/*
  * Copyright 2026 Oleg Borodin <onborodin@gmail.com>
 *
 *
*/

package server

import (
	"context"
	"fmt"
	"net"
	"os"
	"os/signal"
	"os/user"
	"path/filepath"
	"strconv"
	"sync"
	"syscall"
	"time"

	"mproxy/app/config"
	"mproxy/app/handler"
	"mproxy/app/logger"
	"mproxy/app/service"
	"mproxy/pkg/auxtool"

	"mproxy/app/proxoper"
	"mproxy/app/servoper"
)

type Server struct {
	conf   *config.Config
	seop   *servoper.Operator
	prop   *proxoper.Operator
	svc    *service.Service
	hand   *handler.Handler
	logg   *logger.Logger
	ctx    context.Context
	cancel context.CancelFunc
	wg     sync.WaitGroup
	logf   *os.File
	//x509cert []byte
	//x509key  []byte
	listen net.Listener
}

func NewServer() (*Server, error) {
	var err error
	srv := &Server{}
	srv.logg = logger.NewLoggerWithSubject("server")
	srv.ctx, srv.cancel = context.WithCancel(context.Background())
	return srv, err
}

func (srv *Server) Handler() *handler.Handler {
	return srv.hand
}

func (srv *Server) Service() *service.Service {
	return srv.svc
}

func (srv *Server) SetLogdir(dir string) {
	srv.conf.Logpath = dir
}

func (srv *Server) SetRundir(dir string) {
	srv.conf.Runpath = dir
}

func (srv *Server) SetDatadir(dir string) {
	srv.conf.Database.Basepath = dir
	srv.conf.Storage.Basepath = dir
	srv.conf.Datadir = dir
}

func (srv *Server) SetPort(port uint32) {
	srv.conf.Service.Port = port
}

func (srv *Server) SetAsDaemon(asDaemon bool) {
	srv.conf.AsDaemon = asDaemon
}

func (srv *Server) Configure() error {
	var err error
	//srv.logg.Infof("Configuration server")
	srv.conf = config.NewConfig()
	if err != nil {
		return err
	}
	err = srv.conf.ReadConfigfile()
	if err != nil {
		srv.logg.Warningf("Error loading config file: %v", err)
		err = nil
	}
	err = srv.conf.ReadX509Cert()
	if err != nil {
		return err
	}
	return err
}

func (srv *Server) Build() error {
	var err error
	//srv.logg.Infof("Server building")

	currUser, err := user.Current()
	if err != nil {
		err = fmt.Errorf("Error getting current user: %v\n", err)
		return err
	}
	cuid64, err := strconv.ParseInt(currUser.Uid, 10, 64)
	if err != nil {
		return err
	}
	cgid64, err := strconv.ParseInt(currUser.Gid, 10, 64)
	if err != nil {
		return err
	}
	euid := int(cuid64)
	egid := int(cgid64)
	if cuid64 == 0 {
		usr, err := user.Lookup(srv.conf.RunUser)
		if err != nil {
			return err
		}
		uid64, err := strconv.ParseInt(usr.Uid, 10, 64)
		if err != nil {
			return err
		}
		gid64, err := strconv.ParseInt(usr.Gid, 10, 64)
		if err != nil {
			return err
		}
		euid = int(uid64)
		egid = int(gid64)
	}
	// Creating datadir
	datadir := srv.conf.Datadir
	if !auxtool.DirExists(datadir) { // TODO: check access to dir
		//srv.logg.Infof("Creating data directory %s ", datadir)
		err = os.MkdirAll(datadir, 0750)
		if err != nil {
			return err
		}
	}
	err = os.Chown(datadir, euid, egid)
	if err != nil {
		return err
	}

	if srv.conf.AsDaemon {
		logdir := filepath.Dir(srv.conf.Logpath)
		//srv.logg.Infof("Creating log directory %s", logdir)
		err = os.MkdirAll(logdir, 0750)
		if err != nil {
			return err
		}
		err = os.Chown(logdir, euid, egid)
		if err != nil {
			return err
		}
		rundir := filepath.Dir(srv.conf.Runpath)
		//srv.logg.Infof("Creating run directory %s", rundir)
		err = os.MkdirAll(rundir, 0750)
		if err != nil {
			return err
		}
		err = os.Chown(rundir, euid, egid)
		if err != nil {
			return err
		}
		// Redirect stderr and stout
		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
		}
		srv.logf = logFile
	}

	confDump := srv.conf.String()
	srv.logg.Infof("Current server configuration is:\n%s\n", confDump)

	if cuid64 == 0 {
		// Change effective user and group
		err = syscall.Setgid(egid)
		if err != nil {
			return err
		}
		err = syscall.Setuid(euid)
		if err != nil {
			return err
		}
	}
	//return fmt.Errorf("Debug break")

	uidstr := strconv.FormatInt(int64(syscall.Geteuid()), 10)
	usr, err := user.LookupId(uidstr)
	if err != nil {
		return err
	}
	srv.logg.Warningf("Now run as user: %s", usr.Username)

	// Creating service operator
	srv.logg.Infof("Creating operator")
	servoperParams := &servoper.OperatorParams{}
	srv.seop, err = servoper.NewOperator(servoperParams)
	if err != nil {
		return err
	}
	// Creating proxy operator
	srv.logg.Infof("Creating operator")
	proxoperParams := &proxoper.OperatorParams{}
	srv.prop, err = proxoper.NewOperator(proxoperParams)
	if err != nil {
		return err
	}
	// Creating handler
	srv.logg.Infof("Creating handler")
	handlerParams := &handler.HandlerParams{
		ServOper: srv.seop,
		ProxOper: srv.prop,
	}
	srv.hand, err = handler.NewHandler(handlerParams)
	if err != nil {
		return err
	}
	// Creating service
	serviceParams := &service.ServiceParams{
		Handler:  srv.hand,
		X509cert: srv.conf.X509Cert,
		X509key:  srv.conf.X509Key,
		Address:  srv.conf.Service.Address,
		Portnum:  srv.conf.Service.Port,
	}
	srv.logg.Infof("Creating service")
	srv.svc, err = service.NewService(serviceParams)
	if err != nil {
		return err
	}
	// Building service
	err = srv.svc.Build()
	if err != nil {
		return err
	}
	return err
}

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

	if srv.conf.AsDaemon {
		// 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
		}
		// Write process ID
		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
		}
		// Start log rotator
		srv.Rotator()
	}

	currUser, err := user.Current()
	if err != nil {
		return err
	}
	srv.logg.Infof("Server started with user: %s", currUser.Username)
	uidstr := strconv.FormatInt(int64(syscall.Geteuid()), 10)
	usr, err := user.LookupId(uidstr)
	if err != nil {
		return err
	}
	srv.logg.Infof("Server run with user: %s", usr.Username)

	svcDone := make(chan error, 1)
	// Service run
	srv.logg.Infof("Start service")
	startService := func(svc *service.Service, done chan error) {
		err = svc.Run()
		if err != nil {
			srv.logg.Errorf("Service error: %v", err)
			done <- err
		}
	}
	go startService(srv.svc, svcDone)

	sigs := make(chan os.Signal, 1)
	signal.Notify(sigs, syscall.SIGINT, syscall.SIGTERM)
	var signal os.Signal

	select {
	case signal = <-sigs:
		srv.logg.Infof("Services stopped by signal: %v", signal)
		srv.cancel()
		srv.svc.Stop()
		srv.wg.Wait()
	case err = <-svcDone:
		srv.logg.Infof("Service stopped by service error: %v", err)
		srv.cancel()
		srv.svc.Stop()
		srv.wg.Wait()
	}
	return err
}

func (srv *Server) PseudoFork() error {
	const successExit int = 0
	var keyEnv string = "IMX0LTSELMRF8K"
	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.AsDaemon {
		// Restart process process
		err = srv.PseudoFork()
		if err != nil {
			return err
		}
	}
	return err
}

func (srv *Server) Rotator() {
	srv.wg.Add(1)
	var counter uint64
	logFunc := func() {
		for {
			counter += 1
			select {
			case <-srv.ctx.Done():
				srv.wg.Done()
				srv.logg.Infof("Log file rotator done")
				return
			default:
			}
			if (counter % 60) == 1 {
				stat, err := srv.logf.Stat()
				if err == nil && stat.Size() > srv.conf.LogLimit {
					srv.logg.Infof("Rotate log file")
					countFiles := 3
					for i := 1; i < countFiles; i++ {
						nextName := fmt.Sprintf("%s.%d", srv.conf.Logpath, i+1)
						prevName := fmt.Sprintf("%s.%d", srv.conf.Logpath, i)
						os.Rename(prevName, nextName)
					}
					os.Rename(srv.conf.Logpath, srv.conf.Logpath+".1")
					logFile, err := os.OpenFile(srv.conf.Logpath, os.O_WRONLY|os.O_CREATE|os.O_APPEND, 0640)
					if err == nil {
						syscall.Dup2(int(logFile.Fd()), int(os.Stdout.Fd()))
						syscall.Dup2(int(logFile.Fd()), int(os.Stderr.Fd()))
						srv.logf.Close()
						srv.logf = logFile
					}
				}
			}
			time.Sleep(1 * time.Second)
		}
	}
	go logFunc()
}