package broker

import (
	"strings"
	"testing"
)

func telegramSeat() DeclaredSeat {
	return DeclaredSeat{Name: "telegram-sender", Accepts: []string{"send"}}
}

// The stream exists from registration, not assignment: work queues until a holder appears, so
// installing the module a week later flushes the backlog rather than having lost it.
func TestASeatGetsAWorkQueueOfItsOwn(t *testing.T) {
	got := SeatStreams([]DeclaredSeat{telegramSeat()})
	if len(got) != 1 {
		t.Fatalf("expected one stream, got %d", len(got))
	}
	s := got[0]
	if s.Retention != RetentionWorkQueue {
		t.Fatalf("a seat's inbound queue retains as %q; one holder must take each message once", s.Retention)
	}
	if s.Subjects[0] != "mesh.seat.telegram-sender.accept.>" {
		t.Fatalf("filters on %v", s.Subjects)
	}
}

// A seat that only emits and serves needs no stream: its events ride EVENTS and its tools are
// core request/reply, which is never persisted.
func TestASeatThatAcceptsNothingGetsNoStream(t *testing.T) {
	if got := SeatStreams([]DeclaredSeat{{Name: "announcer"}}); len(got) != 0 {
		t.Fatalf("a seat with no inbound work got %d stream(s)", len(got))
	}
}

// Retention belongs to whoever owns the namespace, and a seat owns its own.
func TestASeatsRetentionIsItsOwn(t *testing.T) {
	s := SeatStreams([]DeclaredSeat{{Name: "slow", Accepts: []string{"work"}, RetainSeconds: 30 * 24 * 60 * 60}})
	if s[0].MaxAge != 30*24*60*60 {
		t.Fatalf("the seat's declared retention was not used: %d", s[0].MaxAge)
	}
	d := SeatStreams([]DeclaredSeat{telegramSeat()})
	if d[0].MaxAge == 0 {
		t.Fatal("a seat that declares no retention got an unbounded queue")
	}
}

// NATS refuses an overlapping stream outright, so a clash here is a registration that fails.
func TestNoDerivedStreamOverlapsTheMeshsOwn(t *testing.T) {
	seats := []DeclaredSeat{telegramSeat(), {Name: "licensing-master", Accepts: []string{"report"}}}
	if c := AllOverlaps(seats); len(c) != 0 {
		t.Fatalf("overlapping filters: %v", c)
	}
}

// One consumer per module, with every consumed subject as a filter — because its ack permission
// is derived from its name, and a consumer per event would need an ack permission per consumer.
func TestAModuleGetsOneConsumerCarryingEveryFilter(t *testing.T) {
	c, ok := ConsumerFor(Principal{Kind: KindModule, Node: "one", Module: "audit",
		Consumes: []string{"shop.order.placed", "billing.invoice.sent"}, PasswordHash: "x"})
	if !ok {
		t.Fatal("a module that consumes got no consumer")
	}
	if len(c.Filters) != 2 {
		t.Fatalf("expected both subjects as filters, got %v", c.Filters)
	}
	perms, _ := PermissionsFor(Principal{Kind: KindModule, Node: "one", Module: "audit",
		Consumes: []string{"shop.order.placed"}, PasswordHash: "x"})
	ack := "$JS.ACK." + c.Stream + "." + c.Name + ".>"
	found := false
	for _, p := range perms.Publish {
		if p == ack {
			found = true
		}
	}
	if !found {
		t.Fatalf("the consumer is named %q but the ack permission is %v; a module could not ack "+
			"its own deliveries", c.Name, perms.Publish)
	}
}

// A module that subscribes to nothing needs no consumer, and creating one would leave an object
// nothing reads and everything has to maintain.
func TestAModuleThatConsumesNothingGetsNoConsumer(t *testing.T) {
	if _, ok := ConsumerFor(Principal{Kind: KindModule, Node: "one", Module: "shop",
		Emits: []string{"order.placed"}, PasswordHash: "x"}); ok {
		t.Fatal("a pure emitter got a consumer")
	}
}

// The seat is authority and the queue group is delivery. Tie them together and the day somebody
// allows two holders, every message is processed twice with nothing reporting it.
func TestAHoldersWorkerUsesAQueueGroupAnyway(t *testing.T) {
	c, ok := HolderConsumerFor("one", "telegram", telegramSeat())
	if !ok {
		t.Fatal("the holder of a seat with inbound work got no worker")
	}
	if c.Queue == "" {
		t.Fatal("the worker is not in a queue group, so a second holder would double-process")
	}
	if c.Stream != "SEAT_TELEGRAM_SENDER" {
		t.Fatalf("the worker reads %q, not the seat's own stream", c.Stream)
	}
	if c.MaxDeliver == 0 {
		t.Fatal("a failing worker would redeliver forever rather than dead-letter")
	}
}

// The stream is named after the seat, not its holder: the holder can change and the queued work
// must not care.
func TestASeatsStreamIsNamedAfterTheSeat(t *testing.T) {
	name := seatStreamName("telegram-sender")
	if strings.Contains(name, "telegram-sender") {
		t.Fatalf("%q keeps characters a stream name may not hold", name)
	}
	if name != "SEAT_TELEGRAM_SENDER" {
		t.Fatalf("unexpected stream name %q", name)
	}
}

// A node hears its declaration through a consumer only the controller can make.
//
// The three things that would each break it silently: a name other than the node's is one the host
// cannot acknowledge a delivery from, because its ack grant is derived from the node's name; a
// filter other than its own declaration subject is a node reading another's; and a pull consumer is
// one the host cannot bind a channel to without creating something, which it has no authority for.
func TestANodesDeclarationConsumerIsWhatItsOwnGrantAllows(t *testing.T) {
	c := NodeConsumer("anchor")
	if c.Name != "anchor" {
		t.Fatalf("named %q, so the node cannot ack from it: its grant is $JS.ACK.NODES.anchor.>", c.Name)
	}
	if c.Stream != "NODES" {
		t.Fatalf("on stream %q rather than the one declarations live in", c.Stream)
	}
	if len(c.Filters) != 1 || c.Filters[0] != "mesh.node.anchor.declare" {
		t.Fatalf("filters %v, which is not this node's own declaration and nothing else", c.Filters)
	}
	if !c.Push {
		t.Fatal("pulled, which a host cannot do: pulling needs the JetStream API and a host reaches none of it")
	}
	if c.MaxDeliver != 0 {
		t.Fatalf("max-deliver %d: a declaration a node has not taken yet is not one to dead-letter, "+
			"because the stream holds exactly one per node", c.MaxDeliver)
	}

	// And the grant the node actually gets has to match, or none of the above matters.
	perms, err := PermissionsFor(Principal{Kind: KindNode, Node: "anchor"})
	if err != nil {
		t.Fatal(err)
	}
	// Without the ack grant every declaration a node receives is redelivered for ever; without the
	// subscribe grant its consumer delivers to nobody.
	has(t, perms.Publish, "$JS.ACK.NODES."+c.Name+".>")
	has(t, perms.Subscribe, c.Filters[0])
}