# rudder.build/server

The game server of Rudder for Go. It calls the functions of the modules of a project for a player
the game server names, and it updates the profile of a player, its ban and the environment of
the key. It uses the standard library only.

## Install

```sh
go get rudder.build/server@v1.0.0
```

The module path is resolved through the `go-import` meta tag of `rudder.build/server`; set
`GOPRIVATE=rudder.build` (or `GONOSUMDB`/`GONOSUMCHECK`) so the Go command fetches it from the
Rudder Gitea instead of the public proxy.

## Generate the client

In the Go module of the game server, where `rudder project use` chose the project:

```sh
rudder server generate --lang go --output ./rudderclient --package rudderclient \
  [--game-address https://api.rudder.build] [--environment staging|prod]
```

The client follows the newest release of the environment, staging by default. It writes a
package with a `Client` and one subpackage per module (`stores`, `battlepass`), a method per
function, the functions marked `server` included, and the types of their arguments and results.
Every method names the player first. Generate it again when a release changes the functions or
their types.

## Use

```go
import (
	"context"

	"game/rudderclient"
	"rudder.build/server"
)

client := rudderclient.New(server.Options{ServerKey: serverKey})

environment, err := client.Server.Environment(ctx)
purchase, err := client.Stores.Buy(ctx, playerID, rudderclient.StoresBuyArguments{Offer: "pumpkin-pack"}, nil)

err = client.Server.SetPlayerProfile(ctx, playerID, server.Profile{Nickname: "Ada", Avatar: "https://example.com/ada.png"})
err = client.Server.BanPlayer(ctx, playerID, server.Ban{Until: time.Date(2026, 12, 1, 0, 0, 0, 0, time.UTC), Reason: "cheating"})
err = client.Server.UnbanPlayer(ctx, playerID)
```

The generated root `Client` holds `Server *server.Client` and a client per module; `New` takes
`server.Options` (`ServerKey`, `Address`, `Attempts`, `HTTPClient`).

- **Environment.** `client.Server.Environment(ctx)` answers `staging` or `prod`, the environment
  of the server key. The header of the generated files names the environment they were generated
  from, which can be another one.
- **Calls.** A query reads and a mutation changes data, for the player id the method names
  first. A mutation sends an `Idempotency-Key`, generated for each call unless
  `server.MutationOptions{IdempotencyKey: ...}` is passed. A banned player is refused to the game
  client only.
- **Profile and ban.** `SetPlayerProfile` replaces the nickname and the avatar, `BanPlayer` bans
  until the moment given, `UnbanPlayer` lifts it.
- **Errors.** A refused call answers `*server.Error` with `Code`, `Message` and `Status`; use
  `errors.As` to read it.
- **Retries.** A request that got no answer or the answer `try_again` is sent again after the
  `Retry-After` it gave or a short backoff, at most `Attempts` times (5), with the same
  idempotency key. 429 is not retried. Pass `context.Context` to cancel.