add config

Author: adelowo

config/env.go

@@ -14,9 +14,16 @@ import (
 //	}
 //
 // if your envPrefix is XXX, it can be set in env like XXX_DSN
-func BindEnvs(v *viper.Viper, envPrefix string, iface any) { bindEnvs(v, envPrefix, "", iface) }
+func BindEnvs(v *viper.Viper, envPrefix string, iface any) {
+	walkStruct(iface, "", func(fieldv reflect.Value, path, envKey string) error {
+		if err := v.BindEnv(path, envPrefix+envKey); err != nil {
+			panic(err)
+		}
+		return nil
+	})
+}
 
-func bindEnvs(v *viper.Viper, envPrefix string, prefix string, iface any) {
+func walkStruct(iface any, prefix string, fn func(fieldv reflect.Value, path, envKey string) error) error {
 	ifv := reflect.Indirect(reflect.ValueOf(iface))
 	ift := ifv.Type()
 
@@ -34,14 +41,17 @@ func bindEnvs(v *viper.Viper, envPrefix string, prefix string, iface any) {
 			path = prefix + "." + name
 		}
 
-		switch fieldv.Kind() {
-		case reflect.Struct:
-			bindEnvs(v, envPrefix, path, fieldv.Addr().Interface())
-		default:
-			envKey := strings.ToUpper(strings.ReplaceAll(path, ".", "_"))
-			if err := v.BindEnv(path, envPrefix+envKey); err != nil {
-				panic(err)
+		envKey := strings.ToUpper(strings.ReplaceAll(path, ".", "_"))
+
+		if fieldv.Kind() == reflect.Struct {
+			if err := walkStruct(fieldv.Addr().Interface(), path, fn); err != nil {
+				return err
+			}
+		} else {
+			if err := fn(fieldv, path, envKey); err != nil {
+				return err
 			}
 		}
 	}
+	return nil
 }

config/export.go

@@ -0,0 +1,49 @@
+package config
+
+import (
+	"encoding/json"
+	"fmt"
+	"io"
+	"reflect"
+	"strings"
+
+	"gopkg.in/yaml.v3"
+)
+
+// ENUM(yml,json,env)
+type ExportType uint8
+
+func Export(w io.Writer, cfg any, exportType ExportType, envPrefix string) error {
+	switch exportType {
+	case ExportTypeJson:
+		enc := json.NewEncoder(w)
+		enc.SetIndent("", "  ")
+		return enc.Encode(cfg)
+	case ExportTypeYml:
+		return yaml.NewEncoder(w).Encode(cfg)
+	case ExportTypeEnv:
+		return exportEnv(w, cfg, envPrefix, "")
+	default:
+		return fmt.Errorf("unsupported export type: %v", exportType)
+	}
+}
+
+func exportEnv(w io.Writer, iface any, envPrefix string, prefix string) error {
+	var sb strings.Builder
+	if err := walkStruct(iface, prefix, func(fieldv reflect.Value, path, envKey string) error {
+
+		key := envPrefix + envKey
+
+		value := fmt.Sprintf("%v", fieldv.Interface())
+		sb.WriteString(key)
+		sb.WriteString("=")
+		sb.WriteString(value)
+		sb.WriteString("\n")
+
+		return nil
+	}); err != nil {
+		return err
+	}
+	_, err := w.Write([]byte(sb.String()))
+	return err
+}

config/export_enum.go

@@ -0,0 +1,69 @@
+package config
+
+import (
+	"bytes"
+	"os"
+	"path/filepath"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+type testConfig struct {
+	Database struct {
+		Host string `mapstructure:"host" json:"host"`
+		Port int    `mapstructure:"port" json:"port"`
+	} `mapstructure:"database" json:"database"`
+	API struct {
+		Key    string `mapstructure:"key" json:"key"`
+		Secret string `mapstructure:"secret" json:"secret"`
+	} `mapstructure:"api" json:"api"`
+	Debug bool `mapstructure:"debug" json:"debug"`
+}
+
+func TestExport(t *testing.T) {
+	cfg := testConfig{}
+	cfg.Database.Host = "localhost"
+	cfg.Database.Port = 5432
+	cfg.API.Key = "test-key"
+	cfg.API.Secret = "secret123"
+	cfg.Debug = true
+
+	envPrefix := "APP_"
+
+	tests := []struct {
+		name         string
+		exportType   ExportType
+		expectedFile string
+	}{
+		{
+			name:         "json export",
+			exportType:   ExportTypeJson,
+			expectedFile: "expected.json",
+		},
+		{
+			name:         "yml export",
+			exportType:   ExportTypeYml,
+			expectedFile: "expected.yml",
+		},
+		{
+			name:         "env export",
+			exportType:   ExportTypeEnv,
+			expectedFile: "expected.env",
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			var buf bytes.Buffer
+			err := Export(&buf, &cfg, tt.exportType, envPrefix)
+			require.NoError(t, err)
+
+			expectedPath := filepath.Join("testdata", tt.expectedFile)
+			expected, err := os.ReadFile(expectedPath)
+			require.NoError(t, err)
+
+			require.Equal(t, string(expected), buf.String())
+		})
+	}
+}

config/export_test.go

@@ -0,0 +1,5 @@
+APP_DATABASE_HOST=localhost
+APP_DATABASE_PORT=5432
+APP_API_KEY=test-key
+APP_API_SECRET=secret123
+APP_DEBUG=true

config/testdata/expected.env

@@ -0,0 +1,11 @@
+{
+  "database": {
+    "host": "localhost",
+    "port": 5432
+  },
+  "api": {
+    "key": "test-key",
+    "secret": "secret123"
+  },
+  "debug": true
+}

config/testdata/expected.json

@@ -0,0 +1,7 @@
+database:
+    host: localhost
+    port: 5432
+api:
+    key: test-key
+    secret: secret123
+debug: true