package connectivity

import (
	"context"
	"errors"
	"git.openprivacy.ca/openprivacy/libricochet-go/log"
	"git.openprivacy.ca/openprivacy/libricochet-go/utils"
	"github.com/cretz/bine/control"
	"github.com/cretz/bine/process"
	"github.com/cretz/bine/tor"
	bineed255192 "github.com/cretz/bine/torutil/ed25519"
	"golang.org/x/crypto/ed25519"
	"golang.org/x/crypto/sha3"
	"net"
	"net/textproto"
	"os"
	"os/exec"
	"path"
	"regexp"
	"strconv"
	"strings"
	"sync"
	"time"
)

const (
	// CannotResolveLocalTCPAddressError is thrown when a local ricochet connection has the wrong format.
	CannotResolveLocalTCPAddressError = utils.Error("CannotResolveLocalTCPAddressError")
	// CannotDialLocalTCPAddressError is thrown when a connection to a local ricochet address fails.
	CannotDialLocalTCPAddressError = utils.Error("CannotDialLocalTCPAddressError")
	// CannotDialRicochetAddressError is thrown when a connection to a ricochet address fails.
	CannotDialRicochetAddressError = utils.Error("CannotDialRicochetAddressError")
)

const (
	minStatusIntervalMs = 200
	maxStatusIntervalMs = 2000
)

type onionListenService struct {
	os *tor.OnionService
	tp *torProvider
}

type torProvider struct {
	t               *tor.Tor
	dialer          *tor.Dialer
	appDirectory    string
	bundeledTorPath string
	lock            sync.Mutex
	breakChan       chan bool
	childListeners  map[string]*onionListenService
	statusCallback  func(int, string)
}

func (ols *onionListenService) AddressFull() string {
	return ols.os.Addr().String()
}

func (ols *onionListenService) AddressIdentity() string {
	return ols.os.Addr().String()[:56]
}

func (ols *onionListenService) Accept() (net.Conn, error) {
	return ols.os.Accept()
}

func (ols *onionListenService) Close() {
	ols.tp.unregisterListener(ols.AddressIdentity())
	ols.os.Close()
}

// GetBootstrapStatus returns an int -1 on error or 0-100 on the percent the bootstrapping of the underlying network is at and an optional string message
func (tp *torProvider) GetBootstrapStatus() (int, string) {
	if tp.t == nil {
		return -1, "error: no tor, trying to restart..."
	}
	kvs, err := tp.t.Control.GetInfo("status/bootstrap-phase")
	if err != nil {
		return -1, "error"
	}
	progress := 0
	status := ""

	if len(kvs) > 0 {
		progRe := regexp.MustCompile("PROGRESS=([0-9]*)")
		sumRe := regexp.MustCompile("SUMMARY=\"(.*)\"$")

		if progMatches := progRe.FindStringSubmatch(kvs[0].Val); len(progMatches) > 1 {
			progress, _ = strconv.Atoi(progMatches[1])
		}

		if statusMatches := sumRe.FindStringSubmatch(kvs[0].Val); len(statusMatches) > 1 {
			status = statusMatches[1]
		}
	}
	return progress, status
}

// WaitTillBootstrapped Blocks until underlying network is bootstrapped
func (tp *torProvider) WaitTillBootstrapped() {
	for true {
		progress, _ := tp.GetBootstrapStatus()
		if progress == 100 {
			break
		}
		time.Sleep(100 * time.Millisecond)
	}
}

func (tp *torProvider) Listen(identity PrivateKey, port int) (ListenService, error) {
	var onion = ""
	var privkey ed25519.PrivateKey

	tp.lock.Lock()
	defer tp.lock.Unlock()

	if tp.t == nil {
		return nil, errors.New("Tor Provider closed")
	}

	switch pk := identity.(type) {
	case ed25519.PrivateKey:
		privkey = pk
		gpubk := pk.Public()
		switch pubk := gpubk.(type) {
		case ed25519.PublicKey:
			onion = utils.GetTorV3Hostname(pubk)
		}
	}

	// Hack around tor detached onions not having a more obvious resume mechanism
	// So we use deterministic ports
	seedbytes := sha3.New224().Sum([]byte(onion))
	localport := int(seedbytes[0]) + (int(seedbytes[1]) << 8)
	if localport < 1024 { // this is not uniformly random, but we don't need it to be
		localport += 1024
	}

	localListener, err := net.Listen("tcp", "127.0.0.1:"+strconv.Itoa(localport))

	conf := &tor.ListenConf{NoWait: true, Version3: true, Key: identity, RemotePorts: []int{port}, Detach: true, DiscardKey: true, LocalListener: localListener}
	os, err := tp.t.Listen(nil, conf)
	if err != nil && strings.Contains(err.Error(), "550 Unspecified Tor error: Onion address collision") {
		os = &tor.OnionService{Tor: tp.t, LocalListener: localListener, ID: onion, Version3: true, Key: bineed255192.FromCryptoPrivateKey(privkey), ClientAuths: make(map[string]string, 0), RemotePorts: []int{port}}
		err = nil
	}
	// Not set in t.Listen if supplied, we want it to handle this however
	os.CloseLocalListenerOnClose = true

	if err != nil {
		return nil, err
	}

	ols := &onionListenService{os: os, tp: tp}
	tp.childListeners[ols.AddressIdentity()] = ols
	return ols, nil
}

func (tp *torProvider) Restart() {
	if tp.statusCallback != nil {
		tp.statusCallback(0, "rebooting")
	}
	tp.restart()
}

func (tp *torProvider) Open(hostname string) (net.Conn, string, error) {
	tp.lock.Lock()

	if tp.t == nil {
		tp.lock.Unlock()
		return nil, hostname, errors.New("Tor is offline")
	}
	tp.lock.Unlock()

	resolvedHostname := hostname
	if strings.HasPrefix(hostname, "ricochet:") {
		addrParts := strings.Split(hostname, ":")
		resolvedHostname = addrParts[1]
	}

	conn, err := tp.dialer.Dial("tcp", resolvedHostname+".onion:9878")
	return conn, resolvedHostname, err
}

func (tp *torProvider) Close() {
	for _, child := range tp.childListeners {
		child.Close()
	}

	tp.lock.Lock()
	defer tp.lock.Unlock()
	tp.breakChan <- true
	if tp.t != nil {
		tp.t.Close()
		tp.t = nil
	}
}

func (tp *torProvider) SetStatusCallback(callback func(int, string)) {
	tp.lock.Lock()
	defer tp.lock.Unlock()
	tp.statusCallback = callback
}

// StartTor creates/starts a Tor ACN and returns a usable ACN object
func StartTor(appDirectory string, bundledTorPath string) (ACN, error) {
	tp, err := startTor(appDirectory, bundledTorPath)
	if err == nil {
		tp.dialer, err = tp.t.Dialer(nil, &tor.DialConf{})
		if err == nil {
			go tp.monitorRestart()
		}
	}
	return tp, err
}

// newHideCmd creates a Creator function for bine which generates a cmd that one windows will hide the dosbox
func newHideCmd(exePath string) process.Creator {
	return process.CmdCreatorFunc(func(ctx context.Context, args ...string) (*exec.Cmd, error) {
		cmd := exec.CommandContext(ctx, exePath, args...)
		cmd.Stdout = os.Stdout
		cmd.Stderr = os.Stderr
		cmd.SysProcAttr = sysProcAttr
		return cmd, nil
	})
}

func startTor(appDirectory string, bundledTorPath string) (*torProvider, error) {
	dataDir := path.Join(appDirectory, "tor")
	os.MkdirAll(dataDir, 0700)
	tp := &torProvider{appDirectory: appDirectory, bundeledTorPath: bundledTorPath, childListeners: make(map[string]*onionListenService), breakChan: make(chan bool), statusCallback: nil}

	// attempt connect to system tor
	log.Debugf("dialing system tor control port\n")
	controlport, err := dialControlPort(9051)

	if err == nil {
		// TODO: configurable auth
		err := controlport.Authenticate("")
		if err == nil {
			log.Debugln("connected to control port")
			pinfo, err := controlport.ProtocolInfo()
			if err == nil && minTorVersionReqs(pinfo.TorVersion) {
				log.Debugln("OK version " + pinfo.TorVersion)
				tp.t = createFromExisting(controlport, dataDir)
				return tp, nil
			}
			controlport.Close()
		}
	}

	// if not, try running system tor
	if checkCmdlineTorVersion("tor") {
		t, err := tor.Start(nil, &tor.StartConf{EnableNetwork: true, DataDir: dataDir, DebugWriter: nil, ProcessCreator: newHideCmd("tor")})
		if err == nil {
			tp.t = t
			return tp, nil
		}
		log.Debugf("Error connecting to self-run system tor: %v\n", err)
	}

	// try running bundledTor
	if bundledTorPath != "" && checkCmdlineTorVersion(bundledTorPath) {
		log.Debugln("using bundled tor '" + bundledTorPath + "'")
		t, err := tor.Start(nil, &tor.StartConf{EnableNetwork: true, DataDir: dataDir, ExePath: bundledTorPath, DebugWriter: nil, ProcessCreator: newHideCmd(bundledTorPath)})
		if err != nil {
			log.Debugf("Error running bundled tor: %v\n", err)
		}
		tp.t = t
		return tp, err
	}
	return nil, errors.New("Could not connect to or start Tor that met requirments (min Tor version 0.3.5.x)")
}

func (tp *torProvider) unregisterListener(id string) {
	tp.lock.Lock()
	defer tp.lock.Unlock()
	delete(tp.childListeners, id)
}

func (tp *torProvider) monitorRestart() {
	lastBootstrapProgress := 0
	interval := minStatusIntervalMs

	for {
		select {
		case <-time.After(time.Millisecond * time.Duration(interval)):
			prog, status := tp.GetBootstrapStatus()

			if prog == -1 && tp.t != nil {
				if tp.statusCallback != nil {
					tp.statusCallback(prog, status)
				}
				tp.restart()
				interval = minStatusIntervalMs
			} else if prog != lastBootstrapProgress {
				if tp.statusCallback != nil {
					tp.statusCallback(prog, status)
				}
				interval = minStatusIntervalMs
			} else {
				if interval < maxStatusIntervalMs {
					interval *= 2
				}
			}
			lastBootstrapProgress = prog
		case <-tp.breakChan:
			return
		}
	}
}

func (tp *torProvider) restart() {

	for _, child := range tp.childListeners {
		child.Close()
	}

	tp.lock.Lock()
	defer tp.lock.Unlock()

	tp.t.Close()
	tp.t = nil

	for {
		newTp, err := startTor(tp.appDirectory, tp.bundeledTorPath)
		if err == nil {
			tp.t = newTp.t
			tp.dialer, _ = tp.t.Dialer(nil, &tor.DialConf{})
			return
		}
	}
}

func createFromExisting(controlport *control.Conn, datadir string) *tor.Tor {
	t := &tor.Tor{
		Process:              nil,
		Control:              controlport,
		ProcessCancelFunc:    nil,
		DataDir:              datadir,
		DeleteDataDirOnClose: false,
		DebugWriter:          nil,
		StopProcessOnClose:   false,
		GeoIPCreatedFile:     "",
		GeoIPv6CreatedFile:   "",
	}
	t.Control.DebugWriter = t.DebugWriter

	t.EnableNetwork(nil, true)

	return t
}

func checkCmdlineTorVersion(torCmd string) bool {
	cmd := exec.Command(torCmd, "--version")
	cmd.SysProcAttr = sysProcAttr
	out, err := cmd.CombinedOutput()
	re := regexp.MustCompile("[0-1]\\.[0-9]\\.[0-9]\\.[0-9]")
	sysTorVersion := re.Find(out)
	log.Infoln("tor version: " + string(sysTorVersion))
	return err == nil && minTorVersionReqs(string(sysTorVersion))
}

// returns true if supplied version meets our min requirments
// min requirement: 0.3.5.x
func minTorVersionReqs(torversion string) bool {
	torversions := strings.Split(torversion, ".") //eg: 0.3.4.8 or 0.3.5.1-alpha
	log.Debugf("torversions: %v", torversions)
	tva, _ := strconv.Atoi(torversions[0])
	tvb, _ := strconv.Atoi(torversions[1])
	tvc, _ := strconv.Atoi(torversions[2])
	return tva > 0 || (tva == 0 && (tvb > 3 || (tvb == 3 && tvc >= 5)))
}

func dialControlPort(port int) (*control.Conn, error) {
	textConn, err := textproto.Dial("tcp", "127.0.0.1:"+strconv.Itoa(port))
	if err != nil {
		return nil, err
	}
	return control.NewConn(textConn), nil
}