Simplify defaultBranch

It doesn't need a proper repo.

Author: vHanda

bin/git.dart

@@ -47,8 +47,8 @@ void main(List<String> arguments) {
           bindings.push(arguments[1], directory, pemBytes, arguments[3]);
           break;
         case 'defaultBranch':
-          var branch = bindings.defaultBranch(
-              arguments[1], directory, pemBytes, arguments[3]);
+          var branch =
+              bindings.defaultBranch(arguments[1], pemBytes, arguments[3]);
           print("DefaultBranch: $branch");
           break;
       }

lib/go_git_dart.dart

@@ -136,8 +136,7 @@ class GitBindings {
   }
 
   String defaultBranch(
-    String remote,
-    String directory,
+    String remoteUrl,
     Uint8List pemBytes,
     String password,
   ) {
@@ -146,13 +145,11 @@ class GitBindings {
       cPemBytes[i] = pemBytes[i];
     }
 
-    var remoteName = remote.toNativeUtf8();
-    var cloneDir = directory.toNativeUtf8();
+    var remoteUrlN = remoteUrl.toNativeUtf8();
     var pemPassphrase = password.toNativeUtf8();
 
     var retValue = lib.GitDefaultBranch(
-      remoteName.cast<Char>(),
-      cloneDir.cast<Char>(),
+      remoteUrlN.cast<Char>(),
       cPemBytes.cast<Char>(),
       pemBytes.length,
       pemPassphrase.cast<Char>(),
@@ -162,8 +159,7 @@ class GitBindings {
     // }
 
     malloc.free(cPemBytes);
-    malloc.free(remoteName);
-    malloc.free(cloneDir);
+    malloc.free(remoteUrlN);
     malloc.free(pemPassphrase);
 
     var branch = retValue.cast<Utf8>().toDartString();

src/gitjournal.go

@@ -10,7 +10,9 @@ import (
 	"unsafe"
 
 	git "github.com/go-git/go-git/v5"
+	"github.com/go-git/go-git/v5/config"
 	"github.com/go-git/go-git/v5/plumbing/transport/ssh"
+	"github.com/go-git/go-git/v5/storage/memory"
 	stdssh "golang.org/x/crypto/ssh"
 )
 
@@ -128,33 +130,26 @@ type GitDefaultBranchResult struct {
 */
 
 //export GitDefaultBranch
-func GitDefaultBranch(remote *C.char, directory *C.char, privateKey *C.char, privateKeyLen C.int, password *C.char) *C.char {
-	err, val := gitDefaultBranch(C.GoString(remote), C.GoString(directory), C.GoBytes(unsafe.Pointer(privateKey), privateKeyLen), C.GoString(password))
+func GitDefaultBranch(remoteUrl *C.char, privateKey *C.char, privateKeyLen C.int, password *C.char) *C.char {
+	err, val := gitDefaultBranch(C.GoString(remoteUrl), C.GoBytes(unsafe.Pointer(privateKey), privateKeyLen), C.GoString(password))
 	if err != 0 {
 		return nil
 	}
 	return C.CString(val)
 }
 
-func gitDefaultBranch(remoteName string, directory string, privateKey []byte, password string) (int, string) {
+func gitDefaultBranch(remoteUrl string, privateKey []byte, password string) (int, string) {
 	publicKeys, err := ssh.NewPublicKeys("git", privateKey, password)
 	if err != nil {
 		fmt.Println("generate publickeys failed:", err.Error())
 		return 1, ""
 	}
 	publicKeys.HostKeyCallback = stdssh.InsecureIgnoreHostKey()
 
-	repo, err := git.PlainOpen(directory)
-	if err != nil {
-		fmt.Println("git open failed:", err.Error())
-		return 1, ""
-	}
-
-	remote, err := repo.Remote(remoteName)
-	if err != nil {
-		fmt.Println("git remote failed:", err.Error())
-		return 1, ""
-	}
+	remote := git.NewRemote(memory.NewStorage(), &config.RemoteConfig{
+		Name: "origin",
+		URLs: []string{remoteUrl},
+	})
 
 	refs, err := remote.List(&git.ListOptions{Auth: publicKeys})
 	if err != nil {