package peer

import (
	"cwtch.im/cwtch/event"
	"cwtch.im/cwtch/model"
	"cwtch.im/cwtch/protocol"
	"cwtch.im/cwtch/protocol/connections"
	"encoding/base64"
	"errors"
	"git.openprivacy.ca/openprivacy/libricochet-go/connectivity"
	"git.openprivacy.ca/openprivacy/libricochet-go/identity"
	"git.openprivacy.ca/openprivacy/libricochet-go/utils"
	"github.com/ethereum/go-ethereum/log"
	"github.com/golang/protobuf/proto"
	"golang.org/x/crypto/ed25519"
	"strings"
	"sync"
)

// cwtchPeer manages incoming and outgoing connections and all processing for a Cwtch cwtchPeer
type cwtchPeer struct {
	Profile  *model.Profile
	mutex    sync.Mutex
	shutdown bool
	started  bool

	engine   *connections.Engine
	queue    *event.Queue
	eventBus *event.Manager
}

// CwtchPeer provides us with a way of testing systems built on top of cwtch without having to
// directly implement a cwtchPeer.
type CwtchPeer interface {
	Init(connectivity.ACN, *event.Manager)
	PeerWithOnion(string) *connections.PeerPeerConnection
	InviteOnionToGroup(string, string) error
	SendMessageToPeer(string, string)

	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

	IsStarted() bool
	Listen()
	Shutdown()
}

// NewCwtchPeer creates and returns a new cwtchPeer with the given name.
func NewCwtchPeer(name string) CwtchPeer {
	cp := new(cwtchPeer)
	cp.Profile = model.GenerateNewProfile(name)
	cp.shutdown = false
	return cp
}

// FromProfile generates a new peer from a profile.
func FromProfile(profile *model.Profile) CwtchPeer {
	cp := new(cwtchPeer)
	cp.Profile = profile
	return cp
}

// Init instantiates a cwtchPeer
func (cp *cwtchPeer) Init(acn connectivity.ACN, eventBus *event.Manager) {
	cp.queue = event.NewEventQueue(100)
	go cp.eventHandler()

	cp.eventBus = eventBus
	cp.eventBus.Subscribe(event.EncryptedGroupMessage, cp.queue.EventChannel)
	cp.eventBus.Subscribe(event.NewGroupInvite, cp.queue.EventChannel)

	// TODO: Would be nice if ProtocolEngine did not need to explictly be given the Private Key.
	cp.engine = connections.NewProtocolEngine(cp.Profile.Ed25519PrivateKey, acn, eventBus)
	cp.engine.Identity = identity.InitializeV3(cp.Profile.Name, &cp.Profile.Ed25519PrivateKey, &cp.Profile.Ed25519PublicKey)
}

// 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, "torv3") {
		data, err := base64.StdEncoding.DecodeString(exportedInvite[5+44:])
		if err == nil {
			cpp := &protocol.CwtchPeerPacket{}
			err := proto.Unmarshal(data, cpp)
			if err == nil {
				pk, err := base64.StdEncoding.DecodeString(exportedInvite[5 : 5+44])
				if err == nil {
					edpk := ed25519.PublicKey(pk)
					onion := utils.GetTorV3Hostname(edpk)
					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(group.GetInitialMessage())
		if err == nil {
			exportedInvite := "torv3" + 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)
}

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

// 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 cwtchPeer.
func (cp *cwtchPeer) GetProfile() *model.Profile {
	return cp.Profile
}

// PeerWithOnion is the entry point for cwtchPeer relationships
func (cp *cwtchPeer) PeerWithOnion(onion string) *connections.PeerPeerConnection {
	cp.eventBus.Publish(event.NewEvent(event.PeerRequest, map[string]string{"Onion": onion}))
	return nil
}

// InviteOnionToGroup kicks off the invite process
func (cp *cwtchPeer) InviteOnionToGroup(onion string, groupid string) error {
	group := cp.Profile.GetGroupByGroupID(groupid)
	if group == nil {
		return errors.New("invalid group id")
	}

	invite, err := group.Invite(group.InitialMessage)
	if err == nil {
		cp.eventBus.Publish(event.NewEvent(event.InvitePeerToGroup, map[string]string{"Onion": onion, "Invite": string(invite)}))
	}
	return err
}

// JoinServer manages a new server connection with the given onion address
func (cp *cwtchPeer) JoinServer(onion string) {
	cp.eventBus.Publish(event.NewEvent(event.JoinServer, map[string]string{"Onion": onion}))
}

// 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("invalid group id")
	}
	ct, sig, err := cp.Profile.EncryptMessageToGroup(message, groupid)

	if err == nil {
		cp.eventBus.Publish(event.NewEvent(event.SendMessageToGroup, map[string]string{"Server": group.GroupServer, "Ciphertext": string(ct), "Signature": string(sig)}))
	}

	return err
}

func (cp *cwtchPeer) SendMessageToPeer(onion string, message string) {
	cp.eventBus.Publish(event.NewEvent(event.SendMessageToPeer, map[string]string{"Peer": onion, "Message": message}))
}

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

// GetServers returns a list of server connections
func (cp *cwtchPeer) GetServers() map[string]connections.ConnectionState {
	return cp.engine.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.eventBus.Publish(event.NewEvent(event.BlockPeer, map[string]string{"Onion": 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)
}

func (cp *cwtchPeer) Listen() {
	cp.eventBus.Publish(event.NewEvent(event.ProtocolEngineStartListen, map[string]string{}))
}

// Shutdown kills all connections and cleans up all goroutines for the peer
func (cp *cwtchPeer) Shutdown() {
	cp.shutdown = true
	cp.engine.Shutdown()
	cp.queue.Shutdown()
}

// IsStarted returns true if Listen() has successfully been run before on this connection (ever). TODO: we will need to properly unset this flag on error if we want to support resumption in the future
func (cp *cwtchPeer) IsStarted() bool {
	return cp.started
}

// eventHandler process events from other subsystems
func (cp *cwtchPeer) eventHandler() {
	for {
		ev := cp.queue.Next()
		switch ev.EventType {
		case event.EncryptedGroupMessage:
			ok, groupID, _ := cp.Profile.AttemptDecryption([]byte(ev.Data["Ciphertext"]), []byte(ev.Data["Signature"]))
			if ok {
				cp.eventBus.Publish(event.NewEvent(event.NewMessageFromGroup, map[string]string{"GroupID": groupID}))
			}
		case event.NewGroupInvite:
			var groupInvite protocol.GroupChatInvite
			proto.Unmarshal([]byte(ev.Data["GroupInvite"]), &groupInvite)
			cp.Profile.ProcessInvite(&groupInvite, ev.Data["Onion"])
		default:
			if ev.EventType != "" {
				log.Error("peer event handler received an event it was not subscribed for: %v")
			}
			return
		}
	}
}