package service

import (
	"testing"
	"time"

	"github.com/stretchr/testify/assert"
	"github.com/stretchr/testify/require"
)

func TestRequestEventBus_PublishToSubscriber(t *testing.T) {
	bus := NewRequestEventBus()

	id, ch := bus.Subscribe()
	defer bus.Unsubscribe(id)

	evt := RequestEvent{Model: "claude-3", Status: "success", LatencyMS: 100}
	bus.Publish(evt)

	select {
	case got := <-ch:
		assert.Equal(t, evt, got)
	case <-time.After(time.Second):
		t.Fatal("timed out waiting for event")
	}
}

func TestRequestEventBus_MultipleSubscribers(t *testing.T) {
	bus := NewRequestEventBus()

	id1, ch1 := bus.Subscribe()
	id2, ch2 := bus.Subscribe()
	defer bus.Unsubscribe(id1)
	defer bus.Unsubscribe(id2)

	evt := RequestEvent{Model: "claude-3", Status: "error"}
	bus.Publish(evt)

	for _, ch := range []<-chan RequestEvent{ch1, ch2} {
		select {
		case got := <-ch:
			assert.Equal(t, evt, got)
		case <-time.After(time.Second):
			t.Fatal("timed out waiting for event on one subscriber")
		}
	}
}

func TestRequestEventBus_UnsubscribeClosesChannel(t *testing.T) {
	bus := NewRequestEventBus()
	id, ch := bus.Subscribe()

	bus.Unsubscribe(id)

	// Channel should be closed.
	_, ok := <-ch
	assert.False(t, ok, "channel should be closed after Unsubscribe")
}

func TestRequestEventBus_UnsubscribedMissesEvents(t *testing.T) {
	bus := NewRequestEventBus()
	id, _ := bus.Subscribe()
	bus.Unsubscribe(id)

	// Publish after unsubscribe should not panic.
	require.NotPanics(t, func() {
		bus.Publish(RequestEvent{Model: "test"})
	})
}

func TestRequestEventBus_DropWhenFull(t *testing.T) {
	bus := NewRequestEventBus()
	id, ch := bus.Subscribe()
	defer bus.Unsubscribe(id)

	// Fill the buffer then publish one more — should drop, not block.
	evt := RequestEvent{Model: "model", Status: "success"}
	for i := 0; i < requestEventBufSize; i++ {
		bus.Publish(evt)
	}
	// This publish should return immediately (dropped).
	done := make(chan struct{})
	go func() {
		bus.Publish(evt)
		close(done)
	}()
	select {
	case <-done:
	case <-time.After(time.Second):
		t.Fatal("Publish blocked when buffer was full")
	}
	assert.Len(t, ch, requestEventBufSize)
}

func TestRequestEventBus_NilSafePublish(t *testing.T) {
	var bus *RequestEventBus
	require.NotPanics(t, func() {
		bus.Publish(RequestEvent{Model: "test"})
	})
}