From ef74c148e25c0a49172d7e8b1513911331ae79b4 Mon Sep 17 00:00:00 2001
From: Kuisong Tong <kuisong.tong@gmail.com>
Date: Sun, 7 Jan 2024 03:35:44 -0800
Subject: [PATCH] Switch from mitchellh/mapstructure to go-viper/mapstructure
 (#69)

Reference:
https://github.com/mitchellh/mapstructure/issues/349#issuecomment-1860372162

mitchellh stops the maintenance for
[mapstructure](https://github.com/mitchellh/mapstructure) and other
https://github.com/mitchellh/mapstructure/issues/349#issuecomment-1859202291.

The mapstructure project is already forked by viper project, since they
have a strong dependency against it.

https://github.com/go-viper/mapstructure
---
 CHANGELOG.md |  4 +++
 config.go    | 74 ++--------------------------------------------------
 go.mod       |  2 +-
 go.sum       |  4 +--
 option.go    |  2 +-
 5 files changed, 10 insertions(+), 76 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index d0606baa..b2f8ec39 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -7,6 +7,10 @@ to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
 ## [Unreleased]
 
+### Changed
+
+- Switch from mitchellh/mapstructure to go-viper/mapstructure (#69).
+
 ## [v0.3.0] - 11/17/2023
 
 ### Changed
diff --git a/config.go b/config.go
index 682f1b1a..f0931fd9 100644
--- a/config.go
+++ b/config.go
@@ -5,15 +5,13 @@ package konf
 
 import (
 	"context"
-	"encoding"
 	"errors"
 	"fmt"
 	"log/slog"
-	"reflect"
 	"strings"
 	"sync"
 
-	"github.com/mitchellh/mapstructure"
+	"github.com/go-viper/mapstructure/v2"
 
 	"github.com/ktong/konf/internal/maps"
 )
@@ -47,7 +45,7 @@ func New(opts ...Option) *Config {
 		decodeHook: mapstructure.ComposeDecodeHookFunc(
 			mapstructure.StringToTimeDurationHookFunc(),
 			mapstructure.StringToSliceHookFunc(","),
-			textUnmarshalerHookFunc(),
+			mapstructure.TextUnmarshallerHookFunc(),
 		),
 		values:    make(map[string]any),
 		onChanges: make(map[string][]func(*Config)),
@@ -257,71 +255,3 @@ func (c *Config) Unmarshal(path string, target any) error {
 
 	return nil
 }
-
-// textUnmarshalerHookFunc is a fixed version of mapstructure.TextUnmarshallerHookFunc.
-// This hook allows to additionally unmarshal text into custom string types
-// that implement the encoding.Text(Un)Marshaler interface(s).
-//
-//nolint:wrapcheck
-func textUnmarshalerHookFunc() mapstructure.DecodeHookFuncType {
-	return func(
-		from reflect.Type,
-		to reflect.Type, //nolint:varnamelen
-		data interface{},
-	) (interface{}, error) {
-		if from.Kind() != reflect.String {
-			return data, nil
-		}
-		result := reflect.New(to).Interface()
-		unmarshaller, ok := result.(encoding.TextUnmarshaler)
-		if !ok {
-			return data, nil
-		}
-
-		// default text representation is the actual value of the `from` string
-		var (
-			dataVal = reflect.ValueOf(data)
-			text    = []byte(dataVal.String())
-		)
-		if from.Kind() == to.Kind() { //nolint:nestif
-			// source and target are of underlying type string
-			var (
-				err    error
-				ptrVal = reflect.New(dataVal.Type())
-			)
-			if !ptrVal.Elem().CanSet() {
-				// cannot set, skip, this should not happen
-				if err := unmarshaller.UnmarshalText(text); err != nil {
-					return nil, err
-				}
-
-				return result, nil
-			}
-			ptrVal.Elem().Set(dataVal)
-
-			// We need to assert that both, the value type and the pointer type
-			// do (not) implement the TextMarshaller interface before proceeding and simply
-			// using the string value of the string type.
-			// it might be the case that the internal string representation differs from
-			// the (un)marshaled string.
-			for _, v := range []reflect.Value{dataVal, ptrVal} {
-				if marshaller, ok := v.Interface().(encoding.TextMarshaler); ok {
-					text, err = marshaller.MarshalText()
-					if err != nil {
-						return nil, err
-					}
-
-					break
-				}
-			}
-		}
-
-		// text is either the source string's value or the source string type's marshaled value
-		// which may differ from its internal string value.
-		if err := unmarshaller.UnmarshalText(text); err != nil {
-			return nil, err
-		}
-
-		return result, nil
-	}
-}
diff --git a/go.mod b/go.mod
index 63f8d7da..d7da430a 100644
--- a/go.mod
+++ b/go.mod
@@ -2,4 +2,4 @@ module github.com/ktong/konf
 
 go 1.21
 
-require github.com/mitchellh/mapstructure v1.5.0
+require github.com/go-viper/mapstructure/v2 v2.0.0-alpha.1
diff --git a/go.sum b/go.sum
index 59f4b8e6..aa920064 100644
--- a/go.sum
+++ b/go.sum
@@ -1,2 +1,2 @@
-github.com/mitchellh/mapstructure v1.5.0 h1:jeMsZIYE/09sWLaz43PL7Gy6RuMjD2eJVyuac5Z2hdY=
-github.com/mitchellh/mapstructure v1.5.0/go.mod h1:bFUtVrKA4DC2yAKiSyO/QUcy7e+RRV2QTWOzhPopBRo=
+github.com/go-viper/mapstructure/v2 v2.0.0-alpha.1 h1:TQcrn6Wq+sKGkpyPvppOz99zsMBaUOKXq6HSv655U1c=
+github.com/go-viper/mapstructure/v2 v2.0.0-alpha.1/go.mod h1:oJDH3BJKyqBA2TXFhDsKDGDTlndYOZ6rGS0BRZIxGhM=
diff --git a/option.go b/option.go
index c9513c30..6466696c 100644
--- a/option.go
+++ b/option.go
@@ -3,7 +3,7 @@
 
 package konf
 
-import "github.com/mitchellh/mapstructure"
+import "github.com/go-viper/mapstructure/v2"
 
 // WithDelimiter provides the delimiter used when specifying config paths.
 // The delimiter is used to separate keys in the path.