// Copyright (c) HashiCorp, Inc.
// SPDX-License-Identifier: MPL-2.0

package eventbus

import (
	"context"
	"fmt"
	"sync/atomic"
	"testing"
	"time"

	"github.com/hashicorp/eventlogger"
	"github.com/hashicorp/go-secure-stdlib/strutil"
	"github.com/hashicorp/vault/helper/namespace"
	"github.com/hashicorp/vault/sdk/logical"
)

// TestBusBasics tests that basic event sending and subscribing function.
func TestBusBasics(t *testing.T) {
	bus, err := NewEventBus(nil)
	if err != nil {
		t.Fatal(err)
	}
	ctx := context.Background()

	eventType := logical.EventType("someType")

	event, err := logical.NewEvent()
	if err != nil {
		t.Fatal(err)
	}

	err = bus.SendInternal(ctx, namespace.RootNamespace, nil, eventType, event)
	if err != ErrNotStarted {
		t.Errorf("Expected not started error but got: %v", err)
	}

	bus.Start()

	err = bus.SendInternal(ctx, namespace.RootNamespace, nil, eventType, event)
	if err != nil {
		t.Errorf("Expected no error sending: %v", err)
	}

	ch, cancel, err := bus.Subscribe(ctx, namespace.RootNamespace, string(eventType))
	if err != nil {
		t.Fatal(err)
	}
	defer cancel()

	event, err = logical.NewEvent()
	if err != nil {
		t.Fatal(err)
	}

	err = bus.SendInternal(ctx, namespace.RootNamespace, nil, eventType, event)
	if err != nil {
		t.Error(err)
	}

	timeout := time.After(1 * time.Second)
	select {
	case message := <-ch:
		if message.Payload.(*logical.EventReceived).Event.Id != event.Id {
			t.Errorf("Got unexpected message: %+v", message)
		}
	case <-timeout:
		t.Error("Timeout waiting for message")
	}
}

// TestNamespaceFiltering verifies that events for other namespaces are filtered out by the bus.
func TestNamespaceFiltering(t *testing.T) {
	bus, err := NewEventBus(nil)
	if err != nil {
		t.Fatal(err)
	}
	bus.Start()
	ctx := context.Background()

	eventType := logical.EventType("someType")

	event, err := logical.NewEvent()
	if err != nil {
		t.Fatal(err)
	}

	ch, cancel, err := bus.Subscribe(ctx, namespace.RootNamespace, string(eventType))
	if err != nil {
		t.Fatal(err)
	}
	defer cancel()

	event, err = logical.NewEvent()
	if err != nil {
		t.Fatal(err)
	}

	err = bus.SendInternal(ctx, &namespace.Namespace{
		ID:   "abc",
		Path: "/abc",
	}, nil, eventType, event)
	if err != nil {
		t.Error(err)
	}

	timeout := time.After(100 * time.Millisecond)
	select {
	case <-ch:
		t.Errorf("Got abc namespace message when root namespace was specified")
	case <-timeout:
		// okay
	}

	err = bus.SendInternal(ctx, namespace.RootNamespace, nil, eventType, event)
	if err != nil {
		t.Error(err)
	}

	timeout = time.After(1 * time.Second)
	select {
	case message := <-ch:
		if message.Payload.(*logical.EventReceived).Event.Id != event.Id {
			t.Errorf("Got unexpected message %+v but was waiting for %+v", message, event)
		}

	case <-timeout:
		t.Error("Timed out waiting for message")
	}
}

// TestBus2Subscriptions verifies that events of different types are successfully routed to the correct subscribers.
func TestBus2Subscriptions(t *testing.T) {
	bus, err := NewEventBus(nil)
	if err != nil {
		t.Fatal(err)
	}
	ctx := context.Background()

	eventType1 := logical.EventType("someType1")
	eventType2 := logical.EventType("someType2")
	bus.Start()

	ch1, cancel1, err := bus.Subscribe(ctx, namespace.RootNamespace, string(eventType1))
	if err != nil {
		t.Fatal(err)
	}
	defer cancel1()

	ch2, cancel2, err := bus.Subscribe(ctx, namespace.RootNamespace, string(eventType2))
	if err != nil {
		t.Fatal(err)
	}
	defer cancel2()

	event1, err := logical.NewEvent()
	if err != nil {
		t.Fatal(err)
	}
	event2, err := logical.NewEvent()
	if err != nil {
		t.Fatal(err)
	}

	err = bus.SendInternal(ctx, namespace.RootNamespace, nil, eventType2, event2)
	if err != nil {
		t.Error(err)
	}
	err = bus.SendInternal(ctx, namespace.RootNamespace, nil, eventType1, event1)
	if err != nil {
		t.Error(err)
	}

	timeout := time.After(1 * time.Second)
	select {
	case message := <-ch1:
		if message.Payload.(*logical.EventReceived).Event.Id != event1.Id {
			t.Errorf("Got unexpected message: %v", message)
		}
	case <-timeout:
		t.Error("Timeout waiting for event1")
	}
	select {
	case message := <-ch2:
		if message.Payload.(*logical.EventReceived).Event.Id != event2.Id {
			t.Errorf("Got unexpected message: %v", message)
		}
	case <-timeout:
		t.Error("Timeout waiting for event2")
	}
}

// TestBusSubscriptionsCancel verifies that canceled subscriptions are cleaned up.
func TestBusSubscriptionsCancel(t *testing.T) {
	testCases := []struct {
		cancel bool
	}{
		{cancel: true},
		{cancel: false},
	}

	for _, tc := range testCases {
		t.Run(fmt.Sprintf("cancel=%v", tc.cancel), func(t *testing.T) {
			subscriptions.Store(0)
			bus, err := NewEventBus(nil)
			if err != nil {
				t.Fatal(err)
			}
			ctx := context.Background()
			if !tc.cancel {
				// set the timeout very short to make the test faster if we aren't canceling explicitly
				bus.SetSendTimeout(100 * time.Millisecond)
			}
			bus.Start()

			// create and stop a bunch of subscriptions
			const create = 100
			const stop = 50

			eventType := logical.EventType("someType")

			var channels []<-chan *eventlogger.Event
			var cancels []context.CancelFunc
			stopped := atomic.Int32{}

			received := atomic.Int32{}

			for i := 0; i < create; i++ {
				ch, cancelFunc, err := bus.Subscribe(ctx, namespace.RootNamespace, string(eventType))
				if err != nil {
					t.Fatal(err)
				}
				t.Cleanup(cancelFunc)
				channels = append(channels, ch)
				cancels = append(cancels, cancelFunc)

				go func(i int32) {
					<-ch // always receive one message
					received.Add(1)
					// continue receiving messages as long as are not stopped
					for i < int32(stop) {
						<-ch
						received.Add(1)
					}
					if tc.cancel {
						cancelFunc() // stop explicitly to unsubscribe
					}
					stopped.Add(1)
				}(int32(i))
			}

			// check that all channels receive a message
			event, err := logical.NewEvent()
			if err != nil {
				t.Fatal(err)
			}
			err = bus.SendInternal(ctx, namespace.RootNamespace, nil, eventType, event)
			if err != nil {
				t.Error(err)
			}
			waitFor(t, 1*time.Second, func() bool { return received.Load() == int32(create) })
			waitFor(t, 1*time.Second, func() bool { return stopped.Load() == int32(stop) })

			// send another message, but half should stop receiving
			event, err = logical.NewEvent()
			if err != nil {
				t.Fatal(err)
			}
			err = bus.SendInternal(ctx, namespace.RootNamespace, nil, eventType, event)
			if err != nil {
				t.Error(err)
			}
			waitFor(t, 1*time.Second, func() bool { return received.Load() == int32(create*2-stop) })
			// the sends should time out and the subscriptions should drop when cancelFunc is called or the context cancels
			waitFor(t, 1*time.Second, func() bool { return subscriptions.Load() == int64(create-stop) })
		})
	}
}

// waitFor waits for a condition to be true, up to the maximum timeout.
// It waits with a capped exponential backoff starting at 1ms.
// It is guaranteed to try f() at least once.
func waitFor(t *testing.T, maxWait time.Duration, f func() bool) {
	t.Helper()
	start := time.Now()

	if f() {
		return
	}
	sleepAmount := 1 * time.Millisecond
	for time.Now().Sub(start) <= maxWait {
		left := time.Now().Sub(start)
		sleepAmount = sleepAmount * 2
		if sleepAmount > left {
			sleepAmount = left
		}
		time.Sleep(sleepAmount)
		if f() {
			return
		}
	}
	t.Error("Timeout waiting for condition")
}

// TestBusWildcardSubscriptions tests that a single subscription can receive
// multiple event types using * for glob patterns.
func TestBusWildcardSubscriptions(t *testing.T) {
	bus, err := NewEventBus(nil)
	if err != nil {
		t.Fatal(err)
	}
	ctx := context.Background()

	fooEventType := logical.EventType("kv/foo")
	barEventType := logical.EventType("kv/bar")
	bus.Start()

	ch1, cancel1, err := bus.Subscribe(ctx, namespace.RootNamespace, "kv/*")
	if err != nil {
		t.Fatal(err)
	}
	defer cancel1()

	ch2, cancel2, err := bus.Subscribe(ctx, namespace.RootNamespace, "*/bar")
	if err != nil {
		t.Fatal(err)
	}
	defer cancel2()

	event1, err := logical.NewEvent()
	if err != nil {
		t.Fatal(err)
	}
	event2, err := logical.NewEvent()
	if err != nil {
		t.Fatal(err)
	}

	err = bus.SendInternal(ctx, namespace.RootNamespace, nil, barEventType, event2)
	if err != nil {
		t.Error(err)
	}
	err = bus.SendInternal(ctx, namespace.RootNamespace, nil, fooEventType, event1)
	if err != nil {
		t.Error(err)
	}

	timeout := time.After(1 * time.Second)
	// Expect to receive both events on ch1, which subscribed to kv/*
	var ch1Seen []string
	for i := 0; i < 2; i++ {
		select {
		case message := <-ch1:
			ch1Seen = append(ch1Seen, message.Payload.(*logical.EventReceived).Event.Id)
		case <-timeout:
			t.Error("Timeout waiting for event1")
		}
	}
	if len(ch1Seen) != 2 {
		t.Errorf("Expected 2 events but got: %v", ch1Seen)
	} else {
		if !strutil.StrListContains(ch1Seen, event1.Id) {
			t.Errorf("Did not find %s event1 ID in ch1seen", event1.Id)
		}
		if !strutil.StrListContains(ch1Seen, event2.Id) {
			t.Errorf("Did not find %s event2 ID in ch1seen", event2.Id)
		}
	}
	// Expect to receive just kv/bar on ch2, which subscribed to */bar
	select {
	case message := <-ch2:
		if message.Payload.(*logical.EventReceived).Event.Id != event2.Id {
			t.Errorf("Got unexpected message: %v", message)
		}
	case <-timeout:
		t.Error("Timeout waiting for event2")
	}
}