//go:build integration

package views_test

import (
	"context"
	"encoding/json"
	"testing"
	"time"

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

	"git.novox.be/novox/mesh-sdk/go/process"
	"git.novox.be/novox/mesh-sdk/go/testbus"
	"git.novox.be/novox/mesh-sdk/go/views"
	"git.novox.be/novox/mesh-sdk/go/views/viewstest"
)

// An owner's change is an ordinary event on the shared events stream (novox/hq ADR 0635 §5): a reader that follows the
// owner's state by its read tool hears it on the module's durable consumer of that stream, with no stream of the owner's,
// and a message that is no views event goes to Other.
func TestAReaderHearsAnOwnersChangesAsOrdinaryEvents(t *testing.T) {
	nc, err := nats.Connect(testbus.URL(t))
	if err != nil {
		t.Fatal(err)
	}
	defer nc.Close()
	js, err := jetstream.New(nc)
	if err != nil {
		t.Fatal(err)
	}
	ctx, cancel := context.WithCancel(context.Background())
	defer cancel()
	cred := process.Account{Node: "n1", Module: "reader"}
	kv := viewstest.Serve(t, ctx, js, nc, "o", "modules", "o.o_read_modules", cred.EventConsumerName())
	if _, err := kv.Put(ctx, "a", []byte(`{"n":1}`)); err != nil {
		t.Fatal(err)
	}
	other := make(chan string, 1)
	r := &views.ProcessReader{Module: "reader", Other: func(m jetstream.Msg) { other <- m.Subject(); _ = m.Ack() }, Logf: t.Logf,
		Call: func(tool string, body any) (json.RawMessage, error) {
			raw, _ := json.Marshal(body)
			m, err := nc.Request("mesh.mod.o.call.o_read_modules.n0", raw, 5*time.Second)
			if err != nil {
				return nil, err
			}
			return m.Data, nil
		}}
	if _, err := r.Follow("o", "modules", "o.o_read_modules"); err != nil {
		t.Fatal(err)
	}
	r.Start(ctx, js, cred, nil)
	<-r.Ready()
	pic, err := r.KeyValue(ctx, "o_modules")
	if err != nil {
		t.Fatal(err)
	}
	w, err := pic.Watch(ctx, "b")
	if err != nil {
		t.Fatal(err)
	}
	if _, err := kv.Put(ctx, "b", []byte(`{"n":2}`)); err != nil {
		t.Fatal(err)
	}
	for e := range w.Updates() {
		if e != nil && e.Key() == "b" {
			break
		}
	}
	if s := r.Followers()[0].Status(); s.Asks != 1 || s.Keys != 2 {
		t.Fatalf("the change was not heard as an event alone: %+v", s)
	}
	if _, err := js.Publish(ctx, "mesh.mod.o.event.something-else", []byte("{}")); err != nil {
		t.Fatal(err)
	}
	if got := <-other; got != "mesh.mod.o.event.something-else" {
		t.Fatalf("other got %s", got)
	}
}

// A module has one durable consumer on the shared events stream, so the loops that hear events in one module must share
// one pull (process.EventHub): two handlers and the views reader on the hub each get their own messages and no other's,
// and a message nobody takes is acknowledged.
func TestTheViewsReaderAndTwoHandlersShareTheModulesOneDurable(t *testing.T) {
	nc, err := nats.Connect(testbus.URL(t))
	if err != nil {
		t.Fatal(err)
	}
	defer nc.Close()
	js, err := jetstream.New(nc)
	if err != nil {
		t.Fatal(err)
	}
	ctx, cancel := context.WithCancel(context.Background())
	defer cancel()
	cred := process.Account{Node: "n1", Module: "reader"}
	kv := viewstest.Serve(t, ctx, js, nc, "o", "modules", "o.o_read_modules", cred.EventConsumerName())
	hub := process.NewEventHub(t.Logf)
	got := map[string]chan string{"a": make(chan string, 8), "b": make(chan string, 8)}
	for name, pattern := range map[string]string{"a": "mesh.mod.p.event.a", "b": "mesh.mod.q.event.b.*"} {
		if err := hub.Handle(pattern, func(m jetstream.Msg) { _ = m.Ack(); got[name] <- m.Subject() }); err != nil {
			t.Fatal(err)
		}
	}
	r := &views.ProcessReader{Module: "reader", Hub: hub, Logf: t.Logf,
		Call: func(tool string, body any) (json.RawMessage, error) {
			raw, _ := json.Marshal(body)
			m, err := nc.Request("mesh.mod.o.call.o_read_modules.n0", raw, 5*time.Second)
			if err != nil {
				return nil, err
			}
			return m.Data, nil
		}}
	if _, err := r.Follow("o", "modules", "o.o_read_modules"); err != nil {
		t.Fatal(err)
	}
	r.Start(ctx, js, cred, nil)
	if err := hub.Start(ctx, js, cred); err != nil {
		t.Fatal(err)
	}
	<-r.Ready()
	pic, err := r.KeyValue(ctx, "o_modules")
	if err != nil {
		t.Fatal(err)
	}
	w, err := pic.Watch(ctx, "b")
	if err != nil {
		t.Fatal(err)
	}
	for _, s := range []string{"mesh.mod.p.event.a", "mesh.mod.q.event.b.c", "mesh.mod.z.event.nobody", "mesh.mod.p.event.a"} {
		if _, err := js.Publish(ctx, s, []byte("{}")); err != nil {
			t.Fatal(err)
		}
	}
	if _, err := kv.Put(ctx, "b", []byte(`{"n":2}`)); err != nil {
		t.Fatal(err)
	}
	for e := range w.Updates() {
		if e != nil && e.Key() == "b" {
			break
		}
	}
	for _, want := range []struct{ who, subject string }{{"a", "mesh.mod.p.event.a"}, {"b", "mesh.mod.q.event.b.c"}, {"a", "mesh.mod.p.event.a"}} {
		if s := <-got[want.who]; s != want.subject {
			t.Fatalf("handler %s got %s, wanted %s", want.who, s, want.subject)
		}
	}
	if len(got["a"])+len(got["b"]) != 0 {
		t.Fatal("a handler heard a message that was another's")
	}
	cons, err := js.Consumer(ctx, process.EventsStream, cred.EventConsumerName())
	if err != nil {
		t.Fatal(err)
	}
	if info, err := cons.Info(ctx); err != nil || info.NumAckPending != 0 {
		t.Fatalf("a message was left unacknowledged: %+v %v", info, err)
	}
	// A hub started before the bus holds its durable says so, and binds at a later start: a module is not lost for the
	// order in which the bus makes its consumer.
	late := process.Account{Node: "n1", Module: "late"}
	lateHub := process.NewEventHub(t.Logf)
	heard := make(chan string, 1)
	if err := lateHub.Handle("mesh.mod.l.event.>", func(m jetstream.Msg) { _ = m.Ack(); heard <- m.Subject() }); err != nil {
		t.Fatal(err)
	}
	defer lateHub.Stop()
	if err := lateHub.Start(ctx, js, late); err == nil {
		t.Fatal("a hub with no durable on the bus started")
	}
	if _, err := js.CreateOrUpdateConsumer(ctx, process.EventsStream, jetstream.ConsumerConfig{Durable: late.EventConsumerName(),
		AckPolicy: jetstream.AckExplicitPolicy, FilterSubjects: []string{"mesh.mod.l.event.>"}}); err != nil {
		t.Fatal(err)
	}
	if err := lateHub.Start(ctx, js, late); err != nil {
		t.Fatalf("the hub did not bind at its second start: %v", err)
	}
	if _, err := js.Publish(ctx, "mesh.mod.l.event.x", []byte("{}")); err != nil {
		t.Fatal(err)
	}
	select {
	case <-heard:
	case <-time.After(10 * time.Second):
		t.Fatal("the hub started late heard nothing")
	}
}