package main

import (
	"context"
	"crypto/tls"
	"errors"
	"flag"
	"fmt"
	"io"
	"io/ioutil"
	golog "log"
	"net/http"
	"net/url"
	"os"
	"strconv"
	"strings"

	"git.coolaj86.com/coolaj86/go-telebitd/log"
	telebit "git.coolaj86.com/coolaj86/go-telebitd/mplexer"
	"git.coolaj86.com/coolaj86/go-telebitd/mplexer/dns01"
	"git.coolaj86.com/coolaj86/go-telebitd/relay"
	"git.coolaj86.com/coolaj86/go-telebitd/relay/api"

	//jwt "github.com/dgrijalva/jwt-go"
	"github.com/caddyserver/certmagic"
	"github.com/go-acme/lego/v3/challenge"
	"github.com/go-acme/lego/v3/providers/dns/duckdns"
	"github.com/go-acme/lego/v3/providers/dns/godaddy"
	lumberjack "gopkg.in/natefinch/lumberjack.v2"

	_ "github.com/joho/godotenv/autoload"
)

// Loginfo TODO remove
var Loginfo = log.Loginfo

// Logdebug TODO remove
var Logdebug = log.Logdebug

func init() {
	log.LogFlags = golog.Ldate | golog.Lmicroseconds | golog.Lshortfile
}

var (
	logfile    = "stdout"
	configPath = "./"
	configFile = "telebit-relay"

	tcpPort           int
	argDeadTime       int
	connectionTable   *api.Table
	secretKey         string
	wssHostName       string
	adminHostName     string
	idle              int
	dwell             int
	cancelcheck       int
	loadBalanceMethod api.LoadBalanceStrategy
	nickname          string
	acmeEmail         string
	acmeStorage       string
	acmeAgree         bool
	acmeStaging       bool
	allclients        string
	authURL           string
	acmeRelay         string
)

func init() {
	flag.StringVar(&allclients, "clients", "", "list of client:secret pairings such as example.com:secret123,foo.com:secret321")
	flag.StringVar(&acmeEmail, "acme-email", "", "email to use for Let's Encrypt / ACME registration")
	flag.StringVar(&acmeStorage, "acme-storage", "./acme.d/", "path to ACME storage directory")
	flag.BoolVar(&acmeAgree, "acme-agree", false, "agree to the terms of the ACME service provider (required)")
	flag.BoolVar(&acmeStaging, "staging", false, "get fake certificates for testing")
	flag.StringVar(&authURL, "auth-url", "http://localhost:3010/api", "the auth server url")
	flag.StringVar(&acmeRelay, "acme-relay-url", "", "the ACME DNS-01 relay, if any")
	flag.StringVar(&adminHostName, "admin-hostname", "", "the management domain")
	flag.StringVar(&wssHostName, "wss-hostname", "", "the wss domain for connecting devices, if different from admin")
	flag.StringVar(&configPath, "config-path", configPath, "Configuration File Path")
	flag.StringVar(&secretKey, "secret", "", "a >= 16-character random string for JWT key signing") // SECRET
	flag.StringVar(&logfile, "log", logfile, "Log file (or stdout/stderr; empty for none)")
	flag.IntVar(&tcpPort, "port", 0, "tcp port on which to listen")                           // PORT
	flag.StringVar(&nickname, "nickname", "", "a nickname for this server, as an identifier") // NICKNAME
}

var logoutput io.Writer

// Client is a domain and secret pair
type Client struct {
	domain string
	secret string
}

//Main -- main entry point
func main() {
	var err error
	var provider challenge.Provider = nil

	flag.Parse()

	if !acmeAgree {
		fmt.Fprintf(os.Stderr, "set --acme-agree=true to accept the terms of the ACME service provider.\n")
		os.Exit(1)
	}

	clients := []Client{}
	for _, pair := range strings.Split(allclients, ", ") {
		if 0 == len(pair) {
			continue
		}
		keyval := strings.Split(pair, ":")
		clients = append(clients, Client{
			domain: keyval[0],
			secret: keyval[1],
		})
	}

	if 0 == len(secretKey) {
		secretKey = os.Getenv("SECRET")
	}
	if len(secretKey) < 16 {
		fmt.Fprintf(os.Stderr, "Invalid secret: %q. See --help for details.\n", secretKey)
		os.Exit(1)
	}

	switch logfile {
	case "stdout":
		logoutput = os.Stdout
	case "stderr":
		logoutput = os.Stderr
	case "":
		logoutput = ioutil.Discard
	default:
		logoutput = &lumberjack.Logger{
			Filename:   logfile,
			MaxSize:    100,
			MaxAge:     120,
			MaxBackups: 10,
		}
	}

	// send the output io.Writing to the other packages
	log.InitLogging(logoutput)

	flag.IntVar(&argDeadTime, "dead-time-counter", 5, "deadtime counter in seconds")

	if 0 == tcpPort {
		tcpPort, _ = strconv.Atoi(os.Getenv("PORT"))
		if 0 == tcpPort {
			fmt.Fprintf(os.Stderr, "must specify --port or PORT\n")
			os.Exit(1)
		}
	}

	if 0 == len(adminHostName) {
		adminHostName = os.Getenv("ADMIN_HOSTNAME")
	}
	if 0 == len(wssHostName) {
		wssHostName = os.Getenv("WSS_HOSTNAME")
	}
	if 0 == len(wssHostName) {
		wssHostName = adminHostName
	}

	// load balancer method
	loadBalanceMethod = api.RoundRobin
	if 0 == len(nickname) {
		nickname = os.Getenv("NICKNAME")
	}

	// TODO what do these "deadtimes" do exactly?
	dwell := 120
	idle := 60
	cancelcheck := 10

	Loginfo.Println("startup")

	if "" != os.Getenv("GODADDY_API_KEY") {
		id := os.Getenv("GODADDY_API_KEY")
		secret := os.Getenv("GODADDY_API_SECRET")
		if provider, err = newGoDaddyDNSProvider(id, secret); nil != err {
			panic(err)
		}
	} else if "" != os.Getenv("DUCKDNS_TOKEN") {
		if provider, err = newDuckDNSProvider(os.Getenv("DUCKDNS_TOKEN")); nil != err {
			panic(err)
		}
	} else {
		endpoint := acmeRelay
		if strings.HasSuffix(endpoint, "/") {
			endpoint = endpoint[:len(endpoint)-1]
		}
		endpoint += "/api/dns/"
		/*
			if provider, err = newAPIDNSProvider(endpoint, *token); nil != err {
				panic(err)
			}
		*/
		panic(errors.New("allow for fetching / creating token"))
	}

	ctx, cancelContext := context.WithCancel(context.Background())
	defer cancelContext()

	// CertMagic is Greenlock for Go
	directory := certmagic.LetsEncryptProductionCA
	if acmeStaging {
		directory = certmagic.LetsEncryptStagingCA
	}
	magic, err := newCertMagic(directory, acmeEmail, provider, &certmagic.FileStorage{Path: acmeStorage})
	if nil != err {
		fmt.Fprintf(os.Stderr, "failed to initialize certificate management (discovery url? local folder perms?): %s\n", err)
		os.Exit(1)
	}

	serverStatus := api.NewStatus(ctx)
	serverStatus.AdminDomain = adminHostName
	serverStatus.WssDomain = wssHostName
	serverStatus.Name = nickname
	serverStatus.DeadTime = api.NewStatusDeadTime(dwell, idle, cancelcheck)
	serverStatus.LoadbalanceDefaultMethod = string(loadBalanceMethod)

	connectionTable := api.NewTable(dwell, idle, loadBalanceMethod)

	tlsConfig := &tls.Config{
		GetCertificate: func(hello *tls.ClientHelloInfo) (*tls.Certificate, error) {
			return magic.GetCertificate(hello)
			/*
				if false {
					_, _ = magic.GetCertificate(hello)
				}

				// TODO
				// 1. call out to greenlock for validation
				// 2. push challenges through http channel
				// 3. receive certificates (or don't)
				certbundleT, err := tls.LoadX509KeyPair("certs/fullchain.pem", "certs/privkey.pem")
				certbundle := &certbundleT
				if err != nil {
					return nil, err
				}
				return certbundle, nil
			*/
		},
	}

	authorizer := func(r *http.Request) (*telebit.Grants, error) {
		// do we have a valid wss_client?

		var tokenString string
		if auth := strings.Split(r.Header.Get("Authorization"), " "); len(auth) > 1 {
			// TODO handle Basic auth tokens as well
			tokenString = auth[1]
		}
		if "" == tokenString {
			// Browsers do not allow Authorization Headers and must use access_token query string
			tokenString = r.URL.Query().Get("access_token")
		}
		if "" != r.URL.Query().Get("access_token") {
			r.URL.Query().Set("access_token", "[redacted]")
		}

		grants, err := telebit.Inspect(authURL, tokenString)
		/*
			tok, err := jwt.Parse(tokenString, func(token *jwt.Token) (interface{}, error) {
				return []byte(secretKey), nil
			})
		*/
		if nil != err {
			fmt.Println("return an error, do not go on")
			return nil, err
		}
		if "" != r.URL.Query().Get("access_token") {
			r.URL.Query().Set("access_token", "[redacted:"+grants.Subject+"]")
		}

		/*
			fmt.Printf("client claims:\n%+v\n", tok.Claims)
		*/

		/*
				domains := []string{}
				for _, name := range tok.Claims.(jwt.MapClaims)["domains"].([]interface{}) {
					domains = append(domains, name.(string))
				}
			authz := &mplexy.Authz{
				Domains: grants.Domains,
			}
		*/
		return grants, err

		/*
			tokenString := r.URL.Query().Get("access_token")
			result, err := jwt.Parse(tokenString, func(token *jwt.Token) (interface{}, error) {
				return []byte(secretKey), nil
			})

			if err != nil || !result.Valid {
				w.WriteHeader(http.StatusForbidden)
				w.Write([]byte("Not Authorized"))
				Loginfo.Println("access_token invalid...closing connection")
				return
			}

			// TODO
			claims := result.Claims.(jwt.MapClaims)
			domains, ok := claims["domains"].([]interface{})
		*/
	}

	r := relay.New(ctx, tlsConfig, authorizer, serverStatus, connectionTable)
	r.ListenAndServe(tcpPort)
}

func newCertMagic(
	directory string,
	email string,
	provider challenge.Provider,
	storage certmagic.Storage,
) (*certmagic.Config, error) {
	cache := certmagic.NewCache(certmagic.CacheOptions{
		GetConfigForCert: func(cert certmagic.Certificate) (*certmagic.Config, error) {
			// do whatever you need to do to get the right
			// configuration for this certificate; keep in
			// mind that this config value is used as a
			// template, and will be completed with any
			// defaults that are set in the Default config
			return &certmagic.Config{}, nil
		},
	})
	magic := certmagic.New(cache, certmagic.Config{
		Storage: storage,
		OnDemand: &certmagic.OnDemandConfig{
			DecisionFunc: func(name string) error {
				return nil
			},
		},
	})
	// Ummm... just a little confusing
	magic.Issuer = certmagic.NewACMEManager(magic, certmagic.ACMEManager{
		DNSProvider:             provider,
		CA:                      directory,
		Email:                   email,
		Agreed:                  true,
		DisableHTTPChallenge:    true,
		DisableTLSALPNChallenge: true,
		// plus any other customizations you need
	})
	return magic, nil
}

// newDuckDNSProvider is for the sake of demoing the tunnel
func newDuckDNSProvider(token string) (*duckdns.DNSProvider, error) {
	config := duckdns.NewDefaultConfig()
	config.Token = token
	return duckdns.NewDNSProviderConfig(config)
}

// newGoDaddyDNSProvider is for the sake of demoing the tunnel
func newGoDaddyDNSProvider(id, secret string) (*godaddy.DNSProvider, error) {
	config := godaddy.NewDefaultConfig()
	config.APIKey = id
	config.APISecret = secret
	return godaddy.NewDNSProviderConfig(config)
}

// newAPIDNSProvider is for the sake of demoing the tunnel
func newAPIDNSProvider(baseURL string, token string) (*dns01.DNSProvider, error) {
	config := dns01.NewDefaultConfig()
	config.Token = token
	endpoint, err := url.Parse(baseURL)
	if nil != err {
		return nil, err
	}
	config.Endpoint = endpoint
	return dns01.NewDNSProviderConfig(config)
}