package server

import (
	"sort"
	"sync"

	"g.fc.run/misc/byre/internal/api"
)

type hub struct {
	mu   sync.Mutex
	subs map[chan api.Event]api.ConnectedClient
}

func newHub() *hub {
	return &hub{subs: map[chan api.Event]api.ConnectedClient{}}
}

func (h *hub) subscribe(client api.ConnectedClient) chan api.Event {
	h.mu.Lock()
	defer h.mu.Unlock()
	ch := make(chan api.Event, 256)
	h.subs[ch] = client
	return ch
}

func (h *hub) unsubscribe(ch chan api.Event) {
	h.mu.Lock()
	defer h.mu.Unlock()
	_, ok := h.subs[ch]
	if !ok {
		return
	}
	delete(h.subs, ch)
	close(ch)
}

func (h *hub) publish(ev api.Event) {
	h.mu.Lock()
	defer h.mu.Unlock()
	for ch := range h.subs {
		select {
		case ch <- ev:
		default:
			delete(h.subs, ch)
			close(ch)
		}
	}
}

func (h *hub) count() int {
	h.mu.Lock()
	defer h.mu.Unlock()
	return len(h.subs)
}

func (h *hub) clients() []api.ConnectedClient {
	h.mu.Lock()
	defer h.mu.Unlock()
	type key struct{ login, host, commit string }
	oldest := map[key]api.ConnectedClient{}
	for _, c := range h.subs {
		k := key{c.Login, c.Host, c.Commit}
		prev, ok := oldest[k]
		if ok && !c.ConnectedAt.Before(prev.ConnectedAt) {
			continue
		}
		oldest[k] = c
	}
	out := []api.ConnectedClient{}
	for _, c := range oldest {
		out = append(out, c)
	}
	sort.Slice(out, func(i, j int) bool { return out[i].ConnectedAt.Before(out[j].ConnectedAt) })
	return out
}