feat: maintain more info on minimal Java versions (#713)

src/main/java/org/terasology/launcher/game/GameStarter.java

@@ -97,6 +97,11 @@ public Process call() throws IOException {
      * @return the executable {@code java} file to run the game with
      */
     Path getRuntimePath(Semver engineVersion) throws GameVersionNotSupportedException {
+        //TODO: Select the right JRE based on VersionHistory#getJavaVersionForEngine. Probably something along the lines
+        //      of the following:
+        //        Semver minJavaVersion = VersionHistory.getJavaVersionForEngine(engineVersion); // may throw GameVersionNotSupportedException
+        //        <Installation> JRE jre = JreManager.getJreFor(platform, minJavaVersion);       // may throw GameVersionNotSupportedException
+        //        return Paths.get(jre.getPath(), "bin", "java");
         if (VersionHistory.JAVA17.isProvidedBy(engineVersion)) {
             // throw exception as the version is not supported
             throw new GameVersionNotSupportedException(engineVersion);

src/main/java/org/terasology/launcher/game/GameVersionNotSupportedException.java

@@ -6,14 +6,17 @@
 import org.semver4j.Semver;
 
 public class GameVersionNotSupportedException extends RuntimeException {
-    private final Semver engineVersion;
-
     public GameVersionNotSupportedException(Semver engineVersion) {
-        this.engineVersion = engineVersion;
+        this(engineVersion, null);
+    }
+
+    public GameVersionNotSupportedException(Semver engineVersion, String message) {
+        super(errorMessage(engineVersion, message));
     }
 
-    @Override
-    public String getMessage() {
-        return "Unsupported engine version: " + engineVersion.toString();
+    private static String errorMessage(Semver engineVersion, String additionalInfo) {
+        String message = "Unsupported engine version: " + engineVersion.toString();
+        String details = ((additionalInfo != null) ? " (" + additionalInfo + ")" : "");
+        return message + details;
     }
 }

src/main/java/org/terasology/launcher/game/VersionHistory.java

@@ -23,7 +23,20 @@ public enum VersionHistory {
      */
     PICOCLI("5.2.0-SNAPSHOT"),
 
-    /** Since 3aa68c04f192243575f7f78de5b6ce268bb2da1a Terasology requires at least Java 17.
+    /**
+     * Since 1813b15388760a036ed91e6e4d89c67a59bd92e3 Terasology requires at least Java 8.
+     * See <a href="https://github.com/MovingBlocks/Terasology/commit/1813b15388760a036ed91e6e4d89c67a59bd92e3">1813b153</a>
+     */
+    JAVA8("0.54.0"),
+
+    /**
+     * Since 901f35aa135215e463c8600405702af35d507005 Terasology requires at least Java 11.
+     * See <a href="https://github.com/MovingBlocks/Terasology/commit/901f35aa135215e463c8600405702af35d507005">901f35aa</a>
+     */
+    JAVA11("5.2.0-rc.4"),
+
+    /**
+     * Since 3aa68c04f192243575f7f78de5b6ce268bb2da1a Terasology requires at least Java 17.
      * See <a href="https://github.com/MovingBlocks/Terasology/commit/3aa68c04f192243575f7f78de5b6ce268bb2da1a">3aa68c04</a>
      */
     JAVA17("6.0.0-SNAPSHOT");
@@ -37,4 +50,20 @@ public enum VersionHistory {
     boolean isProvidedBy(Semver version) {
         return version.isGreaterThanOrEqualTo(engineVersion);
     }
+
+    public static Semver getJavaVersionForEngine(Semver engineVersion) throws GameVersionNotSupportedException {
+        final Semver javaVersion;
+        if (JAVA17.isProvidedBy(engineVersion)) {
+            javaVersion = new Semver("17.0.0");
+        } else if (JAVA11.isProvidedBy(engineVersion)) {
+            javaVersion = new Semver("11.0.0");
+        } else if (JAVA8.isProvidedBy(engineVersion)) {
+            // Java 11 is backwards compatible to Java 8, so we can use that to serve old games
+            javaVersion = new Semver("11.0.0");
+        } else {
+            // older game releases require even older Java versions and are currently not supported.
+            throw new GameVersionNotSupportedException(engineVersion, "JRE older than Java 8 not supported.");
+        }
+        return javaVersion;
+    }
 }

src/main/java/org/terasology/launcher/repositories/GithubRepository.java

@@ -15,6 +15,8 @@
 import org.kohsuke.github.extras.okhttp3.OkHttpConnector;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
+import org.terasology.launcher.game.GameVersionNotSupportedException;
+import org.terasology.launcher.game.VersionHistory;
 import org.terasology.launcher.model.Build;
 import org.terasology.launcher.model.GameIdentifier;
 import org.terasology.launcher.model.GameRelease;
@@ -64,6 +66,8 @@ static GameRelease fromGithubRelease(GHRelease ghRelease) {
             } else {
                 engineVersion = new Semver(tagName);
             }
+            //TODO: check whether the launcher can fulfil this requirement
+            final Semver minJavaVersion = VersionHistory.getJavaVersionForEngine(engineVersion);
 
             final Optional<GHAsset> gameAsset = ghRelease.assets().stream().filter(asset -> asset.getName().matches("Terasology.*zip")).findFirst();
             final URL url = new URL(gameAsset.map(GHAsset::getBrowserDownloadUrl).orElseThrow(() -> new IOException("Missing game asset.")));
@@ -74,9 +78,13 @@ static GameRelease fromGithubRelease(GHRelease ghRelease) {
             ReleaseMetadata metadata = new ReleaseMetadata(changelog, ghRelease.getPublished_at());
             return new GameRelease(id, url, metadata);
         } catch (SemverException | IOException e) {
-            logger.info("Could not create game release from Github release {}: {}", ghRelease.getHtmlUrl(), e.getMessage());
-            return null;
+            logger.info("Could not create game release from Github release {}: {}",
+                    ghRelease.getHtmlUrl(), e.getMessage());
+        } catch (GameVersionNotSupportedException e) {
+            logger.debug("Game release {} with engine version {} is not supported. ({})",
+                    ghRelease.getHtmlUrl(), tagName, e.getMessage());
         }
+        return null;
     }
 
     @Override

src/main/java/org/terasology/launcher/repositories/JenkinsRepository.java

@@ -89,6 +89,9 @@ private Optional<GameRelease> computeReleaseFrom(Jenkins.Build jenkinsBuildInfo)
             final ReleaseMetadata metadata = computeReleaseMetadataFrom(jenkinsBuildInfo);
             final Optional<GameIdentifier> id = computeIdentifierFrom(jenkinsBuildInfo);
 
+            //TODO: check whether the game release is supported (minimal Java version)
+            //      we probably need to encode the engine version explicitly in the GameIdentifier (instead of just the display version)
+
             if (url != null && id.isPresent()) {
                 return Optional.of(new GameRelease(id.get(), url, metadata));
             } else {