package server

import (
	"io/ioutil"
	"os"
	"os/signal"
	"os/user"
	"path/filepath"
	"strconv"
	"syscall"
	"time"

	"mbase/app/config"
	"mbase/app/maindb"
	"mbase/app/operator"
	"mbase/pkg/aux509"
	"mbase/pkg/descr"
	"mbase/pkg/logger"
	"mbase/pkg/netacl"

	handler "mbase/app/handler"
	service "mbase/app/service"

	"sigs.k8s.io/yaml"
)

type Server struct {
	conf *config.Config
	oper *operator.Operator
	svc  *service.Service
	hand *handler.Handler
	log  *logger.Logger
	nacl *netacl.NetACL

	db       *maindb.Database
	x509cert []byte
	x509key  []byte
	state    descr.Server
	sfile    string
}

func NewServer() (*Server, error) {
	var err error
	srv := &Server{}
	srv.log = logger.NewLogger("server")
	return srv, err
}

func (srv *Server) Configure() error {
	var err error
	srv.conf = config.NewConfig()

	err = srv.conf.ReadFile()
	if err != nil {
		return err
	}
	err = srv.conf.ReadEnv()
	if err != nil {
		return err
	}
	err = srv.conf.ReadOpts()
	if err != nil {
		return err
	}
	srv.sfile = filepath.Join(srv.conf.DataDir, "mbase.yaml")

	return err
}

func (srv *Server) LoadState() error {
	var err error
	_, err = os.Stat(srv.sfile)
	if os.IsNotExist(err) {
		err = nil
		return err
	}
	file, err := os.Open(srv.sfile)
	if err != nil {
		return err
	}
	defer file.Close()
	stateBytes, err := ioutil.ReadAll(file)
	if err != nil {
		return err
	}
	err = yaml.Unmarshal(stateBytes, &srv.state)
	if err != nil {
		return err
	}
	return err
}

func (srv *Server) SaveState() error {
	var err error

	file, err := os.OpenFile(srv.sfile, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, 0640)
	if err != nil {
		return err
	}
	defer file.Close()
	srv.state.UpdatedAt = time.Now().Format(time.RFC3339)
	if srv.state.CreatedAt == "" {
		srv.state.CreatedAt = srv.state.UpdatedAt
	}
	stateBytes, err := yaml.Marshal(srv.state)
	if err != nil {
		return err
	}
	_, err = file.Write(stateBytes)
	if err != nil {
		return err
	}
	return err
}

func (srv *Server) Build() error {
	var err error
	srv.log.Infof("Build server")

	// Mkdir log and data dir
	srv.log.Infof("Create %s dir", srv.conf.DataDir)
	err = os.MkdirAll(srv.conf.DataDir, 0750)
	if err != nil {
		return err
	}
	if srv.conf.Daemon {
		logDir := filepath.Dir(srv.conf.LogPath)
		srv.log.Infof("Create %s dir", logDir)
		err = os.MkdirAll(logDir, 0750)
		if err != nil {
			return err
		}
		runDir := filepath.Dir(srv.conf.RunPath)
		srv.log.Infof("Create %s dir", runDir)
		err = os.MkdirAll(runDir, 0750)
		if err != nil {
			return err
		}
	}
	// Create X509 certs
	srv.x509cert, srv.x509key, err = aux509.CreateX509SelfSignedCert(srv.conf.Hostname)
	if err != nil {
		return err
	}
	// Load state
	err = srv.LoadState()
	if err != nil {
		return err
	}
	// Create netACL
	err = srv.nacl.AddDisabledAddresses(srv.conf.Networks.Disabled...)
	if err != nil {
		return err
	}
	srv.nacl = netacl.NewNetACL()
	err = srv.nacl.AddEnabledAddresses(srv.conf.Networks.Enabled...)
	if err != nil {
		return err
	}
	naclYAML, err := yaml.Marshal(srv.nacl)
	if err != nil {
		return err
	}
	srv.log.Infof("Network ACL is:\n%s\n", string(naclYAML))

	// Create database
	srv.db, err = maindb.NewDatabase(srv.conf.DataDir)

	err = srv.db.OpenDatabase()
	if err != nil {
		return err
	}
	// Load state
	err = srv.LoadState()
	if err != nil {
		return err
	}
	// Create operator
	operConfig := &operator.OperatorConfig{
		Database: srv.db,
	}
	srv.oper, err = operator.NewOperator(operConfig)
	if err != nil {
		return err
	}
	if !srv.state.DatabaseInitialized {
		// Create schema
		srv.log.Infof("Init database")
		err = srv.db.InitDatabase()
		if err != nil {
			return err
		}
		srv.state.DatabaseInitialized = true
		err = srv.SaveState()
		if err != nil {
			return err
		}
	}
	// Create handler
	handlerConfig := &handler.HandlerConfig{
		Operator: srv.oper,
	}
	srv.hand = handler.NewHandler(handlerConfig)
	if err != nil {
		return err
	}
	// Create service
	serviceConfig := &service.ServiceConfig{
		Portnum:  srv.conf.Service.Portnum,
		Address:  srv.conf.Service.Address,
		Protocol: srv.conf.Service.Protocol,
		Hostname: srv.conf.Hostname,

		Handler:  srv.hand,
		Operator: srv.oper,
		X509Cert: srv.x509cert,
		X509Key:  srv.x509key,
		NetACL:   srv.nacl,
	}
	srv.svc = service.NewService(serviceConfig)
	if err != nil {
		return err
	}
	return err
}

func (srv *Server) Run() error {
	var err error
	// Log configuration
	yamlConfig, err := srv.conf.String()
	if err != nil {
		return err
	}
	srv.log.Debugf("Server configuration:\n%s\n", yamlConfig)

	// Show current user
	currUser, err := user.Current()
	if err != nil {
		return err
	}
	srv.log.Infof("Running server as user %s", currUser.Username)

	sigs := make(chan os.Signal, 1)
	done := make(chan error, 1)

	// Run service
	startService := func(svc *service.Service, done chan error) {
		err = svc.Run()
		if err != nil {
			srv.log.Errorf("Service error: %v", err)
			done <- err
		}
	}
	go startService(srv.svc, done)

	signal.Notify(sigs, syscall.SIGINT, syscall.SIGTERM)
	var signal os.Signal

	select {
	case signal = <-sigs:
		srv.log.Infof("Services stopped by signal: %v", signal)
		srv.svc.Stop()
	}
	return err
}

func (srv *Server) PseudoFork() error {
	const successExit int = 0
	var keyEnv string = "IMX0LTSELMRF8KASWER"
	var err error

	_, isChild := os.LookupEnv(keyEnv)
	switch {
	case !isChild:
		os.Setenv(keyEnv, "TRUE")

		procAttr := syscall.ProcAttr{}
		cwd, err := os.Getwd()
		if err != nil {
			return err
		}
		var sysFiles = make([]uintptr, 3)
		sysFiles[0] = uintptr(syscall.Stdin)
		sysFiles[1] = uintptr(syscall.Stdout)
		sysFiles[2] = uintptr(syscall.Stderr)

		procAttr.Files = sysFiles
		procAttr.Env = os.Environ()
		procAttr.Dir = cwd

		_, err = syscall.ForkExec(os.Args[0], os.Args, &procAttr)
		if err != nil {
			return err
		}
		os.Exit(successExit)
	case isChild:
		_, err = syscall.Setsid()
		if err != nil {
			return err
		}
	}
	os.Unsetenv(keyEnv)
	return err
}

func (srv *Server) Daemonize() error {
	var err error
	if srv.conf.Daemon {
		// Restart process process
		err = srv.PseudoFork()
		if err != nil {
			return err
		}

		// Redirect stdin
		nullFile, err := os.OpenFile("/dev/null", os.O_RDWR, 0)
		if err != nil {
			return err
		}
		err = syscall.Dup2(int(nullFile.Fd()), int(os.Stdin.Fd()))
		if err != nil {
			return err
		}
		// Redirect stderr and stout
		logdir := filepath.Dir(srv.conf.LogPath)
		err = os.MkdirAll(logdir, 0750)
		if err != nil {
			return err
		}
		logFile, err := os.OpenFile(srv.conf.LogPath, os.O_WRONLY|os.O_CREATE|os.O_APPEND, 0640)
		if err != nil {
			return err
		}
		err = syscall.Dup2(int(logFile.Fd()), int(os.Stdout.Fd()))
		if err != nil {
			return err
		}
		err = syscall.Dup2(int(logFile.Fd()), int(os.Stderr.Fd()))
		if err != nil {
			return err
		}
		// Write process ID
		rundir := filepath.Dir(srv.conf.RunPath)
		err = os.MkdirAll(rundir, 0750)
		if err != nil {
			return err
		}
		pidFile, err := os.OpenFile(srv.conf.RunPath, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, 0640)
		if err != nil {
			return err
		}
		defer pidFile.Close()
		currPid := os.Getpid()
		_, err = pidFile.WriteString(strconv.Itoa(currPid))
		if err != nil {
			return err
		}
	}
	return err
}