Show branches and tags that contain a commit (#25180)

Now, you can see for a commit which existing branches and tags contain it.
You first have to click on the `load branches and tags` button, they are not preloaded by default.
All branches and tags are ordered descending by creation date.
You can even see without much hassle if the given commit is already part of the default branch.

Closes #25152 

## Screenshots

### Initial

![image](https://github.com/go-gitea/gitea/assets/51889757/84db2c0b-aaef-4f69-ab92-0b812793d2ad)

### Loaded

![image](https://github.com/go-gitea/gitea/assets/51889757/a9b84e66-8e44-4c55-b017-c37f4a45f41b)

---------

Co-authored-by: silverwind <me@silverwind.io>
Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>

1 files changed, 55 insertions, 0 deletions

diff --git a/services/repository/commit.go b/services/repository/commit.go
new file mode 100644
index 0000000000..2497910a83
--- /dev/null
+++ b/services/repository/commit.go
@@ -0,0 +1,55 @@
+// Copyright 2023 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package repository
+
+import (
+	"context"
+	"fmt"
+
+	gitea_ctx "code.gitea.io/gitea/modules/context"
+	"code.gitea.io/gitea/modules/util"
+)
+
+type ContainedLinks struct { // TODO: better name?
+	Branches      []*namedLink `json:"branches"`
+	Tags          []*namedLink `json:"tags"`
+	DefaultBranch string       `json:"default_branch"`
+}
+
+type namedLink struct { // TODO: better name?
+	Name    string `json:"name"`
+	WebLink string `json:"web_link"`
+}
+
+// LoadBranchesAndTags creates a new repository branch
+func LoadBranchesAndTags(ctx context.Context, baseRepo *gitea_ctx.Repository, commitSHA string) (*ContainedLinks, error) {
+	containedTags, err := baseRepo.GitRepo.ListOccurrences(ctx, "tag", commitSHA)
+	if err != nil {
+		return nil, fmt.Errorf("encountered a problem while querying %s: %w", "tags", err)
+	}
+	containedBranches, err := baseRepo.GitRepo.ListOccurrences(ctx, "branch", commitSHA)
+	if err != nil {
+		return nil, fmt.Errorf("encountered a problem while querying %s: %w", "branches", err)
+	}
+
+	result := &ContainedLinks{
+		DefaultBranch: baseRepo.Repository.DefaultBranch,
+		Branches:      make([]*namedLink, 0, len(containedBranches)),
+		Tags:          make([]*namedLink, 0, len(containedTags)),
+	}
+	for _, tag := range containedTags {
+		// TODO: Use a common method to get the link to a branch/tag instead of hard-coding it here
+		result.Tags = append(result.Tags, &namedLink{
+			Name:    tag,
+			WebLink: fmt.Sprintf("%s/src/tag/%s", baseRepo.RepoLink, util.PathEscapeSegments(tag)),
+		})
+	}
+	for _, branch := range containedBranches {
+		result.Branches = append(result.Branches, &namedLink{
+			Name:    branch,
+			WebLink: fmt.Sprintf("%s/src/branch/%s", baseRepo.RepoLink, util.PathEscapeSegments(branch)),
+		})
+	}
+	return result, nil
+}