Add validation to config

src/main/java/net/vinrobot/mcemote/config/Option.java

@@ -2,6 +2,7 @@
 
 import net.vinrobot.mcemote.config.impl.OptionImpl;
 
+import java.util.Objects;
 import java.util.Optional;
 
 public interface Option<T> {
@@ -71,4 +72,30 @@ default T get() {
 	 * @return The default value of this option.
 	 */
 	T getDefault();
+
+	/**
+	 * Validate the value of this option.
+	 *
+	 * @param value The value to validate.
+	 * @throws ValidationFailedException If the validation fails.
+	 */
+	default void validate(final T value) throws ValidationFailedException {
+		Objects.requireNonNull(value);
+	}
+
+	/**
+	 * Check if the value of this option is valid.
+	 *
+	 * @see #validate(T)
+	 * @param value The value to check.
+	 * @return True if the value is valid, false otherwise.
+	 */
+	default boolean isValid(final T value) {
+		try {
+			this.validate(value);
+			return true;
+		} catch (ValidationFailedException e) {
+			return false;
+		}
+	}
 }

src/main/java/net/vinrobot/mcemote/config/ValidationFailedException.java

@@ -0,0 +1,17 @@
+package net.vinrobot.mcemote.config;
+
+public class ValidationFailedException extends RuntimeException {
+	private static final long serialVersionUID = 1L;
+
+	public ValidationFailedException(final String message) {
+		super(message);
+	}
+
+	public ValidationFailedException(final String message, final Throwable cause) {
+		super(message, cause);
+	}
+
+	public ValidationFailedException(final Throwable cause) {
+		super(cause);
+	}
+}

src/main/java/net/vinrobot/mcemote/config/impl/ConfigurationImpl.java

@@ -6,7 +6,7 @@
 public final class ConfigurationImpl implements Configuration {
 	private static final String SCRAPIE_TWITCH_ID = "40646018";
 
-	private final Option<String> twitchId = Option.of(SCRAPIE_TWITCH_ID);
+	private final Option<String> twitchId = new TwitchIdOptionImpl(SCRAPIE_TWITCH_ID);
 
 	@Override
 	public Option<String> twitchId() {

src/main/java/net/vinrobot/mcemote/config/impl/OptionImpl.java

@@ -15,6 +15,7 @@ public OptionImpl(final T defaultValue) {
 
 	@Override
 	public Option<T> set(final Optional<T> value) {
+		value.ifPresent(this::validate);
 		this.value = Objects.requireNonNull(value);
 		return this;
 	}

src/main/java/net/vinrobot/mcemote/config/impl/TwitchIdOptionImpl.java

@@ -0,0 +1,25 @@
+package net.vinrobot.mcemote.config.impl;
+
+import net.vinrobot.mcemote.config.ValidationFailedException;
+
+public class TwitchIdOptionImpl extends OptionImpl<String> {
+	public TwitchIdOptionImpl(final String defaultValue) {
+		super(defaultValue);
+	}
+
+	@Override
+	public void validate(final String value) {
+		super.validate(value);
+
+		final int length = value.length();
+		if (length == 0 || 8 < length) {
+			throw new ValidationFailedException("Twitch ID must be between 1 and 8 digits");
+		}
+
+		try {
+			Long.parseLong(value);
+		} catch (final NumberFormatException e) {
+			throw new ValidationFailedException("Twitch ID must be a number");
+		}
+	}
+}