refactor: fold auth and crypto into deezer domain

internal/deezer/credentials.go

@@ -0,0 +1,61 @@
+package deezer
+
+import (
+	"encoding/json"
+	"errors"
+	"fmt"
+
+	"github.com/zalando/go-keyring"
+)
+
+const (
+	keyringService = "godeez"
+	keyringUser    = "default"
+)
+
+type Credentials struct {
+	Email    string `json:"email"`
+	Password string `json:"password"`
+	ARL      string `json:"arl,omitempty"`
+}
+
+func LoadCredentials() (*Credentials, error) {
+	secret, err := keyring.Get(keyringService, keyringUser)
+	if err != nil {
+		if errors.Is(err, keyring.ErrNotFound) {
+			return nil, nil
+		}
+		return nil, fmt.Errorf("system keyring is unavailable: %v", err)
+	}
+
+	var creds Credentials
+	if err := json.Unmarshal([]byte(secret), &creds); err != nil {
+		return nil, err
+	}
+
+	return &creds, nil
+}
+
+func SaveCredentials(creds *Credentials) error {
+	data, err := json.Marshal(creds)
+	if err != nil {
+		return err
+	}
+
+	if err := keyring.Set(keyringService, keyringUser, string(data)); err != nil {
+		return fmt.Errorf("system keyring is unavailable: %v", err)
+	}
+
+	return nil
+}
+
+func ClearCredentials() error {
+	if err := keyring.Delete(keyringService, keyringUser); err != nil {
+		if errors.Is(err, keyring.ErrNotFound) {
+			return nil
+		}
+		return fmt.Errorf("system keyring is unavailable: %v", err)
+	}
+
+	return nil
+}