package ingest

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

	"github.com/loyaly/behavision-server/internal/contract"
)

type fakeStore struct {
	sites      map[string]Site
	visits     []contract.Visit
	seenEvents map[string]bool
	heartbeats []contract.Heartbeat
	failVisit  error
}

func newFake() *fakeStore {
	return &fakeStore{
		sites:      map[string]Site{"acme.store1": {ClientID: "c1", SiteID: "s1", Slug: "acme.store1"}},
		seenEvents: map[string]bool{},
	}
}

func (f *fakeStore) ResolveSite(_ context.Context, u string) (Site, error) {
	s, ok := f.sites[u]
	if !ok {
		return Site{}, ErrUnknownSite
	}
	return s, nil
}

func (f *fakeStore) RecordVisit(_ context.Context, _ Site, v *contract.Visit) (bool, error) {
	if f.failVisit != nil {
		return false, f.failVisit
	}
	if f.seenEvents[v.EventID] {
		return false, nil
	}
	f.seenEvents[v.EventID] = true
	f.visits = append(f.visits, *v)
	return true, nil
}

func (f *fakeStore) RecordHeartbeat(_ context.Context, _ Site, h *contract.Heartbeat) error {
	f.heartbeats = append(f.heartbeats, *h)
	return nil
}

func visitJSON(id string) []byte {
	b, _ := json.Marshal(contract.Visit{
		EventID: id, OccurredAt: time.Now(), CameraID: "entrance"})
	return b
}

func consumer() (*Consumer, *fakeStore) {
	f := newFake()
	return &Consumer{Store: f}, f
}

func TestAVisitIsStored(t *testing.T) {
	c, f := consumer()
	if err := c.Handle(context.Background(), "bv/acme.store1/visit", visitJSON("e1")); err != nil {
		t.Fatal(err)
	}
	if len(f.visits) != 1 || c.Accepted != 1 {
		t.Fatalf("visits=%d accepted=%d", len(f.visits), c.Accepted)
	}
}

func TestRedeliveryDoesNotDoubleFootfall(t *testing.T) {
	// MQTT is at-least-once by design, so this happens after every reconnect.
	// Getting it wrong inflates the one number the customer pays for.
	c, f := consumer()
	ctx := context.Background()
	c.Handle(ctx, "bv/acme.store1/visit", visitJSON("same-id"))
	c.Handle(ctx, "bv/acme.store1/visit", visitJSON("same-id"))

	if len(f.visits) != 1 {
		t.Fatalf("stored %d rows for one event", len(f.visits))
	}
	if c.Accepted != 1 || c.Duplicate != 1 {
		t.Fatalf("accepted=%d duplicate=%d - a redelivery is normal, not an error",
			c.Accepted, c.Duplicate)
	}
}

func TestAnUnprovisionedSiteIsDroppedNotCreated(t *testing.T) {
	// A site typo'd into existence would silently become a tenant with its own
	// visitors and its own footfall report, and nobody would notice until the
	// numbers stopped adding up. Provisioning is a deliberate act.
	c, f := consumer()
	err := c.Handle(context.Background(), "bv/ghost.store9/visit", visitJSON("e1"))
	if err != nil {
		t.Fatalf("an unknown site must not be a transient error: %v", err)
	}
	if len(f.visits) != 0 || len(f.sites) != 1 {
		t.Fatal("an unprovisioned site produced rows")
	}
	if c.Dropped != 1 {
		t.Fatal("the drop was not counted")
	}
}

func TestMalformedPayloadIsDroppedNotRetriedForever(t *testing.T) {
	// A message retried forever stops every good one behind it - the same
	// failure the agent's spool quarantine exists to prevent.
	c, _ := consumer()
	for _, bad := range [][]byte{
		[]byte("{ truncated"),
		[]byte(`{"event_id":"","occurred_at":"2026-01-01T00:00:00Z"}`),
		[]byte(`{"event_id":"e","occurred_at":"2026-01-01T00:00:00Z","embedding":[1,2,3],"model":"m"}`),
	} {
		if err := c.Handle(context.Background(), "bv/acme.store1/visit", bad); err != nil {
			t.Errorf("malformed payload asked for redelivery: %v", err)
		}
	}
	if c.Dropped != 3 {
		t.Fatalf("dropped=%d, want 3", c.Dropped)
	}
}

func TestADatabaseFailureAsksForRedelivery(t *testing.T) {
	// The one path that must NOT swallow the message: the event is valid and
	// the store is broken, so losing it would lose real footfall.
	c, f := consumer()
	f.failVisit = context.DeadlineExceeded
	err := c.Handle(context.Background(), "bv/acme.store1/visit", visitJSON("e1"))
	if err == nil {
		t.Fatal("a database failure was swallowed")
	}
	if c.Dropped != 0 {
		t.Fatal("a database failure was counted as a drop")
	}
}

func TestABadTopicIsDropped(t *testing.T) {
	c, _ := consumer()
	for _, topic := range []string{"bv/acme/visit", "nope/acme.store1/visit",
		"bv/acme.store1/nonsense"} {
		if err := c.Handle(context.Background(), topic, visitJSON("e1")); err != nil {
			t.Errorf("%s: %v", topic, err)
		}
	}
	if c.Dropped != 3 {
		t.Fatalf("dropped=%d, want 3", c.Dropped)
	}
}

func TestHeartbeatIsRecorded(t *testing.T) {
	c, f := consumer()
	h, _ := json.Marshal(contract.Heartbeat{
		SentAt: time.Now(), RecognitionModel: "w600k_r50.onnx"})
	if err := c.Handle(context.Background(), "bv/acme.store1/heartbeat", h); err != nil {
		t.Fatal(err)
	}
	if len(f.heartbeats) != 1 || f.heartbeats[0].RecognitionModel != "w600k_r50.onnx" {
		t.Fatalf("%+v", f.heartbeats)
	}
}

func TestASiteReportingDroppedEventsIsLoggedLoudly(t *testing.T) {
	// That site lost footfall the customer paid for and will never get back.
	// It must not be discoverable only by staring at a graph.
	var sb strings.Builder
	c, _ := consumer()
	c.Log = newTestLogger(&sb)
	h, _ := json.Marshal(contract.Heartbeat{SentAt: time.Now(), Dropped: 417})
	c.Handle(context.Background(), "bv/acme.store1/heartbeat", h)

	out := sb.String()
	if !strings.Contains(out, "417") || !strings.Contains(out, "WARNING") {
		t.Fatalf("dropped events not surfaced: %q", out)
	}
}

// ---------------------------------------------------------------- the doorbell

// A live arrivals stream should learn about a visitor within milliseconds, not
// whenever its fallback tick next comes round.
func TestANewVisitRingsTheDoorbell(t *testing.T) {
	c, _ := consumer()
	var rung []string
	c.Notify = func(clientID string) { rung = append(rung, clientID) }

	if err := c.Handle(context.Background(), "bv/acme.store1/visit", visitJSON("e1")); err != nil {
		t.Fatal(err)
	}
	if len(rung) != 1 || rung[0] != "c1" {
		t.Fatalf("want one ring carrying the tenant, got %v", rung)
	}
}

// At-least-once delivery makes redelivery normal after any reconnect. Ringing
// for one would wake every live stream on the estate to re-query for rows they
// already have - and a reconnect redelivers a whole batch at once.
func TestARedeliveredVisitDoesNotRingTheDoorbell(t *testing.T) {
	c, _ := consumer()
	rings := 0
	c.Notify = func(string) { rings++ }

	for i := 0; i < 3; i++ {
		if err := c.Handle(context.Background(), "bv/acme.store1/visit", visitJSON("e1")); err != nil {
			t.Fatal(err)
		}
	}
	if rings != 1 {
		t.Fatalf("three deliveries of one event rang %d times, want 1", rings)
	}
}

// The consumer must work unchanged with no listener wired up: a server
// assembled without a hub still has to ingest.
func TestIngestWorksWithNoDoorbellWired(t *testing.T) {
	c, f := consumer()
	c.Notify = nil
	if err := c.Handle(context.Background(), "bv/acme.store1/visit", visitJSON("e1")); err != nil {
		t.Fatal(err)
	}
	if len(f.visits) != 1 {
		t.Fatalf("visits=%d", len(f.visits))
	}
}