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src/main/java/enovy/server/util/VersionUtils.java

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+package enovy.server.util;
+
+import java.util.regex.Pattern;
+
+/**
+ * Implements a comparison algorithm between Envoy versions and defines minimal
+ * and maximal client versions compatible with this server.
+ * <p>
+ * Project: <strong>envoy-server-standalone</strong><br>
+ * File: <strong>VersionUtils.java</strong><br>
+ * Created: <strong>23.06.2020</strong><br>
+ * 
+ * @author KSKE
+ * @since Envoy Server Standalone v0.1-beta
+ */
+public class VersionUtils {
+
+	/**
+	 * The minimal client version compatible with this server.
+	 * 
+	 * @since Envoy Server Standalone v0.1-beta
+	 */
+	public static final String MIN_CLIENT_VERSION = "0.1-beta";
+
+	/**
+	 * The maximal client version compatible with this server.
+	 * 
+	 * @since Envoy Server Standalone v0.1-beta
+	 */
+	public static final String MAX_CLIENT_VERSION = "0.1-beta";
+
+	private static final Pattern versionPattern = Pattern.compile("(?<major>\\d).(?<minor>\\d)(?:-(?<suffix>\\w+))?");
+
+	private VersionUtils() {}
+
+	/**
+	 * Parses an Envoy Client version string and checks whether that version is
+	 * compatible with this server.
+	 * 
+	 * @param version the version string to parse
+	 * @return {@code true} if the given version is compatible with this server
+	 * @since Envoy Server Standalone v0.1-beta
+	 */
+	public static boolean verifyCompatibility(String version) {
+		final var currentMatcher = versionPattern.matcher(version);
+
+		if (!currentMatcher.matches()) return false;
+
+		final var	minMatcher	= versionPattern.matcher(MIN_CLIENT_VERSION);
+		final var	maxMatcher	= versionPattern.matcher(MAX_CLIENT_VERSION);
+
+		if (!minMatcher.matches() || !maxMatcher.matches()) throw new RuntimeException("Invalid min or max client version configured!");
+
+		// Compare suffixes
+		{
+			final var	currentSuffix	= convertSuffix(currentMatcher.group("suffix"));
+			final var	minSuffix		= convertSuffix(minMatcher.group("suffix"));
+			final var	maxSuffix		= convertSuffix(maxMatcher.group("suffix"));
+
+			if (currentSuffix < minSuffix || currentSuffix > maxSuffix) return false;
+		}
+
+		// Compare major
+		{
+			final var	currentMajor	= Integer.parseInt(currentMatcher.group("major"));
+			final var	minMajor		= Integer.parseInt(minMatcher.group("major"));
+			final var	maxMajor		= Integer.parseInt(maxMatcher.group("major"));
+
+			if (currentMajor < minMajor || currentMajor > maxMajor) return false;
+		}
+
+		// Compare minor
+		{
+			final var	currentMinor	= Integer.parseInt(currentMatcher.group("minor"));
+			final var	minMinor		= Integer.parseInt(minMatcher.group("minor"));
+			final var	maxMinor		= Integer.parseInt(maxMatcher.group("minor"));
+
+			if (currentMinor < minMinor || currentMinor > maxMinor) return false;
+		}
+
+		return true;
+	}
+
+	private static int convertSuffix(String suffix) {
+		switch (suffix == null ? "" : suffix) {
+			case "alpha":
+				return 0;
+			case "beta":
+				return 1;
+			default:
+				return 2;
+		}
+	}
+}

src/main/java/enovy/server/util/package-info.java

@@ -0,0 +1,11 @@
+/**
+ * This package contains utility classes used in Envoy Server.
+ * <p>
+ * Project: <strong>envoy-server-standalone</strong><br>
+ * File: <strong>package-info.java</strong><br>
+ * Created: <strong>23.06.2020</strong><br>
+ * 
+ * @author Kai S. K. Engelbart
+ * @since Envoy Server Standalone v0.1-beta
+ */
+package enovy.server.util;