package broker_test

import (
	"sync"
	"testing"
	"time"

	"git.eeqj.de/sneak/chat/internal/broker"
)

func TestNewBroker(t *testing.T) {
	t.Parallel()

	brk := broker.New()
	if brk == nil {
		t.Fatal("expected non-nil broker")
	}
}

func TestWaitAndNotify(t *testing.T) {
	t.Parallel()

	brk := broker.New()
	waitCh := brk.Wait(1)

	go func() {
		time.Sleep(10 * time.Millisecond)
		brk.Notify(1)
	}()

	select {
	case <-waitCh:
	case <-time.After(2 * time.Second):
		t.Fatal("timeout")
	}
}

func TestNotifyWithoutWaiters(t *testing.T) {
	t.Parallel()

	brk := broker.New()
	brk.Notify(42) // should not panic.
}

func TestRemove(t *testing.T) {
	t.Parallel()

	brk := broker.New()
	waitCh := brk.Wait(1)

	brk.Remove(1, waitCh)

	brk.Notify(1)

	select {
	case <-waitCh:
		t.Fatal("should not receive after remove")
	case <-time.After(50 * time.Millisecond):
	}
}

func TestMultipleWaiters(t *testing.T) {
	t.Parallel()

	brk := broker.New()
	waitCh1 := brk.Wait(1)
	waitCh2 := brk.Wait(1)

	brk.Notify(1)

	select {
	case <-waitCh1:
	case <-time.After(time.Second):
		t.Fatal("ch1 timeout")
	}

	select {
	case <-waitCh2:
	case <-time.After(time.Second):
		t.Fatal("ch2 timeout")
	}
}

func TestConcurrentWaitNotify(t *testing.T) {
	t.Parallel()

	brk := broker.New()

	var waitGroup sync.WaitGroup

	const concurrency = 100

	for idx := range concurrency {
		waitGroup.Add(1)

		go func(uid int64) {
			defer waitGroup.Done()

			waitCh := brk.Wait(uid)

			brk.Notify(uid)

			select {
			case <-waitCh:
			case <-time.After(time.Second):
				t.Error("timeout")
			}
		}(int64(idx % 10))
	}

	waitGroup.Wait()
}

func TestRemoveNonexistent(t *testing.T) {
	t.Parallel()

	brk := broker.New()
	waitCh := make(chan struct{}, 1)

	brk.Remove(999, waitCh) // should not panic.
}