Add Inner Ring code

pkg/morph/client/balance/client.go

@@ -0,0 +1,102 @@
+package balance
+
+import (
+	"errors"
+
+	"github.com/nspcc-dev/neofs-node/pkg/morph/client"
+)
+
+// Client is a wrapper over StaticClient
+// which makes calls with the names and arguments
+// of the NeoFS Balance contract.
+//
+// Working client must be created via constructor New.
+// Using the Client that has been created with new(Client)
+// expression (or just declaring a Client variable) is unsafe
+// and can lead to panic.
+type Client struct {
+	client *client.StaticClient // static Balance contract client
+
+	*cfg // contract method names
+}
+
+// ErrNilClient is returned by functions that expect
+// a non-nil Client pointer, but received nil.
+var ErrNilClient = errors.New("balance contract client is nil")
+
+// Option is a client configuration change function.
+type Option func(*cfg)
+
+type cfg struct {
+	balanceOfMethod, // balanceOf method name for invocation
+	decimalsMethod string // decimals method name for invocation
+}
+
+const (
+	defaultBalanceOfMethod = "balanceOf" // default "balance of" method name
+	defaultDecimalsMethod  = "decimals"  // default decimals method name
+)
+
+func defaultConfig() *cfg {
+	return &cfg{
+		balanceOfMethod: defaultBalanceOfMethod,
+		decimalsMethod:  defaultDecimalsMethod,
+	}
+}
+
+// New creates, initializes and returns the Client instance.
+//
+// If StaticClient is nil, client.ErrNilStaticClient is returned.
+//
+// Other values are set according to provided options, or by default:
+//  * "balance of" method name: balanceOf;
+//  * decimals method name: decimals.
+//
+// If desired option satisfies the default value, it can be omitted.
+// If multiple options of the same config value are supplied,
+// the option with the highest index in the arguments will be used.
+func New(c *client.StaticClient, opts ...Option) (*Client, error) {
+	if c == nil {
+		return nil, client.ErrNilStaticClient
+	}
+
+	res := &Client{
+		client: c,
+		cfg:    defaultConfig(), // build default configuration
+	}
+
+	// apply options
+	for _, opt := range opts {
+		opt(res.cfg)
+	}
+
+	return res, nil
+}
+
+// WithBalanceOfMethod returns a client constructor option that
+// specifies the "balance of" method name.
+//
+// Ignores empty value.
+//
+// If option not provided, "balanceOf" is used.
+func WithBalanceOfMethod(n string) Option {
+	return func(c *cfg) {
+		if n != "" {
+			c.balanceOfMethod = n
+		}
+	}
+}
+
+// WithDecimalsMethod returns a client constructor option that
+// specifies the method name of decimals receiving operation.
+//
+// Ignores empty value.
+//
+// If option not provided, "decimals" is used.
+func WithDecimalsMethod(n string) Option {
+	return func(c *cfg) {
+		if n != "" {
+			c.decimalsMethod = n
+		}
+	}
+}