();
final result = await socket.followUsers(friendIds);

for (var presence in result.presences) {
    print('${presence.username} is online with status: ${presence.status}');
}
```


### Unfollow users

Sagi-shi players can unfollow others:

```dart
await socket.unfollowUsers(['<userId>']);
```


### Updating player status

Sagi-shi players can change and publish their status to their followers:

```dart
await socket.updateStatus('Viewing the Main Menu');
```


## Groups

Nakama [Groups](../../concepts/groups/) is a group or clan system with public/private visibility, user memberships and permissions, metadata and group chat.

Sagi-shi allows players to form and join groups to socialize and compete.

<figure>
  <img src={{< fingerprint_image "/images/pages/nakama/client-libraries/groups-list.png" >}} alt="Sagi-shi groups screen">
  <figcaption>Groups list screen</figcaption>
</figure>


### Creating groups

Groups have a public or private "open" visibility. Anyone can join public groups, but they must request to join and be accepted by a superadmin/admin of a private group.

Sagi-shi players can create groups around common interests:

```dart
final group = await client.createGroup(
    session: session,
    name: 'Imposters R Us',
    description: 'A group for people who love playing the imposter.',
    open: true, // public group
    maxCount: 100,
);
```


### Update group visibility

Nakama allows group superadmin or admin members to update some properties from the client, like the open visibility:

```dart
await client.updateGroup(
    session: session,
    id: '<GroupId>',
    name: '<NewGroupName>',
    open: true,
);
```


### Update group size

Other properties, like the group's maximum member size, can only be changed on the server.

See the [updating group size](../../concepts/groups/#updating-group-size) recipe for an example, and the [Groups server function reference](../../server-framework/typescript-runtime/function-reference/#groups) to learn more about updating groups on the server.

<figure>
  <img src={{< fingerprint_image "/images/pages/nakama/client-libraries/group-edit.png" >}} alt="Sagi-shi group edit screen">
  <figcaption>Sagi-shi group edit</figcaption>
</figure>


### Listing and filtering groups

Groups can be listed like other Nakama resources and also [filtered](../../concepts/groups/#list-and-filter-groups) with a wildcard group name.

Sagi-shi players use group listing and filtering to search for existing groups to join:


```dart
const limit = 20;
final result = await client.listGroups(
    session: session,
    name: "imposter%",
    limit: limit,
);

for (var group in result.groups) {
    print('${group.name} [${group.open ? 'Public' : 'Private'}]');
}

// Get the next page of results.
final nextResults = await client.listGroups(
    session: session,
    name: "imposter%",
    limit: limit,
    cursor: result.cursor,
);
```


### Deleting groups

Nakama allows group superadmins to delete groups.

Developers can disable this feature entirely, see the [Guarding APIs guide](../../guides/server-framework/guarding-apis/) for an example on how to protect various Nakama APIs.

Sagi-shi players can delete groups which they are superadmins for:

```dart
await client.deleteGroup(
    session: session,
    groupId: "<GroupId>"
);
```


### Group metadata

Like Users Accounts, Groups can have public metadata.

Sagi-shi uses group metadata to store the group's interests, active player times and languages spoken.

Group metadata can only be updated on the server. See the [updating group metadata](../snippets/group-metadata/) recipe for an example.

The Sagi-shi client makes an RPC with the group metadata payload:

```dart
final payload = {
    groupId: '<GroupId>',
    interests: ['Deception', 'Sabotage', 'Cute Furry Bunnies'],
    activeTimes: ['9am-2pm Weekdays', '9am-10pm Weekends'],
    languages: ['English', 'German'],
};

try {
    final result = await client.rpc(
        session: session,
        'UpdateGroupMetadata',
        jsonEncode(payload),
    );
    print('Successfully updated group metadata');
} catch (e) {
    print(e);
}
```


### Group membership states

Nakama group memberships are categorized with the following [states](../../concepts/groups/#groups-and-clans):

| Code | Purpose | |
| ---- | ------- | - |
|    0 | Superadmin | There must at least be 1 superadmin in any group. The superadmin has all the privileges of the admin and can additionally delete the group and promote admin members. |
|    1 | Admin | There can be one of more admins. Admins can update groups as well as accept, kick, promote, demote, ban or add members. |
|    2 | Member | Regular group member. They cannot accept join requests from new users. |
|    3 | Join request | A new join request from a new user. This does not count towards the maximum group member count. |


### Joining a group

If a player joins a public group they immediately become a member, but if they try and join a private group they must be accepted by a group admin.

Sagi-shi players can join a group:

```dart
await client.joinGroup(
    session: session,
    groupId: '<GroupId>',
);
```


### Listing the user's groups

Sagi-shi players can list groups they are a member of:

```dart
final results = await client.listUserGroups(session: session);

for (var userGroup in results.userGroups) {
    print('${userGroup.group.name}: ${userGroup.state}' );
}
```


### Listing members

Sagi-shi players can list a group's members:

```dart
final result = await client.listGroupUsers(
    session: session,
    groupId: '<GroupId>',
);

for (var groupUser in result.groupUsers) {
    print('${groupUser.user.id}: ${groupUser.state}');
}
```


### Accepting join requests

Private group admins or superadmins can accept join requests by re-adding the user to the group.

Sagi-shi first lists all the users with a join request state and then loops over and adds them to the group:


```dart
final result = await client.listGroupUsers(
    session: session,
    groupId: '<GroupId>',
    state: GroupMembershipState.joinRequest,
);

for (var groupUser in result.groupUsers) {
    await client.addGroupUsers(
        session: session,
        groupId: '<GroupId>',
        userIds: [groupUser.user.id],
    );
}
```


### Promoting members

Nakama group members can be promoted to admin or superadmin roles to help manage a growing group or take over if members leave.

Admins can promote other members to admins, and superadmins can promote other members up to superadmins.

The members will be promoted up one level. For example:

- Promoting a member will make them an admin
- Promoting an admin will make them a superadmin

```dart
await client.promoteGroupUsers(
    session: session,
    groupId: '<GroupId>', 
    userIds: ['<UserId'>],
);
```


### Demoting members

Sagi-shi group admins and superadmins can demote members:

```dart
await client.demoteGroupUsers(
    session: session,
    groupId: '<GroupId>', 
    userIds: ['<UserId>'],
);
```


### Kicking members

Sagi-shi group admins and superadmins can remove group members:

```dart
await client.kickGroupUsers(
    session: session,
    groupId: '<GroupId>', 
    userIds: ['<UserId'>],
);
```


### Banning members

Sagi-shi group admins and superadmins can ban a user when demoting or kicking is not severe enough:

```dart
await client.banGroupUsers(
    session: session,
    groupId: '<GroupId>',
    userIds: ['<UserId>'],
);
```

### Leaving groups

Sagi-shi players can leave a group:

```dart
await client.leaveGroup(
    session: session,
    groupId: '<GroupId>',
);
```


## Chat

Nakama Chat is a real-time chat system for groups, private/direct messages and dynamic chat rooms.

Sagi-shi uses dynamic chat during matches, for players to mislead each other and discuss who the imposters are, group chat and private/direct messages.

<figure>
  <img src={{< fingerprint_image "/images/pages/nakama/client-libraries/chat.png" >}} alt="Sagi-shi chat screen">
  <figcaption>Sagi-shi Chat</figcaption>
</figure>


### Joining dynamic rooms

Sagi-shi matches have a non-persistent chat room for players to communicate in:

```dart
final channel = await socket.joinChannel(
    target: '<MatchId>',
    type: ChannelType.room,
    persistence: true,
    hidden: false,
);

print('Connected to dynamic room channel: ${channel.id}');
```


### Joining group chat

Sagi-shi group members can have conversations that span play sessions in a persistent group chat channel:

```dart
final channel = await socket.joinChannel(
    target: '<GroupId>',
    type: ChannelType.group,
    persistence: true,
    hidden: false,
);

print('Connected to group channel: ${channel.id}');
```


### Joining direct chat

Sagi-shi players can also chat privately one-to-one during or after matches and view past messages:

```dart
final channel = await socket.joinChannel(
    target: '<UserId>',
    type: ChannelType.directMessage,
    persistence: true,
    hidden: false,
);

print('Connected to direct message channel: ${channel.id}');
```


### Sending messages

Sending messages is the same for every type of chat channel. Messages contain chat text and emotes and are sent as JSON serialized data:

```dart
final messageSendAck = await socket.sendMessage(
    channelId: '<ChannelId>',
    content: {'message': 'I think Red is the imposter!'},
);

final emoteContent = {
    'emote': 'point',
    'emoteTarget': '<RedPlayerUserId>',
};
final emoteSendAck = await socket.sendMessage(
    channelId: '<ChannelId>',
    content: emoteContent,
);
```


### Listing message history

Message listing takes a parameter which indicates if messages are received from oldest to newest (forward) or newest to oldest.

Sagi-shi players can list a group's message history:

```dart
final result = await client.listChannelMessages(
    session: session,
    groupId: '<GroupId>',
    limit: 100,
    forward: true,
    cursor: null,
);

for (var message in result.messages) {
    print('${message.username}: ${message.content}');
}
```


### Updating messages

Nakama also supports updating messages. It is up to you whether you want to use this feature, but in a game of deception like Sagi-shi it can add an extra element of deception.

For example a player sends the following message:

```dart
const channelId = '<ChannelId>'
final messageContent = {'message': 'I think Red is the imposter!'};
final messageSendAck = await socket.sendMessage(
    channelId: channelId,
    messageContent,
);
```

They then quickly edit their message to confuse others:

```dart
final newMessageContent = {'message': 'I think BLUE is the imposter!'};
final messageUpdateAck = await socket.updateMessage(
    channelId: channelId,
    messageSendAck.messageId,
    content: newMessageContent,
);
```


## Matches

Nakama supports [Server Authoritative](../../concepts/multiplayer/authoritative/) and [Server Relayed](../../concepts/multiplayer/relayed/) multiplayer matches.

In server authoritative matches the server controls the gameplay loop and must keep all clients up to date with the current state of the game.

In server relayed matches the client is in control, with the server only relaying information to the other connected clients.

In a competitive game such as Sagi-shi, server authoritative matches would likely be used to prevent clients from interacting with your game in unauthorized ways.

For the simplicity of this guide, the server relayed model is used.


### Creating matches

Sagi-shi players can create their own matches and invite their online friends to join:

```dart
final match = await socket.createMatch();
final friendsList = await client.listFriends(
    session: session,
    friendshipState: FriendshipState.mutual,
    limit: 100,
);
final onlineFriends = friendsList.friends.where((friend) => friend.user.online).toList();

for (var friend in onlineFriends) {
    final content = {
        message: 'Hey ${friend.username}, join me for a match!',
        matchId: match.id,
    };

    final channel = await socket.joinChannel(
        target: friend.id,
        type: ChannelType.directMessage,
    );
    final messageAck = await socket.sendMessage(
        channelId: channel.id,
        content: content,
    );
}
```

**Creating a match by match name**

Sagi-shi players can also create matches with a specific match name, this allows them to invite their friends by telling them the name of the match. It should be noted that when creating a match by name (which is an arbitrary name and not something tied to authoritative match handlers), the match will always be a relayed match rather than an authoritative match.

```dart
const matchName = 'NoImpostersAllowed';
final match = await socket.createMatch(matchName);
```

### Joining matches

Sagi-shi players can try to join existing matches if they know the id:
```dart
const matchId = "<MatchId>";
final match = await socket.joinMatch(matchId);
```

Or set up a real-time matchmaker listener and add themselves to the matchmaker:

```dart
socket.onMatchmakerMatched.listen((matchmakerMatched) {
    final match = await socket.joinMatch(matchmakerMatched.matchId);
});

const minPlayers = 2;
const maxPlayers = 10;

final matchmakingTicket = await socket.addMatchmaker(
    query: '',
    minCount: minPlayers,
    maxCount: maxPlayers,
);
```

**Joining matches by match name**

Sagi-shi players can join a match by match name if their friends have shared one with them.

<!-- ```dart
const matchName = "NoImpostersAllowed";

// When joining by match name, you use the CreateMatchAsync function instead of the JoinMatchAsync function
var match = await socket.CreateMatch(matchName);
``` -->

**Joining matches from player status**

Sagi-shi players can update their status when they join a new match:

```dart
final status = {
    'Status': 'Playing a match',
    'MatchId': '<MatchId>',
};

await socket.updateStatus(jsonEncode(status));
```

When their followers receive the real-time status event they can try and join the match:

```dart
socket.onStatusPresence.listen((statusPresence) {
    // Join the first match found in a friend's status
    final presence = event.joins.firstWhere((element) {
        if (element.status == null) return false;

        final status = jsonDecode(element.status!);

        return status.containsKey('MatchId');
    });
    
    // No presence with a match found
    if (presence == null) return;

    final status = jsonDecode(presence.status!);
    socket.joinMatch(status['MatchId']);
});
```

### Listing matches

[Match Listing](../../concepts/multiplayer/match-listing/) takes a number of criteria to filter matches by including player count, a match label and an option to provide a more complex [search query](../../concepts/multiplayer/query-syntax/).

Sagi-shi matches start in a lobby state. The match exists on the server but the actual gameplay doesn't start until enough players have joined.

Sagi-shi can then list matches that are waiting for more players:

```dart
const minPlayers = 2;
const maxPlayers = 10;
const limit = 10;
const authoritative = true;
const label = "";
const query = "";

final result = await client.listMatches(
    session: session,
    minSize: minPlayers,
    maxSize: maxPlayers,
    limit: limit,
    authoritative: authoritative,
    label: label,
    query: query,
);

for (var match in result.matches) {
    print('{match.matchId}: ${match.size}/10 players');
}
```

To find a match that has a label of `"AnExactMatchLabel"`:

```dart
const label = "AnExactMatchLabel";
```

**Advanced:**

In order to use a more complex structured query, the match label must be in JSON format.

To find a match where it expects player skill level to be `>100` and optionally has a game mode of `"sabotage"`:

```dart
const query = "+label.skill:>100 label.mode:sabotage"
```


### Spawning players

The match object has a list of current online users, known as presences.

Sagi-shi uses the match presences to spawn players on the client:

<!-- ```dart
final match = await socket.joinMatch(matchId);

final players = new Dictionary<string, GameObject>();

for (var presence in match.presences) {
    // Spawn a player for this presence and store it in a dictionary by session id.
    var go = Instantiate(playerPrefab);
    players.Add(presence.SessionId, go);
}
``` -->

Sagi-shi keeps the spawned players up-to-date as they leave and join the match using the match presence received event:

```dart
socket.onMatchPresence.listen((matchPresenceEvent) {
    // For each player that has joined in this event...
    for (var presence in matchPresenceEvent.joins) {
        // Spawn a player for this presence and store it in a dictionary by session id.
        players[presence.sessionId] = presence;
    }

    // For each player that has left in this event...
    for (var presence in matchPresenceEvent.leaves) {
        // Remove the player from the game if they've been spawned
        if (players.containsKey(presence.sessionId)) {
            players.removeWhere((key, value) => key == presence.sessionId);
        }

    }
});
```


### Sending match state

Nakama has real-time networking to [send](../../concepts/multiplayer/relayed/#send-data-messages) and [receive](../../concepts/multiplayer/relayed/#receive-data-messages) match state as players move and interact with the game world.

During the match, each Sagi-shi client sends match state to the server to be relayed to the other clients.

Match state contains an op code that lets the receiver know what data is being received so they can deserialize it and update their view of the game.

Example op codes used in Sagi-shi:
- 1: player position
- 2: player calling vote


**Sending player position**

Define a list to represent Sagi-shi player position states in the format [X, Y, Z]:

```dart
final playersPosition = [
    transform.position.x,
    transform.position.y,
    transform.position.z,
];
```

Set the op code and send the JSON encoded state:

```dart
const opCode = 1;

await socket.sendMatchData(match.id, opCode, jsonEncode(playersPosition));
```


**Op Codes as a static class**

Sagi-shi has many networked game actions. Using a static class of constants for op codes will keep your code easier to follow and maintain:

```dart
class OpCodes {
  static const position = 1;
  static const vote = 2;
}

await socket.sendMatchData(
    match.id,
    OpCodes.position,
    jsonEncode(state).codeUnits,
);
```


### Receiving match sate

Sagi-shi players can receive match data from the other connected clients by subscribing to the match state received event:

```dart
socket.onMatchData.listen((matchData) {
    switch (matchData.opCode) {
        case OpCodes.position:
            // Get the updated position data
            final stateJson = String.fromCharCodes(matchData.data);
            final positionState = jsonDecode(stateJson);

            // Update the GameObject associated with that player
            if (players.containsKey(matchData.presence.sessionId)) {
                // Here we would normally do something like smoothly interpolate to the new position, but for this example let's just set the position directly.
                players[matchData.presence.sessionId].transform.position = positionState;
            }
            break;
        default:
            print("Unsupported op code");
            break;
    }
});
```


## Matchmaker

Developers can find matches for players using Match Listing or the Nakama [Matchmaker](../../concepts/multiplayer/matchmaker/), which enables players join the real-time matchmaking pool and be notified when they are matched with other players that match their specified criteria.

Matchmaking helps players find each other, it does not create a match. This decoupling is by design, allowing you to use matchmaking for more than finding a game match. For example, if you were building a social experience you could use matchmaking to find others to chat with.


### Add matchmaker

Matchmaking criteria can be simple, find 2 players, or more complex, find 2-10 players with a minimum skill level interested in a specific game mode.

Sagi-shi allows players to join the matchmaking pool and have the server match them with other players:

```dart
const minPlayers = 2;
const maxPlayers = 10;

final matchmakerTicket = await socket.addMatchmaker(
    query: '+skill:>100 mode:sabotage',
    minCount: minPlayers,
    maxCount: maxPlayers,
    stringProperties: {'mode': 'sabotage'},
    numericProperties: {'skill': 125 },
);
```

## Parties

Nakama [Parties](../../concepts/parties/) is a real-time system that allows players to form short lived parties that don't persist after all players have disconnected.

Sagi-shi allows friends to form a party and matchmake together.


### Creating parties

The player who creates the party is the party's leader. Parties have maximum number of players and can be open to automatically accept players or closed so that the party leader can accept incoming join requests.

Sagi-shi uses closed parties with a maximum of 4 players:

```dart
var party = await socket.createParty(
    open: false,
    maxSize: maxPlayers,
);
```

Sagi-shi shares party ids with friends via private/direct messages:

```dart
final friendsList = await client.listFriends(
    session: session,
    friendshipState: FriendshipState.mutual,
    limit: 100,
);
final onlineFriends = friendsList.friends.where((friend) => friend.user.online).toList();

for (var friend in onlineFriends) {
    final content = {
        message: 'Hey ${friend.username}, wanna join the party?!',
        partyId: party.id,
    };

    final channel = await socket.joinChannel(
        target: friend.id,
        type: ChannelType.directMessage,
    );
    final messageAck = await socket.sendMessage(
        channelId: channel.id,
        content: content,
    );
}
```


### Joining parties

Safi-shi players can join parties from chat messages by checking for the party id in the message:

```dart
socket.onChannelMessage.listen((channelMessage) {
    final content = jsonDecode(channelMessage.content);

    if (content.containsKey('partyId')) {
        socket.joinParty(content['partyId']);
    }
});
```


<!-- ### Promoting a member

Sagi-shi party members can be promoted to the party leader:

```csharp
var newLeader = party.Presences.Where(p => p.SessionId != party.Leader.SessionId).First();
await socket.PromotePartyMember(party.Id, newLeader);
``` -->

### Leaving parties

Sagi-shi players can leave parties:

```dart
await socket.leaveParty(party.id);
```


### Matchmaking with parties

One of the main benefits of joining a party is that all the players can join the matchmaking pool together.

Sagi-shi players can listen to the the matchmaker matched event and join the match when one is found:

```dart
socket.onMatchmakerMatched.listen((event) {
    socket.joinMatch(event.matchId!);
});
```

The party leader will start the matchmaking for their party:

```dart
const minPlayers = 2;
const maxPlayers = 10;

final matchmakerTicket = await socket.addMatchmakerParty(
    partyId: '<PartyId>',
    query: '',
    minCount: minPlayers,
    maxCount: maxPlayers,
);
```


### Sending party data

Sagi-shi players can send data to other members of their party to indicate they wish to start a vote.

```dart
final state = {
    'username': '<Username>',
    'reason': 'Emergency',
};

await socket.sendPartyData(
    partyId: party.id,
    opCode: OpCodes.partyCallVote,
    data: jsonEncode(state).codeUnits,
);
```


### Receiving party data

Sagi-shi players can receive party data from other party members by subscribing to the party data event.

```dart
socket.onPartyData.listen((event) {
    switch (event.opCode) {
        case OpCodes.partyCallVote:
            // Get the vote data
            final stateJson = String.fromCharCodes(event.data);
            final voteState = jsonDecode(stateJson);

            // Show a UI dialogue - "<username> has proposed to call a vote for <reason>. Do you agree? Yes/No"
            break;
        default:
            print('Unsupported opcode');
            break;
    }
});
```


## Leaderboards

Nakama [Leaderboards](../../concepts/leaderboards/) introduce a competitive aspect to your game and increase player engagement and retention.

Sagi-shi has a leaderboard of weekly imposter wins, where player scores increase each time they win, and similarly a leaderboard for weekly crew member wins.

<figure>
  <img src={{< fingerprint_image "/images/pages/nakama/client-libraries/leaderboard.png" >}} alt="Sagi-shi leaderboard screen">
  <figcaption>Sagi-shi Leaderboard</figcaption>
</figure>


### Creating leaderboards

Leaderboards have to be created on the server, see the [leaderboard](../../concepts/leaderboards/#create-a-leaderboard) documentation for details on creating leaderboards.


### Submitting scores

When players submit scores, Nakama will increment the player's existing score by the submitted score value.

Along with the score value, Nakama also has a subscore, which can be used for ordering when the scores are the same.

Sagi-shi players can submit scores to the leaderboard with contextual metadata, like the map the score was achieved on:

```dart
const score = 1;
const subscore = 0;
final metadata = {'map': 'space_station'};

await client.writeLeaderboardRecord(
    session: session,
    leaderboardName: 'weekly_imposter_wins',
    score: score,
    subscore: subscore,
    jsonEncode(metaData),
);
```

### Listing the top records

Sagi-shi players can list the top records of the leaderboard:

```dart
const limit = 20;
final leaderboardName = 'weekly_imposter_wins';

final result = await client.listLeaderboardRecords(
    session: session,
    leaderboardName: leaderboardName,
    ownerIds: null,
    expiry: null,
    limit: limit,
    cursor: null,
);

for (var record in result.records) {
    print('${record.ownerId}: ${record.score}');
}
```


**Listing records around the user**

Nakama allows developers to list leaderboard records around a player.

Sagi-shi gives players a snapshot of how they are doing against players around them:

```dart
const limit = 5;
const leaderboardName = 'weekly_imposter_wins';
final result = await client.listLeaderboardRecordsAroundOwner(
    session: session,
    leaderboardName: leaderboardName,
    ownerId: session.userId,
    expiry: null,
    limit: limit,
);

for (var record in result.Records) {
    print('${record.ownerId}: ${record.score}');
}
```
For example, if the leaderboard contains 100 records and the ownerId = "player123" with limit = 5, the result will include the specified user along with nearby records:

```json
{
  "records": [
    { "ownerId": "player120", "rank": 48, "score": 1500 },
    { "ownerId": "player121", "rank": 49, "score": 1480 },
    { "ownerId": "player123", "rank": 50, "score": 1450 },  // Your ownerId
    { "ownerId": "player125", "rank": 51, "score": 1430 },
    { "ownerId": "player127", "rank": 52, "score": 1400 }
  ]
}
```

**Listing records for a list of users**

Sagi-shi players can get their friends' scores by supplying their user ids to the owner id parameter:

```dart
final friendsList = await client.listFriends(
    session: session,
    friendshipState: FriendshipState.mutual,
    limit: 100,
);
final userIds = friendsList.friends.map((e) => e.user.id).toList();
final recordList = await client.listLeaderboardRecords(
    session: session,
    leaderboardName: 'weekly_imposter_wins',
    ownerIds: userIds,
    expiry: null,
    limit: 100,
    cursor: null,
);

for (var record in recordList.records) {
    print('${record.username} scored ${record.score}');
}
```

The same approach can be used to get group member's scores by supplying their user ids to the owner id parameter:

```dart
final groupUserList = await client.listGroupUsers(
    session: session,
    groupId: '<GroupId>',
    state: null,
    limit: 100,
    cursor: null,
);

final userIds = groupUserList.groupUsers
    .where((x) => x.state.index < 3)
    .map((g) => g.user.id)
    .toList();

final recordList = await client.listLeaderboardRecords(
    session: session,
    leaderboardName: 'weekly_imposter_wins',
    ownerIds: userIds,
    expiry: null,
    limit: 100,
    cursor: null,
);

for (var record in recordList.records) {
    print('${record.username} scored ${record.score}');
}
```


### Deleting records

Sagi-shi players can delete their own leaderboard records:

```dart
await client.deleteLeaderboardRecord(
    session: session,
    leaderboardId: '<LeaderboardId>',
);
```


## Tournaments

Nakama [Tournaments](../../concepts/tournaments/) are short lived competitions where players compete for a prize.

Sagi-shi players can view, filter and join running tournaments.

<figure>
  <img src={{< fingerprint_image "/images/pages/nakama/client-libraries/tournaments.png" >}} alt="Sagi-shi tournaments screen">
  <figcaption>Sagi-shi Tournaments</figcaption>
</figure>


### Creating tournaments

Tournaments have to be created on the server, see the [tournament](../../concepts/tournaments/#create-tournament) documentation for details on how to create a tournament.

Sagi-shi has a weekly tournament which challenges players to get the most correct imposter votes. At the end of the week the top players receive a prize of in-game currency.


### Joining tournaments

By default in Nakama players don't have to join tournaments before they can submit a score, but Sagi-shi makes this mandatory:

```dart
await client.joinTournament(
    session: session,
    tournamentId: '<TournamentId>',
);
```

### Listing tournaments

Sagi-shi players can list and filter tournaments with various criteria:

```dart
const categoryStart = 1;
const categoryEnd = 2;
const limit = 100;
final result = await client.listTournaments(
    session: session,
    categoryStart: categoryStart,
    categoryEnd: categoryEnd,
    startTime: null,
    endTime: null,
    limit: limit,
    cursor: null,
);

for (var tournament in result.tournaments) {
    print('${tournament.id}:${tournament.title}');
}
```

For performance reasons categories are filtered using a range, not individual numbers. Structure your categories to take advantage of this (e.g. all PVE tournaments in the 1XX range, all PVP tournaments in the 2XX range, etc.).

### Listing records

Sagi-shi players can list tournament records:

```dart
const limit = 20;
const tournamentName = "weekly_top_detective";
final result = await client.listTournamentRecords(
    session: session,
    tournamentId: tournamentName,
    ownerIds: null,
    expiry: null,
    limit: limit,
    cursor: null,
);

for (var record in result.records) {
    print('${record.ownerId}:${record.score}');
}
```


**Listing records around a user**

Similarly to leaderboards, Sagi-shi players can get other player scores around them:

```dart
const limit = 20;
const tournamentName = 'weekly_top_detective';

final result = await client.listTournamentRecordsAroundOwner(
    session: session,
    tournamentId: tournamentName,
    ownerId: session.userId,
    expiry: null,
    limit: limit,
);

for (var record in result.records) {
    print('${record.ownerId}:${record.score}');
}
```


### Submitting scores

Sagi-shi players can submit scores, subscores and metadata to the tournament:

```dart
const score = 1;
const subscore = 0;
final metadata = {'map': 'space_station'};

await client.writeTournamentRecord(
    session: session,
    tournamentId: 'weekly_top_detective',
    score: score,
    subscore: subscore,
    metadata: jsonEncode(metadata),
);
```


## Notifications

Nakama [Notifications](../../concepts/notifications/) can be used for the game backend to broadcast real-time messages to players.

Notifications can be either persistent (remaining until a player has viewed it) or transient (received only if the player is currently online).

Sagi-shi uses Notifications to notify tournament winners about their winnings.

<figure>
  <img src={{< fingerprint_image "/images/pages/nakama/client-libraries/notifications.png" >}} alt="Sagi-shi notification screen">
  <figcaption>Sagi-shi notifications</figcaption>
</figure>


### Receiving notifications

Notifications have to be sent from the server.

Nakama uses a code to differentiate notifications. Codes of `0` and below are [system reserved](../../concepts/notifications/#notification-codes) for Nakama internals.

Sagi-shi players can subscribe to the notification received event. Sagi-shi uses a code of `100` for tournament winnings:

```dart
socket.onNotifications.listen((notification) {
    const int rewardCode = 100;

    switch (notification.code) {
        case rewardCode:
            print(
                'Congratulations, you won the tournament!\n${notification.subject}\n${notification.content}');
            break;
        default:
            print('Other notification: ${notification.code}:${notification.subject}\n${notification.content}');
            break;
    }
});
```


### Listing notifications

Sagi-shi players can list the notifications they received while offline:

```dart
const limit = 100;
final result = await client.listNotifications(
    session: session,
    limit: limit,
    cursor: null,
);

for (var notification in result.notifications) {
    print('Notification: ${notification.code}:${notification.subject}\n${notification.content}');
}
```


**Pagination and cacheable cursors**

Like other listing methods, notification results can be paginated using a cursor or cacheable cursor from the result.

```dart
prefs.setString('nakama.notificationsCacheableCursor', result.cursor);
```

The next time the player logs in the cacheable cursor can be used to list unread notifications.

```dart
final cacheableCursor = prefs.getString('nakama.notificationsCacheableCursor');
final nextResults = await client.listNotifications(
    session: session,
    limit: limit,
    cursor: cacheableCursor,
);
```


### Deleting notifications

Sagi-shi players can delete notifications once they've read them:

```dart
await client.celeteNotifications(
    session: session,
    notificationIds: ['<NotificationId>'],
);
```