Add configurable report module composition

internal/report/registry.go

@@ -84,6 +84,23 @@ func DefaultRegistry() Registry {
 	return registry
 }
 
+func (r Registry) WithModuleOverrides(overrides map[ID][]module.ConfigItem) (Registry, error) {
+	next := Registry{definitions: map[ID]Definition{}}
+	for id, definition := range r.definitions {
+		definition.Modules = append([]module.ConfigItem(nil), definition.Modules...)
+		next.definitions[id] = definition
+	}
+	for id, items := range overrides {
+		definition, ok := next.definitions[id]
+		if !ok {
+			return Registry{}, fmt.Errorf("unknown report %q", id)
+		}
+		definition.Modules = cloneModuleItems(items)
+		next.definitions[id] = definition
+	}
+	return next, nil
+}
+
 func dailyTodayModules() []module.ConfigItem {
 	return moduleItems(
 		module.Metadata,
@@ -154,6 +171,12 @@ func moduleItems(ids ...module.ID) []module.ConfigItem {
 	return items
 }
 
+func cloneModuleItems(items []module.ConfigItem) []module.ConfigItem {
+	cloned := make([]module.ConfigItem, len(items))
+	copy(cloned, items)
+	return cloned
+}
+
 func (r Registry) Lookup(id ID) (Definition, error) {
 	definition, ok := r.definitions[id]
 	if !ok {