package application

import (
	"sync"

	"chub/internal/domain"
)

// EventBus is the in-process local event channel shared by the UI and CLI
// adapters. Subscribers own cancellation; publishing never blocks a browser
// process monitor on a slow presentation consumer.
type EventBus struct {
	mu      sync.RWMutex
	nextID  uint64
	clients map[uint64]chan domain.BrowserEvent
}

func NewEventBus() *EventBus { return &EventBus{clients: make(map[uint64]chan domain.BrowserEvent)} }

func (b *EventBus) Subscribe(buffer int) (<-chan domain.BrowserEvent, func()) {
	if buffer < 1 {
		buffer = 1
	}
	b.mu.Lock()
	b.nextID++
	id := b.nextID
	ch := make(chan domain.BrowserEvent, buffer)
	b.clients[id] = ch
	b.mu.Unlock()
	return ch, func() {
		b.mu.Lock()
		if existing, ok := b.clients[id]; ok {
			delete(b.clients, id)
			close(existing)
		}
		b.mu.Unlock()
	}
}

func (b *EventBus) Publish(event domain.BrowserEvent) {
	b.mu.RLock()
	defer b.mu.RUnlock()
	for _, ch := range b.clients {
		select {
		case ch <- event:
		default:
		}
	}
}