warning dialog for unsupported groove.exe versions at start and before the first apply of a session (nothing blocked)

src/main/java/com/eliasmueller/llamamod/ui/MainFrame.java

@@ -62,6 +62,7 @@ final class MainFrame extends JFrame {
     private boolean crashReported;
     private boolean oldWineAccepted;
     private final RecoveryNotice recoveryNotice = new RecoveryNotice();
+    final UnsupportedExeWarning exeWarning = new UnsupportedExeWarning();
     private boolean recoveryRunning;
 
     MainFrame(AppState state) {
@@ -223,6 +224,9 @@ final class MainFrame extends JFrame {
             showRecovery(state.recovery);
             state.recovery = ModManager.Recovery.NONE;
         }
+        if (inst) {
+            SwingUtilities.invokeLater(() -> exeWarning.atStart(this, state));
+        }
     }
 
     /** Tells the user once that an interrupted apply was repaired; BUSY is retried later. */

src/main/java/com/eliasmueller/llamamod/ui/ModsPanel.java

@@ -677,6 +677,7 @@ final class ModsPanel extends JPanel {
         }
         List<Mod> mods = selected();
         ModManager mm = frame.state.modManager;
+        frame.exeWarning.beforeApply(frame, frame.state);
         if (!AntivirusDialogs.notice(frame, mm.exeMods(mods), true)) {
             return;
         }

src/main/java/com/eliasmueller/llamamod/ui/UnsupportedExeWarning.java

@@ -0,0 +1,86 @@
+package com.eliasmueller.llamamod.ui;
+
+import com.eliasmueller.llamamod.exe.GameExe;
+import com.eliasmueller.llamamod.platform.FileOps;
+import com.eliasmueller.llamamod.platform.Integrity;
+import java.awt.Component;
+import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.util.Arrays;
+import java.util.stream.Collectors;
+import javax.swing.JOptionPane;
+
+/**
+ * Warns (never blocks) when the installed groove.exe is not one of the supported builds: once at
+ * start and once before the first Apply of a session.
+ */
+final class UnsupportedExeWarning {
+    private boolean shownAtStart;
+    private boolean shownAtApply;
+    private String checkedSha;
+    private boolean unsupported;
+
+    /** The warning text, or null if the build is supported or unknown because nothing is installed. */
+    static String message(String sha256) {
+        if (sha256 == null || sha256.isEmpty()) {
+            return null;
+        }
+        for (GameExe.Build b : GameExe.Build.values()) {
+            if (b.sha256.equalsIgnoreCase(sha256)) {
+                return null;
+            }
+        }
+        return "You are running an unsupported version of the game. Mods, especially mods that modify"
+                + " groove.exe, probably won't work.\n\nSupported are: "
+                + Arrays.stream(GameExe.Build.values())
+                        .map(GameExe.Build::toString)
+                        .collect(Collectors.joining(", "))
+                + ".";
+    }
+
+    /** SHA-256 of the set-up original groove.exe ("" if not installed or unreadable). */
+    static String installedSha(AppState state) {
+        if (!state.cfg.installed()) {
+            return "";
+        }
+        if (!state.cfg.exeSha256.isEmpty()) {
+            return state.cfg.exeSha256;
+        }
+        try {
+            Path hd = state.paths.originalHd();
+            Path exe = Files.isDirectory(hd) ? Integrity.find(hd, "groove.exe") : null;
+            return exe != null && Files.isRegularFile(exe) ? FileOps.sha256(exe) : "";
+        } catch (IOException e) {
+            return "";
+        }
+    }
+
+    private String current(AppState state) {
+        String sha = installedSha(state);
+        if (!sha.equals(checkedSha)) {
+            checkedSha = sha;
+            unsupported = message(sha) != null;
+            shownAtStart = false;
+            shownAtApply = false;
+        }
+        return unsupported ? message(sha) : null;
+    }
+
+    void atStart(Component parent, AppState state) {
+        String m = current(state);
+        if (m != null && !shownAtStart) {
+            shownAtStart = true;
+            JOptionPane.showMessageDialog(parent, m, "Unsupported game version", JOptionPane.WARNING_MESSAGE);
+        }
+    }
+
+    /** Shows the warning before the first Apply of a session; Apply always continues afterwards. */
+    void beforeApply(Component parent, AppState state) {
+        String m = current(state);
+        if (m != null && !shownAtApply) {
+            shownAtApply = true;
+            JOptionPane.showMessageDialog(parent, m, "Unsupported game version", JOptionPane.WARNING_MESSAGE);
+        }
+    }
+}