package sse

import (
	"sync"
)

type Broadcaster struct {
	mu          sync.RWMutex
	subscribers map[chan []byte]struct{}
}

func NewBroadcaster() *Broadcaster {
	return &Broadcaster{
		subscribers: make(map[chan []byte]struct{}),
	}
}

func (b *Broadcaster) Subscribe() chan []byte {
	ch := make(chan []byte, 64)
	b.mu.Lock()
	b.subscribers[ch] = struct{}{}
	b.mu.Unlock()
	return ch
}

func (b *Broadcaster) Unsubscribe(ch chan []byte) {
	b.mu.Lock()
	delete(b.subscribers, ch)
	b.mu.Unlock()
	close(ch)
}

func (b *Broadcaster) Publish(data []byte) {
	b.mu.RLock()
	defer b.mu.RUnlock()
	for ch := range b.subscribers {
		select {
		case ch <- data:
		default:
		}
	}
}