sync: Add Git Importer

admin/main.go

@@ -67,6 +67,7 @@ func main() {
 	cloudUsername := "fic"
 	cloudPassword := ""
 	localImporterDirectory := ""
+	gitImporterRemote := ""
 	localImporterSymlink := false
 	baseURL := "/"
 
@@ -108,6 +109,8 @@ func main() {
 		"Base directory where found challenges files to import, local part")
 	flag.BoolVar(&localImporterSymlink, "localimportsymlink", localImporterSymlink,
 		"Copy files or just create symlink?")
+	flag.StringVar(&gitImporterRemote, "git-import-remote", gitImporterRemote,
+		"Remote URL of the git repository to use as synchronization source")
 	flag.StringVar(&cloudDAVBase, "clouddav", cloudDAVBase,
 		"Base directory where found challenges files to import, cloud part")
 	flag.StringVar(&cloudUsername, "clouduser", cloudUsername, "Username used to sync")
@@ -122,6 +125,11 @@ func main() {
 	if localImporterDirectory != "" && cloudDAVBase != "" {
 		log.Fatal("Cannot have both --clouddav and --localimport defined.")
 		return
+	} else if gitImporterRemote != "" && cloudDAVBase != "" {
+		log.Fatal("Cannot have both --clouddav and --git-import-remote defined.")
+		return
+	} else if gitImporterRemote != "" {
+		sync.GlobalImporter = sync.NewGitImporter(sync.LocalImporter{Base: localImporterDirectory, Symlink: localImporterSymlink}, gitImporterRemote)
 	} else if localImporterDirectory != "" {
 		sync.GlobalImporter = sync.LocalImporter{Base: localImporterDirectory, Symlink: localImporterSymlink}
 	} else if cloudDAVBase != "" {

admin/sync/importer_git.go

@@ -0,0 +1,127 @@
+package sync
+
+import (
+	"bufio"
+	"os"
+
+	"github.com/go-git/go-git/v5"
+	"github.com/go-git/go-git/v5/config"
+)
+
+// GitImporter implements an Importer, where files to imports are located
+// inside a local directory from your filesystem, backed by git.
+type GitImporter struct {
+	li     LocalImporter
+	Remote string
+}
+
+func NewGitImporter(li LocalImporter, remote string) GitImporter {
+	return GitImporter{
+		li:     li,
+		Remote: remote,
+	}
+}
+
+func (i GitImporter) Kind() string {
+	var gitinfo string
+	r, err := git.PlainOpen(i.li.Base)
+	if err == nil {
+		ref, err := r.Head()
+		if err == nil {
+			gitinfo = ref.Hash().String()
+		}
+	}
+
+	return "git originated from " + i.Remote + " on " + i.li.Kind() + ", currently on commit " + gitinfo
+}
+
+func countFileInDir(dirname string) (int, error) {
+	files, err := os.ReadDir(dirname)
+	if err != nil {
+		return 0, err
+	}
+
+	return len(files), nil
+}
+
+func (i GitImporter) Init() error {
+	// Check if the directory exists, create it if needed
+	if err := i.li.Init(); err != nil {
+		return err
+	}
+
+	// If the directory is empty, clone it
+	if n, err := countFileInDir(i.li.Base); err != nil {
+		return err
+	} else if n == 0 {
+		_, err = git.PlainClone(i.li.Base, false, &git.CloneOptions{
+			URL:               i.Remote,
+			RecurseSubmodules: git.DefaultSubmoduleRecursionDepth,
+		})
+		if err != nil {
+			return err
+		}
+	}
+
+	// Check if the .git directory exists, change the origin remote to our
+	r, err := git.PlainOpen(i.li.Base)
+	if err != nil {
+		return err
+	}
+
+	r.DeleteRemote("origin")
+	_, err = r.CreateRemote(&config.RemoteConfig{
+		Name: "origin",
+		URLs: []string{i.Remote},
+	})
+	if err != nil {
+		return err
+	}
+
+	return nil
+}
+
+func (i GitImporter) Sync() error {
+	r, err := git.PlainOpen(i.li.Base)
+	if err != nil {
+		return err
+	}
+
+	w, err := r.Worktree()
+	if err != nil {
+		return err
+	}
+
+	// Perform a git pull --rebase origin/master
+	err = w.Pull(&git.PullOptions{
+		RemoteName:        "origin",
+		Depth:             1,
+		RecurseSubmodules: git.DefaultSubmoduleRecursionDepth,
+		Force:             true,
+	})
+	return err
+}
+
+func (i GitImporter) exists(filename string) bool {
+	return i.li.exists(filename)
+}
+
+func (i GitImporter) toURL(filename string) string {
+	return i.li.toURL(filename)
+}
+
+func (i GitImporter) importFile(URI string, next func(string, string) (interface{}, error)) (interface{}, error) {
+	return i.li.importFile(URI, next)
+}
+
+func (i GitImporter) getFile(filename string, writer *bufio.Writer) error {
+	return i.li.getFile(filename, writer)
+}
+
+func (i GitImporter) listDir(filename string) ([]string, error) {
+	return i.li.listDir(filename)
+}
+
+func (i GitImporter) stat(filename string) (os.FileInfo, error) {
+	return i.li.stat(filename)
+}