package broker

import (
	"os"
	"testing"

	"github.com/nats-io/nats.go"
)

// Raising the bus's objects against a real server.
//
// The pure tests above say what is asked for and in what order. Only a server can say whether it
// accepts them — and two of these are claims about the server's own behaviour that nothing else
// could answer: that asserting twice changes nothing, and that a consumer really is bound to the one
// subject its node is allowed to read.
//
//	docker run -d --rm --name t -p 14227:4222 nats:2.10-alpine -js
//	MESH_TEST_NATS=nats://127.0.0.1:14227 go test ./internal/broker/ -run TestRaising

func aLiveBus(t *testing.T) *JetStream {
	t.Helper()
	url := os.Getenv("MESH_TEST_NATS")
	if url == "" {
		t.Skip("MESH_TEST_NATS unset")
	}
	js, err := Dial(url)
	if err != nil {
		t.Fatal(err)
	}
	t.Cleanup(js.Close)
	// Deleted before, so what this test asserts is what it finds — and after, so the next test does
	// not inherit it. Deleting a stream takes its consumers with it, which is why this is enough.
	clear := func() {
		for _, s := range MeshStreams() {
			_ = js.Context().DeleteStream(s.Name)
		}
	}
	clear()
	t.Cleanup(clear)
	return js
}

// Every object the mesh's own traffic needs, accepted by a real server, and asserting again changes
// nothing — which is the whole requirement, because this runs on every start.
func TestRaisingTheBusIsAcceptedAndIdempotent(t *testing.T) {
	js := aLiveBus(t)

	if err := Raise(js, []string{"anchor", "laptop"}); err != nil {
		t.Fatalf("a real server refused the mesh's own objects: %v", err)
	}
	// Twice, with nothing in between. A start that failed the second time is a controller that
	// cannot restart.
	if err := Raise(js, []string{"anchor", "laptop"}); err != nil {
		t.Fatalf("asserting the bus's objects a second time failed, so a restart would: %v", err)
	}
	// And again with a machine that was not there before, which is what enrolling one is.
	if err := Raise(js, []string{"anchor", "laptop", "workstation"}); err != nil {
		t.Fatalf("a machine joining an already-raised bus was refused: %v", err)
	}

	for _, s := range MeshStreams() {
		if _, err := js.Context().StreamInfo(s.Name); err != nil {
			t.Errorf("stream %s is not there: %v", s.Name, err)
		}
	}
	for _, c := range MeshConsumers() {
		if _, err := js.Context().ConsumerInfo(c.Stream, c.Name); err != nil {
			t.Errorf("the controller's consumer on %s is not there: %v", c.Stream, err)
		}
	}
	for _, node := range []string{"anchor", "laptop", "workstation"} {
		info, err := js.Context().ConsumerInfo("NODES", node)
		if err != nil {
			t.Errorf("%s has no way to hear its declaration: %v", node, err)
			continue
		}
		// **Its own subject and no other node's.** A consumer filtered on anything wider is a node
		// reading another machine's declaration, and its own ack grant would not cover it either.
		if info.Config.FilterSubject != "mesh.node."+node+".declare" {
			t.Errorf("%s's consumer reads %q", node, info.Config.FilterSubject)
		}
		if info.Config.AckPolicy != nats.AckExplicitPolicy {
			t.Errorf("%s's consumer acknowledges on delivery, so a declaration it died applying is "+
				"never sent again", node)
		}
	}
}

// The store window needs unlimited redelivery on CONTROL: the bound belongs to the controller, and a
// server that dead-lettered first would discard the push the stream exists to protect.
func TestTheControlConsumerDoesNotDeadLetterBeforeTheControllerGivesUp(t *testing.T) {
	js := aLiveBus(t)
	if err := Raise(js, nil); err != nil {
		t.Fatal(err)
	}
	info, err := js.Context().ConsumerInfo("CONTROL", ControllerName)
	if err != nil {
		t.Fatal(err)
	}
	if info.Config.MaxDeliver > 0 {
		t.Fatalf("max-deliver is %d: a push held through a store restart would be dead-lettered "+
			"before the controller finished deciding about it", info.Config.MaxDeliver)
	}
}