wip

internal/ui/config/config.go

@@ -27,9 +27,9 @@ type Config struct {
 // Backend configures a backend.
 type Backend struct {
 	Type string `hcl:"type"`
-	User string `hcl:"user"`
-	Host string `hcl:"host"`
-	Path string `hcl:"path"`
+	User string `hcl:"user" valid_for:"sftp"`
+	Host string `hcl:"host" valid_for:"sftp"`
+	Path string `hcl:"path" valid_for:"sftp,local"`
 }
 
 // Backup sets the options for the "backup" command.
@@ -155,7 +155,7 @@ func parseBackends(root *ast.ObjectList) (map[string]Backend, error) {
 				obj.Pos().Line, obj.Pos().Column)
 		}
 
-		// get the type of the backend by decoding it into the Backend truct
+		// decode object
 		var be Backend
 		err := hcl.DecodeObject(&be, obj)
 		if err != nil {
@@ -178,8 +178,8 @@ func parseBackends(root *ast.ObjectList) (map[string]Backend, error) {
 				name, obj.Pos().Line, obj.Pos().Column)
 		}
 
-		// check allowed types
-		err = validateObjects(innerBlock.List, listTags(be, "hcl"))
+		// check valid fields
+		err = validateObjects(innerBlock.List, validBackendFieldNames(be.Type))
 		if err != nil {
 			return nil, err
 		}
@@ -190,6 +190,34 @@ func parseBackends(root *ast.ObjectList) (map[string]Backend, error) {
 	return backends, nil
 }
 
+// validBackendFieldNames returns a set of names of valid options for the backend type be.
+func validBackendFieldNames(be string) map[string]struct{} {
+	target := Backend{}
+	vi := reflect.ValueOf(target)
+
+	attr := make(map[string]struct{})
+	for i := 0; i < vi.NumField(); i++ {
+		typeField := vi.Type().Field(i)
+		tag := typeField.Tag.Get("valid_for")
+		name := typeField.Tag.Get("hcl")
+
+		if tag == "" {
+			// if the tag is not specified, it's valid for all backend types
+			attr[name] = struct{}{}
+			continue
+		}
+
+		for _, v := range strings.Split(tag, ",") {
+			if be == v {
+				attr[name] = struct{}{}
+				break
+			}
+		}
+	}
+
+	return attr
+}
+
 // Load loads a config from a file.
 func Load(filename string) (Config, error) {
 	buf, err := ioutil.ReadFile(filename)

internal/ui/config/testdata/all.conf

@@ -10,3 +10,19 @@ backup {
 
     exclude = ["*.c"]
 }
+
+backend "local" {
+    type = "local"
+    path = "/foo/bar"
+}
+
+backend "local2" {
+    path = "/foo/bar"
+}
+
+backend "sftp" {
+    type = "sftp"
+    user = "foo"
+    host = "bar"
+    path = "/foo/bar"
+}

internal/ui/config/testdata/all.golden

@@ -2,7 +2,26 @@
   "Repo": "sftp:user@server:/srv/repo",
   "Password": "secret",
   "PasswordFile": "/root/secret.txt",
-  "Backends": {},
+  "Backends": {
+    "local": {
+      "Type": "local",
+      "User": "",
+      "Host": "",
+      "Path": "/foo/bar"
+    },
+    "local2": {
+      "Type": "local",
+      "User": "",
+      "Host": "",
+      "Path": "/foo/bar"
+    },
+    "sftp": {
+      "Type": "sftp",
+      "User": "foo",
+      "Host": "bar",
+      "Path": "/foo/bar"
+    }
+  },
   "Backup": {
     "Target": [
       "/home/user/",