// Copyright (C) 2014 The Syncthing Authors.
//
// This Source Code Form is subject to the terms of the Mozilla Public
// License, v. 2.0. If a copy of the MPL was not distributed with this file,
// You can obtain one at http://mozilla.org/MPL/2.0/.

package events_test

import (
	"fmt"
	"testing"
	"time"

	"github.com/syncthing/syncthing/lib/events"
)

const timeout = 100 * time.Millisecond

func TestNewLogger(t *testing.T) {
	l := events.NewLogger()
	if l == nil {
		t.Fatal("Unexpected nil Logger")
	}
}

func TestSubscriber(t *testing.T) {
	l := events.NewLogger()
	s := l.Subscribe(0)
	defer l.Unsubscribe(s)
	if s == nil {
		t.Fatal("Unexpected nil Subscription")
	}
}

func TestTimeout(t *testing.T) {
	l := events.NewLogger()
	s := l.Subscribe(0)
	defer l.Unsubscribe(s)
	_, err := s.Poll(timeout)
	if err != events.ErrTimeout {
		t.Fatal("Unexpected non-Timeout error:", err)
	}
}

func TestEventBeforeSubscribe(t *testing.T) {
	l := events.NewLogger()

	l.Log(events.DeviceConnected, "foo")
	s := l.Subscribe(0)
	defer l.Unsubscribe(s)

	_, err := s.Poll(timeout)
	if err != events.ErrTimeout {
		t.Fatal("Unexpected non-Timeout error:", err)
	}
}

func TestEventAfterSubscribe(t *testing.T) {
	l := events.NewLogger()

	s := l.Subscribe(events.AllEvents)
	defer l.Unsubscribe(s)
	l.Log(events.DeviceConnected, "foo")

	ev, err := s.Poll(timeout)

	if err != nil {
		t.Fatal("Unexpected error:", err)
	}
	if ev.Type != events.DeviceConnected {
		t.Error("Incorrect event type", ev.Type)
	}
	switch v := ev.Data.(type) {
	case string:
		if v != "foo" {
			t.Error("Incorrect Data string", v)
		}
	default:
		t.Errorf("Incorrect Data type %#v", v)
	}
}

func TestEventAfterSubscribeIgnoreMask(t *testing.T) {
	l := events.NewLogger()

	s := l.Subscribe(events.DeviceDisconnected)
	defer l.Unsubscribe(s)
	l.Log(events.DeviceConnected, "foo")

	_, err := s.Poll(timeout)
	if err != events.ErrTimeout {
		t.Fatal("Unexpected non-Timeout error:", err)
	}
}

func TestBufferOverflow(t *testing.T) {
	l := events.NewLogger()

	s := l.Subscribe(events.AllEvents)
	defer l.Unsubscribe(s)

	t0 := time.Now()
	for i := 0; i < events.BufferSize*2; i++ {
		l.Log(events.DeviceConnected, "foo")
	}
	if time.Since(t0) > timeout {
		t.Fatalf("Logging took too long")
	}
}

func TestUnsubscribe(t *testing.T) {
	l := events.NewLogger()

	s := l.Subscribe(events.AllEvents)
	l.Log(events.DeviceConnected, "foo")

	_, err := s.Poll(timeout)
	if err != nil {
		t.Fatal("Unexpected error:", err)
	}

	l.Unsubscribe(s)
	l.Log(events.DeviceConnected, "foo")

	_, err = s.Poll(timeout)
	if err != events.ErrClosed {
		t.Fatal("Unexpected non-Closed error:", err)
	}
}

func TestGlobalIDs(t *testing.T) {
	l := events.NewLogger()

	s := l.Subscribe(events.AllEvents)
	defer l.Unsubscribe(s)
	l.Log(events.DeviceConnected, "foo")
	_ = l.Subscribe(events.AllEvents)
	l.Log(events.DeviceConnected, "bar")

	ev, err := s.Poll(timeout)
	if err != nil {
		t.Fatal("Unexpected error:", err)
	}
	if ev.Data.(string) != "foo" {
		t.Fatal("Incorrect event:", ev)
	}
	id := ev.GlobalID

	ev, err = s.Poll(timeout)
	if err != nil {
		t.Fatal("Unexpected error:", err)
	}
	if ev.Data.(string) != "bar" {
		t.Fatal("Incorrect event:", ev)
	}
	if ev.GlobalID != id+1 {
		t.Fatalf("ID not incremented (%d != %d)", ev.GlobalID, id+1)
	}
}

func TestSubscriptionIDs(t *testing.T) {
	l := events.NewLogger()

	s := l.Subscribe(events.DeviceConnected)
	defer l.Unsubscribe(s)

	l.Log(events.DeviceDisconnected, "a")
	l.Log(events.DeviceConnected, "b")
	l.Log(events.DeviceConnected, "c")
	l.Log(events.DeviceDisconnected, "d")

	ev, err := s.Poll(timeout)
	if err != nil {
		t.Fatal("Unexpected error:", err)
	}

	if ev.GlobalID != 2 {
		t.Fatal("Incorrect GlobalID:", ev.GlobalID)
	}
	if ev.SubscriptionID != 1 {
		t.Fatal("Incorrect SubscriptionID:", ev.SubscriptionID)
	}

	ev, err = s.Poll(timeout)
	if err != nil {
		t.Fatal("Unexpected error:", err)
	}
	if ev.GlobalID != 3 {
		t.Fatal("Incorrect GlobalID:", ev.GlobalID)
	}
	if ev.SubscriptionID != 2 {
		t.Fatal("Incorrect SubscriptionID:", ev.SubscriptionID)
	}

	ev, err = s.Poll(timeout)
	if err != events.ErrTimeout {
		t.Fatal("Unexpected error:", err)
	}
}

func TestBufferedSub(t *testing.T) {
	l := events.NewLogger()

	s := l.Subscribe(events.AllEvents)
	defer l.Unsubscribe(s)
	bs := events.NewBufferedSubscription(s, 10*events.BufferSize)

	go func() {
		for i := 0; i < 10*events.BufferSize; i++ {
			l.Log(events.DeviceConnected, fmt.Sprintf("event-%d", i))
			if i%30 == 0 {
				// Give the buffer routine time to pick up the events
				time.Sleep(20 * time.Millisecond)
			}
		}
	}()

	recv := 0
	for recv < 10*events.BufferSize {
		evs := bs.Since(recv, nil)
		for _, ev := range evs {
			if ev.GlobalID != recv+1 {
				t.Fatalf("Incorrect ID; %d != %d", ev.GlobalID, recv+1)
			}
			recv = ev.GlobalID
		}
	}
}

func BenchmarkBufferedSub(b *testing.B) {
	l := events.NewLogger()

	s := l.Subscribe(events.AllEvents)
	defer l.Unsubscribe(s)
	bufferSize := events.BufferSize
	bs := events.NewBufferedSubscription(s, bufferSize)

	// The coord channel paces the sender according to the receiver,
	// ensuring that no events are dropped. The benchmark measures sending +
	// receiving + synchronization overhead.

	coord := make(chan struct{}, bufferSize)
	for i := 0; i < bufferSize-1; i++ {
		coord <- struct{}{}
	}

	// Receive the events
	done := make(chan struct{})
	go func() {
		defer close(done)
		recv := 0
		var evs []events.Event
		for i := 0; i < b.N; {
			evs = bs.Since(recv, evs[:0])
			for _, ev := range evs {
				if ev.GlobalID != recv+1 {
					b.Fatal("skipped event", ev.GlobalID, recv)
				}
				recv = ev.GlobalID
				coord <- struct{}{}
			}
			i += len(evs)
		}
	}()

	// Send the events
	eventData := map[string]string{
		"foo":   "bar",
		"other": "data",
		"and":   "something else",
	}
	for i := 0; i < b.N; i++ {
		l.Log(events.DeviceConnected, eventData)
		<-coord
	}

	<-done
	b.ReportAllocs()
}

func TestSinceUsesSubscriptionId(t *testing.T) {
	l := events.NewLogger()

	s := l.Subscribe(events.DeviceConnected)
	defer l.Unsubscribe(s)
	bs := events.NewBufferedSubscription(s, 10*events.BufferSize)

	l.Log(events.DeviceConnected, "a") // SubscriptionID = 1
	l.Log(events.DeviceDisconnected, "b")
	l.Log(events.DeviceDisconnected, "c")
	l.Log(events.DeviceConnected, "d") // SubscriptionID = 2

	// We need to loop for the events, as they may not all have been
	// delivered to the buffered subscription when we get here.
	t0 := time.Now()
	for time.Since(t0) < time.Second {
		events := bs.Since(0, nil)
		if len(events) == 2 {
			break
		}
		if len(events) > 2 {
			t.Fatal("Incorrect number of events:", len(events))
		}
	}

	events := bs.Since(1, nil)
	if len(events) != 1 {
		t.Fatal("Incorrect number of events:", len(events))
	}
}
