/*
Copyright 2025 The Kubernetes Authors.

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

package events

import (
	"fmt"
	"net/http"
	"net/http/httptest"
	"os"
	"path/filepath"
	"testing"
	"time"

	log "github.com/sirupsen/logrus"
	"github.com/stretchr/testify/assert"
	"github.com/stretchr/testify/require"
	v1 "k8s.io/api/core/v1"
	eventsv1 "k8s.io/api/events/v1"
	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
	"k8s.io/apimachinery/pkg/runtime"
	"k8s.io/apimachinery/pkg/util/sets"
	"k8s.io/apimachinery/pkg/util/wait"
	"k8s.io/client-go/kubernetes/fake"
	eventsclient "k8s.io/client-go/kubernetes/typed/events/v1"
	"k8s.io/client-go/tools/clientcmd"
	"k8s.io/client-go/util/workqueue"

	clienttesting "k8s.io/client-go/testing"

	logtest "sigs.k8s.io/external-dns/internal/testutils/log"
)

func TestNewEventController_Success(t *testing.T) {
	svr := httptest.NewServer(http.HandlerFunc(func(_ http.ResponseWriter, _ *http.Request) {}))
	defer svr.Close()

	mockKubeCfgDir := filepath.Join(t.TempDir(), ".kube")
	mockKubeCfgPath := filepath.Join(mockKubeCfgDir, "config")
	err := os.MkdirAll(mockKubeCfgDir, 0755)
	require.NoError(t, err)

	kubeCfgTemplate := `
apiVersion: v1
kind: Config
clusters:
- cluster:
    server: %s
  name: test-cluster
contexts:
- context:
    cluster: test-cluster
    user: test-user
  name: test-context
current-context: test-context
users:
- name: test-user
  user:
    token: fake-token
`
	err = os.WriteFile(mockKubeCfgPath, fmt.Appendf(nil, kubeCfgTemplate, svr.URL), os.FileMode(0755))
	require.NoError(t, err)

	restConfig, err := clientcmd.BuildConfigFromFlags(svr.URL, mockKubeCfgPath)
	require.NoError(t, err)
	client, err := eventsclient.NewForConfig(restConfig)
	require.NoError(t, err)

	cfg := NewConfig(
		WithEmitEvents([]string{string(RecordReady)}),
	)
	ctrl, err := NewEventController(client, cfg)
	require.NoError(t, err)
	require.NotNil(t, ctrl)
	require.False(t, ctrl.dryRun)
}

func TestController_Run_NoEmitEvents(t *testing.T) {
	kClient := fake.NewClientset()
	ctrl := &Controller{
		client:     kClient.EventsV1(),
		emitEvents: sets.New[Reason](),
	}

	require.NotPanics(t, func() {
		ctrl.Run(t.Context())
	})
}

func TestController_Run_EmitEvents(t *testing.T) {
	log.SetLevel(log.ErrorLevel)
	ctx := t.Context()

	eventCreated := make(chan struct{})
	kubeClient := fake.NewClientset()
	kubeClient.PrependReactor("create", "events", func(_ clienttesting.Action) (bool, runtime.Object, error) {
		eventCreated <- struct{}{}
		return true, nil, nil
	})

	eventsClient := kubeClient.EventsV1()
	ctrl := &Controller{
		client:     eventsClient,
		emitEvents: sets.New[Reason](RecordReady),
		queue: workqueue.NewTypedRateLimitingQueueWithConfig[any](
			workqueue.DefaultTypedControllerRateLimiter[any](),
			workqueue.TypedRateLimitingQueueConfig[any]{Name: controllerName},
		),
		hostname:        controllerName,
		maxQueuedEvents: 1,
	}

	ctrl.Run(ctx)

	event := NewEvent(NewObjectReference(&v1.Pod{
		TypeMeta: metav1.TypeMeta{
			Kind:       "Pod",
			APIVersion: "v1",
		},
		ObjectMeta: metav1.ObjectMeta{
			Name:      "fake-object",
			Namespace: v1.NamespaceDefault,
			UID:       "9de3fc19-8aeb-4e76-865d-ada955403103",
		},
	}, "fake-source"), "record created", ActionCreate, RecordReady)

	ctrl.Add(event)

	select {
	case <-eventCreated:
	case <-time.After(wait.ForeverTestTimeout):
		t.Fatal("event not created")
	}
}

func TestController_Queue_EmitEvents(t *testing.T) {
	log.SetLevel(log.ErrorLevel)

	eventsClient := fake.NewClientset().EventsV1()
	ctrl := &Controller{
		client:     eventsClient,
		emitEvents: sets.New[Reason](RecordReady),
		queue: workqueue.NewTypedRateLimitingQueueWithConfig[any](
			workqueue.DefaultTypedControllerRateLimiter[any](),
			workqueue.TypedRateLimitingQueueConfig[any]{Name: controllerName},
		),
		hostname:        controllerName,
		maxQueuedEvents: 1,
	}

	event := NewEvent(NewObjectReference(&v1.Pod{
		TypeMeta: metav1.TypeMeta{
			Kind:       "Pod",
			APIVersion: "v1",
		},
		ObjectMeta: metav1.ObjectMeta{
			Name:      "fake-object",
			Namespace: v1.NamespaceDefault,
			UID:       "9de3fc19-8aeb-4e76-865d-ada955403103",
		},
	}, "fake-source"), "record created", ActionCreate, RecordReady)

	ctrl.Add(event)

	queueItem, shutdown := ctrl.queue.Get()
	require.False(t, shutdown)
	value, ok := queueItem.(*eventsv1.Event)
	assert.True(t, ok)
	assert.NotNil(t, value)

	assert.Contains(t, value.Name, "fake-object.")
	assert.Contains(t, value.Reason, RecordReady)
}

func TestController_Add(t *testing.T) {
	for _, tt := range []struct {
		title           string
		maxQueuedEvents int
		events          []Event
		wantQueueLen    int
		wantWarnLog     string
	}{
		{
			title:           "queue full drops events and logs warning",
			maxQueuedEvents: 0, // 0 >= 0 is always true, so queue is immediately "full"
			events:          []Event{NewEvent(&ObjectReference{Name: "test", Namespace: "default"}, "msg", ActionCreate, RecordReady)},
			wantQueueLen:    0,
			wantWarnLog:     "event queue is full, dropping 1 events",
		},
		{
			title:           "nil event is skipped",
			maxQueuedEvents: maxQueuedEvents,
			// NewEvent(nil, ...) returns a zero-value Event; its event() returns nil because ref.Name == "".
			events:       []Event{NewEvent(nil, "msg", ActionCreate, RecordReady)},
			wantQueueLen: 0,
		},
	} {
		t.Run(tt.title, func(t *testing.T) {
			hook := logtest.LogsUnderTestWithLogLevel(log.WarnLevel, t)
			ctrl := &Controller{
				emitEvents:      sets.New[Reason](RecordReady),
				maxQueuedEvents: tt.maxQueuedEvents,
				queue: workqueue.NewTypedRateLimitingQueueWithConfig[any](
					workqueue.DefaultTypedControllerRateLimiter[any](),
					workqueue.TypedRateLimitingQueueConfig[any]{Name: controllerName},
				),
			}
			ctrl.Add(tt.events...)
			assert.Equal(t, tt.wantQueueLen, ctrl.queue.Len())
			if tt.wantWarnLog != "" {
				logtest.TestHelperLogContains(tt.wantWarnLog, hook, t)
			}
		})
	}
}

func TestController_ProcessNextWorkItem(t *testing.T) {
	t.Run("invalid key logs error and returns true", func(t *testing.T) {
		hook := logtest.LogsUnderTestWithLogLevel(log.ErrorLevel, t)
		ctrl := &Controller{
			client: fake.NewClientset().EventsV1(),
			queue: workqueue.NewTypedRateLimitingQueueWithConfig[any](
				workqueue.DefaultTypedControllerRateLimiter[any](),
				workqueue.TypedRateLimitingQueueConfig[any]{Name: controllerName},
			),
		}
		ctrl.queue.Add("not-an-event")
		assert.True(t, ctrl.processNextWorkItem(t.Context()))
		logtest.TestHelperLogContains("failed to convert key to Event", hook, t)
	})

	t.Run("dryRun sets DryRunAll on create options", func(t *testing.T) {
		var capturedDryRun []string
		kubeClient := fake.NewClientset()
		kubeClient.PrependReactor("create", "events", func(action clienttesting.Action) (bool, runtime.Object, error) {
			capturedDryRun = action.(clienttesting.CreateActionImpl).CreateOptions.DryRun
			return true, nil, nil
		})
		ctrl := &Controller{
			client: kubeClient.EventsV1(),
			dryRun: true,
			queue: workqueue.NewTypedRateLimitingQueueWithConfig[any](
				workqueue.DefaultTypedControllerRateLimiter[any](),
				workqueue.TypedRateLimitingQueueConfig[any]{Name: controllerName},
			),
		}
		ctrl.queue.Add(&eventsv1.Event{
			ObjectMeta: metav1.ObjectMeta{Name: "test-event", Namespace: "default"},
		})
		ctrl.processNextWorkItem(t.Context())
		assert.Equal(t, []string{metav1.DryRunAll}, capturedDryRun)
	})

	t.Run("drops event after max retries", func(t *testing.T) {
		hook := logtest.LogsUnderTestWithLogLevel(log.ErrorLevel, t)
		kubeClient := fake.NewClientset()
		kubeClient.PrependReactor("create", "events", func(_ clienttesting.Action) (bool, runtime.Object, error) {
			return true, nil, fmt.Errorf("persistent error")
		})
		ctrl := &Controller{
			client: kubeClient.EventsV1(),
			// 0-delay rate limiter: AddRateLimited calls Add immediately, enabling synchronous looping.
			queue: workqueue.NewTypedRateLimitingQueueWithConfig[any](
				workqueue.NewTypedMaxOfRateLimiter[any](
					workqueue.NewTypedItemFastSlowRateLimiter[any](0, 0, maxTriesPerEvent+1),
				),
				workqueue.TypedRateLimitingQueueConfig[any]{Name: controllerName},
			),
		}
		ctrl.queue.Add(&eventsv1.Event{
			ObjectMeta: metav1.ObjectMeta{Name: "test-event", Namespace: "default"},
		})
		// First maxTriesPerEvent calls requeue; the final call exhausts retries and drops.
		for range maxTriesPerEvent + 1 {
			ctrl.processNextWorkItem(t.Context())
		}
		logtest.TestHelperLogContains("dropping event", hook, t)
	})
}

func TestController_Emit_SkipsUnconfiguredReason(t *testing.T) {
	hook := logtest.LogsUnderTestWithLogLevel(log.DebugLevel, t)

	ctrl := &Controller{
		emitEvents: sets.New[Reason](RecordReady),
		queue: workqueue.NewTypedRateLimitingQueueWithConfig[any](
			workqueue.DefaultTypedControllerRateLimiter[any](),
			workqueue.TypedRateLimitingQueueConfig[any]{Name: controllerName},
		),
	}

	ctrl.emit(&eventsv1.Event{
		ObjectMeta: metav1.ObjectMeta{Name: "test-event", Namespace: "default"},
		Reason:     string(RecordDeleted), // not in emitEvents
	})

	assert.Equal(t, 0, ctrl.queue.Len())
	logtest.TestHelperLogContains("skipping event", hook, t)
}

func TestController_ProcessNextWorkItem_RequeuesOnError(t *testing.T) {
	log.SetLevel(log.ErrorLevel)
	ctx := t.Context()

	createAttempts := 0
	kubeClient := fake.NewClientset()
	kubeClient.PrependReactor("create", "events", func(_ clienttesting.Action) (bool, runtime.Object, error) {
		createAttempts++
		if createAttempts <= maxTriesPerEvent {
			return true, nil, fmt.Errorf("transient API error")
		}
		return true, nil, nil
	})

	eventCreated := make(chan struct{}, 1)
	kubeClient.PrependReactor("create", "events", func(_ clienttesting.Action) (bool, runtime.Object, error) {
		createAttempts++
		if createAttempts <= maxTriesPerEvent {
			return true, nil, fmt.Errorf("transient API error")
		}
		eventCreated <- struct{}{}
		return true, nil, nil
	})

	ctrl := &Controller{
		client:     kubeClient.EventsV1(),
		emitEvents: sets.New[Reason](RecordReady),
		queue: workqueue.NewTypedRateLimitingQueueWithConfig[any](
			workqueue.NewTypedMaxOfRateLimiter[any](
				workqueue.NewTypedItemFastSlowRateLimiter[any](1*time.Millisecond, 1*time.Millisecond, 5),
			),
			workqueue.TypedRateLimitingQueueConfig[any]{Name: controllerName},
		),
		hostname:        controllerName,
		maxQueuedEvents: maxQueuedEvents,
	}

	ctrl.Run(ctx)

	event := NewEvent(NewObjectReference(&v1.Pod{
		TypeMeta: metav1.TypeMeta{
			Kind:       "Pod",
			APIVersion: "v1",
		},
		ObjectMeta: metav1.ObjectMeta{
			Name:      "fake-object",
			Namespace: v1.NamespaceDefault,
			UID:       "9de3fc19-8aeb-4e76-865d-ada955403103",
		},
	}, "fake-source"), "record created", ActionCreate, RecordReady)

	ctrl.Add(event)

	select {
	case <-eventCreated:
		assert.Greater(t, createAttempts, 1, "event should have been retried at least once")
	case <-time.After(5 * time.Second):
		t.Fatalf("event was not retried and delivered; only %d attempt(s) made", createAttempts)
	}
}