package p2p

import (
	"errors"
	"sync"

	net "gx/ipfs/QmQSbtGXCyNrj34LWL8EgXyNNYDZ8r3SwQcpW5pPxVhLnM/go-libp2p-net"
	peer "gx/ipfs/QmQsErDt8Qgw1XrsXf2BpEzDgGWtB1YLsTAARBup5b6B9W/go-libp2p-peer"
	ma "gx/ipfs/QmYmsdtJ3HsodkePE3eU3TsCaP2YvPZJ4LoXnNkDE5Tpt7/go-multiaddr"
	"gx/ipfs/QmZNkThpqfVXs9GNbexPrfBbXSLNYeKrE7jwFM2oqHbyqN/go-libp2p-protocol"
	p2phost "gx/ipfs/QmfH9FKYv3Jp1xiyL8sPchGBUBg6JA6XviwajAo3qgnT3B/go-libp2p-host"
)

// Listener listens for connections and proxies them to a target
type Listener interface {
	Protocol() protocol.ID
	ListenAddress() ma.Multiaddr
	TargetAddress() ma.Multiaddr

	start() error
	key() string

	// Close closes the listener. Does not affect child streams
	Close() error
}

type Listeners struct {
	sync.RWMutex

	Listeners map[string]Listener
	starting  map[string]struct{}
}

func newListenersLocal(id peer.ID) *Listeners {
	return &Listeners{
		Listeners: map[string]Listener{},
		starting:  map[string]struct{}{},
	}
}

func newListenersP2P(id peer.ID, host p2phost.Host) *Listeners {
	reg := &Listeners{
		Listeners: map[string]Listener{},
		starting:  map[string]struct{}{},
	}

	host.SetStreamHandlerMatch("/x/", func(p string) bool {
		reg.RLock()
		defer reg.RUnlock()

		_, ok := reg.Listeners[p]
		return ok
	}, func(stream net.Stream) {
		reg.RLock()
		defer reg.RUnlock()

		l := reg.Listeners[string(stream.Protocol())]
		if l != nil {
			go l.(*remoteListener).handleStream(stream)
		}
	})

	return reg
}

// Register registers listenerInfo into this registry and starts it
func (r *Listeners) Register(l Listener) error {
	r.Lock()
	k := l.key()

	if _, ok := r.Listeners[k]; ok {
		r.Unlock()
		return errors.New("listener already registered")
	}

	r.Listeners[k] = l
	r.starting[k] = struct{}{}

	r.Unlock()

	err := l.start()

	r.Lock()
	defer r.Unlock()

	delete(r.starting, k)

	if err != nil {
		delete(r.Listeners, k)
		return err
	}

	return nil
}

// Deregister removes p2p listener from this registry
func (r *Listeners) Deregister(k string) (bool, error) {
	r.Lock()
	defer r.Unlock()

	if _, ok := r.starting[k]; ok {
		return false, errors.New("listener didn't start yet")
	}

	_, ok := r.Listeners[k]
	delete(r.Listeners, k)
	return ok, nil
}