package link

import (
	"context"
	"strings"
	"testing"
	"time"
)

// The `report` verb (novox/hq to-be 45 §6), what healer H1 asks a machine whose send went unreported:
// the node says again what it last applied, as an ordinary report through the one queue.

// **Asked, the reconcile's account is said even when it is not news** — the mesh asked because it does
// not know, and silence would be the very fault it is asking about.
func TestAskedToReportSaysWhatWasLastAppliedEvenWhenNotNews(t *testing.T) {
	m, _ := aMember(t)
	l := newQuietLink()
	var lines []string
	q := aQueue(m, (&applies{}).apply, &keptInMemory{})
	q.Say = func(s string) { lines = append(lines, s) }
	q.Reconcile = func(context.Context) (Report, bool) {
		return Report{Declared: "d-kept", Order: Order{Epoch: 7, Sequence: 12}, Applied: []string{"a"}}, true
	}
	q.News = func(Report) bool { return false }
	q.attach(context.Background(), l)
	ctx, stop := context.WithCancel(context.Background())
	worker := runWorker(ctx, q)

	q.ReconcileDue() // an ordinary reconcile: not news, not said
	time.Sleep(50 * time.Millisecond)
	if n := len(l.said()); n != 0 {
		t.Fatalf("an ordinary reconcile that is not news said %d report(s)", n)
	}
	q.ReportAsked()
	eventually(t, "asked, the node said nothing", func() bool { return len(l.said()) == 1 })
	stop()
	<-worker
	r := l.said()[0]
	if r.Declared != "d-kept" || r.Sequence != 12 || r.Epoch != 7 || r.ReportSequence == 0 || r.Node != m.Node {
		t.Fatalf("the account said is not the one kept, in order: %+v", r)
	}
	if !strings.Contains(strings.Join(lines, "\n"), "asked by the mesh") {
		t.Errorf("being asked is not said in the journal: %q", lines)
	}
}

// **A delivery waiting answers the question better**: it is applied, once, and its report is the answer.
func TestAskedWhileADeliveryWaitsIsThatDeliverysReport(t *testing.T) {
	m, key := aMember(t)
	l := newQuietLink()
	a := &applies{}
	q := aQueue(m, a.apply, &keptInMemory{})
	reconciled := 0
	q.Reconcile = func(context.Context) (Report, bool) { reconciled++; return Report{}, true }
	q.attach(context.Background(), l)
	q.Deliver(ordered(t, key, "new", 7, 13))
	q.ReportAsked()
	ctx, stop := context.WithCancel(context.Background())
	worker := runWorker(ctx, q)
	eventually(t, "the delivery was never reported", func() bool { return len(l.said()) == 1 })
	time.Sleep(50 * time.Millisecond)
	stop()
	<-worker
	if reconciled != 0 || len(l.said()) != 1 || l.said()[0].Sequence != 13 {
		t.Fatalf("reconciled %d, said %+v", reconciled, l.said())
	}
}

// askingLink is a quiet link the mesh can ask.
type askingLink struct {
	*quietLink
	asks chan struct{}
}

func (l askingLink) AskedToReport() <-chan struct{} { return l.asks }

// **The link hands the question to the queue**: asked on the link, the account is said on it.
func TestALinkThatIsAskedHandsItToTheQueue(t *testing.T) {
	m, _ := aMember(t)
	l := askingLink{quietLink: newQuietLink(), asks: make(chan struct{}, 1)}
	q := aQueue(m, (&applies{}).apply, &keptInMemory{})
	q.Reconcile = func(context.Context) (Report, bool) { return Report{Declared: "d-kept"}, true }
	ctx, stop := context.WithCancel(context.Background())
	defer stop()
	worker := runWorker(ctx, q)
	served := make(chan error, 1)
	go func() { served <- serve(ctx, l, m, q, nil, time.Second) }()
	l.asks <- struct{}{}
	eventually(t, "asked on the link, nothing was said", func() bool {
		for _, r := range l.said() {
			if r.Declared == "d-kept" {
				return true
			}
		}
		return false
	})
	stop()
	<-served
	<-worker
}

// **Against a real server**: the question on the node's own subject reaches it, and another's does not.
func TestNatsTheMeshAsksANodeToReport(t *testing.T) {
	conn, js := aBus(t)
	l := &natsLink{conn: conn, js: js, node: "asked"}
	l.hearAsks()
	defer l.Close()
	if err := conn.Publish(AskReportSubject("another"), []byte(`{}`)); err != nil {
		t.Fatal(err)
	}
	if err := conn.Publish(AskReportSubject("asked"), []byte(`{"by":"the controller's healer H1"}`)); err != nil {
		t.Fatal(err)
	}
	if err := conn.Flush(); err != nil {
		t.Fatal(err)
	}
	select {
	case <-l.AskedToReport():
	case <-time.After(5 * time.Second):
		t.Fatal("the question on the node's own subject never reached it")
	}
	select {
	case <-l.AskedToReport():
		t.Fatal("asked twice: another node's question reached this one")
	case <-time.After(200 * time.Millisecond):
	}
	if AskReportSubject("asked") != "mesh.node.asked.ask.report" {
		t.Fatalf("the subject %q is not the one the controller asks on and grants", AskReportSubject("asked"))
	}
}