pama: implement the revision control logic

Implement the RevisionController interface to interact with a
respository control system. Add the implementation for git. Other
revision systems such as mercurial, pijul or fossil can be extended.

Signed-off-by: Koni Marti <koni.marti@gmail.com>
Acked-by: Robin Jarry <robin@jarry.cc>

1 files changed, 48 insertions, 0 deletions

diff --git a/lib/pama/revctrl/revctrl.go b/lib/pama/revctrl/revctrl.go
new file mode 100644
index 00000000..42532216
--- /dev/null
+++ b/lib/pama/revctrl/revctrl.go
@@ -0,0 +1,48 @@
+package revctrl
+
+import (
+	"errors"
+	"fmt"
+
+	"git.sr.ht/~rjarry/aerc/lib/pama/models"
+	"git.sr.ht/~rjarry/aerc/log"
+)
+
+var ErrUnsupported = errors.New("unsupported")
+
+type factoryFunc func(string) models.RevisionController
+
+var controllers = map[string]factoryFunc{}
+
+func register(controllerID string, fn factoryFunc) {
+	controllers[controllerID] = fn
+}
+
+func New(controllerID string, path string) (models.RevisionController, error) {
+	factoryFunc, ok := controllers[controllerID]
+	if !ok {
+		return nil, errors.New("cannot create revision control instance")
+	}
+	return factoryFunc(path), nil
+}
+
+type detector interface {
+	Support() bool
+	Root() (string, error)
+}
+
+func Detect(path string) (string, string, error) {
+	for controllerID, factoryFunc := range controllers {
+		rc, ok := factoryFunc(path).(detector)
+		if ok && rc.Support() {
+			log.Tracef("support found for %v", controllerID)
+			root, err := rc.Root()
+			if err != nil {
+				continue
+			}
+			log.Tracef("root found in %s", root)
+			return controllerID, root, nil
+		}
+	}
+	return "", "", fmt.Errorf("no supported repository found in %s", path)
+}