Initial commit v2

src/main/java/one/eim/gravitycontrol/UpdateChecker.java

@@ -0,0 +1,68 @@
+package one.eim.gravitycontrol;
+
+import com.google.gson.Gson;
+
+import java.io.IOException;
+import java.net.URI;
+import java.net.http.HttpClient;
+import java.net.http.HttpRequest;
+import java.net.http.HttpResponse;
+import java.time.Duration;
+import java.util.logging.Level;
+
+class UpdateChecker {
+  private final HttpClient httpClient;
+  private final HttpRequest request;
+  private final Gson gson;
+  private final GravityControl plugin;
+
+  UpdateChecker(GravityControl plugin) {
+    this.httpClient = HttpClient.newBuilder()
+      .followRedirects(HttpClient.Redirect.ALWAYS)
+      .connectTimeout(Duration.ofSeconds(2))
+      .build();
+    this.request = HttpRequest.newBuilder(URI.create("https://gravitycontrol.eim.one/version"))
+      .POST(HttpRequest.BodyPublishers.ofString(plugin.getDescription().getVersion()))
+      .build();
+    this.gson = new Gson();
+    this.plugin = plugin;
+  }
+
+  void check() {
+    Compatibility.runTaskAsync(this.plugin, () -> {
+      final Version version;
+      try {
+        version = this.gson.fromJson(
+          this.httpClient.send(this.request, HttpResponse.BodyHandlers.ofString()).body(),
+          Version.class
+        );
+      } catch (IOException | InterruptedException e) {
+        this.plugin.getSLF4JLogger().info("Failed to check for updates", e);
+        return;
+      }
+
+      if (version.outdated()) {
+        this.plugin.getLogger().log(Level.INFO, "GravityControl is out of date! Current version: " + this.plugin.getDescription().getVersion() + " Latest version: " + version.latest() + ".");
+        this.plugin.getLogger().log(Level.INFO, "Please download an updated version of GravityControl from https://dev.bukkit.org/projects/gravity-control");
+      }
+    });
+  }
+
+  private static final class Version {
+    private final boolean outdated;
+    private final String latest;
+
+    public Version(final boolean outdated, final String latest) {
+      this.outdated = outdated;
+      this.latest = latest;
+    }
+
+    public boolean outdated() {
+      return outdated;
+    }
+
+    public String latest() {
+      return latest;
+    }
+  }
+}