package controller

import (
	"context"
	"encoding/base64"
	"fmt"
	"net"
	"net/http"
	"os"
	"os/signal"
	"sync"
	"syscall"

	"github.com/google/uuid"
	"github.com/sethvargo/go-password/password"
	log "github.com/sirupsen/logrus"
	"github.com/spf13/viper"
	"golang.org/x/crypto/argon2"
	"google.golang.org/grpc"
	"google.golang.org/grpc/credentials/insecure"

	pb "code.fbi.h-da.de/danet/gosdn/api/go/gosdn/core"
	cpb "code.fbi.h-da.de/danet/gosdn/api/go/gosdn/csbi"
	ppb "code.fbi.h-da.de/danet/gosdn/api/go/gosdn/pnd"
	apb "code.fbi.h-da.de/danet/gosdn/api/go/gosdn/rbac"
	spb "code.fbi.h-da.de/danet/gosdn/api/go/gosdn/southbound"
	tpb "code.fbi.h-da.de/danet/gosdn/api/go/gosdn/topology"
	"code.fbi.h-da.de/danet/gosdn/controller/config"
	eventservice "code.fbi.h-da.de/danet/gosdn/controller/eventService"
	"code.fbi.h-da.de/danet/gosdn/controller/interfaces/device"
	"code.fbi.h-da.de/danet/gosdn/controller/interfaces/networkdomain"
	"code.fbi.h-da.de/danet/gosdn/controller/interfaces/rbac"
	"code.fbi.h-da.de/danet/gosdn/controller/northbound/server"
	nbi "code.fbi.h-da.de/danet/gosdn/controller/northbound/server"
	rbacImpl "code.fbi.h-da.de/danet/gosdn/controller/rbac"
	"code.fbi.h-da.de/danet/gosdn/controller/store"
	"code.fbi.h-da.de/danet/gosdn/controller/topology"
	"code.fbi.h-da.de/danet/gosdn/controller/topology/nodes"
	"code.fbi.h-da.de/danet/gosdn/controller/topology/ports"

	eventInterfaces "code.fbi.h-da.de/danet/gosdn/controller/interfaces/event"

	"code.fbi.h-da.de/danet/gosdn/controller/nucleus"
)

var coreLock sync.RWMutex
var coreOnce sync.Once

// Core is the representation of the controller's core
type Core struct {
	pndStore        networkdomain.PndStore
	userService     rbac.UserService
	roleService     rbac.RoleService
	topologyService topology.Service
	nodeService     nodes.Service
	portService     ports.Service
	httpServer      *http.Server
	grpcServer      *grpc.Server
	nbi             *nbi.NorthboundInterface
	eventService    eventInterfaces.Service
	stopChan        chan os.Signal

	csbiClient cpb.CsbiServiceClient
}

var c *Core

// initialize does start-up housekeeping like reading controller config files
func initialize() error {
	err := config.InitializeConfig()
	if err != nil {
		return err
	}

	eventService, err := eventservice.NewEventService()
	if err != nil {
		return err
	}

	nodeService := nodes.NewNodeService(nodes.NewDatabaseNodeStore(), eventService)
	portService := ports.NewPortService(ports.NewDatabasePortStore(), eventService)

	c = &Core{
		pndStore:    nucleus.NewPndStore(),
		userService: rbacImpl.NewUserService(rbacImpl.NewUserStore(), eventService),
		roleService: rbacImpl.NewRoleService(rbacImpl.NewRoleStore(), eventService),
		topologyService: topology.NewTopologyService(
			topology.NewDatabaseTopologyStore(),
			nodeService,
			portService,
			eventService,
		),
		nodeService:  nodeService,
		portService:  portService,
		eventService: eventService,
		stopChan:     make(chan os.Signal, 1),
	}

	// Setting up signal capturing
	signal.Notify(c.stopChan, os.Interrupt, syscall.SIGTERM)

	if err := startGrpc(); err != nil {
		return err
	}

	coreLock.Lock()
	startHttpServer()
	coreLock.Unlock()

	err = createPrincipalNetworkDomain()
	if err != nil {
		return err
	}

	err = ensureDefaultRoleExists()
	if err != nil {
		return err
	}

	err = ensureDefaultUserExists()
	if err != nil {
		return err
	}

	return nil
}

func startGrpc() error {
	socket := viper.GetString("socket")
	lislisten, err := net.Listen("tcp", socket)
	if err != nil {
		return err
	}
	log.Infof("listening to %v", lislisten.Addr())

	jwtManager := rbacImpl.NewJWTManager(config.JWTSecret, config.JWTDuration)
	setupGRPCServerWithCorrectSecurityLevel(jwtManager, c.userService, c.roleService)

	c.nbi = nbi.NewNBI(
		c.pndStore,
		c.userService,
		c.roleService,
		*jwtManager,
		c.topologyService,
		c.nodeService,
		c.portService,
	)

	pb.RegisterCoreServiceServer(c.grpcServer, c.nbi.Core)
	ppb.RegisterPndServiceServer(c.grpcServer, c.nbi.Pnd)
	cpb.RegisterCsbiServiceServer(c.grpcServer, c.nbi.Csbi)
	spb.RegisterSbiServiceServer(c.grpcServer, c.nbi.Sbi)
	apb.RegisterAuthServiceServer(c.grpcServer, c.nbi.Auth)
	apb.RegisterUserServiceServer(c.grpcServer, c.nbi.User)
	apb.RegisterRoleServiceServer(c.grpcServer, c.nbi.Role)
	tpb.RegisterTopologyServiceServer(c.grpcServer, c.nbi.Topology)

	go func() {
		if err := c.grpcServer.Serve(lislisten); err != nil {
			log.Fatal(err)
		}
	}()

	orchestrator := viper.GetString("csbi-orchestrator")
	conn, err := grpc.Dial(orchestrator, grpc.WithTransportCredentials(insecure.NewCredentials()))
	if err != nil {
		log.Fatal(err)
	}
	c.csbiClient = cpb.NewCsbiServiceClient(conn)
	return nil
}

// createPrincipalNetworkDomain initializes the controller with an initial PND
func createPrincipalNetworkDomain() error {
	basePnd, err := c.pndStore.Get(store.Query{ID: config.BasePndUUID})
	if err != nil {
		log.Info(err)
	}

	if basePnd == nil {
		pnd, err := nucleus.NewPND(
			"base",
			"gosdn base pnd",
			config.BasePndUUID,
			c.csbiClient,
			callback,
		)
		if err != nil {
			return err
		}
		err = c.pndStore.Add(pnd)
		if err != nil {
			return err
		}
		return nil
	}

	return nil
}

func ensureDefaultRoleExists() error {
	defaultAdminRoleName := "admin"
	adminRole, err := c.roleService.Get(store.Query{ID: uuid.Nil, Name: defaultAdminRoleName})
	if err != nil {
		log.Info(err)
	}

	if adminRole == nil {
		err := c.roleService.Add(rbacImpl.NewRole(uuid.New(), defaultAdminRoleName, "admin role", []string{
			"/gosdn.core.CoreService/GetPnd",
			"/gosdn.core.CoreService/GetPndList",
			"/gosdn.core.CoreService/CreatePndList",
			"/gosdn.core.CoreService/DeletePnd",
			"/gosdn.rbac.UserService/CreateUsers",
			"/gosdn.rbac.UserService/GetUser",
			"/gosdn.rbac.UserService/GetUsers",
			"/gosdn.rbac.UserService/UpdateUsers",
			"/gosdn.rbac.UserService/DeleteUsers",
			"/gosdn.rbac.RoleService/CreateRoles",
			"/gosdn.rbac.RoleService/GetRole",
			"/gosdn.rbac.RoleService/GetRoles",
			"/gosdn.rbac.RoleService/UpdateRoles",
			"/gosdn.rbac.RoleService/DeletePermissionsForRole",
			"/gosdn.rbac.RoleService/DeleteRoles",
			"/gosdn.pnd.PndService/GetOnd",
			"/gosdn.pnd.PndService/GetOndList",
			"/gosdn.pnd.PndService/GetSbi",
			"/gosdn.pnd.PndService/GetSbiList",
			"/gosdn.pnd.PndService/GetPath",
			"/gosdn.pnd.PndService/GetChange",
			"/gosdn.pnd.PndService/GetChangeList",
			"/gosdn.pnd.PndService/SetOndList",
			"/gosdn.pnd.PndService/SetChangeList",
			"/gosdn.pnd.PndService/SetPathList",
			"/gosdn.pnd.PndService/SetSbiList",
			"/gosdn.pnd.PndService/DeleteOnd",
			"/gosdn.southbound.SbiService/GetSchema",
		}))
		if err != nil {
			return err
		}
	}

	return nil
}

func ensureDefaultUserExists() error {
	defaultUserName := "admin"
	adminUser, err := c.userService.Get(store.Query{ID: uuid.Nil, Name: defaultUserName})
	if err != nil {
		log.Info(err)
	}

	if adminUser == nil {
		// Generate a password that is 16 characters long with 3 digits, 0 symbols,
		// allowing upper and lower case letters, disallowing repeat characters.
		generatedPassword, err := password.Generate(16, 3, 0, true, false)
		if err != nil {
			log.Fatal(err)
		}

		salt, err := password.Generate(16, 3, 0, true, false)
		if err != nil {
			log.Fatal(err)
		}

		hashedPassword := base64.RawStdEncoding.EncodeToString(argon2.IDKey([]byte(generatedPassword), []byte(salt), 1, 64*1024, 4, 32))

		err = c.userService.Add(rbacImpl.NewUser(uuid.New(), defaultUserName, map[string]string{config.BasePndUUID.String(): "admin"}, string(hashedPassword), "", salt))
		if err != nil {
			return err
		}

		fmt.Printf("########\n Generated admin password: %s\n########\n", generatedPassword)
	}

	return nil
}

// Run calls initialize to start the controller
func Run(ctx context.Context) error {
	var initError error
	coreOnce.Do(func() {
		initError = initialize()
	})
	if initError != nil {
		log.WithFields(log.Fields{}).Error(initError)
		return initError
	}

	log.WithFields(log.Fields{}).Info("initialisation finished")

	select {
	case <-c.stopChan:
		return shutdown()
	case <-ctx.Done():
		return shutdown()
	}
}

func shutdown() error {
	log.Info("shutting down controller")
	coreLock.Lock()
	defer coreLock.Unlock()
	c.grpcServer.GracefulStop()
	c.eventService.CloseConnection()
	return stopHttpServer()
}

func callback(id uuid.UUID, ch chan device.Details) {
	if ch != nil {
		c.pndStore.AddPendingChannel(id, ch)
		log.Infof("pending channel %v added", id)
	} else {
		c.pndStore.RemovePendingChannel(id)
		log.Infof("pending channel %v removed", id)
	}
}

// setupGRPCServerWithCorrectSecurityLevel sets up a gRPC server with desired security level
//
// Only two options for now: insecure or secure, add 'else if' if required.
// Secure is the recommended mode and is set as default.
// Insecure starts the controller without the gRPC interceptor which is supposed to handle authz.
// This allows users to operate on the controller without any authentication/authorization,
// but they could still login if they want to.
// Use insecure only for testing purposes and with caution.
func setupGRPCServerWithCorrectSecurityLevel(jwt *rbacImpl.JWTManager, userService rbac.UserService, roleService rbac.RoleService) {
	securityLevel := viper.GetString("security")
	if securityLevel == "insecure" {
		c.grpcServer = grpc.NewServer()
		log.Info("set up grpc server in insecure mode")
	} else {
		interceptor := server.NewAuthInterceptor(jwt, userService, roleService)
		c.grpcServer = grpc.NewServer(grpc.UnaryInterceptor(interceptor.Unary()), grpc.StreamInterceptor(interceptor.Stream()))
		log.Info("set up grpc server in secure mode")
	}
}