refactor: simplify merging secondary configs

internal/config/load.go

@@ -38,12 +38,30 @@ func (err NotFoundError) Error() string {
 
 // Loads configs from the given directory with extensions.
 func Load(fs afero.Fs, repo *git.Repository) (*Config, error) {
-	global, err := readOne(fs, repo.RootPath, []string{"lefthook", ".lefthook"})
+	main, err := readOne(fs, repo.RootPath, []string{"lefthook", ".lefthook"})
 	if err != nil {
 		return nil, err
 	}
 
-	extends, err := mergeAll(fs, repo)
+	extends := main.GetStringSlice("extends")
+	var remote *Remote
+	var remotes []*Remote
+	err = main.UnmarshalKey("remotes", &remotes)
+	if err != nil {
+		return nil, err
+	}
+	// Deprecated
+	err = main.UnmarshalKey("remote", &remote)
+	if err != nil {
+		return nil, err
+	}
+
+	// Backward compatibility
+	if remote != nil {
+		remotes = append(remotes, remote)
+	}
+
+	secondary, err := readSecondary(fs, repo, extends, remotes)
 	if err != nil {
 		return nil, err
 	}
@@ -53,7 +71,7 @@ func Load(fs afero.Fs, repo *git.Repository) (*Config, error) {
 	config.SourceDir = DefaultSourceDir
 	config.SourceDirLocal = DefaultSourceDirLocal
 
-	err = unmarshalConfigs(global, extends, &config)
+	err = unmarshalConfigs(main, secondary, &config)
 	if err != nil {
 		return nil, err
 	}
@@ -104,34 +122,26 @@ func readOne(fs afero.Fs, path string, names []string) (*viper.Viper, error) {
 	return nil, NotFoundError{fmt.Sprintf("No config files with names %q have been found in \"%s\"", names, path)}
 }
 
-// mergeAll merges configs using the following order.
-// - lefthook/.lefthook
+// readSecondary reads extends, remotes and local config.
 // - files from `extends`
 // - files from `remotes`
 // - lefthook-local/.lefthook-local.
-func mergeAll(fs afero.Fs, repo *git.Repository) (*viper.Viper, error) {
-	extends, err := readOne(fs, repo.RootPath, []string{"lefthook", ".lefthook"})
-	if err != nil {
+func readSecondary(fs afero.Fs, repo *git.Repository, extends []string, remotes []*Remote) (*viper.Viper, error) {
+	secondary := newViper(fs, repo.RootPath)
+	if err := extend(fs, repo.RootPath, secondary, extends); err != nil {
 		return nil, err
 	}
 
-	if err := extend(fs, extends, repo.RootPath); err != nil {
-		return nil, err
-	}
-
-	// Save global extends to compare them after merging local config
-	globalExtends := extends.GetStringSlice("extends")
-
-	if err := mergeRemotes(fs, repo, extends); err != nil {
+	if err := mergeRemotes(fs, repo, secondary, remotes); err != nil {
 		return nil, err
 	}
 
 	//nolint:nestif
-	if err := mergeLocal(extends); err == nil {
+	if err := mergeLocal(secondary); err == nil {
 		// Local extends need to be re-applied only if they have different settings
-		localExtends := extends.GetStringSlice("extends")
-		if !slices.Equal(globalExtends, localExtends) {
-			if err = extend(fs, extends, repo.RootPath); err != nil {
+		localExtends := secondary.GetStringSlice("extends")
+		if !slices.Equal(extends, localExtends) {
+			if err = extend(fs, repo.RootPath, secondary, localExtends); err != nil {
 				return nil, err
 			}
 		}
@@ -142,30 +152,11 @@ func mergeAll(fs afero.Fs, repo *git.Repository) (*viper.Viper, error) {
 		}
 	}
 
-	return extends, nil
+	return secondary, nil
 }
 
 // mergeRemotes merges remote configs to the current one.
-func mergeRemotes(fs afero.Fs, repo *git.Repository, v *viper.Viper) error {
-	var remote *Remote // Deprecated
-	var remotes []*Remote
-
-	err := v.UnmarshalKey("remotes", &remotes)
-	if err != nil {
-		return err
-	}
-
-	// Deprecated
-	err = v.UnmarshalKey("remote", &remote)
-	if err != nil {
-		return err
-	}
-
-	// Backward compatibility
-	if remote != nil {
-		remotes = append(remotes, remote)
-	}
-
+func mergeRemotes(fs afero.Fs, repo *git.Repository, v *viper.Viper, remotes []*Remote) error {
 	for _, remote := range remotes {
 		if !remote.Configured() {
 			continue
@@ -187,7 +178,7 @@ func mergeRemotes(fs afero.Fs, repo *git.Repository, v *viper.Viper) error {
 
 			log.Debugf("Merging remote config: %s: %s", remote.GitURL, configPath)
 
-			_, err = fs.Stat(configPath)
+			_, err := fs.Stat(configPath)
 			if err != nil {
 				continue
 			}
@@ -196,13 +187,14 @@ func mergeRemotes(fs afero.Fs, repo *git.Repository, v *viper.Viper) error {
 				return err
 			}
 
-			if err = extend(fs, v, filepath.Dir(configPath)); err != nil {
+			extends := v.GetStringSlice("extends")
+			if err = extend(fs, filepath.Dir(configPath), v, extends); err != nil {
 				return err
 			}
 		}
 
 		// Reset extends to omit issues when extending with remote extends.
-		err = v.MergeConfigMap(map[string]interface{}{"extends": nil})
+		err := v.MergeConfigMap(map[string]interface{}{"extends": nil})
 		if err != nil {
 			return err
 		}
@@ -212,14 +204,14 @@ func mergeRemotes(fs afero.Fs, repo *git.Repository, v *viper.Viper) error {
 }
 
 // extend merges all files listed in 'extends' option into the config.
-func extend(fs afero.Fs, v *viper.Viper, root string) error {
-	return extendRecursive(fs, v, root, make(map[string]struct{}))
+func extend(fs afero.Fs, root string, v *viper.Viper, extends []string) error {
+	return extendRecursive(fs, root, v, extends, make(map[string]struct{}))
 }
 
 // extendRecursive merges extends.
 // If extends contain other extends they get merged too.
-func extendRecursive(fs afero.Fs, v *viper.Viper, root string, extends map[string]struct{}) error {
-	for _, pathOrGlob := range v.GetStringSlice("extends") {
+func extendRecursive(fs afero.Fs, root string, v *viper.Viper, extends []string, visited map[string]struct{}) error {
+	for _, pathOrGlob := range extends {
 		if !filepath.IsAbs(pathOrGlob) {
 			pathOrGlob = filepath.Join(root, pathOrGlob)
 		}
@@ -230,18 +222,18 @@ func extendRecursive(fs afero.Fs, v *viper.Viper, root string, extends map[strin
 		}
 
 		for _, path := range paths {
-			if _, contains := extends[path]; contains {
+			if _, contains := visited[path]; contains {
 				return fmt.Errorf("possible recursion in extends: path %s is specified multiple times", path)
 			}
-			extends[path] = struct{}{}
+			visited[path] = struct{}{}
 
 			extendV := newViper(fs, root)
 			extendV.SetConfigFile(path)
 			if err := extendV.ReadInConfig(); err != nil {
 				return err
 			}
 
-			if err := extendRecursive(fs, extendV, root, extends); err != nil {
+			if err := extendRecursive(fs, root, extendV, extendV.GetStringSlice("extends"), visited); err != nil {
 				return err
 			}