Added config options!

README.md

@@ -1,3 +1,5 @@
 # Speed Carts
 
 This mod adds the ability to control minecarts with signs.
+
+All you need to do is place a sign beside the rail, and put a number on the first line of the sign that indicates the desired speed of carts, in meters per second.

build.gradle

@@ -27,8 +27,14 @@ dependencies {
 	// Fabric API. This is technically optional, but you probably want it anyway.
 	modImplementation "net.fabricmc.fabric-api:fabric-api:${project.fabric_version}"
 
-	// PSA: Some older mods, compiled on Loom 0.2.1, might have outdated Maven POMs.
-	// You may need to force-disable transitiveness on them.
+	// Jackson API for config file parsing.
+	implementation group: 'com.fasterxml.jackson.dataformat', name: 'jackson-dataformat-yaml', version: '2.12.4'
+	include group: 'com.fasterxml.jackson.dataformat', name: 'jackson-dataformat-yaml', version: '2.12.4'
+	// Include Jackson dependencies since include directive is not transitive:
+	include group: 'org.yaml', name: 'snakeyaml', version: '1.27'
+	include group: 'com.fasterxml.jackson.core', name: 'jackson-databind', version: '2.12.4'
+	include group: 'com.fasterxml.jackson.core', name: 'jackson-annotations', version: '2.12.4'
+	include group: 'com.fasterxml.jackson.core', name: 'jackson-core', version: '2.12.4'
 }
 
 processResources {

gradle.properties

@@ -8,7 +8,7 @@ org.gradle.jvmargs=-Xmx1G
 	loader_version=0.11.6
 
 # Mod Properties
-	mod_version = 1.0.0
+	mod_version = 1.1.0
 	maven_group = nl.andrewlalis
 	archives_base_name = speed-carts
 

src/main/java/nl/andrewlalis/speed_carts/Config.java

@@ -0,0 +1,65 @@
+package nl.andrewlalis.speed_carts;
+
+import com.fasterxml.jackson.databind.JsonNode;
+import com.fasterxml.jackson.databind.ObjectMapper;
+import com.fasterxml.jackson.dataformat.yaml.YAMLFactory;
+
+import java.io.IOException;
+import java.io.UncheckedIOException;
+import java.nio.file.Files;
+import java.nio.file.Path;
+
+/**
+ * Contains all configuration options and the logic for loading config.
+ */
+public class Config {
+	private static final Path CONFIG_FILE = Path.of("config", "speed_carts.yaml");
+
+	private final double defaultSpeed;
+	private final double minimumSpeed;
+	private final double maximumSpeed;
+	private final String signRegex;
+
+	public Config() {
+		try {
+			this.ensureConfigExists();
+			ObjectMapper mapper = new ObjectMapper(new YAMLFactory());
+			JsonNode configJson = mapper.readTree(Files.newInputStream(CONFIG_FILE));
+			this.defaultSpeed = configJson.get("defaultSpeed").asDouble();
+			this.minimumSpeed = configJson.get("minimumSpeed").asDouble();
+			this.maximumSpeed = configJson.get("maximumSpeed").asDouble();
+			this.signRegex = configJson.get("signRegex").asText();
+		} catch (IOException e) {
+			throw new UncheckedIOException(e);
+		}
+	}
+
+	private void ensureConfigExists() throws IOException {
+		if (!Files.exists(CONFIG_FILE)) {
+			var out = Files.newOutputStream(CONFIG_FILE);
+			var defaultConfigInputStream = SpeedCarts.class.getClassLoader().getResourceAsStream("default_config.yaml");
+			if (defaultConfigInputStream == null) {
+				throw new IOException("Could not load default_config.yaml");
+			}
+			defaultConfigInputStream.transferTo(out);
+			defaultConfigInputStream.close();
+			out.close();
+		}
+	}
+
+	public double getDefaultSpeed() {
+		return defaultSpeed;
+	}
+
+	public double getMinimumSpeed() {
+		return minimumSpeed;
+	}
+
+	public double getMaximumSpeed() {
+		return maximumSpeed;
+	}
+
+	public String getSignRegex() {
+		return signRegex;
+	}
+}

src/main/java/nl/andrewlalis/speed_carts/SpeedCarts.java

@@ -3,8 +3,11 @@ package nl.andrewlalis.speed_carts;
 import net.fabricmc.api.ModInitializer;
 
 public class SpeedCarts implements ModInitializer {
+	public static Config config;
+
 	@Override
 	public void onInitialize() {
+		config = new Config();
 		System.out.println("Speed Carts initialized.");
 	}
 }

src/main/java/nl/andrewlalis/speed_carts/mixin/AbstractMinecartMixin.java

@@ -19,6 +19,7 @@ import net.minecraft.util.math.Direction;
 import net.minecraft.util.math.Vec3d;
 import net.minecraft.util.math.Vec3i;
 import net.minecraft.world.World;
+import nl.andrewlalis.speed_carts.SpeedCarts;
 import org.spongepowered.asm.mixin.Mixin;
 import org.spongepowered.asm.mixin.Shadow;
 import org.spongepowered.asm.mixin.injection.At;
@@ -29,6 +30,7 @@ import org.spongepowered.asm.mixin.injection.callback.CallbackInfoReturnable;
 import java.util.ArrayList;
 import java.util.Collection;
 import java.util.List;
+import java.util.regex.Pattern;
 
 /**
  * Mixin which overrides the default minecart behavior so that we can define a
@@ -36,9 +38,16 @@ import java.util.List;
  */
 @Mixin(AbstractMinecartEntity.class)
 public abstract class AbstractMinecartMixin extends Entity {
-	private static final double DEFAULT_SPEED = 8.0;
-	private static final double MIN_SPEED = 1.0;
-	private static final double MAX_SPEED = 128.0;
+	private static final double DEFAULT_SPEED = SpeedCarts.config.getDefaultSpeed();
+	private static final double MIN_SPEED = SpeedCarts.config.getMinimumSpeed();
+	private static final double MAX_SPEED = SpeedCarts.config.getMaximumSpeed();
+	private static final Pattern SIGN_PATTERN = Pattern.compile(SpeedCarts.config.getSignRegex());
+
+	/**
+	 * Time in game ticks, to wait before attempting to update the cart's speed
+	 * from the same position, after that block/sign has already updated the
+	 * cart's speed just before.
+	 */
 	private static final long SPEED_UPDATE_COOLDOWN = 20 * 3;
 
 	/**
@@ -130,6 +139,9 @@ public abstract class AbstractMinecartMixin extends Entity {
 	private boolean updateSpeedForSign(SignBlockEntity sign) {
 		Text text = sign.getTextOnRow(0, false);
 		String s = text.asString();
+		if (!SIGN_PATTERN.matcher(s).matches()) {
+			return false;
+		}
 		try {
 			double speed = Double.parseDouble(s);
 			if (speed >= MIN_SPEED && speed <= MAX_SPEED) {

src/main/resources/default_config.yaml

@@ -0,0 +1,17 @@
+# Configuration for Speed Carts
+# -----------------------------
+# A server restart is required to apply changes.
+
+# The default speed for all carts in the world, in meters per second.
+defaultSpeed: 8
+
+# The minimum allowable speed limit that can be set, in meters per second.
+minimumSpeed: 1
+
+# The maximum allowable speed limit that can be set, in meters per second.
+# Note: when a player is riding the cart, it cannot exceed 32 m/s regardless of the maximum set here.
+maximumSpeed: 128
+
+# The regular expression that's used to determine if a sign should affect the cart's speed.
+# By default, it matches any positive decimal number.
+signRegex: \d+(\.\d+)?