package bridge

import (
	"context"
	"encoding/json"
	"errors"
	"net/http"
	"net/http/httptest"
	"strings"
	"testing"
)

type fakeQueue struct {
	topics   []string
	payloads []map[string]any
	err      error
}

func (q *fakeQueue) Append(topic string, payload any) error {
	if q.err != nil {
		return q.err
	}
	b, _ := json.Marshal(payload)
	var m map[string]any
	json.Unmarshal(b, &m)
	q.topics = append(q.topics, topic)
	q.payloads = append(q.payloads, m)
	return nil
}

type fakeEmb struct {
	calls int
	err   error
}

func (f *fakeEmb) Embedding(_ context.Context, id int64) ([]float32, string, error) {
	f.calls++
	if f.err != nil {
		return nil, "", f.err
	}
	return make([]float32, 512), "w600k_r50.onnx", nil
}

func newBridge() (*Bridge, *fakeQueue, *fakeEmb) {
	q, e := &fakeQueue{}, &fakeEmb{}
	return &Bridge{Queue: q, Embeddings: e, TopicPrefix: "bv/acme.store1"}, q, e
}

func seen(id int64, ts float64) Event {
	return Event{Type: "person.seen", CameraID: "entrance", TS: ts,
		Data: map[string]any{"identity_id": float64(id), "similarity": 0.58,
			"quality": 0.74, "gender": "Male", "age": float64(34)}}
}

func TestADetectionIsQueuedForTheRightTopic(t *testing.T) {
	b, q, _ := newBridge()
	if err := b.Handle(context.Background(), seen(7, 1787996491)); err != nil {
		t.Fatal(err)
	}
	if len(q.topics) != 1 || q.topics[0] != "bv/acme.store1/visit" {
		t.Fatalf("topics=%v", q.topics)
	}
	p := q.payloads[0]
	if p["camera_id"] != "entrance" || p["is_new"] != false {
		t.Fatalf("%+v", p)
	}
	if p["quality"] != 0.74 || p["similarity"] != 0.58 {
		t.Fatalf("measurements lost: %+v", p)
	}
}

func TestTheEventIDIsStableForTheSameSighting(t *testing.T) {
	// This is what makes at-least-once delivery safe. A random id here would
	// defeat the server's idempotency check and double the store's footfall
	// after every reconnect.
	b, q, _ := newBridge()
	ctx := context.Background()
	b.Handle(ctx, seen(7, 1787996491.20))
	b.Handle(ctx, seen(7, 1787996491.86)) // same second, redelivered

	if q.payloads[0]["event_id"] != q.payloads[1]["event_id"] {
		t.Fatalf("ids differ: %v vs %v",
			q.payloads[0]["event_id"], q.payloads[1]["event_id"])
	}
}

func TestDifferentPeopleAndCamerasGetDifferentIDs(t *testing.T) {
	b, q, _ := newBridge()
	ctx := context.Background()
	b.Handle(ctx, seen(7, 1787996491))
	b.Handle(ctx, seen(8, 1787996491)) // different person, same instant
	other := seen(7, 1787996491)
	other.CameraID = "till"
	b.Handle(ctx, other) // same person, different camera

	ids := map[any]bool{}
	for _, p := range q.payloads {
		ids[p["event_id"]] = true
	}
	if len(ids) != 3 {
		t.Fatalf("collided: %d distinct ids from 3 sightings", len(ids))
	}
}

func TestLocalDiagnosticsAreNotCountedAsVisits(t *testing.T) {
	// person.missed and camera.up are real events, but sending them down the
	// footfall stream would inflate the headcount with things that are not
	// people.
	b, q, _ := newBridge()
	for _, typ := range []string{"person.missed", "camera.up", "camera.down",
		"identity.merged"} {
		b.Handle(context.Background(), Event{Type: typ, CameraID: "entrance"})
	}
	if len(q.payloads) != 0 {
		t.Fatalf("queued %d non-visits", len(q.payloads))
	}
	if b.Skipped != 4 {
		t.Fatalf("skipped=%d", b.Skipped)
	}
}

func TestAnUnclaimedPCQueuesNothing(t *testing.T) {
	// Without a tenant prefix an event would be addressed to nowhere, and the
	// broker would refuse it anyway.
	b, q, _ := newBridge()
	b.TopicPrefix = ""
	b.Handle(context.Background(), seen(7, 1))
	if len(q.payloads) != 0 {
		t.Fatal("queued an event with no tenant")
	}
}

func TestTheTemplateIsFetchedOncePerIdentity(t *testing.T) {
	// A returning customer seen forty times a day would otherwise pull the
	// same 512 floats out of SQLite forty times.
	b, _, e := newBridge()
	ctx := context.Background()
	for i := 0; i < 5; i++ {
		b.Handle(ctx, seen(7, float64(1787996491+i*60)))
	}
	if e.calls != 1 {
		t.Fatalf("fetched the template %d times", e.calls)
	}
}

func TestAMissingTemplateStillQueuesTheVisit(t *testing.T) {
	// A footfall count without a template is still a real visit. Dropping it
	// would lose the number the customer is paying for over an optional field.
	b, q, e := newBridge()
	e.err = errors.New("no embedding")
	if err := b.Handle(context.Background(), seen(7, 1)); err != nil {
		t.Fatal(err)
	}
	if len(q.payloads) != 1 {
		t.Fatal("visit dropped because the template was missing")
	}
	if _, has := q.payloads[0]["embedding"]; has {
		t.Fatal("queued an embedding key with no embedding")
	}
}

func TestAttributesSurviveButBookkeepingIsDropped(t *testing.T) {
	b, q, _ := newBridge()
	b.Handle(context.Background(), seen(7, 1))
	attrs := q.payloads[0]["attributes"].(map[string]any)
	if attrs["gender"] != "Male" || attrs["age"] != float64(34) {
		t.Fatalf("attributes lost: %+v", attrs)
	}
	for _, k := range []string{"identity_id", "similarity", "quality"} {
		if _, dup := attrs[k]; dup {
			t.Errorf("%q duplicated into attributes; it is already a column", k)
		}
	}
}

func TestMalformedJSONIsRejectedNotRetried(t *testing.T) {
	b, _, _ := newBridge()
	srv := httptest.NewServer(b.Handler())
	defer srv.Close()
	resp, err := http.Post(srv.URL+"/events", "application/json",
		strings.NewReader("{ truncated"))
	if err != nil {
		t.Fatal(err)
	}
	defer resp.Body.Close()
	if resp.StatusCode != http.StatusBadRequest {
		t.Fatalf("status %d — the engine would retry this forever", resp.StatusCode)
	}
}

func TestTheWebhookQueuesARealPost(t *testing.T) {
	b, q, _ := newBridge()
	srv := httptest.NewServer(b.Handler())
	defer srv.Close()
	body, _ := json.Marshal(seen(7, 1787996491))
	resp, err := http.Post(srv.URL+"/events", "application/json",
		strings.NewReader(string(body)))
	if err != nil {
		t.Fatal(err)
	}
	defer resp.Body.Close()
	if resp.StatusCode != http.StatusNoContent {
		t.Fatalf("status %d", resp.StatusCode)
	}
	if len(q.payloads) != 1 {
		t.Fatal("nothing queued")
	}
}

func TestListenBindsLoopbackOnly(t *testing.T) {
	// The webhook accepts unauthenticated posts that become footfall rows;
	// it must not be reachable from the network.
	b, _, _ := newBridge()
	url, stop, err := b.Listen(context.Background())
	if err != nil {
		t.Fatal(err)
	}
	defer stop()
	if !strings.HasPrefix(url, "http://127.0.0.1:") {
		t.Fatalf("bridge listening on %s", url)
	}
}

// ---------------------------------------------------------------- waking

// Waking BEFORE the append would send the pump to look at a queue the event
// has not reached yet: it finds nothing, goes back to sleep, and the visit then
// waits out the full idle interval anyway - the exact delay the wake exists to
// remove, with an extra wasted drain on top.
func TestTheQueueIsWokenOnlyAfterTheVisitIsOnDisk(t *testing.T) {
	b, q, _ := newBridge()
	var depthWhenWoken = -1
	b.Wake = func() { depthWhenWoken = len(q.payloads) }

	if err := b.Handle(context.Background(), seen(7, 1_700_000_000)); err != nil {
		t.Fatal(err)
	}
	if depthWhenWoken != 1 {
		t.Fatalf("woken with %d events queued, want 1 - the event must be durable first",
			depthWhenWoken)
	}
}

// A visit that never reached the queue must not wake anything: there is nothing
// to drain, and the pump would spin on an empty spool.
func TestAFailedAppendDoesNotWakeThePump(t *testing.T) {
	b, q, _ := newBridge()
	q.err = errors.New("disk full")
	woken := 0
	b.Wake = func() { woken++ }

	if err := b.Handle(context.Background(), seen(7, 1_700_000_000)); err == nil {
		t.Fatal("a failed append should surface as an error")
	}
	if woken != 0 {
		t.Fatalf("woke the pump %d times for an event that was never queued", woken)
	}
}

// Diagnostics are not visits. They are skipped before the queue, so they must
// not wake a pump either.
func TestASkippedEventDoesNotWakeThePump(t *testing.T) {
	b, _, _ := newBridge()
	woken := 0
	b.Wake = func() { woken++ }

	ev := seen(7, 1_700_000_000)
	ev.Type = "person.missed"
	if err := b.Handle(context.Background(), ev); err != nil {
		t.Fatal(err)
	}
	if woken != 0 {
		t.Fatalf("a diagnostic event woke the pump %d times", woken)
	}
}

// The bridge must run unchanged with no waker wired, which is what an agent
// built before this existed looks like.
func TestNoWakerIsFine(t *testing.T) {
	b, q, _ := newBridge()
	b.Wake = nil
	if err := b.Handle(context.Background(), seen(7, 1_700_000_000)); err != nil {
		t.Fatal(err)
	}
	if len(q.payloads) != 1 {
		t.Fatalf("queued %d visits, want 1", len(q.payloads))
	}
}