1 files changed, 65 insertions, 0 deletions
diff --git a/drive/path.go b/drive/path.go
new file mode 100644
index 0000000..f5d1ad5
--- /dev/null
+++ b/drive/path.go
@@ -0,0 +1,65 @@
+package drive
+
+import (
+    "fmt"
+    "path/filepath"
+    "google.golang.org/api/drive/v3"
+)
+
+func (self *Drive) newPathfinder() *remotePathfinder {
+    return &remotePathfinder{
+        service: self.service.Files,
+        files: make(map[string]*drive.File),
+    }
+}
+
+type remotePathfinder struct {
+    service *drive.FilesService
+    files map[string]*drive.File
+}
+
+func (self *remotePathfinder) absPath(f *drive.File) (string, error) {
+    name := f.Name
+
+    if len(f.Parents) == 0 {
+        return name, nil
+    }
+
+    var path []string
+
+    for {
+        parent, err := self.getParent(f.Parents[0])
+        if err != nil {
+            return "", err
+        }
+
+        // Stop when we find the root dir
+        if len(parent.Parents) == 0 {
+            break
+        }
+
+        path = append([]string{parent.Name}, path...)
+        f = parent
+    }
+
+    path = append(path, name)
+    return filepath.Join(path...), nil
+}
+
+func (self *remotePathfinder) getParent(id string) (*drive.File, error) {
+    // Check cache
+    if f, ok := self.files[id]; ok {
+        return f, nil
+    }
+
+    // Fetch file from drive
+    f, err := self.service.Get(id).Fields("id", "name", "parents").Do()
+    if err != nil {
+        return nil, fmt.Errorf("Failed to get file: %s", err)
+    }
+
+    // Save in cache
+    self.files[f.Id] = f
+
+    return f, nil
+}