Use the type RefName for all the needed places and fix pull mirror sync bugs (#24634)

This PR replaces all string refName as a type `git.RefName` to make the
code more maintainable.

Fix #15367
Replaces #23070 
It also fixed a bug that tags are not sync because `git remote --prune
origin` will not remove local tags if remote removed.

We in fact should use `git fetch --prune --tags origin` but not `git
remote update origin` to do the sync.

Some answer from ChatGPT as ref.

> If the git fetch --prune --tags command is not working as expected,
there could be a few reasons why. Here are a few things to check:
> 
>Make sure that you have the latest version of Git installed on your
system. You can check the version by running git --version in your
terminal. If you have an outdated version, try updating Git and see if
that resolves the issue.
> 
>Check that your Git repository is properly configured to track the
remote repository's tags. You can check this by running git config
--get-all remote.origin.fetch and verifying that it includes
+refs/tags/*:refs/tags/*. If it does not, you can add it by running git
config --add remote.origin.fetch "+refs/tags/*:refs/tags/*".
> 
>Verify that the tags you are trying to prune actually exist on the
remote repository. You can do this by running git ls-remote --tags
origin to list all the tags on the remote repository.
> 
>Check if any local tags have been created that match the names of tags
on the remote repository. If so, these local tags may be preventing the
git fetch --prune --tags command from working properly. You can delete
local tags using the git tag -d command.

---------

Co-authored-by: delvh <dev.lh@web.de>

2 files changed, 88 insertions, 32 deletions

diff --git a/services/mirror/mirror_pull.go b/services/mirror/mirror_pull.go
index 60699294c1..53ab632b01 100644
--- a/services/mirror/mirror_pull.go
+++ b/services/mirror/mirror_pull.go
@@ -78,13 +78,23 @@ func UpdateAddress(ctx context.Context, m *repo_model.Mirror, addr string) error
 // If the oldCommitID is "0000000", it means a new reference, the value of newCommitID is empty.
 // If the newCommitID is "0000000", it means the reference is deleted, the value of oldCommitID is empty.
 type mirrorSyncResult struct {
-	refName     string
+	refName     git.RefName
 	oldCommitID string
 	newCommitID string
 }
 
 // parseRemoteUpdateOutput detects create, update and delete operations of references from upstream.
-func parseRemoteUpdateOutput(output string) []*mirrorSyncResult {
+// possible output example:
+/*
+// * [new tag]         v0.1.8     -> v0.1.8
+// * [new branch]      master     -> origin/master
+// - [deleted]         (none)     -> origin/test // delete a branch
+// - [deleted]         (none)     -> 1 // delete a tag
+//   957a993..a87ba5f  test       -> origin/test
+// + f895a1e...957a993 test       -> origin/test  (forced update)
+*/
+// TODO: return whether it's a force update
+func parseRemoteUpdateOutput(output, remoteName string) []*mirrorSyncResult {
 	results := make([]*mirrorSyncResult, 0, 3)
 	lines := strings.Split(output, "\n")
 	for i := range lines {
@@ -94,22 +104,30 @@ func parseRemoteUpdateOutput(output string) []*mirrorSyncResult {
 			continue
 		}
 
-		refName := lines[i][idx+3:]
+		refName := strings.TrimSpace(lines[i][idx+3:])
 
 		switch {
-		case strings.HasPrefix(lines[i], " * "): // New reference
-			if strings.HasPrefix(lines[i], " * [new tag]") {
-				refName = git.TagPrefix + refName
-			} else if strings.HasPrefix(lines[i], " * [new branch]") {
-				refName = git.BranchPrefix + refName
-			}
+		case strings.HasPrefix(lines[i], " * [new tag]"): // new tag
 			results = append(results, &mirrorSyncResult{
-				refName:     refName,
+				refName:     git.RefNameFromTag(refName),
+				oldCommitID: gitShortEmptySha,
+			})
+		case strings.HasPrefix(lines[i], " * [new branch]"): // new branch
+			refName = strings.TrimPrefix(refName, remoteName+"/")
+			results = append(results, &mirrorSyncResult{
+				refName:     git.RefNameFromBranch(refName),
 				oldCommitID: gitShortEmptySha,
 			})
 		case strings.HasPrefix(lines[i], " - "): // Delete reference
+			isTag := !strings.HasPrefix(refName, remoteName+"/")
+			var refFullName git.RefName
+			if isTag {
+				refFullName = git.RefNameFromTag(refName)
+			} else {
+				refFullName = git.RefNameFromBranch(strings.TrimPrefix(refName, remoteName+"/"))
+			}
 			results = append(results, &mirrorSyncResult{
-				refName:     refName,
+				refName:     refFullName,
 				newCommitID: gitShortEmptySha,
 			})
 		case strings.HasPrefix(lines[i], " + "): // Force update
@@ -127,7 +145,7 @@ func parseRemoteUpdateOutput(output string) []*mirrorSyncResult {
 				continue
 			}
 			results = append(results, &mirrorSyncResult{
-				refName:     refName,
+				refName:     git.RefNameFromBranch(strings.TrimPrefix(refName, remoteName+"/")),
 				oldCommitID: shas[0],
 				newCommitID: shas[1],
 			})
@@ -143,7 +161,7 @@ func parseRemoteUpdateOutput(output string) []*mirrorSyncResult {
 				continue
 			}
 			results = append(results, &mirrorSyncResult{
-				refName:     refName,
+				refName:     git.RefNameFromBranch(strings.TrimPrefix(refName, remoteName+"/")),
 				oldCommitID: shas[0],
 				newCommitID: shas[1],
 			})
@@ -204,11 +222,12 @@ func runSync(ctx context.Context, m *repo_model.Mirror) ([]*mirrorSyncResult, bo
 
 	log.Trace("SyncMirrors [repo: %-v]: running git remote update...", m.Repo)
 
-	cmd := git.NewCommand(ctx, "remote", "update")
+	// use fetch but not remote update because git fetch support --tags but remote update doesn't
+	cmd := git.NewCommand(ctx, "fetch")
 	if m.EnablePrune {
 		cmd.AddArguments("--prune")
 	}
-	cmd.AddDynamicArguments(m.GetRemoteName())
+	cmd.AddArguments("--tags").AddDynamicArguments(m.GetRemoteName())
 
 	remoteURL, remoteErr := git.GetRemoteURL(ctx, repoPath, m.GetRemoteName())
 	if remoteErr != nil {
@@ -384,7 +403,7 @@ func runSync(ctx context.Context, m *repo_model.Mirror) ([]*mirrorSyncResult, bo
 	}
 
 	m.UpdatedUnix = timeutil.TimeStampNow()
-	return parseRemoteUpdateOutput(output), true
+	return parseRemoteUpdateOutput(output, m.GetRemoteName()), true
 }
 
 // SyncPullMirror starts the sync of the pull mirror and schedules the next run.
@@ -444,20 +463,13 @@ func SyncPullMirror(ctx context.Context, repoID int64) bool {
 
 	for _, result := range results {
 		// Discard GitHub pull requests, i.e. refs/pull/*
-		if strings.HasPrefix(result.refName, git.PullPrefix) {
+		if result.refName.IsPull() {
 			continue
 		}
 
-		tp, _ := git.SplitRefName(result.refName)
-
 		// Create reference
 		if result.oldCommitID == gitShortEmptySha {
-			if tp == git.TagPrefix {
-				tp = "tag"
-			} else if tp == git.BranchPrefix {
-				tp = "branch"
-			}
-			commitID, err := gitRepo.GetRefCommitID(result.refName)
+			commitID, err := gitRepo.GetRefCommitID(result.refName.String())
 			if err != nil {
 				log.Error("SyncMirrors [repo: %-v]: unable to GetRefCommitID [ref_name: %s]: %v", m.Repo, result.refName, err)
 				continue
@@ -467,13 +479,13 @@ func SyncPullMirror(ctx context.Context, repoID int64) bool {
 				OldCommitID: git.EmptySHA,
 				NewCommitID: commitID,
 			}, repo_module.NewPushCommits())
-			notification.NotifySyncCreateRef(ctx, m.Repo.MustOwner(ctx), m.Repo, tp, result.refName, commitID)
+			notification.NotifySyncCreateRef(ctx, m.Repo.MustOwner(ctx), m.Repo, result.refName, commitID)
 			continue
 		}
 
 		// Delete reference
 		if result.newCommitID == gitShortEmptySha {
-			notification.NotifySyncDeleteRef(ctx, m.Repo.MustOwner(ctx), m.Repo, tp, result.refName)
+			notification.NotifySyncDeleteRef(ctx, m.Repo.MustOwner(ctx), m.Repo, result.refName)
 			continue
 		}
 
@@ -547,13 +559,11 @@ func checkAndUpdateEmptyRepository(m *repo_model.Mirror, gitRepo *git.Repository
 	}
 	firstName := ""
 	for _, result := range results {
-		if strings.HasPrefix(result.refName, git.PullPrefix) {
-			continue
-		}
-		tp, name := git.SplitRefName(result.refName)
-		if len(tp) > 0 && tp != git.BranchPrefix {
+		if !result.refName.IsBranch() {
 			continue
 		}
+
+		name := result.refName.BranchName()
 		if len(firstName) == 0 {
 			firstName = name
 		}
diff --git a/services/mirror/mirror_test.go b/services/mirror/mirror_test.go
new file mode 100644
index 0000000000..8ad524b608
--- /dev/null
+++ b/services/mirror/mirror_test.go
@@ -0,0 +1,46 @@
+// Copyright 2023 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package mirror
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func Test_parseRemoteUpdateOutput(t *testing.T) {
+	output := `
+ * [new tag]         v0.1.8     -> v0.1.8
+ * [new branch]      master     -> origin/master
+ - [deleted]         (none)     -> origin/test1
+ - [deleted]         (none)     -> tag1
+ + f895a1e...957a993 test2      -> origin/test2  (forced update)
+   957a993..a87ba5f  test3      -> origin/test3
+`
+	results := parseRemoteUpdateOutput(output, "origin")
+	assert.Len(t, results, 6)
+	assert.EqualValues(t, "refs/tags/v0.1.8", results[0].refName.String())
+	assert.EqualValues(t, gitShortEmptySha, results[0].oldCommitID)
+	assert.EqualValues(t, "", results[0].newCommitID)
+
+	assert.EqualValues(t, "refs/heads/master", results[1].refName.String())
+	assert.EqualValues(t, gitShortEmptySha, results[1].oldCommitID)
+	assert.EqualValues(t, "", results[1].newCommitID)
+
+	assert.EqualValues(t, "refs/heads/test1", results[2].refName.String())
+	assert.EqualValues(t, "", results[2].oldCommitID)
+	assert.EqualValues(t, gitShortEmptySha, results[2].newCommitID)
+
+	assert.EqualValues(t, "refs/tags/tag1", results[3].refName.String())
+	assert.EqualValues(t, "", results[3].oldCommitID)
+	assert.EqualValues(t, gitShortEmptySha, results[3].newCommitID)
+
+	assert.EqualValues(t, "refs/heads/test2", results[4].refName.String())
+	assert.EqualValues(t, "f895a1e", results[4].oldCommitID)
+	assert.EqualValues(t, "957a993", results[4].newCommitID)
+
+	assert.EqualValues(t, "refs/heads/test3", results[5].refName.String())
+	assert.EqualValues(t, "957a993", results[5].oldCommitID)
+	assert.EqualValues(t, "a87ba5f", results[5].newCommitID)
+}