package server

import (
	"bufio"
	"bytes"
	"context"
	"encoding/base64"
	"errors"
	"fmt"
	"io"
	"net"
	"net/http"
	"os"
	"path"
	"path/filepath"
	"reflect"
	"strconv"
	"strings"
	"syscall"
	"unicode"

	"github.com/fnproject/fn/api/agent"
	"github.com/fnproject/fn/api/agent/hybrid"
	"github.com/fnproject/fn/api/common"
	"github.com/fnproject/fn/api/datastore"
	"github.com/fnproject/fn/api/id"
	"github.com/fnproject/fn/api/logs"
	"github.com/fnproject/fn/api/models"
	"github.com/fnproject/fn/api/mqs"
	pool "github.com/fnproject/fn/api/runnerpool"
	"github.com/fnproject/fn/api/version"
	"github.com/fnproject/fn/fnext"
	"github.com/gin-gonic/gin"
	zipkinhttp "github.com/openzipkin/zipkin-go/reporter/http"
	promclient "github.com/prometheus/client_golang/prometheus"
	"github.com/sirupsen/logrus"
	"go.opencensus.io/exporter/jaeger"
	"go.opencensus.io/exporter/prometheus"
	"go.opencensus.io/exporter/zipkin"
	"go.opencensus.io/plugin/ochttp"
	"go.opencensus.io/stats/view"
	"go.opencensus.io/trace"
)

const (
	EnvLogLevel        = "FN_LOG_LEVEL"
	EnvLogDest         = "FN_LOG_DEST"
	EnvLogPrefix       = "FN_LOG_PREFIX"
	EnvMQURL           = "FN_MQ_URL"
	EnvDBURL           = "FN_DB_URL"
	EnvLOGDBURL        = "FN_LOGSTORE_URL"
	EnvRunnerURL       = "FN_RUNNER_API_URL"
	EnvRunnerAddresses = "FN_RUNNER_ADDRESSES"
	EnvNodeType        = "FN_NODE_TYPE"
	EnvPort            = "FN_PORT" // be careful, Gin expects this variable to be "port"
	EnvGRPCPort        = "FN_GRPC_PORT"
	EnvAPICORS         = "FN_API_CORS"
	EnvZipkinURL       = "FN_ZIPKIN_URL"
	EnvJaegerURL       = "FN_JAEGER_URL"
	// Certificates to communicate with other FN nodes
	EnvCert     = "FN_NODE_CERT"
	EnvCertKey  = "FN_NODE_CERT_KEY"
	EnvCertAuth = "FN_NODE_CERT_AUTHORITY"

	EnvProcessCollectorList = "FN_PROCESS_COLLECTOR_LIST"
	EnvLBPlacementAlg       = "FN_PLACER"

	// Defaults
	DefaultLogLevel = "info"
	DefaultLogDest  = "stderr"
	DefaultPort     = 8080
	DefaultGRPCPort = 9190
)

type ServerNodeType int32

const (
	ServerTypeFull ServerNodeType = iota
	ServerTypeAPI
	ServerTypeLB
	ServerTypeRunner
	ServerTypePureRunner
)

func (s ServerNodeType) String() string {
	switch s {
	default:
		return "full"
	case ServerTypeAPI:
		return "api"
	case ServerTypeLB:
		return "lb"
	case ServerTypeRunner:
		return "runner"
	case ServerTypePureRunner:
		return "pure-runner"
	}
}

type Server struct {
	// TODO this one maybe we have `AddRoute` in extensions?
	Router *gin.Engine

	webListenPort   int
	grpcListenPort  int
	agent           agent.Agent
	datastore       models.Datastore
	mq              models.MessageQueue
	logstore        models.LogStore
	nodeType        ServerNodeType
	cert            string
	certKey         string
	certAuthority   string
	appListeners    *appListeners
	routeListeners  *routeListeners
	rootMiddlewares []fnext.Middleware
	apiMiddlewares  []fnext.Middleware
	promExporter    *prometheus.Exporter
	// Extensions can append to this list of contexts so that cancellations are properly handled.
	extraCtxs []context.Context
}

func nodeTypeFromString(value string) ServerNodeType {
	switch value {
	case "api":
		return ServerTypeAPI
	case "lb":
		return ServerTypeLB
	case "runner":
		return ServerTypeRunner
	case "pure-runner":
		return ServerTypePureRunner
	default:
		return ServerTypeFull
	}
}

// NewFromEnv creates a new Functions server based on env vars.
func NewFromEnv(ctx context.Context, opts ...ServerOption) *Server {
	curDir := pwd()
	var defaultDB, defaultMQ string
	nodeType := nodeTypeFromString(getEnv(EnvNodeType, "")) // default to full
	switch nodeType {
	case ServerTypeLB: // nothing
	case ServerTypeRunner: // nothing
	case ServerTypePureRunner: // nothing
	default:
		// only want to activate these for full and api nodes
		defaultDB = fmt.Sprintf("sqlite3://%s/data/fn.db", curDir)
		defaultMQ = fmt.Sprintf("bolt://%s/data/fn.mq", curDir)
	}
	opts = append(opts, WithWebPort(getEnvInt(EnvPort, DefaultPort)))
	opts = append(opts, WithGRPCPort(getEnvInt(EnvGRPCPort, DefaultGRPCPort)))
	opts = append(opts, WithLogLevel(getEnv(EnvLogLevel, DefaultLogLevel)))
	opts = append(opts, WithLogDest(getEnv(EnvLogDest, DefaultLogDest), getEnv(EnvLogPrefix, "")))
	opts = append(opts, WithZipkin(getEnv(EnvZipkinURL, "")))
	opts = append(opts, WithJaeger(getEnv(EnvJaegerURL, "")))
	opts = append(opts, WithPrometheus()) // TODO option to turn this off?
	opts = append(opts, WithDBURL(getEnv(EnvDBURL, defaultDB)))
	opts = append(opts, WithMQURL(getEnv(EnvMQURL, defaultMQ)))
	opts = append(opts, WithLogURL(getEnv(EnvLOGDBURL, "")))
	opts = append(opts, WithRunnerURL(getEnv(EnvRunnerURL, "")))
	opts = append(opts, WithType(nodeType))
	opts = append(opts, WithNodeCert(getEnv(EnvCert, "")))
	opts = append(opts, WithNodeCertKey(getEnv(EnvCertKey, "")))
	opts = append(opts, WithNodeCertAuthority(getEnv(EnvCertAuth, "")))

	// Agent handling depends on node type and several other options so it must be the last processed option.
	// Also we only need to create an agent if this is not an API node.
	if nodeType != ServerTypeAPI {
		opts = append(opts, WithAgentFromEnv())
	} else {
		opts = append(opts, WithLogstoreFromDatastore())
	}
	return New(ctx, opts...)
}

func pwd() string {
	cwd, err := os.Getwd()
	if err != nil {
		logrus.WithError(err).Fatalln("couldn't get working directory, possibly unsupported platform?")
	}
	// Replace forward slashes in case this is windows, URL parser errors
	return strings.Replace(cwd, "\\", "/", -1)
}

func WithWebPort(port int) ServerOption {
	return func(ctx context.Context, s *Server) error {
		s.webListenPort = port
		return nil
	}
}

func WithGRPCPort(port int) ServerOption {
	return func(ctx context.Context, s *Server) error {
		s.grpcListenPort = port
		return nil
	}
}

func WithLogLevel(ll string) ServerOption {
	return func(ctx context.Context, s *Server) error {
		common.SetLogLevel(ll)
		return nil
	}
}

func WithLogDest(dst, prefix string) ServerOption {
	return func(ctx context.Context, s *Server) error {
		common.SetLogDest(dst, prefix)
		return nil
	}
}

func WithDBURL(dbURL string) ServerOption {
	return func(ctx context.Context, s *Server) error {
		if dbURL != "" {
			ds, err := datastore.New(ctx, dbURL)
			if err != nil {
				return err
			}
			s.datastore = ds
		}
		return nil
	}
}

func WithMQURL(mqURL string) ServerOption {
	return func(ctx context.Context, s *Server) error {
		if mqURL != "" {
			mq, err := mqs.New(mqURL)
			if err != nil {
				return err
			}
			s.mq = mq
		}
		return nil
	}
}

func WithLogURL(logstoreURL string) ServerOption {
	return func(ctx context.Context, s *Server) error {
		if ldb := logstoreURL; ldb != "" {
			logDB, err := logs.New(ctx, logstoreURL)
			if err != nil {
				return err
			}
			s.logstore = logDB
		}
		return nil
	}
}

func WithRunnerURL(runnerURL string) ServerOption {
	return func(ctx context.Context, s *Server) error {
		if runnerURL != "" {
			cl, err := hybrid.NewClient(runnerURL)
			if err != nil {
				return err
			}
			s.agent = agent.New(agent.NewCachedDataAccess(cl))
		}
		return nil
	}
}

func WithType(t ServerNodeType) ServerOption {
	return func(ctx context.Context, s *Server) error {
		s.nodeType = t
		return nil
	}
}

func WithNodeCert(cert string) ServerOption {
	return func(ctx context.Context, s *Server) error {
		if cert != "" {
			abscert, err := filepath.Abs(cert)
			if err != nil {
				return fmt.Errorf("Unable to resolve %v: please specify a valid and readable cert file", cert)
			}
			_, err = os.Stat(abscert)
			if err != nil {
				return fmt.Errorf("Cannot stat %v: please specify a valid and readable cert file", abscert)
			}
			s.cert = abscert
		}
		return nil
	}
}

func WithNodeCertKey(key string) ServerOption {
	return func(ctx context.Context, s *Server) error {
		if key != "" {
			abskey, err := filepath.Abs(key)
			if err != nil {
				return fmt.Errorf("Unable to resolve %v: please specify a valid and readable cert key file", key)
			}
			_, err = os.Stat(abskey)
			if err != nil {
				return fmt.Errorf("Cannot stat %v: please specify a valid and readable cert key file", abskey)
			}
			s.certKey = abskey
		}
		return nil
	}
}

func WithNodeCertAuthority(ca string) ServerOption {
	return func(ctx context.Context, s *Server) error {
		if ca != "" {
			absca, err := filepath.Abs(ca)
			if err != nil {
				return fmt.Errorf("Unable to resolve %v: please specify a valid and readable cert authority file", ca)
			}
			_, err = os.Stat(absca)
			if err != nil {
				return fmt.Errorf("Cannot stat %v: please specify a valid and readable cert authority file", absca)
			}
			s.certAuthority = absca
		}
		return nil
	}
}

func WithDatastore(ds models.Datastore) ServerOption {
	return func(ctx context.Context, s *Server) error {
		s.datastore = ds
		return nil
	}
}

func WithMQ(mq models.MessageQueue) ServerOption {
	return func(ctx context.Context, s *Server) error {
		s.mq = mq
		return nil
	}
}

func WithLogstore(ls models.LogStore) ServerOption {
	return func(ctx context.Context, s *Server) error {
		s.logstore = ls
		return nil
	}
}

func WithAgent(agent agent.Agent) ServerOption {
	return func(ctx context.Context, s *Server) error {
		s.agent = agent
		return nil
	}
}

func (s *Server) defaultRunnerPool() (pool.RunnerPool, error) {
	runnerAddresses := getEnv(EnvRunnerAddresses, "")
	if runnerAddresses == "" {
		return nil, errors.New("Must provide FN_RUNNER_ADDRESSES  when running in default load-balanced mode!")
	}
	return agent.DefaultStaticRunnerPool(strings.Split(runnerAddresses, ",")), nil
}

func WithLogstoreFromDatastore() ServerOption {
	return func(ctx context.Context, s *Server) error {
		if s.datastore == nil {
			return errors.New("Need a datastore in order to use it as a logstore")
		}
		if s.logstore == nil {
			s.logstore = s.datastore
		}
		return nil
	}
}

// WithFullAgent is a shorthand for WithAgent(... create a full agent here ...)
func WithFullAgent() ServerOption {
	return func(ctx context.Context, s *Server) error {
		s.nodeType = ServerTypeFull
		if s.logstore == nil {
			s.logstore = s.datastore
		}
		if s.datastore == nil || s.logstore == nil || s.mq == nil {
			return errors.New("Full nodes must configure FN_DB_URL, FN_LOG_URL, FN_MQ_URL.")
		}
		s.agent = agent.New(agent.NewCachedDataAccess(agent.NewDirectDataAccess(s.datastore, s.logstore, s.mq)))
		return nil
	}
}

// WithAgentFromEnv must be provided as the last server option because it relies
// on all other options being set first.
func WithAgentFromEnv() ServerOption {
	return func(ctx context.Context, s *Server) error {
		switch s.nodeType {
		case ServerTypeAPI:
			return errors.New("Should not initialize an agent for an Fn API node.")
		case ServerTypeRunner:
			runnerURL := getEnv(EnvRunnerURL, "")
			if runnerURL == "" {
				return errors.New("No FN_RUNNER_API_URL provided for an Fn Runner node.")
			}
			cl, err := hybrid.NewClient(runnerURL)
			if err != nil {
				return err
			}
			s.agent = agent.New(agent.NewCachedDataAccess(cl))
		case ServerTypePureRunner:
			if s.datastore != nil {
				return errors.New("Pure runner nodes must not be configured with a datastore (FN_DB_URL).")
			}
			if s.mq != nil {
				return errors.New("Pure runner nodes must not be configured with a message queue (FN_MQ_URL).")
			}
			ds, err := hybrid.NewNopDataStore()
			if err != nil {
				return err
			}
			grpcAddr := fmt.Sprintf(":%d", s.grpcListenPort)
			cancelCtx, cancel := context.WithCancel(ctx)
			prAgent, err := agent.DefaultPureRunner(cancel, grpcAddr, ds, s.cert, s.certKey, s.certAuthority)
			if err != nil {
				return err
			}
			s.agent = prAgent
			s.extraCtxs = append(s.extraCtxs, cancelCtx)
		case ServerTypeLB:
			s.nodeType = ServerTypeLB
			runnerURL := getEnv(EnvRunnerURL, "")
			if runnerURL == "" {
				return errors.New("No FN_RUNNER_API_URL provided for an Fn NuLB node.")
			}
			if s.datastore != nil {
				return errors.New("NuLB nodes must not be configured with a datastore (FN_DB_URL).")
			}
			if s.mq != nil {
				return errors.New("NuLB nodes must not be configured with a message queue (FN_MQ_URL).")
			}

			cl, err := hybrid.NewClient(runnerURL)
			if err != nil {
				return err
			}

			runnerPool, err := s.defaultRunnerPool()
			if err != nil {
				return err
			}

			// Select the placement algorithm
			var placer pool.Placer
			switch getEnv(EnvLBPlacementAlg, "") {
			case "ch":
				placer = pool.NewCHPlacer()
			default:
				placer = pool.NewNaivePlacer()
			}

			s.agent, err = agent.NewLBAgent(agent.NewCachedDataAccess(cl), runnerPool, placer)
			if err != nil {
				return errors.New("LBAgent creation failed")
			}
		default:
			s.nodeType = ServerTypeFull
			if s.logstore == nil { // TODO seems weird?
				s.logstore = s.datastore
			}
			if s.datastore == nil || s.logstore == nil || s.mq == nil {
				return errors.New("Full nodes must configure FN_DB_URL, FN_LOG_URL, FN_MQ_URL.")
			}
			s.agent = agent.New(agent.NewCachedDataAccess(agent.NewDirectDataAccess(s.datastore, s.logstore, s.mq)))
		}
		return nil
	}
}

// WithExtraCtx appends a context to the list of contexts the server will watch for cancellations / errors / signals.
func WithExtraCtx(extraCtx context.Context) ServerOption {
	return func(ctx context.Context, s *Server) error {
		s.extraCtxs = append(s.extraCtxs, extraCtx)
		return nil
	}
}

// New creates a new Functions server with the opts given. For convenience, users may
// prefer to use NewFromEnv but New is more flexible if needed.
func New(ctx context.Context, opts ...ServerOption) *Server {
	ctx, span := trace.StartSpan(ctx, "server_init")
	defer span.End()

	log := common.Logger(ctx)
	s := &Server{
		Router: gin.New(),
		// Add default ports
		webListenPort:  DefaultPort,
		grpcListenPort: DefaultGRPCPort,
		// Almost everything else is configured through opts (see NewFromEnv for ex.) or below
	}

	for _, opt := range opts {
		if opt == nil {
			continue
		}
		err := opt(ctx, s)
		if err != nil {
			log.WithError(err).Fatal("Error during server opt initialization.")
		}
	}

	// Check that WithAgent options have been processed correctly.
	switch s.nodeType {
	case ServerTypeAPI:
		if s.agent != nil {
			log.Fatal("Incorrect configuration, API nodes must not have an agent initialized.")
		}
	default:
		if s.agent == nil {
			log.Fatal("Incorrect configuration, non-API nodes must have an agent initialized.")
		}
	}

	setMachineID()
	s.Router.Use(loggerWrap, traceWrap, panicWrap) // TODO should be opts
	optionalCorsWrap(s.Router)                     // TODO should be an opt
	s.bindHandlers(ctx)

	s.appListeners = new(appListeners)
	s.routeListeners = new(routeListeners)

	s.datastore = fnext.NewDatastore(s.datastore, s.appListeners, s.routeListeners)

	return s
}

func WithPrometheus() ServerOption {
	return func(ctx context.Context, s *Server) error {
		reg := promclient.NewRegistry()
		reg.MustRegister(promclient.NewProcessCollector(os.Getpid(), "fn"),
			promclient.NewGoCollector(),
		)

		for _, exeName := range getMonitoredCmdNames() {
			san := promSanitizeMetricName(exeName)
			err := reg.Register(promclient.NewProcessCollectorPIDFn(getPidCmd(exeName), san))
			if err != nil {
				panic(err)
			}
		}

		exporter, err := prometheus.NewExporter(prometheus.Options{
			Namespace: "fn",
			Registry:  reg,
			OnError:   func(err error) { logrus.WithError(err).Error("opencensus prometheus exporter err") },
		})
		if err != nil {
			return fmt.Errorf("error starting prometheus exporter: %v", err)
		}
		s.promExporter = exporter
		view.RegisterExporter(exporter)
		return nil
	}
}

func WithJaeger(jaegerURL string) ServerOption {
	return func(ctx context.Context, s *Server) error {
		// ex: "http://localhost:14268"
		if jaegerURL == "" {
			return nil
		}

		exporter, err := jaeger.NewExporter(jaeger.Options{
			Endpoint:    jaegerURL,
			ServiceName: "fn",
		})
		if err != nil {
			return fmt.Errorf("error connecting to jaeger: %v", err)
		}
		trace.RegisterExporter(exporter)
		logrus.WithFields(logrus.Fields{"url": jaegerURL}).Info("exporting spans to jaeger")

		// TODO don't do this. testing parity.
		trace.SetDefaultSampler(trace.AlwaysSample())
		return nil
	}
}

func WithZipkin(zipkinURL string) ServerOption {
	return func(ctx context.Context, s *Server) error {
		// ex: "http://zipkin:9411/api/v2/spans"

		if zipkinURL == "" {
			return nil
		}

		reporter := zipkinhttp.NewReporter(zipkinURL, zipkinhttp.MaxBacklog(10000))
		exporter := zipkin.NewExporter(reporter, nil)
		trace.RegisterExporter(exporter)
		logrus.WithFields(logrus.Fields{"url": zipkinURL}).Info("exporting spans to zipkin")

		// TODO don't do this. testing parity.
		trace.SetDefaultSampler(trace.AlwaysSample())
		return nil
	}
}

// prometheus only allows [a-zA-Z0-9:_] in metrics names.
func promSanitizeMetricName(name string) string {
	res := make([]rune, 0, len(name))
	for _, rVal := range name {
		if unicode.IsDigit(rVal) || unicode.IsLetter(rVal) || rVal == ':' {
			res = append(res, rVal)
		} else {
			res = append(res, '_')
		}
	}
	return string(res)
}

// determine sidecar-monitored cmd names. But by default
// we track dockerd + containerd
func getMonitoredCmdNames() []string {

	// override? empty variable to disable trackers
	val, ok := os.LookupEnv(EnvProcessCollectorList)
	if ok {
		return strings.Fields(val)
	}

	// by default, we monitor dockerd and containerd
	return []string{"dockerd", "docker-containerd"}
}

// TODO plumbing considerations, we've put the S pipe next to the chandalier...
func getPidCmd(cmdName string) func() (int, error) {
	// prometheus' process collector only works on linux anyway. let them do the
	// process detection, if we return an error here we just get 0 metrics and it
	// does not log / blow up (that's fine!) it's also likely we hit permissions
	// errors here for many installations, we want to do similar and ignore (we
	// just want for prod).

	var pid int

	return func() (int, error) {
		if pid != 0 {
			// make sure it's our pid.
			if isPidMatchCmd(cmdName, pid) {
				return pid, nil
			}
			pid = 0 // reset to go search
		}

		if pids, err := getPidList(); err == nil {
			for _, test := range pids {
				if isPidMatchCmd(cmdName, test) {
					pid = test
					return pid, nil
				}
			}
		}

		return pid, io.EOF
	}
}

func isPidMatchCmd(cmdName string, pid int) bool {
	fs, err := os.Open("/proc/" + strconv.Itoa(pid) + "/cmdline")
	if err != nil {
		return false
	}
	defer fs.Close()

	rd := bufio.NewReader(fs)
	tok, err := rd.ReadSlice(0)
	if err != nil || len(tok) < len(cmdName) {
		return false
	}

	return filepath.Base(string(tok[:len(tok)-1])) == cmdName
}

func getPidList() ([]int, error) {
	var pids []int
	dir, err := os.Open("/proc")
	if err != nil {
		return pids, nil
	}
	defer dir.Close()

	files, err := dir.Readdirnames(0)
	if err != nil {
		return pids, nil
	}

	pids = make([]int, 0, len(files))
	for _, tok := range files {
		if conv, err := strconv.ParseUint(tok, 10, 64); err == nil {
			pids = append(pids, int(conv))
		}
	}
	return pids, nil
}

func setMachineID() {
	port := uint16(getEnvInt(EnvPort, DefaultPort))
	addr := whoAmI().To4()
	if addr == nil {
		addr = net.ParseIP("127.0.0.1").To4()
		logrus.Warn("could not find non-local ipv4 address to use, using '127.0.0.1' for ids, if this is a cluster beware of duplicate ids!")
	}
	id.SetMachineIdHost(addr, port)
}

// whoAmI searches for a non-local address on any network interface, returning
// the first one it finds. it could be expanded to search eth0 or en0 only but
// to date this has been unnecessary.
func whoAmI() net.IP {
	ints, _ := net.Interfaces()
	for _, i := range ints {
		if i.Name == "docker0" || i.Name == "lo" {
			// not perfect
			continue
		}
		addrs, _ := i.Addrs()
		for _, a := range addrs {
			ip, _, err := net.ParseCIDR(a.String())
			if a.Network() == "ip+net" && err == nil && ip.To4() != nil {
				if !bytes.Equal(ip, net.ParseIP("127.0.0.1")) {
					return ip
				}
			}
		}
	}
	return nil
}

func extractFields(c *gin.Context) logrus.Fields {
	fields := logrus.Fields{"action": path.Base(c.HandlerName())}
	for _, param := range c.Params {
		fields[param.Key] = param.Value
	}
	return fields
}

func (s *Server) Start(ctx context.Context) {
	newctx, cancel := contextWithSignal(ctx, os.Interrupt, syscall.SIGTERM)
	s.startGears(newctx, cancel)
}

func (s *Server) startGears(ctx context.Context, cancel context.CancelFunc) {
	// By default it serves on :8080 unless a
	// FN_PORT environment variable was defined.
	listen := fmt.Sprintf(":%d", s.webListenPort)

	const runHeader = `
        ______
       / ____/___
      / /_  / __ \
     / __/ / / / /
    /_/   /_/ /_/`
	fmt.Println(runHeader)
	fmt.Printf("        v%s\n\n", version.Version)

	logrus.WithField("type", s.nodeType).Infof("Fn serving on `%v`", listen)

	installChildReaper()

	server := http.Server{
		Addr:    listen,
		Handler: &ochttp.Handler{Handler: s.Router},

		// TODO we should set read/write timeouts
	}

	go func() {
		err := server.ListenAndServe()
		if err != nil && err != http.ErrServerClosed {
			logrus.WithError(err).Error("server error")
			cancel()
		} else {
			logrus.Info("server stopped")
		}
	}()

	// listening for signals or listener errors or cancellations on all registered contexts.
	s.extraCtxs = append(s.extraCtxs, ctx)
	cases := make([]reflect.SelectCase, len(s.extraCtxs))
	for i, ctx := range s.extraCtxs {
		cases[i] = reflect.SelectCase{Dir: reflect.SelectRecv, Chan: reflect.ValueOf(ctx.Done())}
	}
	nth, recv, wasSend := reflect.Select(cases)
	if wasSend {
		logrus.WithFields(logrus.Fields{
			"ctxNumber":     nth,
			"receivedValue": recv.String(),
		}).Debug("Stopping because of received value from done context.")
	} else {
		logrus.WithFields(logrus.Fields{
			"ctxNumber": nth,
		}).Debug("Stopping because of closed channel from done context.")
	}

	// TODO: do not wait forever during graceful shutdown (add graceful shutdown timeout)
	if err := server.Shutdown(context.Background()); err != nil {
		logrus.WithError(err).Error("server shutdown error")
	}

	if s.agent != nil {
		err := s.agent.Close() // after we stop taking requests, wait for all tasks to finish
		if err != nil {
			logrus.WithError(err).Error("Fail to close the agent")
		}
	}
}

func (s *Server) bindHandlers(ctx context.Context) {
	engine := s.Router
	// now for extensible middleware
	engine.Use(s.rootMiddlewareWrapper())

	engine.GET("/", handlePing)
	engine.GET("/version", handleVersion)

	// TODO: move under v1 ?
	if s.promExporter != nil {
		engine.GET("/metrics", gin.WrapH(s.promExporter))
	}

	profilerSetup(engine, "/debug")

	// Pure runners don't have any route, they have grpc
	if s.nodeType != ServerTypePureRunner {
		if s.nodeType != ServerTypeRunner {
			clean := engine.Group("/v1")
			v1 := clean.Group("")
			v1.Use(setAppNameInCtx)
			v1.Use(s.apiMiddlewareWrapper())
			v1.GET("/apps", s.handleAppList)
			v1.POST("/apps", s.handleAppCreate)

			{
				apps := v1.Group("/apps/:app")
				apps.Use(appNameCheck)

				{
					withAppCheck := apps.Group("")
					withAppCheck.Use(s.checkAppPresenceByName())
					withAppCheck.GET("", s.handleAppGetByName)
					withAppCheck.PATCH("", s.handleAppUpdate)
					withAppCheck.DELETE("", s.handleAppDelete)
					withAppCheck.GET("/routes", s.handleRouteList)
					withAppCheck.GET("/routes/:route", s.handleRouteGetAPI)
					withAppCheck.PATCH("/routes/*route", s.handleRoutesPatch)
					withAppCheck.DELETE("/routes/*route", s.handleRouteDelete)
					withAppCheck.GET("/calls/:call", s.handleCallGet)
					withAppCheck.GET("/calls/:call/log", s.handleCallLogGet)
					withAppCheck.GET("/calls", s.handleCallList)
				}

				apps.POST("/routes", s.handleRoutesPostPut)
				apps.PUT("/routes/*route", s.handleRoutesPostPut)
			}

			{
				runner := clean.Group("/runner")
				runner.PUT("/async", s.handleRunnerEnqueue)
				runner.GET("/async", s.handleRunnerDequeue)

				runner.POST("/start", s.handleRunnerStart)
				runner.POST("/finish", s.handleRunnerFinish)

				appsAPIV2 := runner.Group("/apps/:app")
				appsAPIV2.Use(setAppNameInCtx)
				appsAPIV2.GET("", s.handleAppGetByID)
				appsAPIV2.GET("/routes/:route", s.handleRouteGetRunner)

			}
		}

		if s.nodeType != ServerTypeAPI {
			runner := engine.Group("/r")
			runner.Use(s.checkAppPresenceByNameAtRunner())
			runner.Any("/:app", s.handleFunctionCall)
			runner.Any("/:app/*route", s.handleFunctionCall)
		}

	}

	engine.NoRoute(func(c *gin.Context) {
		var err error
		switch {
		case s.nodeType == ServerTypeAPI && strings.HasPrefix(c.Request.URL.Path, "/r/"):
			err = models.ErrInvokeNotSupported
		case s.nodeType == ServerTypeRunner && strings.HasPrefix(c.Request.URL.Path, "/v1/"):
			err = models.ErrAPINotSupported
		default:
			var e models.APIError = models.ErrPathNotFound
			err = models.NewAPIError(e.Code(), fmt.Errorf("%v: %s", e.Error(), c.Request.URL.Path))
		}
		handleErrorResponse(c, err)
	})

}

// implements fnext.ExtServer
func (s *Server) Datastore() models.Datastore {
	return s.datastore
}

// returns the unescaped ?cursor and ?perPage values
// pageParams clamps 0 < ?perPage <= 100 and defaults to 30 if 0
// ignores parsing errors and falls back to defaults.
func pageParams(c *gin.Context, base64d bool) (cursor string, perPage int) {
	cursor = c.Query("cursor")
	if base64d {
		cbytes, _ := base64.RawURLEncoding.DecodeString(cursor)
		cursor = string(cbytes)
	}

	perPage, _ = strconv.Atoi(c.Query("per_page"))
	if perPage > 100 {
		perPage = 100
	} else if perPage <= 0 {
		perPage = 30
	}
	return cursor, perPage
}

type appResponse struct {
	Message string      `json:"message"`
	App     *models.App `json:"app"`
}

type appsResponse struct {
	Message    string        `json:"message"`
	NextCursor string        `json:"next_cursor"`
	Apps       []*models.App `json:"apps"`
}

type routeResponse struct {
	Message string        `json:"message"`
	Route   *models.Route `json:"route"`
}

type routesResponse struct {
	Message    string          `json:"message"`
	NextCursor string          `json:"next_cursor"`
	Routes     []*models.Route `json:"routes"`
}

type callResponse struct {
	Message string       `json:"message"`
	Call    *models.Call `json:"call"`
}

type callsResponse struct {
	Message    string         `json:"message"`
	NextCursor string         `json:"next_cursor"`
	Calls      []*models.Call `json:"calls"`
}