feat(encoding): add ini codec

Signed-off-by: Mark Sagi-Kazar <mark.sagikazar@gmail.com>

internal/encoding/ini/codec.go

@@ -0,0 +1,99 @@
+package ini
+
+import (
+	"bytes"
+	"sort"
+	"strings"
+
+	"github.com/spf13/cast"
+	"gopkg.in/ini.v1"
+)
+
+// LoadOptions contains all customized options used for load data source(s).
+// This type is added here for convenience: this way consumers can import a single package called "ini".
+type LoadOptions = ini.LoadOptions
+
+// Codec implements the encoding.Encoder and encoding.Decoder interfaces for INI encoding.
+type Codec struct {
+	KeyDelimiter string
+	LoadOptions  LoadOptions
+}
+
+func (c Codec) Encode(v map[string]interface{}) ([]byte, error) {
+	cfg := ini.Empty()
+	ini.PrettyFormat = false
+
+	flattened := map[string]interface{}{}
+
+	flattened = flattenAndMergeMap(flattened, v, "", c.keyDelimiter())
+
+	keys := make([]string, 0, len(flattened))
+
+	for key := range flattened {
+		keys = append(keys, key)
+	}
+
+	sort.Strings(keys)
+
+	for _, key := range keys {
+		sectionName, keyName := "", key
+
+		lastSep := strings.LastIndex(key, ".")
+		if lastSep != -1 {
+			sectionName = key[:(lastSep)]
+			keyName = key[(lastSep + 1):]
+		}
+
+		// TODO: is this a good idea?
+		if sectionName == "default" {
+			sectionName = ""
+		}
+
+		cfg.Section(sectionName).Key(keyName).SetValue(cast.ToString(flattened[key]))
+	}
+
+	var buf bytes.Buffer
+
+	_, err := cfg.WriteTo(&buf)
+	if err != nil {
+		return nil, err
+	}
+
+	return buf.Bytes(), nil
+}
+
+func (c Codec) Decode(b []byte, v map[string]interface{}) error {
+	cfg := ini.Empty(c.LoadOptions)
+
+	err := cfg.Append(b)
+	if err != nil {
+		return err
+	}
+
+	sections := cfg.Sections()
+
+	for i := 0; i < len(sections); i++ {
+		section := sections[i]
+		keys := section.Keys()
+
+		for j := 0; j < len(keys); j++ {
+			key := keys[j]
+			value := cfg.Section(section.Name()).Key(key.Name()).String()
+
+			deepestMap := deepSearch(v, strings.Split(section.Name(), c.keyDelimiter()))
+
+			// set innermost value
+			deepestMap[key.Name()] = value
+		}
+	}
+
+	return nil
+}
+
+func (c Codec) keyDelimiter() string {
+	if c.KeyDelimiter == "" {
+		return "."
+	}
+
+	return c.KeyDelimiter
+}

internal/encoding/ini/codec_test.go

@@ -0,0 +1,112 @@
+package ini
+
+import (
+	"reflect"
+	"testing"
+)
+
+// original form of the data
+const original = `; key-value pair
+key=value ; key-value pair
+
+# map
+[map] # map
+key=%(key)s
+
+`
+
+// encoded form of the data
+const encoded = `key=value
+
+[map]
+key=value
+
+`
+
+// decoded form of the data
+//
+// in case of INI it's slightly different from Viper's internal representation
+// (eg. top level keys land in a section called default)
+var decoded = map[string]interface{}{
+	"DEFAULT": map[string]interface{}{
+		"key": "value",
+	},
+	"map": map[string]interface{}{
+		"key": "value",
+	},
+}
+
+// Viper's internal representation
+var data = map[string]interface{}{
+	"key": "value",
+	"map": map[string]interface{}{
+		"key": "value",
+	},
+}
+
+func TestCodec_Encode(t *testing.T) {
+	t.Run("OK", func(t *testing.T) {
+		codec := Codec{}
+
+		b, err := codec.Encode(data)
+		if err != nil {
+			t.Fatal(err)
+		}
+
+		if encoded != string(b) {
+			t.Fatalf("decoded value does not match the expected one\nactual:   %#v\nexpected: %#v", string(b), encoded)
+		}
+	})
+
+	t.Run("Default", func(t *testing.T) {
+		codec := Codec{}
+
+		data := map[string]interface{}{
+			"default": map[string]interface{}{
+				"key": "value",
+			},
+			"map": map[string]interface{}{
+				"key": "value",
+			},
+		}
+
+		b, err := codec.Encode(data)
+		if err != nil {
+			t.Fatal(err)
+		}
+
+		if encoded != string(b) {
+			t.Fatalf("decoded value does not match the expected one\nactual:   %#v\nexpected: %#v", string(b), encoded)
+		}
+	})
+}
+
+func TestCodec_Decode(t *testing.T) {
+	t.Run("OK", func(t *testing.T) {
+		codec := Codec{}
+
+		v := map[string]interface{}{}
+
+		err := codec.Decode([]byte(original), v)
+		if err != nil {
+			t.Fatal(err)
+		}
+
+		if !reflect.DeepEqual(decoded, v) {
+			t.Fatalf("decoded value does not match the expected one\nactual:   %#v\nexpected: %#v", v, decoded)
+		}
+	})
+
+	t.Run("InvalidData", func(t *testing.T) {
+		codec := Codec{}
+
+		v := map[string]interface{}{}
+
+		err := codec.Decode([]byte(`invalid data`), v)
+		if err == nil {
+			t.Fatal("expected decoding to fail")
+		}
+
+		t.Logf("decoding failed as expected: %s", err)
+	})
+}

internal/encoding/ini/map_utils.go

@@ -0,0 +1,74 @@
+package ini
+
+import (
+	"strings"
+
+	"github.com/spf13/cast"
+)
+
+// THIS CODE IS COPIED HERE: IT SHOULD NOT BE MODIFIED
+// AT SOME POINT IT WILL BE MOVED TO A COMMON PLACE
+// deepSearch scans deep maps, following the key indexes listed in the
+// sequence "path".
+// The last value is expected to be another map, and is returned.
+//
+// In case intermediate keys do not exist, or map to a non-map value,
+// a new map is created and inserted, and the search continues from there:
+// the initial map "m" may be modified!
+func deepSearch(m map[string]interface{}, path []string) map[string]interface{} {
+	for _, k := range path {
+		m2, ok := m[k]
+		if !ok {
+			// intermediate key does not exist
+			// => create it and continue from there
+			m3 := make(map[string]interface{})
+			m[k] = m3
+			m = m3
+			continue
+		}
+		m3, ok := m2.(map[string]interface{})
+		if !ok {
+			// intermediate key is a value
+			// => replace with a new map
+			m3 = make(map[string]interface{})
+			m[k] = m3
+		}
+		// continue search from here
+		m = m3
+	}
+	return m
+}
+
+// flattenAndMergeMap recursively flattens the given map into a new map
+// Code is based on the function with the same name in tha main package.
+// TODO: move it to a common place
+func flattenAndMergeMap(shadow map[string]interface{}, m map[string]interface{}, prefix string, delimiter string) map[string]interface{} {
+	if shadow != nil && prefix != "" && shadow[prefix] != nil {
+		// prefix is shadowed => nothing more to flatten
+		return shadow
+	}
+	if shadow == nil {
+		shadow = make(map[string]interface{})
+	}
+
+	var m2 map[string]interface{}
+	if prefix != "" {
+		prefix += delimiter
+	}
+	for k, val := range m {
+		fullKey := prefix + k
+		switch val.(type) {
+		case map[string]interface{}:
+			m2 = val.(map[string]interface{})
+		case map[interface{}]interface{}:
+			m2 = cast.ToStringMap(val)
+		default:
+			// immediate value
+			shadow[strings.ToLower(fullKey)] = val
+			continue
+		}
+		// recursively merge to shadow map
+		shadow = flattenAndMergeMap(shadow, m2, fullKey, delimiter)
+	}
+	return shadow
+}