package core

import (
	"crypto/rsa"
	"encoding/base64"
	"errors"
	"github.com/ricochet-im/ricochet-go/core/utils"
	protocol "github.com/s-rah/go-ricochet"
	connection "github.com/s-rah/go-ricochet/connection"
	"github.com/yawning/bulb/utils/pkcs1"
	"log"
	"net"
	"sync"
)

// Identity represents the local user, including their contact address,
// and contains the contacts list.
type Identity struct {
	core *Ricochet

	mutex sync.Mutex

	address     string
	privateKey  *rsa.PrivateKey
	contactList *ContactList

	ConversationStream *utils.Publisher
}

func CreateIdentity(core *Ricochet) (*Identity, error) {
	me := &Identity{
		core:               core,
		ConversationStream: utils.CreatePublisher(),
	}

	if err := me.loadIdentity(); err != nil {
		log.Printf("Failed loading identity: %v", err)
		return nil, err
	}

	contactList, err := LoadContactList(core)
	if err != nil {
		log.Printf("Failed loading contact list: %v", err)
		return nil, err
	}
	me.contactList = contactList

	contactList.StartConnections()
	go me.publishService(me.privateKey)
	return me, nil
}

func (me *Identity) loadIdentity() error {
	config := me.core.Config.OpenRead()
	defer config.Close()

	if config.Identity.ServiceKey != "" {
		keyData, err := base64.StdEncoding.DecodeString(config.Identity.ServiceKey)
		if err != nil {
			return err
		}

		me.privateKey, _, err = pkcs1.DecodePrivateKeyDER(keyData)
		if err != nil {
			return err
		}
		me.address, err = AddressFromKey(&me.privateKey.PublicKey)
		if err != nil {
			return err
		}

		log.Printf("Loaded identity %s", me.address)
	} else {
		log.Printf("Initializing new identity")
	}

	return nil
}

func (me *Identity) setPrivateKey(key *rsa.PrivateKey) error {
	me.mutex.Lock()
	defer me.mutex.Unlock()

	if me.privateKey != nil || me.address != "" {
		return errors.New("Cannot change private key on identity")
	}

	// Save key to config
	keyData, err := pkcs1.EncodePrivateKeyDER(key)
	if err != nil {
		return err
	}
	config := me.core.Config.OpenWrite()
	config.Identity.ServiceKey = base64.StdEncoding.EncodeToString(keyData)
	config.Save()

	// Update Identity
	me.address, err = AddressFromKey(&key.PublicKey)
	if err != nil {
		return err
	}
	me.privateKey = key

	log.Printf("Created new identity %s", me.address)
	return nil
}

// BUG(special): No error handling for failures under publishService
func (me *Identity) publishService(key *rsa.PrivateKey) {
	// This call will block until a control connection is available and the
	// ADD_ONION command has returned. After creating the listener, it will
	// be automatically re-published if the control connection is lost and
	// later reconnected.
	service, listener, err := me.core.Network.NewOnionListener(9878, key)
	if err != nil {
		log.Printf("Identity listener failed: %v", err)
		// XXX handle
		return
	}

	if key == nil {
		if service.PrivateKey == nil {
			log.Printf("Setting private key failed: no key returned")
			// XXX handle
			return
		}

		err := me.setPrivateKey(service.PrivateKey.(*rsa.PrivateKey))
		if err != nil {
			log.Printf("Setting private key failed: %v", err)
			// XXX handle
			return
		}
	}

	log.Printf("Identity service published, accepting connections")
	for {
		conn, err := listener.Accept()
		if err != nil {
			log.Printf("Identity listener failed: %v", err)
			// XXX handle
			return
		}

		// Handle connection in a separate goroutine and continue listening
		go me.handleInboundConnection(conn)
	}
}

func (me *Identity) handleInboundConnection(conn net.Conn) error {
	defer func() {
		// Close conn on return unless explicitly cleared
		if conn != nil {
			conn.Close()
		}
	}()

	contactByHostname := func(hostname string) (*Contact, error) {
		address, ok := AddressFromPlainHost(hostname)
		if !ok {
			// This would be a bug
			return nil, errors.New("invalid authenticated hostname")
		}
		return me.contactList.ContactByAddress(address), nil
	}
	lookupContactAuth := func(hostname string, publicKey rsa.PublicKey) (bool, bool) {
		contact, err := contactByHostname(hostname)
		if err != nil {
			return false, false
		}
		// allowed, known
		return true, contact != nil
	}

	rc, err := protocol.NegotiateVersionInbound(conn)
	if err != nil {
		log.Printf("Inbound connection failed: %v", err)
		return err
	}

	authHandler := connection.HandleInboundConnection(rc)
	err = authHandler.ProcessAuthAsServer(me.privateKey, lookupContactAuth)
	if err != nil {
		log.Printf("Inbound connection auth failed: %v", err)
		return err
	}
	contact, err := contactByHostname(rc.RemoteHostname)
	if err != nil {
		log.Printf("Inbound connection lookup failed: %v", err)
		return err
	}

	if contact != nil {
		// Known contact, pass the new connection to Contact
		contact.AssignConnection(rc)
		conn = nil
		return nil
	}

	// XXX-protocol Unknown contact, should pass to handler for contact requests
	log.Printf("Inbound connection is a contact request, but that's not implemented yet")
	return errors.New("inbound contact request connections aren't implemented")
}

func (me *Identity) Address() string {
	return me.address
}

func (me *Identity) ContactList() *ContactList {
	return me.contactList
}

func (me *Identity) PrivateKey() rsa.PrivateKey {
	return *me.privateKey
}