Fix profile updates and validate configuration before apply

internal/budget/units.go

@@ -48,6 +48,11 @@ func (c config) unitProfile(unit string) string {
 			return name
 		}
 	}
+	for _, app := range keys(c.Shared) {
+		if appMatches(app, unit) {
+			return c.Shared[app]
+		}
+	}
 	for _, name := range keys(c.Apps) {
 		for _, app := range c.Apps[name] {
 			if appMatches(app, unit) {
@@ -57,10 +62,7 @@ func (c config) unitProfile(unit string) string {
 	}
 	for _, name := range keys(c.Prefixes) {
 		for _, prefix := range c.Prefixes[name] {
-			parts := strings.Split(prefix, ".")
-			stem := strings.Join(parts[:len(parts)-2], ".")
-			kind := "." + parts[len(parts)-2]
-			if strings.HasPrefix(unit, stem) && strings.HasSuffix(unit, kind) {
+			if prefixMatches(prefix, unit) {
 				return name
 			}
 		}
@@ -77,16 +79,51 @@ func (c config) unitProfile(unit string) string {
 	return ""
 }
 
+func (c config) activeProfile(u unit) string {
+	if name := c.unitProfile(u.Name); name != "" {
+		return name
+	}
+	if strings.HasPrefix(u.Name, "budget-") && strings.HasSuffix(u.Name, ".scope") {
+		if name, ok := strings.CutSuffix(u.Description, " workload"); ok && name != "search" {
+			return name
+		}
+	}
+	return ""
+}
+
+func prefixMatches(directory, unit string) bool {
+	for _, kind := range []string{".service", ".scope", ".slice"} {
+		if stem, ok := strings.CutSuffix(directory, kind+".d"); ok {
+			return strings.HasPrefix(unit, stem) && strings.HasSuffix(unit, kind)
+		}
+	}
+	return false
+}
+
+func dropSection(directory string) (string, error) {
+	for _, kind := range []struct{ suffix, section string }{
+		{".service.d", "Service"}, {".scope.d", "Scope"}, {".slice.d", "Slice"},
+	} {
+		if stem, ok := strings.CutSuffix(directory, kind.suffix); ok && stem != "" {
+			return kind.section, nil
+		}
+	}
+	return "", fmt.Errorf("invalid drop-in directory %q", directory)
+}
+
 func (c config) render() (map[string]string, error) {
+	if err := c.validate(); err != nil {
+		return nil, err
+	}
 	files := map[string]string{}
 	add := func(directory, name, extra string) error {
 		values, err := c.assignments(name)
 		if err != nil {
 			return err
 		}
-		section := "Service"
-		if strings.Contains(directory, ".scope.") {
-			section = "Scope"
+		section, err := dropSection(directory)
+		if err != nil {
+			return err
 		}
 		files[directory+"/50-budget.conf"] = "[" + section + "]\n" + strings.Join(values, "\n") + "\n" + extra
 		return nil