Only show the latest version in the Arch index (#33262)

Only show the latest version of the package in the arch repo.

closes #33534

---------

Co-authored-by: Giteabot <teabot@gitea.io>
Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>

services/packages/arch/vercmp.go

@@ -0,0 +1,113 @@
+// Copyright 2025 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package arch
+
+import (
+	"strings"
+	"unicode"
+)
+
+// https://gitlab.archlinux.org/pacman/pacman/-/blob/d55b47e5512808b67bc944feb20c2bcc6c1a4c45/lib/libalpm/version.c
+
+import (
+	"strconv"
+)
+
+func parseEVR(evr string) (epoch, version, release string) {
+	if before, after, f := strings.Cut(evr, ":"); f {
+		epoch = before
+		evr = after
+	} else {
+		epoch = "0"
+	}
+
+	if before, after, f := strings.Cut(evr, "-"); f {
+		version = before
+		release = after
+	} else {
+		version = evr
+		release = "1"
+	}
+	return epoch, version, release
+}
+
+func compareSegments(a, b []string) int {
+	lenA, lenB := len(a), len(b)
+	var l int
+	if lenA > lenB {
+		l = lenB
+	} else {
+		l = lenA
+	}
+	for i := 0; i < l; i++ {
+		if r := compare(a[i], b[i]); r != 0 {
+			return r
+		}
+	}
+	if lenA == lenB {
+		return 0
+	} else if l == lenA {
+		return -1
+	}
+	return 1
+}
+
+func compare(a, b string) int {
+	if a == b {
+		return 0
+	}
+
+	aNumeric := isNumeric(a)
+	bNumeric := isNumeric(b)
+
+	if aNumeric && bNumeric {
+		aInt, _ := strconv.Atoi(a)
+		bInt, _ := strconv.Atoi(b)
+		switch {
+		case aInt < bInt:
+			return -1
+		case aInt > bInt:
+			return 1
+		default:
+			return 0
+		}
+	}
+
+	if aNumeric {
+		return 1
+	}
+	if bNumeric {
+		return -1
+	}
+
+	return strings.Compare(a, b)
+}
+
+func isNumeric(s string) bool {
+	for _, c := range s {
+		if !unicode.IsDigit(c) {
+			return false
+		}
+	}
+	return true
+}
+
+func compareVersions(a, b string) int {
+	if a == b {
+		return 0
+	}
+
+	epochA, versionA, releaseA := parseEVR(a)
+	epochB, versionB, releaseB := parseEVR(b)
+
+	if res := compareSegments([]string{epochA}, []string{epochB}); res != 0 {
+		return res
+	}
+
+	if res := compareSegments(strings.Split(versionA, "."), strings.Split(versionB, ".")); res != 0 {
+		return res
+	}
+
+	return compareSegments([]string{releaseA}, []string{releaseB})
+}