Using Hooks #

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initializer.RegisterBeforeCreateGroup(func(ctx context.Context, logger runtime.Logger, db *sql.DB, nk runtime.NakamaModule, in *api.CreateGroupRequest) (*api.CreateGroupRequest, error) {
  if containsProfanity(in.Name) {
    return nil, runtime.NewError("profanity detected", 3)
  }
  
  return in, nil
})

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initializer.RegisterBeforeDeleteGroup(func(ctx context.Context, logger runtime.Logger, db *sql.DB, nk runtime.NakamaModule, in *api.DeleteGroupRequest) (*api.DeleteGroupRequest, error) {
  groupUsers, _, err := nk.GroupUsersList(ctx, in.GroupId, 100, nil, "")
  if err != nil {
    return nil, runtime.NewError("error retrieving group users", 13)
  }

  if len(groupUsers) > 1 {
    return nil, runtime.NewError("group still has users", 9)
  }
  
  return in, nil
})

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initializer.RegisterAfterAddFriends(func(ctx context.Context, logger runtime.Logger, db *sql.DB, nk runtime.NakamaModule, in *api.AddFriendsRequest) error {
  username, ok := ctx.Value(runtime.RUNTIME_CTX_USERNAME).(string)
  if !ok {
    return runtime.NewError("error getting username", 13)
  }
  
  for _, friendId := range in.Ids {
    content := map[string]interface{} {
      "message": fmt.Sprintf("You have received a friend request from %s", username),
    }
    
    nk.NotificationSend(ctx, friendId, "Friend Request Received", content, 1, nil, true)
  }
  
  return nil
})

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initializer.RegisterAfterLeaveGroup(func(ctx context.Context, logger runtime.Logger, db *sql.DB, nk runtime.NakamaModule, in *api.LeaveGroupRequest) error {
  username, ok := ctx.Value(runtime.RUNTIME_CTX_USERNAME).(string)
  if !ok {
    return runtime.NewError("error getting username", 13)
  }
  
  channelId, err := nk.ChannelIdBuild(ctx, nil, in.GroupId, runtime.Group)
  if err != nil {
    return runtime.NewError("error getting channel id", 13)
  }
  
  content := map[string]interface{}{
    "message": fmt.Sprintf("%s left the group.", username),
  }
  
  nk.ChannelMessageSend(ctx, channelId, content, nil, nil, true)
  return nil
})

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initializer.RegisterAfterAuthenticateDevice(func(ctx context.Context, logger runtime.Logger, db *sql.DB, nk runtime.NakamaModule, out *api.Session, in *api.AuthenticateDeviceRequest) error {
  // Give the player 10 coins for logging in
  userId, ok := ctx.Value(runtime.RUNTIME_CTX_USER_ID).(string)
  if !ok {
    return runtime.NewError("error getting userId", 13)
  }
  
  changeset := map[string]int64{
    "coins": 10,
  }
  
  nk.WalletUpdate(ctx, userId, changeset, nil, true)
  return nil
})

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initializer.RegisterLeaderboardReset(func(ctx context.Context, logger runtime.Logger, db *sql.DB, nk runtime.NakamaModule, leaderboard *api.Leaderboard, reset int64) error {
  // Reward top 3 players with 1,000 coins and send them a notification telling them what their rank was
  topRecords, _, _, _, err := nk.LeaderboardRecordsList(ctx, leaderboard.Id, nil, 3, "", 0)
  if err != nil {
    return runtime.NewError("error getting leaderboard records", 13)
  }

  for _, record := range topRecords {
    changeset := map[string]int64 {
      "coins": 1000,
    }
    
    content := map[string]interface{} {
      "message": fmt.Sprintf("Well done, you ranked %d!", record.Rank),
    }
    
    nk.WalletUpdate(ctx, record.OwnerId, changeset, nil, true)
    nk.NotificationSend(ctx, record.OwnerId, "Congratulations", content, 2, "", true)
  }
  
  return nil
})

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initializer.RegisterTournamentEnd(func(ctx context.Context, logger runtime.Logger, db *sql.DB, nk runtime.NakamaModule, tournament *api.Tournament, end, reset int64) error {
  // Reward tournament leader with 10,000 coins and a rare item
  topRecord, _, _, _, err := nk.TournamentRecordsList(ctx, tournament.Id, nil, 1, "", 0)
  if err != nil {
    return runtime.NewError("error getting tournament records", 13)
  }

  winnerId := topRecord[0].OwnerId

  // Give the player 10,000 coins
  changeset := map[string]int64 {
    "coins": 10000,
  }
  nk.WalletUpdate(ctx, winnerId, changeset, nil, true)

  // Get the player's existing inventory
  storageRead := &runtime.StorageRead{
    Collection: "inventory",
    Key: winnerId,
    UserID: winnerId,
  }

  result, err := nk.StorageRead(ctx, []*runtime.StorageRead { storageRead })
  if err != nil {
    return runtime.NewError("error reading player inventory", 13)
  }

  var inventory map[string]int

  if len(result) > 0 {
    if err := json.Unmarshal([]byte(result[0].Value), &inventory); err != nil {
      logger.Error("error unmarshaling inventory", err)
      return runtime.NewError("error unmarshaling inventory", 13)
    }
  } else {
    inventory = make(map[string]int)
  }

  // Add the rare item or increase quantity
  if _, ok := inventory["rare-sword"]; !ok {
    inventory["rare-sword"] = 1
  } else {
    inventory["rare-sword"] += 1
  }
  
  // Write the updated inventory to the storage engine
  inventoryJson, err := json.Marshal(inventory)
  if err != nil {
    return runtime.NewError("error marshaling inventory", 13)
  }
  
  storageWrite := &runtime.StorageWrite{
    Collection: "inventory",
    Key: winnerId,
    UserID: winnerId,
    PermissionWrite: 0,
    PermissionRead: 1,
    Value: string(inventoryJson),
  }
  
  _, err = nk.StorageWrite(ctx, []*runtime.StorageWrite { storageWrite })
  if err != nil {
    return runtime.NewError("error writing inventory", 13)
  }

  return nil
})

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initializer.RegisterBeforeRt("ChannelJoin", func(ctx context.Context, logger runtime.Logger, db *sql.DB, nk runtime.NakamaModule, in *rtapi.Envelope) (*rtapi.Envelope, error) {
  envelope, ok := in.Message.(*rtapi.Envelope_ChannelJoin)
  if !ok {
    return nil, runtime.NewError("error getting envelope as ChannelJoin envelope", 13)
  }

  userId, ok := ctx.Value(runtime.RUNTIME_CTX_USER_ID).(string)
  if !ok {
    return nil, runtime.NewError("error getting userId", 13)
  }

  // If the channel join is a DirectMessage type, check to see if the user is friends with the recipient first
  if envelope.ChannelJoin.Type == 2 {
    state := 0
    friends, _, err := nk.FriendsList(ctx, userId, 100, &state, "")
    if err != nil {
      return nil, runtime.NewError("error getting friends list", 13)
    }

    isFriends := false
    for _, friend := range friends {
      if friend.User.Id == envelope.ChannelJoin.Target {
        isFriends = true
        break
      }
    }

    if !isFriends {
      return nil, runtime.NewError("you cannot direct message someone you are not friends with.", 9)
    }
  }

  return in, nil
})

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initializer.RegisterAfterRt("ChannelLeave", func(ctx context.Context, logger runtime.Logger, db *sql.DB, nk runtime.NakamaModule, out, in *rtapi.Envelope) error {
  envelope, ok := in.Message.(*rtapi.Envelope_ChannelLeave)
  if !ok {
    return runtime.NewError("error getting envelope as ChannelLeave envelope", 13)
  }

  userId, ok := ctx.Value(runtime.RUNTIME_CTX_USER_ID).(string)
  if !ok {
    return runtime.NewError("error getting userId", 13)
  }

  // Send a message to the channel after leaving, notifying others that the user left
  content := map[string]interface{}{
    "message": fmt.Sprintf("%s left the channel.", userId),
  }

  nk.ChannelMessageSend(ctx, envelope.ChannelLeave.ChannelId, content, "", "", true)

  return nil
})