added golangci-linting, refactor, simplified error msgs and fixed some error handling

internal/utils/fs.go

@@ -7,7 +7,7 @@ import (
 )
 
 // Recursively lists all files in a directory until `maxDepth` is reached
-// Returns a slice of file paths relative to `dir`
+// Returns a slice of file paths relative to `dir`.
 func ListFiles(dir string, maxDepth int) ([]string, error) {
 	entries, err := os.ReadDir(dir)
 	if err != nil {

internal/utils/functional/map.go

@@ -4,9 +4,8 @@ import (
 	"sync"
 
 	"github.com/puzpuzpuz/xsync/v3"
-	"gopkg.in/yaml.v3"
-
 	E "github.com/yusing/go-proxy/internal/error"
+	"gopkg.in/yaml.v3"
 )
 
 type Map[KT comparable, VT any] struct {
@@ -25,6 +24,17 @@ func NewMapFrom[KT comparable, VT any](m map[KT]VT) (res Map[KT, VT]) {
 	return
 }
 
+// MapFind iterates over the map and returns the first value
+// that satisfies the given criteria. The iteration is stopped
+// once a value is found. If no value satisfies the criteria,
+// the function returns the zero value of CT.
+//
+// The criteria function takes a value of type VT and returns a
+// value of type CT and a boolean indicating whether the value
+// satisfies the criteria. The boolean value is used to determine
+// whether the iteration should be stopped.
+//
+// The function is safe for concurrent use.
 func MapFind[KT comparable, VT, CT any](m Map[KT, VT], criteria func(VT) (CT, bool)) (_ CT) {
 	result := make(chan CT, 1)
 
@@ -49,13 +59,15 @@ func MapFind[KT comparable, VT, CT any](m Map[KT, VT], criteria func(VT) (CT, bo
 	}
 }
 
-// MergeFrom add contents from another `Map`, ignore duplicated keys
+// MergeFrom merges the contents of another Map into this one, ignoring duplicated keys.
 //
 // Parameters:
-// - other: `Map` of values to add from
 //
-// Return:
-// - Map: a `Map` of duplicated keys-value pairs
+//	other: Map of values to add from
+//
+// Returns:
+//
+//	Map of duplicated keys-value pairs
 func (m Map[KT, VT]) MergeFrom(other Map[KT, VT]) Map[KT, VT] {
 	dups := NewMapOf[KT, VT]()
 
@@ -70,6 +82,15 @@ func (m Map[KT, VT]) MergeFrom(other Map[KT, VT]) Map[KT, VT] {
 	return dups
 }
 
+// RangeAll calls the given function for each key-value pair in the map.
+//
+// Parameters:
+//
+//	do: function to call for each key-value pair
+//
+// Returns:
+//
+//	nothing
 func (m Map[KT, VT]) RangeAll(do func(k KT, v VT)) {
 	m.Range(func(k KT, v VT) bool {
 		do(k, v)
@@ -77,6 +98,16 @@ func (m Map[KT, VT]) RangeAll(do func(k KT, v VT)) {
 	})
 }
 
+// RangeAllParallel calls the given function for each key-value pair in the map,
+// in parallel. The map is not safe for modification from within the function.
+//
+// Parameters:
+//
+//	do: function to call for each key-value pair
+//
+// Returns:
+//
+//	nothing
 func (m Map[KT, VT]) RangeAllParallel(do func(k KT, v VT)) {
 	var wg sync.WaitGroup
 	wg.Add(m.Size())
@@ -91,6 +122,15 @@ func (m Map[KT, VT]) RangeAllParallel(do func(k KT, v VT)) {
 	wg.Wait()
 }
 
+// RemoveAll removes all key-value pairs from the map where the value matches the given criteria.
+//
+// Parameters:
+//
+//	criteria: function to determine whether a value should be removed
+//
+// Returns:
+//
+//	nothing
 func (m Map[KT, VT]) RemoveAll(criteria func(VT) bool) {
 	m.Range(func(k KT, v VT) bool {
 		if criteria(v) {
@@ -105,6 +145,17 @@ func (m Map[KT, VT]) Has(k KT) bool {
 	return ok
 }
 
+// UnmarshalFromYAML unmarshals a yaml byte slice into the map.
+//
+// It overwrites all existing key-value pairs in the map.
+//
+// Parameters:
+//
+//	data: yaml byte slice to unmarshal
+//
+// Returns:
+//
+//	error: if the unmarshaling fails
 func (m Map[KT, VT]) UnmarshalFromYAML(data []byte) E.NestedError {
 	if m.Size() != 0 {
 		return E.FailedWhy("unmarshal from yaml", "map is not empty")

internal/utils/io.go

@@ -12,7 +12,7 @@ import (
 	E "github.com/yusing/go-proxy/internal/error"
 )
 
-// TODO: move to "utils/io"
+// TODO: move to "utils/io".
 type (
 	FileReader struct {
 		Path string
@@ -108,7 +108,7 @@ func Copy2(ctx context.Context, dst io.Writer, src io.Reader) error {
 	return Copy(&ContextWriter{ctx: ctx, Writer: dst}, &ContextReader{ctx: ctx, Reader: src})
 }
 
-func LoadJson[T any](path string, pointer *T) E.NestedError {
+func LoadJSON[T any](path string, pointer *T) E.NestedError {
 	data, err := E.Check(os.ReadFile(path))
 	if err.HasError() {
 		return err
@@ -116,7 +116,7 @@ func LoadJson[T any](path string, pointer *T) E.NestedError {
 	return E.From(json.Unmarshal(data, pointer))
 }
 
-func SaveJson[T any](path string, pointer *T, perm os.FileMode) E.NestedError {
+func SaveJSON[T any](path string, pointer *T, perm os.FileMode) E.NestedError {
 	data, err := E.Check(json.Marshal(pointer))
 	if err.HasError() {
 		return err

internal/utils/serialization.go

@@ -3,6 +3,7 @@ package utils
 import (
 	"bytes"
 	"encoding/json"
+	"errors"
 	"fmt"
 	"reflect"
 	"strconv"
@@ -14,10 +15,12 @@ import (
 	"gopkg.in/yaml.v3"
 )
 
-type SerializedObject = map[string]any
-type Converter interface {
-	ConvertFrom(value any) (any, E.NestedError)
-}
+type (
+	SerializedObject = map[string]any
+	Converter        interface {
+		ConvertFrom(value any) (any, E.NestedError)
+	}
+)
 
 func ValidateYaml(schema *jsonschema.Schema, data []byte) E.NestedError {
 	var i any
@@ -37,11 +40,16 @@ func ValidateYaml(schema *jsonschema.Schema, data []byte) E.NestedError {
 		return nil
 	}
 
-	errors := E.NewBuilder("yaml validation error")
-	for _, e := range err.(*jsonschema.ValidationError).Causes {
-		errors.AddE(e)
+	var valErr *jsonschema.ValidationError
+	if !errors.As(err, &valErr) {
+		return E.UnexpectedError(err)
 	}
-	return errors.Build()
+
+	b := E.NewBuilder("yaml validation error")
+	for _, e := range valErr.Causes {
+		b.AddE(e)
+	}
+	return b.Build()
 }
 
 // Serialize converts the given data into a map[string]any representation.
@@ -80,7 +88,7 @@ func Serialize(data any) (SerializedObject, E.NestedError) {
 			result[key.String()] = value.MapIndex(key).Interface()
 		}
 	case reflect.Struct:
-		for i := 0; i < value.NumField(); i++ {
+		for i := range value.NumField() {
 			field := value.Type().Field(i)
 			if !field.IsExported() {
 				continue
@@ -91,9 +99,10 @@ func Serialize(data any) (SerializedObject, E.NestedError) {
 			}
 
 			// If the json tag is not empty, use it as the key
-			if jsonTag != "" {
+			switch {
+			case jsonTag != "":
 				result[jsonTag] = value.Field(i).Interface()
-			} else if field.Anonymous {
+			case field.Anonymous:
 				// If the field is an embedded struct, add its fields to the result
 				fieldMap, err := Serialize(value.Field(i).Interface())
 				if err != nil {
@@ -102,7 +111,7 @@ func Serialize(data any) (SerializedObject, E.NestedError) {
 				for k, v := range fieldMap {
 					result[k] = v
 				}
-			} else {
+			default:
 				result[field.Name] = value.Field(i).Interface()
 			}
 		}
@@ -147,7 +156,8 @@ func Deserialize(src SerializedObject, dst any) E.NestedError {
 
 	// TODO: use E.Builder to collect errors from all fields
 
-	if dstV.Kind() == reflect.Struct {
+	switch dstV.Kind() {
+	case reflect.Struct:
 		mapping := make(map[string]reflect.Value)
 		for _, field := range reflect.VisibleFields(dstT) {
 			mapping[ToLowerNoSnake(field.Name)] = dstV.FieldByName(field.Name)
@@ -162,7 +172,7 @@ func Deserialize(src SerializedObject, dst any) E.NestedError {
 				return E.Unexpected("field", k).Subjectf("%T", dst)
 			}
 		}
-	} else if dstV.Kind() == reflect.Map && dstT.Key().Kind() == reflect.String {
+	case reflect.Map:
 		if dstV.IsNil() {
 			dstV.Set(reflect.MakeMap(dstT))
 		}
@@ -174,8 +184,7 @@ func Deserialize(src SerializedObject, dst any) E.NestedError {
 			}
 			dstV.SetMapIndex(reflect.ValueOf(ToLowerNoSnake(k)), tmp)
 		}
-		return nil
-	} else {
+	default:
 		return E.Unsupported("target type", fmt.Sprintf("%T", dst))
 	}
 
@@ -362,7 +371,7 @@ func ConvertString(src string, dst reflect.Value) (convertible bool, convErr E.N
 	return true, Convert(reflect.ValueOf(tmp), dst)
 }
 
-func DeserializeJson(j map[string]string, target any) E.NestedError {
+func DeserializeJSON(j map[string]string, target any) E.NestedError {
 	data, err := E.Check(json.Marshal(j))
 	if err != nil {
 		return err

internal/utils/string.go

@@ -9,7 +9,7 @@ import (
 	"golang.org/x/text/language"
 )
 
-// TODO: support other languages
+// TODO: support other languages.
 var titleCaser = cases.Title(language.AmericanEnglish)
 
 func CommaSeperatedList(s string) []string {
@@ -31,3 +31,7 @@ func ExtractPort(fullURL string) (int, error) {
 	}
 	return strconv.Atoi(url.Port())
 }
+
+func PortString(port uint16) string {
+	return strconv.FormatUint(uint64(port), 10)
+}

internal/utils/testing/testing.go

@@ -92,7 +92,6 @@ func ExpectType[T any](t *testing.T, got any) (_ T) {
 	_, ok := got.(T)
 	if !ok {
 		t.Fatalf("expected type %s, got %s", tExpect, reflect.TypeOf(got).Elem())
-		t.FailNow()
 		return
 	}
 	return got.(T)