package main

import (
	"fmt"
	"math"
	"net"
	"net/http"
	"net/http/pprof"
	"os"
	"strings"
	"sync"
	"time"

	"github.com/getsentry/sentry-go"
	"github.com/gofrs/uuid/v3"
	"github.com/gorilla/mux"
	"github.com/orandin/sentrus"
	"github.com/pkg/errors"
	"github.com/robfig/cron/v3"
	log "github.com/sirupsen/logrus"

	"github.com/Luzifer/go_helpers/v2/str"
	"github.com/Luzifer/rconfig/v2"
	"github.com/Luzifer/twitch-bot/v3/internal/helpers"
	"github.com/Luzifer/twitch-bot/v3/internal/service/access"
	"github.com/Luzifer/twitch-bot/v3/internal/service/authcache"
	"github.com/Luzifer/twitch-bot/v3/internal/service/editortoken"
	"github.com/Luzifer/twitch-bot/v3/internal/service/timer"
	"github.com/Luzifer/twitch-bot/v3/pkg/database"
	"github.com/Luzifer/twitch-bot/v3/pkg/twitch"
)

const (
	ircReconnectDelay = 100 * time.Millisecond

	initialIRCRetryBackoff    = 500 * time.Millisecond
	ircRetryBackoffMultiplier = 1.5
	maxIRCRetryBackoff        = time.Minute

	httpReadHeaderTimeout = 5 * time.Second
)

var (
	cfg = struct {
		BaseURL               string        `flag:"base-url" default:"" description:"External URL of the config-editor interface (used to generate auth-urls)"`
		CommandTimeout        time.Duration `flag:"command-timeout" default:"30s" description:"Timeout for command execution"`
		Config                string        `flag:"config,c" default:"./config.yaml" description:"Location of configuration file"`
		IRCRateLimit          time.Duration `flag:"rate-limit" default:"1500ms" description:"How often to send a message (default: 20/30s=1500ms, if your bot is mod everywhere: 100/30s=300ms, different for known/verified bots)"`
		LogLevel              string        `flag:"log-level" default:"info" description:"Log level (debug, info, warn, error, fatal)"`
		PluginDir             string        `flag:"plugin-dir" default:"/usr/lib/twitch-bot" description:"Where to find and load plugins"`
		SentryDSN             string        `flag:"sentry-dsn" default:"" description:"Sentry / GlitchTip DSN for error reporting"`
		SentryEnvironment     string        `flag:"sentry-environment" default:"" description:"Environment to submit to Sentry to distinguish bot instances"`
		StorageConnString     string        `flag:"storage-conn-string" default:"./storage.db" description:"Connection string for the database"`
		StorageConnType       string        `flag:"storage-conn-type" default:"sqlite" description:"One of: mysql, postgres, sqlite"`
		StorageEncryptionPass string        `flag:"storage-encryption-pass" default:"" description:"Passphrase to encrypt secrets inside storage (defaults to twitch-client:twitch-client-secret)"`
		TwitchClient          string        `flag:"twitch-client" default:"" description:"Client ID to act as"`
		TwitchClientSecret    string        `flag:"twitch-client-secret" default:"" description:"Secret for the Client ID"`
		ValidateConfig        bool          `flag:"validate-config,v" default:"false" description:"Loads the config, logs any errors and quits with status 0 on success"`
		VersionAndExit        bool          `flag:"version" default:"false" description:"Prints current version and exits"`
		WaitForSelfcheck      time.Duration `flag:"wait-for-selfcheck" default:"60s" description:"Maximum time to wait for the self-check to respond when behind load-balancers"`
	}{}

	config     *configFile
	configLock = new(sync.RWMutex)

	cronService *cron.Cron
	ircHdl      *ircHandler
	router      = mux.NewRouter()

	runID = uuid.Must(uuid.NewV4()).String()

	db                 database.Connector
	accessService      *access.Service
	authService        *authcache.Service
	editorTokenService *editortoken.Service
	timerService       *timer.Service

	twitchClient *twitch.Client

	version = "dev"
)

func initApp() error {
	rconfig.AutoEnv(true)
	if err := rconfig.ParseAndValidate(&cfg); err != nil {
		return errors.Wrap(err, "parsing cli options")
	}

	if cfg.VersionAndExit {
		fmt.Printf("twitch-bot %s\n", version) //nolint:forbidigo // Fine here
		os.Exit(0)                             //revive:disable-line:deep-exit
	}

	l, err := log.ParseLevel(cfg.LogLevel)
	if err != nil {
		return errors.Wrap(err, "parsing log level")
	}
	log.SetLevel(l)

	if cfg.SentryDSN != "" {
		if err := sentry.Init(sentry.ClientOptions{
			Dsn:         cfg.SentryDSN,
			Environment: cfg.SentryEnvironment,
			Release:     strings.Join([]string{"twitch-bot", version}, "@"),
		}); err != nil {
			return errors.Wrap(err, "initializing sentry sdk")
		}
		log.AddHook(sentrus.NewHook(
			[]log.Level{log.ErrorLevel, log.FatalLevel, log.PanicLevel},
		))
	}

	if cfg.StorageEncryptionPass == "" {
		log.Warn("No storage encryption passphrase was set, falling back to client-id:client-secret")
		cfg.StorageEncryptionPass = strings.Join([]string{
			cfg.TwitchClient,
			cfg.TwitchClientSecret,
		}, ":")
	}

	return nil
}

//nolint:funlen,gocognit,gocyclo // Complexity is a little too high but makes no sense to split
func main() {
	var err error

	if err = initApp(); err != nil {
		log.WithError(err).Fatal("initializing application")
	}

	if db, err = database.New(cfg.StorageConnType, cfg.StorageConnString, cfg.StorageEncryptionPass); err != nil {
		log.WithError(err).Fatal("opening storage backend")
	}

	if accessService, err = access.New(db); err != nil {
		log.WithError(err).Fatal("applying access migration")
	}

	authService = authcache.New(
		authBackendInternalAppToken,
		authBackendInternalEditorToken,
		authBackendTwitchToken,
	)

	cronService = cron.New(cron.WithSeconds())
	editorTokenService = editortoken.New(db)

	if timerService, err = timer.New(db, cronService); err != nil {
		log.WithError(err).Fatal("applying timer migration")
	}

	// Allow config to subscribe to external rules
	updCron := updateConfigCron()
	if _, err = cronService.AddFunc(updCron, updateConfigFromRemote); err != nil {
		log.WithError(err).Error("adding remote-update cron")
	}
	log.WithField("cron", updCron).Debug("Initialized remote update cron")

	router.Use(corsMiddleware)
	router.HandleFunc("/openapi.html", handleSwaggerHTML)
	router.HandleFunc("/openapi.json", handleSwaggerRequest)
	router.HandleFunc("/selfcheck", func(w http.ResponseWriter, _ *http.Request) {
		http.Error(w, runID, http.StatusOK)
	})

	if os.Getenv("ENABLE_PROFILING") == "true" {
		router.HandleFunc("/debug/pprof/", pprof.Index)
		router.Handle("/debug/pprof/allocs", pprof.Handler("allocs"))
		router.Handle("/debug/pprof/block", pprof.Handler("block"))
		router.HandleFunc("/debug/pprof/cmdline", pprof.Cmdline)
		router.Handle("/debug/pprof/goroutine", pprof.Handler("goroutine"))
		router.Handle("/debug/pprof/heap", pprof.Handler("heap"))
		router.Handle("/debug/pprof/mutex", pprof.Handler("mutex"))
		router.HandleFunc("/debug/pprof/profile", pprof.Profile)
		router.HandleFunc("/debug/pprof/symbol", pprof.Symbol)
		router.Handle("/debug/pprof/threadcreate", pprof.Handler("threadcreate"))
		router.HandleFunc("/debug/pprof/trace", pprof.Trace)
	}

	router.MethodNotAllowedHandler = corsMiddleware(http.HandlerFunc(func(res http.ResponseWriter, r *http.Request) {
		if r.Method == http.MethodOptions {
			// Most likely JS client asking for CORS headers
			res.WriteHeader(http.StatusNoContent)
			return
		}

		res.WriteHeader(http.StatusMethodNotAllowed)
	}))

	if err = initCorePlugins(); err != nil {
		log.WithError(err).Fatal("Unable to load core plugins")
	}

	if err = loadPlugins(cfg.PluginDir); err != nil {
		log.WithError(err).Fatal("Unable to load plugins")
	}

	if len(rconfig.Args()) > 1 {
		if err = cliTool.Call(rconfig.Args()[1:]); err != nil {
			log.Fatalf("error in command: %s", err)
		}
		return
	}

	if err = db.ValidateEncryption(); err != nil {
		log.WithError(err).Fatal("validation of database encryption failed, fix encryption passphrase or use 'twitch-bot reset-secrets' to wipe encrypted data")
	}

	if err = loadConfig(cfg.Config); err != nil {
		if os.IsNotExist(errors.Cause(err)) {
			if err = writeDefaultConfigFile(cfg.Config); err != nil {
				log.WithError(err).Fatal("Initial config not found and not able to create example config")
			}

			log.WithField("filename", cfg.Config).Warn("No config was found, created example config: Please review that config!")
			return
		}

		log.WithError(err).Fatal("Initial config load failed")
	}
	defer func() {
		config.CloseRawMessageWriter() //nolint:errcheck,gosec,revive // That close is enforced by process exit
	}()

	if cfg.ValidateConfig {
		// We were asked to only validate the config, this was successful
		log.Info("Config validated successfully")
		return
	}

	if err = startCheck(); err != nil {
		log.WithError(err).Fatal("Missing required parameters")
	}

	if twitchClient, err = accessService.GetBotTwitchClient(access.ClientConfig{
		TwitchClient:       cfg.TwitchClient,
		TwitchClientSecret: cfg.TwitchClientSecret,
		TokenUpdateHook: func() {
			// make frontend reload its state as of token change
			frontendNotifyHooks.Ping(frontendNotifyTypeReload)
		},
	}); err != nil {
		if !errors.Is(err, access.ErrChannelNotAuthorized) {
			log.WithError(err).Fatal("initializing Twitch client")
		}
		twitchClient = twitch.New(cfg.TwitchClient, cfg.TwitchClientSecret, "", "")
	}

	twitchWatch := newTwitchWatcher()

	// Query may run that often as the twitchClient has an internal
	// cache but shouldn't run more often as EventSub subscriptions
	// are retried on error each time
	if _, err = cronService.AddFunc("@every 30s", twitchWatch.Check); err != nil {
		log.WithError(err).Fatal("registering twitchWatch cron")
	}

	fsEvents := make(chan configChangeEvent, 1)
	go watchConfigChanges(cfg.Config, fsEvents)

	var (
		ircDisconnected   = make(chan struct{}, 1)
		ircRetryBackoff   = initialIRCRetryBackoff
		autoMessageTicker = time.NewTicker(time.Second)
	)

	cronService.Start()

	if config.HTTPListen != "" {
		// If listen address is configured start HTTP server
		listener, err := net.Listen("tcp", config.HTTPListen)
		if err != nil {
			log.WithError(err).Fatal("Unable to open http_listen port")
		}

		server := &http.Server{
			ReadHeaderTimeout: httpReadHeaderTimeout, // gosec: G114 - Mitigate "slowloris" DoS attack vector
			Handler:           router,
		}

		go func() {
			if err := server.Serve(listener); err != nil {
				log.WithError(err).Fatal("running HTTP server")
			}
		}()
		log.WithField("address", listener.Addr().String()).Info("HTTP server started")
	}

	for _, c := range config.Channels {
		if err := twitchWatch.AddChannel(c); err != nil {
			log.WithError(err).WithField("channel", c).Error("Unable to add channel to watcher")
		}
	}

	ircDisconnected <- struct{}{}

	for {
		select {
		case <-ircDisconnected:
			if ircHdl != nil {
				if err = ircHdl.Close(); err != nil {
					log.WithError(err).Error("closing IRC handle")
				}
			}

			if ircHdl, err = newIRCHandler(); err != nil {
				log.WithError(err).Error("connecting to IRC")
				go func() {
					time.Sleep(ircRetryBackoff)
					ircRetryBackoff = time.Duration(math.Min(float64(maxIRCRetryBackoff), float64(ircRetryBackoff)*ircRetryBackoffMultiplier))
					ircDisconnected <- struct{}{}
				}()
				continue
			}

			ircRetryBackoff = initialIRCRetryBackoff // Successfully created, reset backoff

			go func() {
				log.Info("(re-)connecting IRC client")
				if err := ircHdl.Run(); err != nil {
					log.WithError(helpers.CleanNetworkAddressFromError(err)).Error("IRC run exited unexpectedly")
				}
				time.Sleep(ircReconnectDelay)
				ircDisconnected <- struct{}{}
			}()

		case evt := <-fsEvents:
			switch evt {
			case configChangeEventUnkown:
				continue

			case configChangeEventNotExist:
				log.Error("Config file is not available, not reloading config")
				continue

			case configChangeEventModified:
				// Fine, reload
			}

			previousChannels := append([]string{}, config.Channels...)

			if err := loadConfig(cfg.Config); err != nil {
				log.WithError(err).Error("Unable to reload config")
				continue
			}

			if ircHdl != nil {
				ircHdl.ExecuteJoins(config.Channels)
			}

			for _, c := range config.Channels {
				if err := twitchWatch.AddChannel(c); err != nil {
					log.WithError(err).WithField("channel", c).Error("Unable to add channel to watcher")
				}
			}

			for _, c := range previousChannels {
				if !str.StringInSlice(c, config.Channels) {
					log.WithField("channel", c).Info("Leaving removed channel...")
					ircHdl.ExecutePart(c)

					if err := twitchWatch.RemoveChannel(c); err != nil {
						log.WithError(err).WithField("channel", c).Error("Unable to remove channel from watcher")
					}
				}
			}

		case <-autoMessageTicker.C:
			configLock.RLock()
			for _, am := range config.AutoMessages {
				if !am.CanSend() {
					continue
				}

				if err := am.Send(ircHdl.c); err != nil {
					log.WithError(err).Error("Unable to send automated message")
				}
			}
			configLock.RUnlock()
		}
	}
}

func startCheck() error {
	var errs []string

	if cfg.TwitchClient == "" {
		errs = append(errs, "No Twitch-ClientId given")
	}

	if cfg.TwitchClientSecret == "" {
		errs = append(errs, "No Twitch-ClientSecret given")
	}

	if len(errs) > 0 {
		return errors.New(strings.Join(errs, ", "))
	}

	return nil
}