From f1e4a084d18cf14bff0a3bfabfb04ee3ccbfe8e8 Mon Sep 17 00:00:00 2001
From: Ben Soares <b.soares@dundee.ac.uk>
Date: Tue, 25 Jun 2024 10:22:42 +0100
Subject: [PATCH] JAL-3631 Forgot to add this file for 'Change parity of
 comparison for convention' commit

---
 .../src/main/java/jalview/util/LaunchUtils.java    |   69 ++++++++++++--------
 1 file changed, 42 insertions(+), 27 deletions(-)

diff --git a/getdown/src/getdown/core/src/main/java/jalview/util/LaunchUtils.java b/getdown/src/getdown/core/src/main/java/jalview/util/LaunchUtils.java
index dc8961f..58910a8 100644
--- a/getdown/src/getdown/core/src/main/java/jalview/util/LaunchUtils.java
+++ b/getdown/src/getdown/core/src/main/java/jalview/util/LaunchUtils.java
@@ -693,29 +693,35 @@ public class LaunchUtils
     }
     if (!f0.exists())
     {
-      return 1;
+      return -1;
     }
     if (!f1.exists())
     {
-      return -1;
+      return 1;
     }
     String v0 = getJarImplementationVersion(f0);
     String v1 = getJarImplementationVersion(f1);
     syserr(true, false,
             "Got launcher versions '" + v0 + "' and '" + v1 + "'");
+    return compareGetdownLauncherJarVersions(v0, v1);
+  }
+
+  public static int compareGetdownLauncherJarVersions(String v0, String v1)
+  {
     if (v0 == null && v1 == null)
     {
       return 0;
     }
     if (v0 == null)
     {
-      return 1;
+      return -1;
     }
     if (v1 == null)
     {
-      return -1;
+      return 1;
     }
-    // now for the fun
+
+    // remove the subscript
     if (v0.endsWith("JVL"))
     {
       v0 = v0.substring(0, v0.lastIndexOf('_'));
@@ -731,30 +737,23 @@ public class LaunchUtils
     int compare = 0;
     for (int j = 0; j < Math.min(v0parts.length, v1parts.length); j++)
     {
-      compare = 0;
-      try
-      {
-        compare = compareVersions(v0parts[j], v1parts[j]);
-      } catch (NumberFormatException e)
-      {
-        syserr(true, false,
-                "Problem parsing one of the getdown launcher version numbers: '"
-                        + v0 + "', '" + v1 + "'");
-      }
-
-      if (compare != 0
-              || (v0parts.length == j + 1 && v1parts.length == j + 1))
+      compare = compareVersions(v0parts[j], v1parts[j]);
+      if (compare != 0)
       {
         return compare;
       }
     }
 
-    return v1parts.length - v0parts.length;
+    return v0parts.length - v1parts.length;
   }
 
-  // just comparing 1.2.3.4...n
+  /**
+   * comparing versions numbers of the form 1.2.3.4...n ONLY returns 0 if v0 and
+   * v1 are the same, a negative number if v0 < v1 and a positive number if v0 >
+   * v1. The number returned does NOT show how far apart the version numbers
+   * are.
+   */
   public static int compareVersions(String v0, String v1)
-          throws NumberFormatException
   {
     if (v0 == null && v1 == null)
     {
@@ -762,24 +761,40 @@ public class LaunchUtils
     }
     if (v0 == null)
     {
-      return 1;
+      return -1;
     }
     if (v1 == null)
     {
-      return -1;
+      return 1;
     }
     String[] v0dots = v0.split("\\.");
     String[] v1dots = v1.split("\\.");
+    int compare = 0;
     for (int i = 0; i < Math.min(v0dots.length, v1dots.length); i++)
     {
-      if (!v0dots[i].equals(v1dots[i]))
+      if (!v0dots[i].equals(v1dots[i])) // avoids unnecessary
+                                        // NumberFormatException
       {
-        return Integer.parseInt(v1dots[i]) - Integer.parseInt(v0dots[i]);
+        try
+        {
+          compare = Integer.parseInt(v0dots[i])
+                  - Integer.parseInt(v1dots[i]);
+        } catch (NumberFormatException e)
+        {
+          syserr(true, false, "Couldn't parse one of '" + v0dots[i]
+                  + "' or '" + v1dots[i] + "': " + e.getMessage());
+          syserr(true, false, "Comparing as strings.");
+          compare = v0dots[i].compareTo(v1dots[i]);
+        }
+        if (compare != 0)
+        {
+          return compare;
+        }
       }
     }
     // all numbers match up to min length. If one has more dots, assume it's
-    // bigger.
-    return v1dots.length - v0dots.length;
+    // a greater version (e.g. 1.3.2 > 1.3)
+    return v0dots.length - v1dots.length;
   }
 
   public static String getJarImplementationVersion(File jarFile)
-- 
1.7.10.2