package channels

import (
	"errors"
	"log"
	"sync"

	"github.com/cskr/pubsub"
)

type ChannelManager struct {
	channels     map[string]*Channel
	channelsLock sync.RWMutex
	pubsub       *pubsub.PubSub
}

func NewChannelManager() *ChannelManager {
	mgr := &ChannelManager{
		pubsub:   pubsub.New(1),
		channels: map[string]*Channel{},
	}
	return mgr
}

func (manager *ChannelManager) Events() *pubsub.PubSub {
	return manager.pubsub
}

func (manager *ChannelManager) Channel(uuid string) *Channel {
	manager.channelsLock.RLock()
	defer manager.channelsLock.RUnlock()

	channel, ok := manager.channels[uuid]
	if !ok {
		return nil
	}

	return channel
}

func (manager *ChannelManager) Close(uuid string) (err error) {
	manager.channelsLock.Lock()
	defer manager.channelsLock.Unlock()

	_, ok := manager.channels[uuid]
	if !ok {
		err = errors.New("channel uuid is not known")
		return
	}

	manager.pubsub.Pub(uuid, "close")
	delete(manager.channels, uuid)

	return
}

func (manager *ChannelManager) Open(uuid string) (channel *Channel, err error) {
	manager.channelsLock.Lock()
	defer manager.channelsLock.Unlock()

	if _, ok := manager.channels[uuid]; ok {
		err = errors.New("channel uuid is already in use")
		return
	}

	channel = NewChannel()
	manager.channels[uuid] = channel

	log.Println("Channel opened:", uuid)
	manager.pubsub.Pub(uuid, "open")

	return
}

func (manager *ChannelManager) Shutdown() {
	manager.pubsub.Shutdown()
}