package connections

import (
	"crypto/rsa"
	"cwtch.im/cwtch/event"
	"cwtch.im/cwtch/protocol"
	"cwtch.im/cwtch/protocol/connections/peer"
	"errors"
	"git.openprivacy.ca/openprivacy/libricochet-go/application"
	"git.openprivacy.ca/openprivacy/libricochet-go/channels"
	"git.openprivacy.ca/openprivacy/libricochet-go/connectivity"
	"git.openprivacy.ca/openprivacy/libricochet-go/identity"
	"git.openprivacy.ca/openprivacy/libricochet-go/log"
	"github.com/golang/protobuf/proto"
	"golang.org/x/crypto/ed25519"
	"sync"
	"time"
)

// Engine (ProtocolEngine) encapsulates the logic necessary to make and receive Cwtch connections.
// Note: ProtocolEngine doesn't have access to any information necessary to encrypt or decrypt GroupMessages
type Engine struct {
	queue              *event.Queue
	connectionsManager *Manager

	// Engine Attributes
	Identity identity.Identity
	ACN      connectivity.ACN

	app *application.RicochetApplication

	// Engine State
	started bool

	// Blocklist
	blocked sync.Map

	// Pointer to the Global Event Manager
	eventManager *event.Manager
	privateKey   ed25519.PrivateKey
}

// NewProtocolEngine initializes a new engine that runs Cwtch using the given parameters
func NewProtocolEngine(privateKey ed25519.PrivateKey, acn connectivity.ACN, eventManager *event.Manager, blockedPeers []string) *Engine {
	engine := new(Engine)
	engine.privateKey = privateKey
	engine.queue = event.NewEventQueue(100)
	go engine.eventHandler()

	engine.ACN = acn
	engine.connectionsManager = NewConnectionsManager(engine.ACN)
	go engine.connectionsManager.AttemptReconnections()

	engine.eventManager = eventManager

	engine.eventManager.Subscribe(event.ProtocolEngineStartListen, engine.queue.EventChannel)
	engine.eventManager.Subscribe(event.PeerRequest, engine.queue.EventChannel)
	engine.eventManager.Subscribe(event.InvitePeerToGroup, engine.queue.EventChannel)
	engine.eventManager.Subscribe(event.JoinServer, engine.queue.EventChannel)
	engine.eventManager.Subscribe(event.SendMessageToGroup, engine.queue.EventChannel)
	engine.eventManager.Subscribe(event.SendMessageToPeer, engine.queue.EventChannel)

	engine.eventManager.Subscribe(event.BlockPeer, engine.queue.EventChannel)
	for _, peer := range blockedPeers {
		engine.blocked.Store(peer, true)
	}
	return engine
}

// eventHandler process events from other subsystems
func (e *Engine) eventHandler() {
	for {
		ev := e.queue.Next()
		switch ev.EventType {
		case event.StatusRequest:
			e.eventManager.Publish(event.Event{EventType: event.ProtocolEngineStatus, EventID: ev.EventID})
		case event.PeerRequest:
			e.PeerWithOnion(ev.Data[event.RemotePeer])
		case event.InvitePeerToGroup:
			e.InviteOnionToGroup(ev.Data[event.RemotePeer], []byte(ev.Data[event.GroupInvite]))
		case event.JoinServer:
			e.JoinServer(ev.Data[event.GroupServer])
		case event.SendMessageToGroup:
			e.SendMessageToGroup(ev.Data[event.GroupServer], []byte(ev.Data[event.Ciphertext]), []byte(ev.Data[event.Signature]))
		case event.SendMessageToPeer:
			log.Debugf("Sending Message to Peer.....")
			ppc := e.connectionsManager.GetPeerPeerConnectionForOnion(ev.Data[event.RemotePeer])
			if ppc != nil {
				// TODO this will block.
				ppc.SendPacket([]byte(ev.Data[event.Data]))
			}
		case event.BlockPeer:
			e.blocked.Store(ev.Data[event.RemotePeer], true)
		case event.ProtocolEngineStartListen:
			go e.listenFn()
		default:
			return
		}
	}
}

// GetPeerHandler is an external interface function that allows callers access to a CwtchPeerHandler
// TODO: There is likely a slightly better way to encapsulate this behavior
func (e *Engine) GetPeerHandler(remotePeerHostname string) *CwtchPeerHandler {
	return &CwtchPeerHandler{Onion: remotePeerHostname, EventBus: e.eventManager}
}

// Listen sets up an onion listener to process incoming cwtch messages
func (e *Engine) listenFn() {
	ra := new(application.RicochetApplication)
	onionService, err := e.ACN.Listen(e.privateKey, application.RicochetPort)
	if err != nil /*&& fmt.Sprintf("%v", err) != "550 Unspecified Tor error: Onion address collision"*/ {
		e.eventManager.Publish(event.NewEvent(event.ProtocolEngineStopped, map[event.Field]string{event.Identity: e.Identity.Hostname(), event.Error: err.Error()}))
		return
	}

	af := application.ApplicationInstanceFactory{}
	af.Init()
	af.AddHandler("im.cwtch.peer", func(rai *application.ApplicationInstance) func() channels.Handler {
		cpi := new(CwtchPeerInstance)
		cpi.Init(rai, ra)
		return func() channels.Handler {
			cpc := new(peer.CwtchPeerChannel)
			cpc.Handler = e.GetPeerHandler(rai.RemoteHostname)
			return cpc
		}
	})

	af.AddHandler("im.cwtch.peer.data", func(rai *application.ApplicationInstance) func() channels.Handler {
		cpi := new(CwtchPeerInstance)
		cpi.Init(rai, ra)
		return func() channels.Handler {
			cpc := new(peer.CwtchPeerDataChannel)
			cpc.Handler = e.GetPeerHandler(rai.RemoteHostname)
			return cpc
		}
	})

	ra.Init(e.ACN, e.Identity.Name, e.Identity, af, e)
	log.Infof("Running cwtch peer on %v", onionService.AddressFull())
	e.started = true
	e.app = ra
	ra.Run(onionService)
	e.eventManager.Publish(event.NewEvent(event.ProtocolEngineStopped, map[event.Field]string{event.Identity: e.Identity.Hostname()}))
	return
}

// LookupContact is a V2 API Call, we want to reject all V2 Peers
// TODO Deprecate
func (e *Engine) LookupContact(hostname string, publicKey rsa.PublicKey) (allowed, known bool) {
	return false, false
}

// ContactRequest is a V2 API Call needed to implement ContactRequestHandler Interface
// TODO Deprecate
func (e *Engine) ContactRequest(name string, message string) string {
	return "Rejected"
}

// LookupContactV3 returns that a contact is known and allowed to communicate for all cases.
func (e *Engine) LookupContactV3(hostname string, publicKey ed25519.PublicKey) (allowed, known bool) {
	// TODO: We want to autoblock those that are blocked, The known parameter has no use anymore and should be
	// disregarded by peers, so we set it to false.
	if _, blocked := e.blocked.Load(hostname); blocked {
		return false, false
	}
	return true, false
}

// Shutdown tears down the eventHandler goroutine
func (e *Engine) Shutdown() {
	e.connectionsManager.Shutdown()
	e.app.Shutdown()
	e.queue.Shutdown()
}

// PeerWithOnion is the entry point for cwtchPeer relationships
func (e *Engine) PeerWithOnion(onion string) *PeerPeerConnection {
	return e.connectionsManager.ManagePeerConnection(onion, e)
}

// InviteOnionToGroup kicks off the invite process
func (e *Engine) InviteOnionToGroup(onion string, invite []byte) error {
	ppc := e.connectionsManager.GetPeerPeerConnectionForOnion(onion)
	if ppc == nil {
		return errors.New("peer connection not setup for onion. peers must be trusted before sending")
	}
	if ppc.GetState() == AUTHENTICATED {
		log.Infof("Got connection for group: %v - Sending Invite\n", ppc)
		ppc.SendGroupInvite(invite)
	} else {
		return errors.New("cannot send invite to onion: peer connection is not ready")
	}
	return nil
}

// ReceiveGroupMessage is a callback function that processes GroupMessages from a given server
func (e *Engine) ReceiveGroupMessage(server string, gm *protocol.GroupMessage) {
	// Publish Event so that a Profile Engine can deal with it.
	// Note: This technically means that *multiple* Profile Engines could listen to the same ProtocolEngine!
	e.eventManager.Publish(event.NewEvent(event.EncryptedGroupMessage, map[event.Field]string{event.Ciphertext: string(gm.GetCiphertext()), event.Signature: string(gm.GetSignature())}))
}

// JoinServer manages a new server connection with the given onion address
func (e *Engine) JoinServer(onion string) {
	e.connectionsManager.ManageServerConnection(onion, e.ReceiveGroupMessage)
}

// SendMessageToGroup attemps to sent the given message to the given group id.
func (e *Engine) SendMessageToGroup(server string, ct []byte, sig []byte) error {
	psc := e.connectionsManager.GetPeerServerConnectionForOnion(server)
	if psc == nil {
		return errors.New("could not find server connection to send message to")
	}
	gm := &protocol.GroupMessage{
		Ciphertext: ct,
		Signature:  sig,
	}
	err := psc.SendGroupMessage(gm)
	return err
}

// GetPeers returns a list of peer connections.
func (e *Engine) GetPeers() map[string]ConnectionState {
	return e.connectionsManager.GetPeers()
}

// GetServers returns a list of server connections
func (e *Engine) GetServers() map[string]ConnectionState {
	return e.connectionsManager.GetServers()
}

// CwtchPeerInstance encapsulates incoming peer connections
type CwtchPeerInstance struct {
	rai *application.ApplicationInstance
	ra  *application.RicochetApplication
}

// Init sets up a CwtchPeerInstance
func (cpi *CwtchPeerInstance) Init(rai *application.ApplicationInstance, ra *application.RicochetApplication) {
	cpi.rai = rai
	cpi.ra = ra
}

// CwtchPeerHandler encapsulates handling of incoming CwtchPackets
type CwtchPeerHandler struct {
	Onion       string
	EventBus    *event.Manager
	DataHandler func(string, []byte) []byte
}

// HandleGroupInvite handles incoming GroupInvites
func (cph *CwtchPeerHandler) HandleGroupInvite(gci *protocol.GroupChatInvite) {
	log.Debugf("Received GroupID from %v %v\n", cph.Onion, gci.String())
	marshal, err := proto.Marshal(gci)
	if err == nil {
		cph.EventBus.Publish(event.NewEvent(event.NewGroupInvite, map[event.Field]string{event.TimestampReceived: time.Now().String(), event.RemotePeer: cph.Onion, event.GroupInvite: string(marshal)}))
	}
}

// HandlePacket handles the Cwtch cwtchPeer Data Channel
func (cph *CwtchPeerHandler) HandlePacket(data []byte) []byte {
	cph.EventBus.Publish(event.NewEvent(event.NewMessageFromPeer, map[event.Field]string{event.TimestampReceived: time.Now().String(), event.RemotePeer: cph.Onion, event.Data: string(data)}))
	return []byte{} // TODO remove this
}