package peer

import (
	"crypto/rsa"
	"cwtch.im/cwtch/model"
	"cwtch.im/cwtch/peer/connections"
	"cwtch.im/cwtch/peer/peer"
	"cwtch.im/cwtch/protocol"
	"encoding/base64"
	"encoding/json"
	"errors"
	"github.com/golang/protobuf/proto"
	"git.openprivacy.ca/openprivacy/libricochet-go/application"
	"git.openprivacy.ca/openprivacy/libricochet-go/channels"
	"git.openprivacy.ca/openprivacy/libricochet-go/connection"
	"golang.org/x/crypto/ed25519"
	"io/ioutil"
	"log"
	"strings"
	"sync"
)

// cwtchPeer manages incoming and outgoing connections and all processing for a Cwtch Peer
type cwtchPeer struct {
	connection.AutoConnectionHandler
	Profile            *model.Profile
	app                *application.RicochetApplication
	mutex              sync.Mutex
	Log                chan string `json:"-"`
	connectionsManager *connections.Manager
	profilefile        string
	password           [32]byte
	salt               [128]byte
}

// CwtchPeerInterface provides us with a way of testing systems built on top of cwtch without having to
// directly implement a cwtchPeer.
type CwtchPeerInterface interface {
	Save(string) error
	PeerWithOnion(string)
	InviteOnionToGroup(string, string) error

	TrustPeer(string) error
	BlockPeer(string) error
	AcceptInvite(string) error
	RejectInvite(string)

	JoinServer(string)
	SendMessageToGroup(string, string) error

	GetProfile() *model.Profile

	GetPeers() map[string]connections.ConnectionState
	GetServers() map[string]connections.ConnectionState

	StartGroup(string) (string, []byte, error)

	ImportGroup(string) (string, error)
	ExportGroup(string) (string, error)

	GetGroup(string) *model.Group
	GetGroups() []string
	GetContacts() []string
	GetContact(string) *model.PublicProfile

	Listen() error
	Shutdown()
}

// CreateHash hashes the user's password to a length suitable for file encryption
func CreateKey(key string) ([32]byte, [128]byte) {
var salt [128]byte
if _, err := io.ReadFull(rand.Reader, salt[:]);
err != nil {
	panic(err)
}
dk := pbkdf2.Key([]byte(key), salt[:], 4096, 32, sha3.New512)

var dkr [32]byte
copy(dkr[:], dk)
return dkr, salt
}

//EncryptMessage takes a message and encrypts the message under the group key.
func EncryptProfile(p *cwtchPeer, password [32]byte) []byte {
	var nonce [24]byte
	if _, err := io.ReadFull(rand.Reader, nonce[:]); err != nil {
		panic(err)
	}
	//copy Peer struct, then remove password and save the copy
	cpc := &cwtchPeer{}
	deepcopier.Copy(p).To(cpc)
	var blankpass [32]byte
	var blanksalt [128]byte
	cpc.password = blankpass
	cpc.salt = blanksalt
	bytes, _ := json.Marshal(cpc)

	encrypted := secretbox.Seal(nonce[:], []byte(bytes), &nonce, &password)
	return encrypted
}

//EncryptMessage takes a message and encrypts the message under the group key.
func DecryptProfile(ciphertext []byte, password [32]byte) (error, *cwtchPeer){

	var decryptNonce [24]byte
  copy(decryptNonce[:], ciphertext[:24])
  decrypted, ok := secretbox.Open(nil, ciphertext[24:], &decryptNonce, &password)
  if ok {
	  cp := &cwtchPeer{}
	  err := json.Unmarshal(decrypted, &cp)
	  if err == nil {
	  	return nil, cp
	  }		else {
			return err, nil
		}
  }
  return fmt.Errorf("Failed to decrypt"), nil
}

func (cp *cwtchPeer) setup() {
	cp.Log = make(chan string)
	cp.connectionsManager = connections.NewConnectionsManager()
	cp.Init()

	go cp.connectionsManager.AttemptReconnections()

	for onion, profile := range cp.Profile.Contacts {
		if profile.Trusted && !profile.Blocked {
			cp.PeerWithOnion(onion)
		}
	}

	for _, group := range cp.Profile.Groups {
		if group.Accepted || group.Owner == "self" {
			cp.JoinServer(group.GroupServer)
		}
	}
}

// NewCwtchPeer creates and returns a new CwtchPeer with the given name.
func NewCwtchPeer(name string, password string) *cwtchPeer {
	cp := new(cwtchPeer)
	cp.Profile = model.GenerateNewProfile(name)
	cp.setup()
	pass, salt := CreateKey(password)
	cp.password = pass
	cp.salt = salt
	return cp
}

// Save saves the CwtchPeer profile state to a file.
func (cp *cwtchPeer) Save(profilefile string) error {
	cp.mutex.Lock()
	encryptedbytes := EncryptProfile(cp, cp.password)
	encryptedbytes = append(cp.salt[:],encryptedbytes...)
	err := ioutil.WriteFile(profilefile, encryptedbytes, 0600)
	cp.profilefile = profilefile
	cp.mutex.Unlock()
	return err
}

// LoadCwtchPeer loads an existing CwtchPeer from a file. CHECK METHOD RETURN
func LoadCwtchPeer(profilefile string, password string) (*cwtchPeer, error) {
	encryptedbytes, _ := ioutil.ReadFile(profilefile)

	//get the salt
	salt, encryptedbytes := encryptedbytes[0:128], encryptedbytes[128:]

	dk := pbkdf2.Key([]byte(password), salt, 4096, 32, sha3.New512)
	var dkr [32]byte
	copy(dkr[:], dk)

	err, cp := DecryptProfile(encryptedbytes, dkr)
	if err == nil {
	  cp.setup()
	  cp.profilefile = profilefile
	  cp.password = dkr
	  return cp, nil
  } else {
	  return nil, err
  }
}

// ImportGroup intializes a group from an imported source rather than a peer invite
func (cp *cwtchPeer) ImportGroup(exportedInvite string) (groupID string, err error) {
	if strings.HasPrefix(exportedInvite, "torv2") {
		data, err := base64.StdEncoding.DecodeString(exportedInvite[21+44:])
		if err == nil {
			cpp := &protocol.CwtchPeerPacket{}
			err := proto.Unmarshal(data, cpp)
			if err == nil {
				pk, err := base64.StdEncoding.DecodeString(exportedInvite[21 : 21+44])
				if err == nil {
					edpk := ed25519.PublicKey(pk)
					onion := exportedInvite[5:21]
					cp.Profile.AddContact(onion, &model.PublicProfile{Name: "", Ed25519PublicKey: edpk, Trusted: true, Blocked: false, Onion: onion})
					cp.Profile.ProcessInvite(cpp.GetGroupChatInvite(), onion)
					return cpp.GroupChatInvite.GetGroupName(), nil
				}
			}
		}
	} else {
		err = errors.New("unsupported exported group type")
	}
	return
}

// ExportGroup serializes a group invite so it can be given offline
func (cp *cwtchPeer) ExportGroup(groupID string) (string, error) {
	group := cp.Profile.GetGroupByGroupID(groupID)
	if group != nil {
		invite, err := group.Invite()
		if err == nil {
			exportedInvite := "torv2" + cp.Profile.Onion + base64.StdEncoding.EncodeToString(cp.Profile.Ed25519PublicKey) + base64.StdEncoding.EncodeToString(invite)
			return exportedInvite, err
		}
	}
	return "", errors.New("group id could not be found")
}

// StartGroup create a new group linked to the given server and returns the group ID, an invite or an error.
func (cp *cwtchPeer) StartGroup(server string) (string, []byte, error) {
	return cp.Profile.StartGroup(server)
}

// GetGroups returns an unordered list of all group IDs.
func (cp *cwtchPeer) GetGroups() []string {
	return cp.Profile.GetGroups()
}

// GetGroup returns a pointer to a specific group, nil if no group exists.
func (cp *cwtchPeer) GetGroup(groupID string) *model.Group {
	return cp.Profile.GetGroupByGroupID(groupID)
}

// GetContacts returns an unordered list of onions
func (cp *cwtchPeer) GetContacts() []string {
	return cp.Profile.GetContacts()
}

// GetContact returns a given contact, nil is no such contact exists
func (cp *cwtchPeer) GetContact(onion string) *model.PublicProfile {
	contact, _ := cp.Profile.GetContact(onion)
	return contact
}

// GetProfile returns the profile associated with this Peer.
// TODO While it is probably "safe", it is not really "safe", to call functions on this profile. This only exists to return things like Name and Onion,we should gate these.
func (cp *cwtchPeer) GetProfile() *model.Profile {
	return cp.Profile
}

// PeerWithOnion is the entry point for cwtchPeer relationships
func (cp *cwtchPeer) PeerWithOnion(onion string) {
	cp.connectionsManager.ManagePeerConnection(onion, cp.Profile)
}

// InviteOnionToGroup kicks off the invite process
func (cp *cwtchPeer) InviteOnionToGroup(onion string, groupid string) error {

	group := cp.Profile.GetGroupByGroupID(groupid)
	if group != nil {
		log.Printf("Constructing invite for group: %v\n", group)
		invite, err := group.Invite()
		if err != nil {
			return err
		}
		ppc := cp.connectionsManager.GetPeerPeerConnectionForOnion(onion)
		if ppc == nil {
			return errors.New("peer connection not setup for onion. peers must be trusted before sending")
		}
		if ppc.GetState() == connections.AUTHENTICATED {
			log.Printf("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
	}
	return errors.New("group id could not be found")
}

// ReceiveGroupMessage is a callback function that processes GroupMessages from a given server
func (cp *cwtchPeer) ReceiveGroupMessage(server string, gm *protocol.GroupMessage) {
	cp.Profile.AttemptDecryption(gm.Ciphertext, gm.Signature)
}

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

// SendMessageToGroup attemps to sent the given message to the given group id.
func (cp *cwtchPeer) SendMessageToGroup(groupid string, message string) error {
	group := cp.Profile.GetGroupByGroupID(groupid)
	if group == nil {
		return errors.New("group does not exist")
	}
	psc := cp.connectionsManager.GetPeerServerConnectionForOnion(group.GroupServer)
	if psc == nil {
		return errors.New("could not find server connection to send message to")
	}
	ct, sig, err := cp.Profile.EncryptMessageToGroup(message, groupid)
	if err != nil {
		return err
	}
	gm := &protocol.GroupMessage{
		Ciphertext: ct,
		Signature:  sig,
	}
	err = psc.SendGroupMessage(gm)
	return err
}

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

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

// TrustPeer sets an existing peer relationship to trusted
func (cp *cwtchPeer) TrustPeer(peer string) error {
	err := cp.Profile.TrustPeer(peer)
	if err == nil {
		cp.PeerWithOnion(peer)
	}
	return err
}

// BlockPeer blocks an existing peer relationship.
func (cp *cwtchPeer) BlockPeer(peer string) error {
	err := cp.Profile.BlockPeer(peer)
	cp.connectionsManager.ClosePeerConnection(peer)
	return err
}

// AcceptInvite accepts a given existing group invite
func (cp *cwtchPeer) AcceptInvite(groupID string) error {
	return cp.Profile.AcceptInvite(groupID)
}

// RejectInvite rejects a given group invite.
func (cp *cwtchPeer) RejectInvite(groupID string) {
	cp.Profile.RejectInvite(groupID)
}

// LookupContact returns that a contact is known and allowed to communicate for all cases.
func (cp *cwtchPeer) LookupContact(hostname string, publicKey rsa.PublicKey) (allowed, known bool) {
	blocked := cp.Profile.IsBlocked(hostname)
	return !blocked, true
}

// ContactRequest needed to implement ContactRequestHandler Interface
func (cp *cwtchPeer) ContactRequest(name string, message string) string {
	return "Accepted"
}

// Listen sets up an onion listener to process incoming cwtch messages
func (cp *cwtchPeer) Listen() error {
	cwtchpeer := new(application.RicochetApplication)
	l, err := application.SetupOnion("127.0.0.1:9051", "tcp4", "", cp.Profile.OnionPrivateKey, 9878)

	if err != nil {
		return err
	}

	af := application.ApplicationInstanceFactory{}
	af.Init()
	af.AddHandler("im.cwtch.peer", func(rai *application.ApplicationInstance) func() channels.Handler {
		cpi := new(CwtchPeerInstance)
		cpi.Init(rai, cwtchpeer)
		return func() channels.Handler {
			cpc := new(peer.CwtchPeerChannel)
			cpc.Handler = &CwtchPeerHandler{Onion: rai.RemoteHostname, Peer: cp}
			return cpc
		}
	})
	cwtchpeer.Init(cp.Profile.Name, cp.Profile.OnionPrivateKey, af, cp)
	log.Printf("Running cwtch peer on %v", l.Addr().String())
	cp.app = cwtchpeer
	cwtchpeer.Run(l)
	return nil
}

// Shutdown kills all connections and cleans up all goroutines for the peer
func (cp *cwtchPeer) Shutdown() {
	cp.connectionsManager.Shutdown()
	cp.app.Shutdown()
}

// 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
	Peer  *cwtchPeer
}

// ClientIdentity handles incoming ClientIdentity packets
func (cph *CwtchPeerHandler) ClientIdentity(ci *protocol.CwtchIdentity) {
	log.Printf("Received Client Identity from %v %v\n", cph.Onion, ci.String())
	cph.Peer.Profile.AddCwtchIdentity(cph.Onion, ci)
	cph.Peer.Save(cph.Peer.profilefile)
}

// HandleGroupInvite handles incoming GroupInvites
func (cph *CwtchPeerHandler) HandleGroupInvite(gci *protocol.GroupChatInvite) {
	log.Printf("Received GroupID from %v %v\n", cph.Onion, gci.String())
	cph.Peer.Profile.ProcessInvite(gci, cph.Onion)
}

// GetClientIdentityPacket returns our ClientIdentity packet so it can be sent to the connected peer.
func (cph *CwtchPeerHandler) GetClientIdentityPacket() []byte {
	return cph.Peer.Profile.GetCwtchIdentityPacket()
}