// RAINBOND, Application Management Platform
// Copyright (C) 2014-2017 Goodrain Co., Ltd.

// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version. For any non-GPL usage of Rainbond,
// one or multiple Commercial Licenses authorized by Goodrain Co., Ltd.
// must be obtained first.

// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.

// You should have received a copy of the GNU General Public License
// along with this program. If not, see <http://www.gnu.org/licenses/>.

package windows

import (
	"fmt"
	"strings"
	"time"
	"unsafe"

	"golang.org/x/sys/windows"
	"golang.org/x/sys/windows/svc"
	"golang.org/x/sys/windows/svc/debug"
	"golang.org/x/sys/windows/svc/eventlog"
	"golang.org/x/sys/windows/svc/mgr"
)

//RegisterService register a service
func RegisterService(serviceName, execPath, displayName string, depends, args []string) error {
	m, err := mgr.Connect()
	if err != nil {
		return err
	}
	defer m.Disconnect()
	c := mgr.Config{
		ServiceType:  windows.SERVICE_WIN32_OWN_PROCESS,
		StartType:    mgr.StartAutomatic,
		ErrorControl: mgr.ErrorNormal,
		Dependencies: depends,
		DisplayName:  displayName,
	}

	s, err := m.CreateService(serviceName, execPath, c, args...)
	if err != nil {
		return err
	}
	defer s.Close()

	// See http://stackoverflow.com/questions/35151052/how-do-i-configure-failure-actions-of-a-windows-service-written-in-go
	const (
		scActionNone       = 0
		scActionRestart    = 1
		scActionReboot     = 2
		scActionRunCommand = 3

		serviceConfigFailureActions = 2
	)

	type serviceFailureActions struct {
		ResetPeriod  uint32
		RebootMsg    *uint16
		Command      *uint16
		ActionsCount uint32
		Actions      uintptr
	}

	type scAction struct {
		Type  uint32
		Delay uint32
	}
	t := []scAction{
		{Type: scActionRestart, Delay: uint32(60 * time.Second / time.Millisecond)},
		{Type: scActionRestart, Delay: uint32(60 * time.Second / time.Millisecond)},
		{Type: scActionNone},
	}
	lpInfo := serviceFailureActions{ResetPeriod: uint32(24 * time.Hour / time.Second), ActionsCount: uint32(3), Actions: uintptr(unsafe.Pointer(&t[0]))}
	err = windows.ChangeServiceConfig2(s.Handle, serviceConfigFailureActions, (*byte)(unsafe.Pointer(&lpInfo)))
	if err != nil {
		return err
	}
	return eventlog.Install(serviceName, execPath, false, eventlog.Info|eventlog.Warning|eventlog.Error)
}

//UnRegisterService unres
func UnRegisterService(serviceName string) error {
	m, err := mgr.Connect()
	if err != nil {
		return err
	}
	defer m.Disconnect()
	s, err := m.OpenService(serviceName)
	if err != nil {
		return err
	}
	defer s.Close()
	eventlog.Remove(serviceName)
	err = s.Delete()
	if err != nil {
		return err
	}
	return nil
}

//StartService start a windows service
func StartService(serviceName string) error {
	m, err := mgr.Connect()
	if err != nil {
		return err
	}
	defer m.Disconnect()
	s, err := m.OpenService(serviceName)
	if err != nil {
		return fmt.Errorf("could not open service: %v", err)
	}
	defer s.Close()
	err = s.Start()
	if err != nil {
		return fmt.Errorf("could not start service: %v", err)
	}
	return nil
}

//StopService stop a windows service
func StopService(serviceName string) error {
	return controlService(serviceName, svc.Stop, svc.Stopped)
}

//RestartService restart a windows service
func RestartService(serviceName string) error {
	if err := controlService(serviceName, svc.Stop, svc.Stopped); err != nil &&
		!strings.Contains(err.Error(), "service has not been started") {
		return err
	}
	return StartService(serviceName)
}

func controlService(name string, c svc.Cmd, to svc.State) error {
	m, err := mgr.Connect()
	if err != nil {
		return err
	}
	defer m.Disconnect()
	s, err := m.OpenService(name)
	if err != nil {
		return fmt.Errorf("could not access service: %v", err)
	}
	defer s.Close()
	status, err := s.Control(c)
	if err != nil {
		return fmt.Errorf("could not send control=%d: %v", c, err)
	}
	timeout := time.Now().Add(10 * time.Second)
	for status.State != to {
		if timeout.Before(time.Now()) {
			return fmt.Errorf("timeout waiting for service to go to state=%d", to)
		}
		time.Sleep(300 * time.Millisecond)
		status, err = s.Query()
		if err != nil {
			return fmt.Errorf("could not retrieve service status: %v", err)
		}
	}
	return nil
}

var elog debug.Log

//RunAsService run as windows service
func RunAsService(name string, start, stop func() error, isDebug bool) (err error) {
	if isDebug {
		elog = debug.New(name)
	} else {
		elog, err = eventlog.Open(name)
		if err != nil {
			return err
		}
	}
	defer elog.Close()
	run := svc.Run
	if isDebug {
		run = debug.Run
	}

	elog.Info(1, fmt.Sprintf("winsvc.RunAsService: starting %s service", name))
	if err = run(name, &winService{Start: start, Stop: stop}); err != nil {
		elog.Error(1, fmt.Sprintf("%s service failed: %v", name, err))
		return err
	}
	elog.Info(1, fmt.Sprintf("winsvc.RunAsService: %s service stopped", name))
	return nil
}

type winService struct {
	Start func() error
	Stop  func() error
}

func (p *winService) Execute(args []string, r <-chan svc.ChangeRequest, changes chan<- svc.Status) (ssec bool, errno uint32) {
	elog.Info(1, "winsvc.Execute:"+"begin")
	const cmdsAccepted = svc.AcceptStop | svc.AcceptShutdown | svc.AcceptPauseAndContinue
	changes <- svc.Status{State: svc.StartPending}
	changes <- svc.Status{State: svc.Running, Accepts: cmdsAccepted}
	go func() {
		defer func() {
			changes <- svc.Status{State: svc.StopPending}
			p.Stop()
		}()
		for {
			select {
			case c := <-r:
				switch c.Cmd {
				case svc.Interrogate:
					changes <- c.CurrentStatus
					// testing deadlock from https://code.google.com/p/winsvc/issues/detail?id=4
					time.Sleep(100 * time.Millisecond)
					changes <- c.CurrentStatus
				case svc.Stop, svc.Shutdown:
					return
				case svc.Pause:
					changes <- svc.Status{State: svc.Paused, Accepts: cmdsAccepted}
				case svc.Continue:
					changes <- svc.Status{State: svc.Running, Accepts: cmdsAccepted}
				default:
					elog.Error(1, fmt.Sprintf("winsvc.Execute:: unexpected control request #%d", c))
				}
			}
		}
	}()
	p.Start()
	elog.Info(1, "winsvc.Execute:"+"end")
	return
}