package operator

import (
	"context"
	"testing"
	"time"

	"github.com/alicebob/miniredis/v2"
	goredis "github.com/redis/go-redis/v9"
	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
	"k8s.io/apimachinery/pkg/runtime"
	clientgoscheme "k8s.io/client-go/kubernetes/scheme"
	"sigs.k8s.io/controller-runtime/pkg/client"
	"sigs.k8s.io/controller-runtime/pkg/client/fake"

	kmsvcv1 "github.com/rockliang/kafka-management-service/apis/kmsvc/v1"
	"github.com/rockliang/kafka-management-service/internal/kafka"
	kmsvcredis "github.com/rockliang/kafka-management-service/internal/redis"
)

func newTestScheme(t *testing.T) *runtime.Scheme {
	t.Helper()
	scheme := runtime.NewScheme()
	if err := clientgoscheme.AddToScheme(scheme); err != nil {
		t.Fatalf("add client-go scheme: %v", err)
	}
	if err := kmsvcv1.AddToScheme(scheme); err != nil {
		t.Fatalf("add kmsvc scheme: %v", err)
	}
	return scheme
}

func newTestRedis(t *testing.T) *goredis.Client {
	t.Helper()
	mr, err := miniredis.Run()
	if err != nil {
		t.Fatalf("starting miniredis: %v", err)
	}
	t.Cleanup(mr.Close)
	return goredis.NewClient(&goredis.Options{Addr: mr.Addr()})
}

func newTestReconciler(t *testing.T, objs ...client.Object) (*QueueReconciler, *fakeAdmin) {
	t.Helper()
	scheme := newTestScheme(t)
	cl := fake.NewClientBuilder().
		WithScheme(scheme).
		WithStatusSubresource(&kmsvcv1.Queue{}).
		WithObjects(objs...).
		Build()
	admin := newFakeAdmin()
	return &QueueReconciler{
		Client: cl,
		Admin:  admin,
		Redis:  newTestRedis(t),
		Now:    time.Now,
	}, admin
}

func baseQueue(name string) *kmsvcv1.Queue {
	return &kmsvcv1.Queue{
		ObjectMeta: metav1.ObjectMeta{Name: name},
		Spec: kmsvcv1.QueueSpec{
			VisibilityTimeoutSeconds:      30,
			MessageRetentionPeriodSeconds: 345600,
			MaxReceiveCount:               5,
			PartitionsPerShard:            6,
			MinShards:                     1,
			MaxShards:                     8,
		},
	}
}

func TestReconcileCreatesShardZeroAndPublishesRedisState(t *testing.T) {
	queue := baseQueue("orders")
	r, admin := newTestReconciler(t, queue)
	ctx := context.Background()

	if err := r.Reconcile(ctx, "", "orders"); err != nil {
		t.Fatalf("Reconcile: %v", err)
	}

	var got kmsvcv1.Queue
	if err := r.Client.Get(ctx, client.ObjectKey{Name: "orders"}, &got); err != nil {
		t.Fatalf("get queue: %v", err)
	}
	if got.Status.Phase != kmsvcv1.QueuePhaseReady {
		t.Fatalf("phase = %v, want Ready", got.Status.Phase)
	}
	if len(got.Status.Shards) != 1 || got.Status.Shards[0].ID != "0" {
		t.Fatalf("shards = %+v, want one shard-0", got.Status.Shards)
	}
	wantTopic := kafka.ShardTopicName("orders", false, "0")
	if got.Status.Shards[0].Topic != wantTopic {
		t.Errorf("shard-0 topic = %q, want %q", got.Status.Shards[0].Topic, wantTopic)
	}
	if !admin.hasTopic(wantTopic) {
		t.Errorf("expected topic %q to be created", wantTopic)
	}

	meta, ok, err := kmsvcredis.GetQueueMeta(ctx, r.Redis, "orders")
	if err != nil || !ok {
		t.Fatalf("GetQueueMeta: ok=%v err=%v", ok, err)
	}
	if meta.MaxReceiveCount != 5 {
		t.Errorf("meta.MaxReceiveCount = %d, want 5", meta.MaxReceiveCount)
	}

	shards, ok, err := kmsvcredis.GetShardMap(ctx, r.Redis, "orders")
	if err != nil || !ok || len(shards) != 1 {
		t.Fatalf("GetShardMap: shards=%+v ok=%v err=%v", shards, ok, err)
	}
}

func TestReconcileRejectsDLQSelfReference(t *testing.T) {
	queue := baseQueue("orders")
	queue.Spec.DeadLetterTargetQueue = "orders"
	r, _ := newTestReconciler(t, queue)
	ctx := context.Background()

	err := r.Reconcile(ctx, "", "orders")
	if err == nil {
		t.Fatal("expected reconcile to fail for self-referencing DLQ")
	}

	var got kmsvcv1.Queue
	if err := r.Client.Get(ctx, client.ObjectKey{Name: "orders"}, &got); err != nil {
		t.Fatalf("get queue: %v", err)
	}
	if got.Status.Phase != kmsvcv1.QueuePhaseFailed {
		t.Errorf("phase = %v, want Failed", got.Status.Phase)
	}
}

func TestReconcileDeleteCleansUpTopicsAndRedis(t *testing.T) {
	queue := baseQueue("orders")
	r, admin := newTestReconciler(t, queue)
	ctx := context.Background()

	if err := r.Reconcile(ctx, "", "orders"); err != nil {
		t.Fatalf("initial reconcile: %v", err)
	}

	var got kmsvcv1.Queue
	if err := r.Client.Get(ctx, client.ObjectKey{Name: "orders"}, &got); err != nil {
		t.Fatalf("get queue: %v", err)
	}
	topic := got.Status.Shards[0].Topic

	if err := r.Client.Delete(ctx, &got); err != nil {
		t.Fatalf("delete queue: %v", err)
	}
	if err := r.Reconcile(ctx, "", "orders"); err != nil {
		t.Fatalf("delete reconcile: %v", err)
	}

	if admin.hasTopic(topic) {
		t.Errorf("expected topic %q to be deleted", topic)
	}
	if _, ok, _ := kmsvcredis.GetQueueMeta(ctx, r.Redis, "orders"); ok {
		t.Error("expected queue meta to be removed")
	}
	if _, ok, _ := kmsvcredis.GetShardMap(ctx, r.Redis, "orders"); ok {
		t.Error("expected shard map to be removed")
	}
}

func TestReconcileSplitsShardOverThreshold(t *testing.T) {
	queue := baseQueue("orders")
	queue.Spec.ShardSplitThresholdBytesPerSec = 1000
	queue.Spec.ShardSplitCooldownSeconds = 0
	now := time.Now()
	r, admin := newTestReconciler(t, queue)
	r.Now = func() time.Time { return now }
	ctx := context.Background()

	if err := r.Reconcile(ctx, "", "orders"); err != nil {
		t.Fatalf("initial reconcile: %v", err)
	}
	var got kmsvcv1.Queue
	if err := r.Client.Get(ctx, client.ObjectKey{Name: "orders"}, &got); err != nil {
		t.Fatalf("get queue: %v", err)
	}
	shard0Topic := got.Status.Shards[0].Topic
	admin.setOffsetSum(shard0Topic, 0)

	// First sample establishes the baseline (no delta to compare yet).
	if err := r.Reconcile(ctx, "", "orders"); err != nil {
		t.Fatalf("baseline reconcile: %v", err)
	}

	// Advance time and offsets enough to exceed 1000 bytes/sec at the
	// 1024-byte/record estimate: 10 records over 1s ≈ 10240 bytes/sec.
	now = now.Add(time.Second)
	admin.setOffsetSum(shard0Topic, 10)

	if err := r.Reconcile(ctx, "", "orders"); err != nil {
		t.Fatalf("split-triggering reconcile: %v", err)
	}

	if err := r.Client.Get(ctx, client.ObjectKey{Name: "orders"}, &got); err != nil {
		t.Fatalf("get queue after split: %v", err)
	}
	if len(got.Status.Shards) != 3 {
		t.Fatalf("shards = %+v, want 3 (1 closing parent + 2 active children)", got.Status.Shards)
	}
	var parent *kmsvcv1.ShardStatus
	var children []kmsvcv1.ShardStatus
	for i := range got.Status.Shards {
		s := &got.Status.Shards[i]
		if s.ID == "0" {
			parent = s
		} else {
			children = append(children, *s)
		}
	}
	if parent == nil || parent.Phase != kmsvcv1.ShardPhaseClosing {
		t.Fatalf("parent shard = %+v, want Closing", parent)
	}
	if len(children) != 2 {
		t.Fatalf("children = %+v, want 2", children)
	}
	mid := kafka.SplitHashRange(uint32(parent.HashRangeStart), uint32(parent.HashRangeEnd))
	gotRanges := map[[2]uint32]bool{}
	for _, c := range children {
		if c.Phase != kmsvcv1.ShardPhaseActive {
			t.Errorf("child %s phase = %v, want Active", c.ID, c.Phase)
		}
		gotRanges[[2]uint32{uint32(c.HashRangeStart), uint32(c.HashRangeEnd)}] = true
	}
	if !gotRanges[[2]uint32{0, mid}] || !gotRanges[[2]uint32{mid, kafka.FullHashRangeEnd}] {
		t.Errorf("child ranges = %+v, want [0,%d) and [%d,%d)", children, mid, mid, kafka.FullHashRangeEnd)
	}
}

func TestReconcileDrainsClosingShardWhenLagZero(t *testing.T) {
	queue := baseQueue("orders")
	queue.Spec.MessageRetentionPeriodSeconds = 60
	now := time.Now()
	r, admin := newTestReconciler(t, queue)
	r.Now = func() time.Time { return now }
	ctx := context.Background()

	if err := r.Reconcile(ctx, "", "orders"); err != nil {
		t.Fatalf("initial reconcile: %v", err)
	}
	var got kmsvcv1.Queue
	if err := r.Client.Get(ctx, client.ObjectKey{Name: "orders"}, &got); err != nil {
		t.Fatalf("get queue: %v", err)
	}

	// Manually mark shard-0 as Closing (simulating a prior split) to isolate
	// drain behavior from split behavior.
	got.Status.Shards[0].Phase = kmsvcv1.ShardPhaseClosing
	got.Status.Shards[0].CreatedAt = metav1.NewTime(now.Add(-2 * time.Minute))
	if err := r.Client.Status().Update(ctx, &got); err != nil {
		t.Fatalf("seed closing shard: %v", err)
	}
	topic := got.Status.Shards[0].Topic
	admin.setLag(kafka.ConsumerGroup("orders"), topic, 0)

	if err := r.Reconcile(ctx, "", "orders"); err != nil {
		t.Fatalf("drain reconcile: %v", err)
	}

	if err := r.Client.Get(ctx, client.ObjectKey{Name: "orders"}, &got); err != nil {
		t.Fatalf("get queue after drain: %v", err)
	}
	if got.Status.Shards[0].Phase != kmsvcv1.ShardPhaseClosed {
		t.Errorf("shard-0 phase = %v, want Closed", got.Status.Shards[0].Phase)
	}
	if admin.hasTopic(topic) {
		t.Errorf("expected drained topic %q to be deleted", topic)
	}
}