feat: sync forks (#2364)

This allows syncing a branch of a fork with a branch of the base repo. It looks like this:
![grafik](/attachments/4508920c-7d0b-4330-9083-e3048733e38d)
This is only possible, if the fork don't have commits that are not in the main repo.

The feature is already working, but it is missing Finetuning, a better API, translations and tests, so this is currently WIP. It is also not tested with go-git.

<!--start release-notes-assistant-->

## Release notes
<!--URL:https://codeberg.org/forgejo/forgejo-->
- Features
  - [PR](https://codeberg.org/forgejo/forgejo/pulls/2364): <!--number 2364 --><!--line 0 --><!--description c3luYyBmb3Jrcw==-->sync forks<!--description-->
<!--end release-notes-assistant-->

Reviewed-on: https://codeberg.org/forgejo/forgejo/pulls/2364
Reviewed-by: Earl Warren <earl-warren@noreply.codeberg.org>
Co-authored-by: JakobDev <jakobdev@gmx.de>
Co-committed-by: JakobDev <jakobdev@gmx.de>

modules/git/commit.go

@@ -432,6 +432,11 @@ func (c *Commit) GetBranchName() (string, error) {
 	return strings.SplitN(strings.TrimSpace(data), "~", 2)[0], nil
 }
 
+// GetAllBranches returns a slice with all branches that contains this commit
+func (c *Commit) GetAllBranches() ([]string, error) {
+	return c.repo.getBranches(c, -1)
+}
+
 // CommitFileStatus represents status of files in a commit.
 type CommitFileStatus struct {
 	Added    []string

modules/git/commit_test.go

@@ -5,6 +5,7 @@ package git
 
 import (
 	"path/filepath"
+	"slices"
 	"strings"
 	"testing"
 
@@ -370,6 +371,23 @@ func TestParseCommitRenames(t *testing.T) {
 	}
 }
 
+func TestGetAllBranches(t *testing.T) {
+	bareRepo1Path := filepath.Join(testReposDir, "repo1_bare")
+
+	bareRepo1, err := openRepositoryWithDefaultContext(bareRepo1Path)
+	require.NoError(t, err)
+
+	commit, err := bareRepo1.GetCommit("95bb4d39648ee7e325106df01a621c530863a653")
+	require.NoError(t, err)
+
+	branches, err := commit.GetAllBranches()
+	require.NoError(t, err)
+
+	slices.Sort(branches)
+
+	assert.Equal(t, []string{"branch1", "branch2", "master"}, branches)
+}
+
 func Test_parseSubmoduleContent(t *testing.T) {
 	submoduleFiles := []struct {
 		fileContent  string

modules/git/repo_commit.go

@@ -444,10 +444,13 @@ func (repo *Repository) getCommitsBeforeLimit(id ObjectID, num int) ([]*Commit,
 
 func (repo *Repository) getBranches(commit *Commit, limit int) ([]string, error) {
 	if CheckGitVersionAtLeast("2.7.0") == nil {
-		stdout, _, err := NewCommand(repo.Ctx, "for-each-ref", "--format=%(refname:strip=2)").
-			AddOptionFormat("--count=%d", limit).
-			AddOptionValues("--contains", commit.ID.String(), BranchPrefix).
-			RunStdString(&RunOpts{Dir: repo.Path})
+		command := NewCommand(repo.Ctx, "for-each-ref", "--format=%(refname:strip=2)").AddOptionValues("--contains", commit.ID.String(), BranchPrefix)
+
+		if limit != -1 {
+			command = command.AddOptionFormat("--count=%d", limit)
+		}
+
+		stdout, _, err := command.RunStdString(&RunOpts{Dir: repo.Path})
 		if err != nil {
 			return nil, err
 		}

modules/structs/fork.go

@@ -10,3 +10,11 @@ type CreateForkOption struct {
 	// name of the forked repository
 	Name *string `json:"name"`
 }
+
+// SyncForkInfo information about syncing a fork
+type SyncForkInfo struct {
+	Allowed       bool   `json:"allowed"`
+	ForkCommit    string `json:"fork_commit"`
+	BaseCommit    string `json:"base_commit"`
+	CommitsBehind int    `json:"commits_behind"`
+}