### Configure Server Settings via JSON

Source: https://github.com/movingblocks/terasology/blob/develop/docs/Playing.md

An example JSON configuration file for a headless server. This allows setting default modules, world generation parameters, and other server-specific configurations. Changes in `config.cfg` take priority after initial setup.

```json
{
  "defaultModSelection": {
    "modules": [
      "MyModule",
      "MyModule2"
    ],
    "defaultGameplayModuleName": "MyModule"
  },
  "worldGeneration": {
    "worldTitle": "World Title",
    "defaultSeed": "custom seed for the server",
    "defaultGenerator": "MyModule:MyWorldgen"
  },
  "moduleConfigs": {},
}
```

--------------------------------

### Example Module Configuration

Source: https://github.com/movingblocks/terasology/wiki/Module.txt

This is an example of a Module.txt file, showing the structure for defining a module's metadata, dependencies, and type.

```JSON
{
    "id" : "CoreSampleGameplay",
    "version" : "2.0.0-SNAPSHOT",
    "displayName" : "Core Gameplay",
    "description" : "Minimal gameplay template. Little content but a few starting items.",
    "dependencies" : [
        {"id": "Core", "minVersion": "2.0.0"}
    ],
    "isGameplay" : "true",
    "defaultWorldGenerator" : "Core:FacetedPerlin"
}
```

--------------------------------

### Test Replay Start Logic

Source: https://github.com/movingblocks/terasology/blob/develop/docs/Replay-Tests.md

Implement checks for the start of a replay, verifying player character and initial position.

```java
@Override
    protected void testOnReplayStart() throws Exception {
        LocalPlayer localPlayer = CoreRegistry.get(LocalPlayer.class);
        TestUtils.waitUntil(() -> localPlayer.isValid());
        character = localPlayer.getCharacterEntity();
        initialPosition = new Vector3f(19.79358f, 13.511584f, 2.3982882f);
        LocationComponent location = character.getComponent(LocationComponent.class);
        assertEquals(initialPosition, location.getLocalPosition()); // check initial position.

    }
```

--------------------------------

### Dependency Report Example

Source: https://github.com/movingblocks/terasology/blob/develop/docs/Using-Locally-Developed-Libraries.md

An example entry in the dependency report showing a dependency resolved from a local project.

```text
org.terasology:gestalt-module:5.1.5 ➡ project :gestalt:gestalt-module
```

--------------------------------

### Initialize and Run Replay in a Separate Thread

Source: https://github.com/movingblocks/terasology/wiki/Replay-Tests

Initializes ReplayTestingEnvironment and starts a new thread to open a replay. The replay title is specified, and it can be run headless. This setup allows for testing in the main thread while the replay executes concurrently.

```Java
private ReplayTestingEnvironment environment = new ReplayTestingEnvironment();
 
    /** To test the replay while it is executing, it is necessary to create a thread that will run the replay. */
    private Thread replayThread = new Thread() {

        @Override
        public void run() {
            try {
                //This is the title of the replay to be played. It is generally the name of the folder in the 'recordings' directory.
                String replayTitle = "REPLAY_TITLE";

                /*
                This opens the game and executes the replay desired for testing. The first parameter of the "openReplay" 
 method is the replay title,
                and the second one is if the replay should be headless.
                 */
                environment.openReplay(replayTitle, true);
            } catch (Exception e) {
                throw new RuntimeException(e);
            }
        }
    };
```

--------------------------------

### Get Facade Server

Source: https://github.com/movingblocks/terasology/wiki/Codebase-Structure

Use this command to get the FacadeServer.

```groovy
groovyw facade get FacadeServer
```

--------------------------------

### Prefab Inheritance Example

Source: https://github.com/movingblocks/terasology/wiki/Entity-System-Architecture

Demonstrates prefab inheritance by creating an 'angryGelatinousCube' that inherits from 'core:gelatinousCube' and modifies the movement speed.

```json
{
  "name": "core:angryGelatinousCube",
  "parent": "core:gelatinousCube",
  "CharacterMovement": {
    "speedMultiplier": 0.3
  }
}
```

--------------------------------

### Example Client ID List

Source: https://github.com/movingblocks/terasology/blob/develop/docs/Playing.md

Client IDs are added to the allowlist and denylist in JSON format. This example shows a list of two client IDs.

```json
["6a5f11f7-4038-4ef0-91ac-86cb957588b1","01264d12-27cf-4699-b8e2-bdc92ac8ef73"]
```

--------------------------------

### Java Naming Conventions Example

Source: https://github.com/movingblocks/terasology/wiki/Code-Conventions

Demonstrates standard Java naming conventions for packages, classes, constants, and methods. Adheres to camelCase and PascalCase as specified.

```java
package test;

class TestClass {
    private static final int SOME_CONSTANT = 0;

    int someInt;

    void doSomething() {
    }
}
```

--------------------------------

### Initialize a New Module

Source: https://github.com/movingblocks/terasology/wiki/Terasology's-Multi-Repo-Workspace

Use this command to initialize a new module within your workspace, cloning its repository into the 'modules' directory. This is useful for starting a new module or adding an existing one.

```bash
groovyw module init <distro>
```

--------------------------------

### JavaFX Installation on Arch/Gentoo

Source: https://github.com/movingblocks/terasology/blob/develop/docs/Troubleshooting-Developer.md

Arch and Gentoo do not include JavaFX by default. Install the `java-openjfx` package on Arch or enable the `javafx` USE flag on Gentoo.

```text
java-openjfx
```

--------------------------------

### Blog Post Metadata Example

Source: https://github.com/movingblocks/terasology/wiki/Outreach

This is the required metadata section for a blog post in `index.md`. Ensure all fields are correctly filled.

```markdown
---
posttype: "blog"
title: <title>
cover: "./<cover-image-name>.jpg"
description: <summary>
author: <your-nickname>
date: "YYYY-MM-DD"
tags: [<tag-list>]
---
```

--------------------------------

### Compile and Start Terasology (Command Line)

Source: https://github.com/movingblocks/terasology/wiki/Contributor-Quick-Start

Execute this command in your terminal to compile the Terasology project and launch the game. This is one of the primary ways to run the game during development.

```bash
gradlew game
```

--------------------------------

### Get a Specific Module

Source: https://github.com/movingblocks/terasology/wiki/Terasology's-Multi-Repo-Workspace

Use this command to fetch and clone a specific module's repository into your 'modules' directory. This is the simplest way to add a single module to your workspace.

```bash
groovyw module get <module>
```

--------------------------------

### Declare Gooey Module Dependency with Max Version

Source: https://github.com/movingblocks/terasology/wiki/Module-Dependencies

This example shows how to specify a dependency with both a minimum and maximum version, effectively defining a version range like `0.54.*`.

```json
    "dependencies" : [
            {
                "id" : "Gooey",
                "minVersion" : "0.54.0",
                "maxVersion" : "0.55.0"
            }
    ],
```

--------------------------------

### Run Headless Server with Java

Source: https://github.com/movingblocks/terasology/wiki/Setup-a-headless-server

Execute the Terasology server in headless mode using a Java 11 JAR file. This will start the server on the default port 25777.

```bash
java -jar Terasology.jar --headless
```

--------------------------------

### Initialize Module Foundation

Source: https://github.com/movingblocks/terasology/wiki/Contributor-Quick-Start

Use this command to fetch the core module foundation for your workspace. This is a necessary step after cloning the repository.

```bash
groovyw module init iota
```

--------------------------------

### Create New Facade

Source: https://github.com/movingblocks/terasology/wiki/Codebase-Structure

Use this command to create a new facade, initializing it with template files and a Git repository.

```groovy
groovyw facade create DevFacade
```

--------------------------------

### PC Facade CLI Help

Source: https://github.com/movingblocks/terasology/blob/develop/facades/PC/README.md

Displays the help information for the Terasology command-line interface, detailing available options for configuration and startup.

```sh
./Terasology --help

Usage: terasology [-h] [--[no-]crash-report] [--create-last-game] [--headless] [--load-last-game] [--permissive-security] [--[no-]save-games] [--[no-]sound]
                  [--[no-]splash] [--homedir=<homeDir>] [--max-data-size=<size>] [--oom-score=<score>] [--override-default-config=<overrideConfigPath>]
                  [--server-port=<serverPort>]
                  
      --[no-]crash-report   Enable crash reporting
      --create-last-game    Recreates the world of the latest game with a new save file on startup
      -h, /h, -?, /?, -help, /help, --help
                            Show help
      --headless            Start headless (no graphics)
      --homedir=<homeDir>   Path to home directory
      --load-last-game      Load the latest game on startup
      --max-data-size=<size>
                            Set maximum process data size [Linux only]
      --oom-score=<score>   Adjust out-of-memory score [Linux only]
      --override-default-config=<overrideConfigPath>
                            Override default config
      --permissive-security
      --[no-]save-games     Enable new save games
      --server-port=<serverPort>
                            Change the server port
      --[no-]sound          Enable sound
      --[no-]splash         Enable splash screen

For details, see
 https://github.com/MovingBlocks/Terasology/wiki/Advanced-Options

Alternatively use our standalone Launcher from
 https://github.com/MovingBlocks/TerasologyLauncher/releases

```

--------------------------------

### Create New Module

Source: https://github.com/movingblocks/terasology/wiki/Codebase-Structure

Creates a brand new module and initializes it with template content and a local Git repository.

```groovy
groovyw module create MyNewModule
```

--------------------------------

### Install Java OpenJFX on Arch Linux

Source: https://github.com/movingblocks/terasology/wiki/Troubleshooting-Developer

Arch Linux does not include JavaFX by default. Install the `java-openjfx` package to resolve this.

```bash
sudo pacman -Syu java-openjfx
```

--------------------------------

### Clone Terasology Engine Repository

Source: https://github.com/movingblocks/terasology/wiki/Codebase-Structure

This command is used to clone the primary Terasology engine repository, which is the starting point for the project.

```bash
git clone https://github.com/MovingBlocks/Terasology.git
```

--------------------------------

### Create a New Module

Source: https://github.com/movingblocks/terasology/wiki/Developing-Modules

This command initializes a new module within your workspace. The new module will be created in the 'modules/' directory with the specified name. For Linux-like systems, use './groovyw'.

```bash
groovyw module create MySample
```

--------------------------------

### Clean IntelliJ Project Configuration

Source: https://github.com/movingblocks/terasology/wiki/Troubleshooting-Developer

Command to remove IntelliJ configuration files from the workspace, useful for resetting a buggy IntelliJ setup.

```bash
gradlew cleanIdea
```

--------------------------------

### Get TeraNUI Library Source

Source: https://github.com/movingblocks/terasology/blob/develop/docs/Using-Locally-Developed-Libraries.md

Fetches the TeraNUI source code into the local Terasology workspace for development. This command places the source into `/libs/TeraNUI`.

```shell
groovyw lib get TeraNUI
```

--------------------------------

### Update an Existing Module

Source: https://github.com/movingblocks/terasology/wiki/Developing-Modules

Run this command to synchronize your local module with the latest changes from its main repository. Replace 'Sample' with the name of the module you are working on.

```bash
groovyw module update Sample
```

--------------------------------

### Implement BooleanTypeHandler

Source: https://github.com/movingblocks/terasology/blob/develop/subsystems/TypeHandlerLibrary/README.MD

Example of implementing a `TypeHandler` for the `Boolean` type. This handler serializes booleans using the provided serializer and deserializes them by checking if the data is a boolean.

```java
public class BooleanTypeHandler extends TypeHandler<Boolean> {

    @Override
    public PersistedData serializeNonNull(Boolean value, PersistedDataSerializer serializer) {
        return serializer.serialize(value);
    }

    @Override
    public Optional<Boolean> deserialize(PersistedData data) {
        if (data.isBoolean()) {
            return Optional.of(data.getAsBoolean());
        }
        return Optional.empty();
    }

}
```

--------------------------------

### Non-Guarded Log Statement Example

Source: https://github.com/movingblocks/terasology/blob/develop/docs/Code-Conventions.md

This Java code demonstrates a log statement that is not guarded, leading to unnecessary string creation and manipulation even if logging is disabled.

```java
logger.debug("log something" + method() + " and " + param.toString() + "concat strings");
```

--------------------------------

### Fetch an Existing Module

Source: https://github.com/movingblocks/terasology/wiki/Developing-Modules

Use this command to download an existing module from a remote repository into your local workspace. Ensure you are in the root of your workspace. For Linux-like systems, use './groovyw'.

```bash
groovyw module get Sample
```

--------------------------------

### Chest Item Slots with @Replicate and @Owns

Source: https://github.com/movingblocks/terasology/wiki/Entities,-Components-and-Events-on-the-Network

Example of an InventoryComponent field for chest items, using @Replicate to ensure server-to-client synchronization and @Owns for ownership replication.

```java
@Replicate
@Owns
public List<EntityRef> itemSlots = Lists.newArrayList();
```

--------------------------------

### Replay Test Methods using AcceptanceTestEnvironment

Source: https://github.com/movingblocks/terasology/wiki/Replay-Tests

Implement these methods to define checks at different stages of a replay: start, during, and end. Use TestUtils.waitUntil for synchronization during replay.

```java
@Override
    protected void testOnReplayStart() throws Exception {
        LocalPlayer localPlayer = CoreRegistry.get(LocalPlayer.class);
        TestUtils.waitUntil(() -> localPlayer.isValid());
        character = localPlayer.getCharacterEntity();
        initialPosition = new Vector3f(19.79358f, 13.511584f, 2.3982882f);
        LocationComponent location = character.getComponent(LocationComponent.class);
        assertEquals(initialPosition, location.getLocalPosition()); // check initial position.

    }

    @Override
    protected void testDuringReplay() throws Exception {
        EventSystemReplayImpl eventSystem = (EventSystemReplayImpl) CoreRegistry.get(EventSystem.class);
        TestUtils.waitUntil(() -> eventSystem.getLastRecordedEventIndex() >= 1810); // tests in the middle of a replay needs "checkpoints" like this.
        LocationComponent location = character.getComponent(LocationComponent.class);
        assertNotEquals(initialPosition, location.getLocalPosition()); // checks that the player is not on the initial position after they moved.
    }

    @Override
    protected void testOnReplayEnd() throws Exception {
        LocationComponent location = character.getComponent(LocationComponent.class);
        Vector3f finalPosition = new Vector3f(25.189344f, 13.406443f, 8.6651945f);
        assertEquals(finalPosition, location.getLocalPosition()); // checks final position
    }
```

--------------------------------

### Fetch Additional Modules and Dependencies

Source: https://github.com/movingblocks/terasology/wiki/Contributor-Quick-Start

Use this command to recursively fetch a specified module and all of its dependencies. This is useful when you want to work with specific modules or their features.

```bash
groovyw module recurse <module>
```

--------------------------------

### Basic Command Implementation

Source: https://github.com/movingblocks/terasology/blob/develop/docs/Developing-Commands.md

Implement a simple console command by creating an annotated method within a ComponentSystem. Returned strings are displayed in the console.

```java
import org.terasology.logic.console.commands.Command;
import org.terasology.logic.console.commands.RegisterSystem;
import org.terasology.logic.core.ComponentSystem;

@RegisterSystem
public class MyCommands extends BaseComponentSystem {

    @Command( shortDescription = "Say hello", helpText = "Writes hello world to the console" )
    public String hello() {
        return "hello world";
    }
}
```

--------------------------------

### Event Processing Method Example

Source: https://github.com/movingblocks/terasology/blob/develop/docs/Events-and-Systems.md

This method is called when an OnAddedComponent event occurs on an entity that has both MyComponent and LocationComponent. The parameters are automatically populated with the event, entity, and the specified components.

```java
import org.terasology.entitySystem.event.Event;
import org.terasology.entitySystem.entity.EntityRef;
import org.terasology.entitySystem.systems.RegisterSystem;
import org.terasology.entitySystem.systems.BaseComponentSystem;
import org.terasology.entitySystem.components.ReceiveEvent;
import org.terasology.logic.location.LocationComponent;

@RegisterSystem
public class MySystem extends BaseComponentSystem {

    @ReceiveEvent(components = {MyComponent.class, LocationComponent.class})
    public void onMyComponentAdded(OnAddedComponent event, EntityRef entity, MyComponent myComponent) {
        // Method logic here
    }

    // Other system methods...
}

// Dummy component for example purposes
class MyComponent {
    // Component fields and methods
}

// Dummy event for example purposes
class OnAddedComponent implements Event {
    // Event fields and methods
}
```

--------------------------------

### Run Headless Server from Source

Source: https://github.com/movingblocks/terasology/wiki/Setup-a-headless-server

Compile and run the Terasology server in headless mode directly from the source code using Gradle.

```bash
gradlew server
```

--------------------------------

### Fetch Module and Dependencies

Source: https://github.com/movingblocks/terasology/wiki/Codebase-Structure

Fetches a specified module and all of its dependencies as source code.

```groovy
groovyw module recurse JoshariasSurvival
```

--------------------------------

### Basic Command Implementation

Source: https://github.com/movingblocks/terasology/wiki/Developing-Commands

Implement a simple command that returns a string. The command method must be in a ComponentSystem class and annotated with @Command.

```java
import org.terasology.gestalt.entitysystem.component.ComponentSystem;
import org.terasology.context.annotation.RegisterSystem;
import org.terasology.logic.console.annotations.Command;

@RegisterSystem
public class MyCommands extends BaseComponentSystem {

    @Command( shortDescription = "Say hello", helpText = "Writes hello world to the console" )
    public String hello() {
        return "hello world";
    }
}
```