From e0f282aca959fdf1e862c6a83c0acac55476a4dc Mon Sep 17 00:00:00 2001
From: Yaksh Bariya <yakshbari4@gmail.com>
Date: Mon, 1 Dec 2025 00:22:50 +0530
Subject: [PATCH] make version comparision more similar to that of dpkg

Initially found by automated repository health checks used by Termux
in https://github.com/termux/termux-packages/issues/27472

The root problem was 4.3.5a comparing less than 4.3.5-rc1-1 by aptly
According to debian "4.3.5a" > "4.3.5-rc1-1"

This is because dpkg splits hyphen for revision at the first hyphen,
whereas aptly was splitting at the last hyphen which is different from
dpkg's behaviour.

dpkg behaviour: https://git.dpkg.org/cgit/dpkg/dpkg.git/tree/lib/dpkg/parsehelp.c#n242

Perhaps this wasn't detected as there was broken tests in the repository
since the initial commit of aptly. This also fixes those tests
---
 deb/version.go      | 12 ++++++------
 deb/version_test.go |  5 +++--
 2 files changed, 9 insertions(+), 8 deletions(-)

diff --git a/deb/version.go b/deb/version.go
index 47c6998b..4b915038 100644
--- a/deb/version.go
+++ b/deb/version.go
@@ -30,16 +30,16 @@ func CompareVersions(ver1, ver2 string) int {
 
 // parseVersions breaks down full version to components (possibly empty)
 func parseVersion(ver string) (epoch, upstream, debian string) {
-	i := strings.LastIndex(ver, "-")
-	if i != -1 {
-		debian, ver = ver[i+1:], ver[:i]
-	}
-
-	i = strings.Index(ver, ":")
+	i := strings.Index(ver, ":")
 	if i != -1 {
 		epoch, ver = ver[:i], ver[i+1:]
 	}
 
+	i = strings.Index(ver, "-")
+	if i != -1 {
+		debian, ver = ver[i+1:], ver[:i]
+	}
+
 	upstream = ver
 
 	return
diff --git a/deb/version_test.go b/deb/version_test.go
index 7dbcb145..5b069231 100644
--- a/deb/version_test.go
+++ b/deb/version_test.go
@@ -20,10 +20,10 @@ func (s *VersionSuite) TestParseVersion(c *C) {
 	c.Check([]string{e, u, d}, DeepEquals, []string{"", "1.3.4", "1"})
 
 	e, u, d = parseVersion("1.3-pre4-1")
-	c.Check([]string{e, u, d}, DeepEquals, []string{"", "1.3-pre4", "1"})
+	c.Check([]string{e, u, d}, DeepEquals, []string{"", "1.3", "pre4-1"})
 
 	e, u, d = parseVersion("4:1.3-pre4-1")
-	c.Check([]string{e, u, d}, DeepEquals, []string{"4", "1.3-pre4", "1"})
+	c.Check([]string{e, u, d}, DeepEquals, []string{"4", "1.3", "pre4-1"})
 }
 
 func (s *VersionSuite) TestCompareLexicographic(c *C) {
@@ -100,6 +100,7 @@ func (s *VersionSuite) TestCompareVersions(c *C) {
 	c.Check(CompareVersions("1.0-133-avc", "1.0"), Equals, 1)
 
 	c.Check(CompareVersions("5.2.0.3", "5.2.0.283"), Equals, -1)
+	c.Check(CompareVersions("4.3.5a", "4.3.5-rc3-1"), Equals, 1)
 }
 
 func (s *VersionSuite) TestParseDependency(c *C) {