From 0d497ca0df4d66f5e40b1bcac632c6e0b24c8603 Mon Sep 17 00:00:00 2001
From: Gorbunov Kirill Andreevich <kgorbunov@mtsbank.ru>
Date: Tue, 27 Feb 2024 21:05:42 +0300
Subject: [PATCH] #97 add As for Broker.

---
 broker/wrap.go      | 34 +++++++++++++++++++
 broker/wrap_test.go | 83 +++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 117 insertions(+)
 create mode 100644 broker/wrap.go
 create mode 100644 broker/wrap_test.go

diff --git a/broker/wrap.go b/broker/wrap.go
new file mode 100644
index 00000000..331b1d63
--- /dev/null
+++ b/broker/wrap.go
@@ -0,0 +1,34 @@
+package broker
+
+import (
+	"reflect"
+)
+
+func As(b Broker, target any) bool {
+	if b == nil {
+		return false
+	}
+	if target == nil {
+		return false
+	}
+	val := reflect.ValueOf(target)
+	typ := val.Type()
+	if typ.Kind() != reflect.Ptr || val.IsNil() {
+		return false
+	}
+	targetType := typ.Elem()
+	if targetType.Kind() != reflect.Interface && !targetType.Implements(brokerType) {
+		return false
+	}
+	return as(b, val, targetType)
+}
+
+func as(b Broker, targetVal reflect.Value, targetType reflect.Type) bool {
+	if reflect.TypeOf(b).AssignableTo(targetType) {
+		targetVal.Elem().Set(reflect.ValueOf(b))
+		return true
+	}
+	return false
+}
+
+var brokerType = reflect.TypeOf((*Broker)(nil)).Elem()
diff --git a/broker/wrap_test.go b/broker/wrap_test.go
new file mode 100644
index 00000000..671ea1b3
--- /dev/null
+++ b/broker/wrap_test.go
@@ -0,0 +1,83 @@
+package broker
+
+import (
+	"context"
+	"fmt"
+	"reflect"
+	"testing"
+
+	"go.unistack.org/micro/v4/options"
+)
+
+type bro struct {
+	name string
+}
+
+func (p *bro) Name() string                      { return p.name }
+func (p *bro) Init(opts ...options.Option) error { return nil }
+
+// Options returns broker options
+func (p *bro) Options() Options { return Options{} }
+
+// Address return configured address
+func (p *bro) Address() string { return "" }
+
+// Connect connects to broker
+func (p *bro) Connect(ctx context.Context) error { return nil }
+
+// Disconnect disconnect from broker
+func (p *bro) Disconnect(ctx context.Context) error { return nil }
+
+// Publish message, msg can be single broker.Message or []broker.Message
+func (p *bro) Publish(ctx context.Context, msg interface{}, opts ...options.Option) error { return nil }
+
+// Subscribe subscribes to topic message via handler
+func (p *bro) Subscribe(ctx context.Context, topic string, handler interface{}, opts ...options.Option) (Subscriber, error) {
+	return nil, nil
+}
+
+// String type of broker
+func (p *bro) String() string { return p.name }
+
+func TestAs(t *testing.T) {
+	var b *bro
+	broTarget := &bro{name: "kafka"}
+
+	testCases := []struct {
+		b      Broker
+		target any
+		match  bool
+		want   any
+	}{
+		{
+			broTarget,
+			&b,
+			true,
+			broTarget,
+		},
+		{
+			nil,
+			&b,
+			false,
+			nil,
+		},
+	}
+	for i, tc := range testCases {
+		name := fmt.Sprintf("%d:As(Errorf(..., %v), %v)", i, tc.b, tc.target)
+		// Clear the target pointer, in case it was set in a previous test.
+		rtarget := reflect.ValueOf(tc.target)
+		rtarget.Elem().Set(reflect.Zero(reflect.TypeOf(tc.target).Elem()))
+		t.Run(name, func(t *testing.T) {
+			match := As(tc.b, tc.target)
+			if match != tc.match {
+				t.Fatalf("match: got %v; want %v", match, tc.match)
+			}
+			if !match {
+				return
+			}
+			if got := rtarget.Elem().Interface(); got != tc.want {
+				t.Fatalf("got %#v, want %#v", got, tc.want)
+			}
+		})
+	}
+}