From 6a88e3bdeff620908a9e29bbdd6f739ffde616e7 Mon Sep 17 00:00:00 2001
From: Jeff Carr <jcarr@wit.com>
Date: Tue, 25 Mar 2025 21:06:01 -0500
Subject: more examples

---
 main.go     |  4 +++
 showtags.go | 99 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 103 insertions(+)
 create mode 100644 showtags.go

diff --git a/main.go b/main.go
index cb42b98..25818a4 100644
--- a/main.go
+++ b/main.go
@@ -35,6 +35,10 @@ func main() {
 		return
 	}
 	walkTree(t)
+
+	showtags(repo)
+	// v0.0.8
+	printCommitsForTag(repo, "v0.22.2")
 }
 
 // lists the files in the git repo
diff --git a/showtags.go b/showtags.go
new file mode 100644
index 0000000..880e6d7
--- /dev/null
+++ b/showtags.go
@@ -0,0 +1,99 @@
+package main
+
+import (
+	"fmt"
+	"sort"
+
+	git "go.wit.com/lib/libgit2"
+	"go.wit.com/log"
+)
+
+func showtags(repo *git.Repository) {
+	// Map: commit OID -> list of tags pointing to it
+	tagMap := make(map[string][]string)
+
+	// Walk through all tag names
+	tags, err := repo.NewReferenceIteratorGlob("refs/tags/*")
+	if err != nil {
+		log.Fatalf("Failed to iterate tags: %v", err)
+	}
+
+	for {
+		ref, err := tags.Next()
+		if err != nil {
+			break // Done iterating
+		}
+
+		name := ref.Shorthand()
+		target, err := repo.RevparseSingle(ref.Name())
+		if err != nil {
+			log.Printf("Skipping unresolved tag: %s", name)
+			continue
+		}
+
+		commitOID := target.Id().String()
+		tagMap[commitOID] = append(tagMap[commitOID], name)
+		log.Info("tag:", commitOID, name, target)
+	}
+
+	// Identify and delete duplicate tags
+	for commit, tagList := range tagMap {
+		if len(tagList) > 1 {
+			sort.Strings(tagList)
+			fmt.Printf("Commit %s has duplicates: %v\n", commit, tagList)
+
+			// Keep the first tag, delete the rest
+			for _, tag := range tagList[1:] {
+				refname := "refs/tags/" + tag
+				log.Info(refname)
+				/*
+					if err := repo.References.Remove(refname); err != nil {
+						log.Printf("Failed to delete tag %s: %v", tag, err)
+					} else {
+						fmt.Printf("Deleted tag: %s\n", tag)
+					}
+				*/
+			}
+		}
+	}
+}
+
+func printCommitsForTag(repo *git.Repository, tagName string) error {
+	// Resolve tag reference
+	ref, err := repo.References.Lookup("refs/tags/" + tagName)
+	if err != nil {
+		return fmt.Errorf("failed to find tag %s: %w", tagName, err)
+	}
+
+	// Resolve to commit object (may be annotated tag or direct commit)
+	obj, err := ref.Peel(git.ObjectCommit)
+	if err != nil {
+		return fmt.Errorf("failed to peel tag %s to commit: %w", tagName, err)
+	}
+
+	start, err := obj.AsCommit()
+	if err != nil {
+		return fmt.Errorf("peeled object is not a commit: %w", err)
+	}
+
+	// Walk the history
+	walker, err := repo.Walk()
+	if err != nil {
+		return fmt.Errorf("failed to create walker: %w", err)
+	}
+
+	if err := walker.Push(start.Id()); err != nil {
+		return fmt.Errorf("failed to push start commit: %w", err)
+	}
+
+	fmt.Printf("Commits for tag %s:\n", tagName)
+	err = walker.Iterate(func(c *git.Commit) bool {
+		fmt.Printf("%s %s\n", c.Id().String(), c.Summary())
+		return true
+	})
+	if err != nil {
+		return fmt.Errorf("error during walk: %w", err)
+	}
+
+	return nil
+}
-- 
cgit v1.2.3