> For the complete documentation index, see [llms.txt](https://foxhut.gitbook.io/lamp-docs/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://foxhut.gitbook.io/lamp-docs/platforms/geyser.md).
# Geyser
This page describes how to integrate Lamp with Geyser extensions, as well as what to expect out of it.
## Setting up
### Adding Lamp dependency
To add Lamp to your extension, add the following (depending on your project structure):
{% tabs %}
{% tab title="pom.xml" %}
```markup
io.github.revxrsal
lamp.common
[VERSION]
io.github.revxrsal
lamp.geyser
[VERSION]
```
{% endtab %}
{% tab title="build.gradle" %}
```groovy
dependencies {
// Required for all platforms
implementation 'io.github.revxrsal:lamp.common:[VERSION]'
// Geyser module
implementation 'io.github.revxrsal:lamp.geyser:[VERSION]'
}
```
{% endtab %}
{% tab title="build.gradle.kts" %}
```kotlin
dependencies {
// Required for all platforms
implementation("io.github.revxrsal:lamp.common:[VERSION]")
// Geyser module
implementation("io.github.revxrsal:lamp.geyser:[VERSION]")
}
```
{% endtab %}
{% endtabs %}
Latest version: 
The Geyser module requires Java 21.
#### Optional: Preserve parameter names
Lamp identifies parameters by their names and uses them to generate relevant command metadata. By default, Java does not preserve parameter names reflectively. You need to add the following to your project:
{% tabs %}
{% tab title="pom.xml" %}
```markup
org.apache.maven.plugins
maven-compiler-plugin
3.8.0
-parameters
```
{% endtab %}
{% tab title="build.gradle" %}
```groovy
compileJava {
// Preserve parameter names in the bytecode
options.compilerArgs += ["-parameters"]
}
// optional: if you're using Kotlin
compileKotlin {
kotlinOptions.javaParameters = true
}
```
{% endtab %}
{% tab title="build.gradle.kts" %}
```kotlin
tasks.withType {
// Preserve parameter names in the bytecode
options.compilerArgs.add("-parameters")
}
// optional: if you're using Kotlin
tasks.withType {
compilerOptions {
javaParameters = true
}
}
```
{% endtab %}
{% endtabs %}
## Registering commands
Geyser only accepts commands while it fires `GeyserDefineCommandsEvent`. Therefore, you must create Lamp and register **all** your commands before that, in the `GeyserPreInitializeEvent`:
```java
@Subscribe
public void onPreInitialize(GeyserPreInitializeEvent event) {
Lamp lamp = GeyserLamp.builder(this).build();
lamp.register(new MyCommands());
}
```
Registering a command after Geyser has defined its commands throws an exception.
## Geyser-specific annotations
### `@CommandPermission`
Adds a command permission for the given command.
### `@BedrockOnly`
Marks the command as only executable by Bedrock players. This is implied when the first parameter of the command is a `GeyserConnection` or a `GeyserPlayerEntity`.
### `@PlayerOnly`
Marks the command as only executable by players, either Java or Bedrock.
## How commands appear in Geyser
Geyser knows commands by their first word (e.g. `/game` for `/game arena create`), and allows a single permission per command. Lamp maps your commands as follows:
* If all commands under the same name share one `@CommandPermission`, it is given to Geyser. Otherwise, Lamp checks each command's permission when it is executed.
* If all commands under the same name are `@BedrockOnly` (or `@PlayerOnly`), Geyser rejects the others before the command reaches Lamp.
* The description is the first `@Description` among them.
## Supported Geyser types
### Sender types
When they come first in a command, these are resolved from the command sender:
* `org.geysermc.geyser.api.command.CommandSource`, in place of `GeyserCommandActor`
* `org.geysermc.geyser.api.connection.GeyserConnection`, for Bedrock players only
* `org.geysermc.geyser.api.entity.type.player.GeyserPlayerEntity`, for Bedrock players only
### Parameter types
* `GeyserConnection` and `GeyserPlayerEntity`, by the name of an online Bedrock player. `me`, `self` and `@s` refer to the sender.
### Context parameters
* Your `Extension`, using its interface or its class. It is also available as a dependency through `@Dependency`.
## Messages
`actor.reply(...)` and `actor.error(...)` accept ampersand color codes, such as `&a`.
## Example
{% tabs %}
{% tab title="Java" %}
```java
public class MyExtension implements Extension {
@Subscribe
public void onPreInitialize(GeyserPreInitializeEvent event) {
Lamp lamp = GeyserLamp.builder(this).build();
lamp.register(new MyCommands());
// register all your commands here
lamp.register(...);
}
public static class MyCommands {
@Command("hello")
@CommandPermission("myextension.hello")
public void hello(GeyserCommandActor actor) {
actor.reply("&aHello!");
}
@Command("whoami")
public void whoami(GeyserConnection sender) {
// Bedrock players only, as the sender is a GeyserConnection
...
}
@Command("wave")
public void wave(GeyserCommandActor actor, GeyserConnection target) {
actor.reply("You waved at " + target.name());
}
}
}
```
{% endtab %}
{% tab title="Kotlin" %}
```kotlin
class MyExtension : Extension {
@Subscribe
fun onPreInitialize(event: GeyserPreInitializeEvent) {
val lamp = GeyserLamp.builder(this).build()
lamp.register(MyCommands())
// register all your commands here
lamp.register(...)
}
class MyCommands {
@Command("hello")
@CommandPermission("myextension.hello")
fun hello(actor: GeyserCommandActor) {
actor.reply("&aHello!")
}
@Command("whoami")
fun whoami(sender: GeyserConnection) {
// Bedrock players only, as the sender is a GeyserConnection
...
}
@Command("wave")
fun wave(actor: GeyserCommandActor, target: GeyserConnection) {
actor.reply("You waved at ${target.name()}")
}
}
}
```
{% endtab %}
{% endtabs %}