package main

import (
	"context"
	"os"
	"os/signal"
	"sync"
	"syscall"

	"git.frostfs.info/TrueCloudLab/frostfs-s3-gw/pkg/service/tree"
	"git.frostfs.info/TrueCloudLab/frostfs-s3-lifecycler/internal/frostfs"
	"git.frostfs.info/TrueCloudLab/frostfs-s3-lifecycler/internal/lifecycle"
	"git.frostfs.info/TrueCloudLab/frostfs-s3-lifecycler/internal/logs"
	"git.frostfs.info/TrueCloudLab/frostfs-s3-lifecycler/internal/metrics"
	"git.frostfs.info/TrueCloudLab/frostfs-s3-lifecycler/internal/morph"
	"git.frostfs.info/TrueCloudLab/frostfs-s3-lifecycler/internal/morph/contract"
	"git.frostfs.info/TrueCloudLab/frostfs-s3-lifecycler/internal/notificator"
	"git.frostfs.info/TrueCloudLab/frostfs-s3-lifecycler/internal/resolver"
	"git.frostfs.info/TrueCloudLab/frostfs-sdk-go/pool"
	treepool "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/pool/tree"
	"github.com/nspcc-dev/neo-go/pkg/crypto/keys"
	"github.com/spf13/viper"
	"go.uber.org/zap"
)

type (
	App struct {
		log         *zap.Logger
		logLevel    zap.AtomicLevel
		key         *keys.PrivateKey
		cfg         *viper.Viper
		done        chan struct{}
		appServices []*metrics.Service
		appMetrics  *metrics.AppMetrics
		notificator *notificator.Notificator
		settings    *appSettings
	}

	appSettings struct {
		mu          sync.RWMutex
		serviceKeys []*keys.PublicKey
	}
)

const (
	HealthStatusUndefined    int32 = 0
	HealthStatusStarting     int32 = 1
	HealthStatusReady        int32 = 2
	HealthStatusShuttingDown int32 = 3
)

func newApp(ctx context.Context, cfg *viper.Viper) *App {
	appMetrics := metrics.NewAppMetrics()
	log := pickLogger(cfg, appMetrics)

	a := &App{
		log:        log.logger,
		logLevel:   log.lvl,
		cfg:        cfg,
		done:       make(chan struct{}),
		appMetrics: appMetrics,
		settings:   newAppSettings(cfg, log),
	}
	a.appMetrics.SetHealth(HealthStatusStarting)

	a.init(ctx)

	return a
}

func (a *App) init(ctx context.Context) {
	var err error
	a.key, err = fetchKey(a.cfg)
	if err != nil {
		a.log.Fatal(logs.FailedToLoadPrivateKey, zap.Error(err))
	}

	endpoints := fetchMorphEndpoints(a.cfg, a.log)
	reconnectInterval := fetchMorphReconnectClientsInterval(a.cfg)

	clientCfg := morph.Config{
		Logger:            a.log,
		Endpoints:         endpoints,
		Key:               a.key,
		ReconnectInterval: reconnectInterval,
		DialTimeout:       fetchMorphDialTimeout(a.cfg),
	}

	cli, err := morph.New(ctx, clientCfg)
	if err != nil {
		a.log.Fatal(logs.FailedToInitMorphClient, zap.Error(err))
	}

	credSource := fetchCredentialSource(a.cfg, a.log)

	frostfsidContract, err := resolver.ResolveContractHash(cli, a.cfg.GetString(cfgMorphContractFrostfsID))
	if err != nil {
		a.log.Fatal(logs.ResolveFrostfsIDContract, zap.Error(err))
	}

	ffsidCfg := contract.FrostFSIDConfig{
		Client:       cli,
		ContractHash: frostfsidContract,
	}

	containerContract, err := resolver.ResolveContractHash(cli, a.cfg.GetString(cfgMorphContractContainer))
	if err != nil {
		a.log.Fatal(logs.ResolveContainerContract, zap.Error(err))
	}

	containerCfg := contract.ContainerConfig{
		Client:       cli,
		ContractHash: containerContract,
		Log:          a.log,
	}

	objPool, treePool := getPools(ctx, a.cfg, a.log, a.key)

	epochCh := make(chan uint64)
	go func() {
		<-a.done
		close(epochCh)
	}()

	ffs := frostfs.NewFrostFS(objPool, a.log)
	tr := tree.NewTree(frostfs.NewTreePoolWrapper(treePool), a.log)

	lifecycleCfg := lifecycle.Config{
		UserFetcher:       contract.NewFrostFSID(ffsidCfg),
		ContainerFetcher:  contract.NewContainer(containerCfg),
		FrostFSFetcher:    ffs,
		CredentialSource:  credSource,
		Settings:          a.settings,
		CurrentLifecycler: a.key,
		Logger:            a.log,
		TreeFetcher:       tr,
		BufferSize:        fetchJobFetcherBuffer(a.cfg),
		EpochChannel:      epochCh,
	}

	jobProvider := lifecycle.NewJobProvider(ctx, lifecycleCfg)

	executorCfg := lifecycle.ExecutorConfig{
		Logger:         a.log,
		Jobs:           jobProvider.Jobs(),
		WorkerPoolSize: fetchExecutorPoolSize(a.cfg),
		TreeFetcher:    tr,
		FrostFSFetcher: ffs,
	}

	executor, err := lifecycle.NewExecutor(ctx, executorCfg)
	if err != nil {
		a.log.Fatal(logs.ResolveNetmapContract, zap.Error(err))
	}
	_ = executor // todo consider run with separate method

	netmapContract, err := resolver.ResolveContractHash(cli, a.cfg.GetString(cfgMorphContractNetmap))
	if err != nil {
		a.log.Fatal(logs.ResolveNetmapContract, zap.Error(err))
	}

	notificatorCfg := notificator.Config{
		Handler: func(ctx context.Context, ee notificator.NewEpochEvent) {
			a.log.Info(logs.HandlerTriggered, zap.Uint64("epoch", ee.Epoch))
			select {
			case <-ctx.Done():
				a.log.Debug(logs.HandlerContextCanceled, zap.Error(ctx.Err()))
			case epochCh <- ee.Epoch:
			}
		},
		Logger: a.log,
		NewListenerFn: func(config notificator.ListenerConfig) (notificator.Listener, error) {
			lnCfg := notificator.ConfigListener{
				Client:            cli,
				Logger:            a.log,
				ReconnectInterval: reconnectInterval,
				Parser:            config.Parser,
				Handler:           config.Handler,
			}

			return notificator.NewListener(ctx, lnCfg)
		},
		NetmapContract: netmapContract,
	}

	if a.notificator, err = notificator.New(ctx, notificatorCfg); err != nil {
		a.log.Fatal(logs.InitNotificator, zap.Error(err))
	}
}

func newAppSettings(v *viper.Viper, log *Logger) *appSettings {
	s := &appSettings{}

	s.update(v, log.logger)

	return s
}

func (s *appSettings) update(cfg *viper.Viper, log *zap.Logger) {
	svcKeys, svcKeyErr := fetchLifecycleServices(cfg)
	if svcKeyErr != nil {
		log.Warn(logs.FailedToFetchServicesKeys, zap.Error(svcKeyErr))
	}

	s.mu.Lock()
	defer s.mu.Unlock()

	if svcKeyErr == nil {
		s.serviceKeys = svcKeys
	}
}

func (s *appSettings) ServicesKeys() keys.PublicKeys {
	s.mu.RLock()
	defer s.mu.RUnlock()
	return s.serviceKeys
}

func (a *App) Wait() {
	a.log.Info(logs.ApplicationStarted,
		zap.String("app_name", "frostfs-s3-lifecycler"),
		zap.String("version", Version))

	a.appMetrics.SetHealth(HealthStatusReady)
	a.appMetrics.SetVersion(Version)

	<-a.done

	a.log.Info(logs.ApplicationStopped)
}

func (a *App) Serve(ctx context.Context) {
	sigs := make(chan os.Signal, 1)
	signal.Notify(sigs, syscall.SIGHUP)

	a.startAppServices()

	go a.notificator.Start(ctx)

loop:
	for {
		select {
		case <-ctx.Done():
			break loop
		case <-sigs:
			a.configReload()
		}
	}

	a.log.Info(logs.StoppingApplication)

	a.appMetrics.SetHealth(HealthStatusShuttingDown)
	a.stopAppServices()

	close(a.done)
}

func (a *App) configReload() {
	a.log.Info(logs.SIGHUPConfigReloadStarted)
	if !a.cfg.IsSet(cmdConfig) && !a.cfg.IsSet(cmdConfigDir) {
		a.log.Warn(logs.FailedToReloadConfigBecauseItsMissed)
		return
	}
	if err := readInConfig(a.cfg); err != nil {
		a.log.Warn(logs.FailedToReloadConfig, zap.Error(err))
		return
	}

	if lvl, err := getLogLevel(a.cfg.GetString(cfgLoggerLevel)); err != nil {
		a.log.Warn(logs.LogLevelWontBeUpdated, zap.Error(err))
	} else {
		a.logLevel.SetLevel(lvl)
	}

	a.stopAppServices()
	a.startAppServices()

	a.settings.update(a.cfg, a.log)

	a.log.Info(logs.SIGHUPConfigReloadCompleted)
}

func (a *App) startAppServices() {
	a.appServices = a.appServices[:0]

	pprofConfig := metrics.Config{Enabled: a.cfg.GetBool(cfgPprofEnabled), Address: a.cfg.GetString(cfgPprofAddress)}
	pprofService := metrics.NewPprofService(a.log, pprofConfig)
	a.appServices = append(a.appServices, pprofService)
	go pprofService.Start()

	prometheusConfig := metrics.Config{Enabled: a.cfg.GetBool(cfgPrometheusEnabled), Address: a.cfg.GetString(cfgPrometheusAddress)}
	prometheusService := metrics.NewPrometheusService(a.log, prometheusConfig)
	a.appServices = append(a.appServices, prometheusService)
	go prometheusService.Start()
}

func (a *App) stopAppServices() {
	ctx, cancel := context.WithTimeout(context.Background(), defaultShutdownTimeout)
	defer cancel()

	for _, svc := range a.appServices {
		svc.ShutDown(ctx)
	}
}

func getPools(ctx context.Context, cfg *viper.Viper, logger *zap.Logger, key *keys.PrivateKey) (*pool.Pool, *treepool.Pool) {
	var prm pool.InitParameters
	var prmTree treepool.InitParameters

	prm.SetKey(&key.PrivateKey)
	prmTree.SetKey(key)

	for _, peer := range fetchPeers(cfg, logger) {
		prm.AddNode(peer)
		prmTree.AddNode(peer)
	}

	connTimeout := fetchConnectTimeout(cfg)
	prm.SetNodeDialTimeout(connTimeout)
	prmTree.SetNodeDialTimeout(connTimeout)

	streamTimeout := fetchStreamTimeout(cfg)
	prm.SetNodeStreamTimeout(streamTimeout)
	prmTree.SetNodeStreamTimeout(streamTimeout)

	healthCheckTimeout := fetchHealthCheckTimeout(cfg)
	prm.SetHealthcheckTimeout(healthCheckTimeout)
	prmTree.SetHealthcheckTimeout(healthCheckTimeout)

	rebalanceInterval := fetchRebalanceInterval(cfg)
	prm.SetClientRebalanceInterval(rebalanceInterval)
	prmTree.SetClientRebalanceInterval(rebalanceInterval)

	errorThreshold := fetchErrorThreshold(cfg)
	prm.SetErrorThreshold(errorThreshold)
	prm.SetLogger(logger)
	prmTree.SetLogger(logger)

	prmTree.SetMaxRequestAttempts(cfg.GetInt(cfgFrostFSTreePoolMaxAttempts))

	p, err := pool.NewPool(prm)
	if err != nil {
		logger.Fatal(logs.FailedToCreateConnectionPool, zap.Error(err))
	}

	if err = p.Dial(ctx); err != nil {
		logger.Fatal(logs.FailedToDialConnectionPool, zap.Error(err))
	}

	treePool, err := treepool.NewPool(prmTree)
	if err != nil {
		logger.Fatal(logs.FailedToCreateTreePool, zap.Error(err))
	}
	if err = treePool.Dial(ctx); err != nil {
		logger.Fatal(logs.FailedToDialTreePool, zap.Error(err))
	}

	return p, treePool
}