// SPDX-License-Identifier: Apache-2.0
//
// Copyright The Prometheus Authors
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

//go:build windows

package service

import (
	"context"
	"errors"
	"fmt"
	"log/slog"
	"maps"
	"regexp"
	"slices"
	"strconv"
	"strings"
	"sync"
	"time"
	"unsafe"

	"github.com/alecthomas/kingpin/v2"
	"github.com/prometheus-community/windows_exporter/internal/metriccache"
	"github.com/prometheus-community/windows_exporter/internal/mi"
	"github.com/prometheus-community/windows_exporter/internal/scrapecache"
	"github.com/prometheus-community/windows_exporter/internal/types"
	"github.com/prometheus-community/windows_exporter/internal/utils"
	"github.com/prometheus-community/windows_exporter/internal/utils/recovery"
	"github.com/prometheus/client_golang/prometheus"
	"golang.org/x/sys/windows"
	"golang.org/x/sys/windows/registry"
	"golang.org/x/sys/windows/svc/mgr"
)

const Name = "service"

type Config struct {
	ServiceInclude          *regexp.Regexp `yaml:"include"`
	ServiceExclude          *regexp.Regexp `yaml:"exclude"`
	ServiceStartModeInclude []string       `yaml:"start-mode-include"`
}

//nolint:gochecknoglobals
var ConfigDefaults = Config{
	ServiceInclude:          types.RegExpAny,
	ServiceExclude:          types.RegExpEmpty,
	ServiceStartModeInclude: []string{"auto", "boot", "manual", "disabled", "system"},
}

// A Collector is a Prometheus Collector for service metrics.
type Collector struct {
	config Config

	logger *slog.Logger

	apiStateValues     map[uint32]string
	apiStartModeValues map[uint32]string

	state     *prometheus.Desc
	processID *prometheus.Desc
	info      *prometheus.Desc
	startMode *prometheus.Desc

	// serviceConfigPoolBytes is a pool of byte slices used to avoid allocations
	// ref: https://victoriametrics.com/blog/go-sync-pool/
	serviceConfigPoolBytes sync.Pool

	serviceManagerHandle   *mgr.Mgr
	queryAllServicesMu     sync.Mutex
	queryAllServicesBuffer []byte

	// configCache caches the service configurations between scrapes.
	configCache serviceConfigCache

	// allStartModesIncluded is true if ServiceStartModeInclude contains every start mode.
	// Only then services with an unknown start mode are collected.
	allStartModesIncluded bool

	// metricCache reuses the metrics of services whose values did not change since
	// the last scrape. Each service publishes up to 14 series, and building them is
	// most of the allocations of a scrape. The values are still queried on every
	// scrape, so it saves allocations, not system calls.
	metricCache metriccache.Cache[string, serviceValues]
}

// serviceConfig is the configuration of a service that the collector publishes.
// Of the embedded [mgr.Config], only BinaryPathName, DisplayName, StartType,
// ServiceStartName and DelayedAutoStart are set. DelayedAutoStart is only
// queried for auto-start services and false for the others.
type serviceConfig struct {
	mgr.Config

	// triggerStart is true if the service has triggers, which start or stop it
	// on events such as a device arrival or a network change.
	triggerStart bool

	// extendedAvailable is true if DelayedAutoStart and triggerStart were queried
	// successfully. Otherwise both are false and their labels stay empty.
	extendedAvailable bool
}

// serviceTriggerInfo mirrors SERVICE_TRIGGER_INFO, which QueryServiceConfig2
// returns for SERVICE_CONFIG_TRIGGER_INFO. golang.org/x/sys/windows doesn't define it.
// Only cTriggers is read; the pointers point into the same buffer.
// https://learn.microsoft.com/en-us/windows/win32/api/winsvc/ns-winsvc-service_trigger_info
type serviceTriggerInfo struct {
	triggers uint32  // cTriggers
	trigger  uintptr // pTriggers
	_        uintptr // pReserved
}

// serviceValues holds the inputs of the metrics of a service besides its name.
type serviceValues struct {
	state       uint32
	startMode   string
	displayName string
	runAs       string
	pathName    string
	// delayedStart and triggerStart are the label values "true" or "false".
	delayedStart string
	triggerStart string
	processID    uint32
	// processStartTime is the creation time of the process in nanoseconds,
	// or 0 if it is unknown and the process metric is not published.
	processStartTime uint64
}

// serviceEntry is a copy of an [windows.ENUM_SERVICE_STATUS_PROCESS], which
// does not point into the buffer of queryAllServices.
type serviceEntry struct {
	name   string
	status windows.SERVICE_STATUS_PROCESS
}

func New(config *Config) *Collector {
	if config == nil {
		config = &ConfigDefaults
	}

	if config.ServiceExclude == nil {
		config.ServiceExclude = ConfigDefaults.ServiceExclude
	}

	if config.ServiceInclude == nil {
		config.ServiceInclude = ConfigDefaults.ServiceInclude
	}

	if config.ServiceStartModeInclude == nil {
		config.ServiceStartModeInclude = ConfigDefaults.ServiceStartModeInclude
	}

	c := &Collector{
		config: *config,
	}

	return c
}

func NewWithFlags(app *kingpin.Application) *Collector {
	c := &Collector{
		config: ConfigDefaults,
	}
	c.config.ServiceStartModeInclude = make([]string, 0)

	var serviceStartModeInclude string

	utils.RegexpFlag(app,
		"collector.service.exclude",
		"Regexp of service to exclude. Service name (not the display name!) must both match include and not match exclude to be included.",
		"", &c.config.ServiceExclude,
	)

	utils.RegexpFlag(app,
		"collector.service.include",
		"Regexp of service to include. Service name (not the display name!) must both match include and not match exclude to be included.",
		".+", &c.config.ServiceInclude,
	)

	app.Flag(
		"collector.service.start-mode-include",
		"Comma separated list of service start modes to include. Possible values: auto, boot, manual, disabled, system.",
	).Default(strings.Join(ConfigDefaults.ServiceStartModeInclude, ",")).StringVar(&serviceStartModeInclude)

	app.Action(func(*kingpin.ParseContext) error {
		c.config.ServiceStartModeInclude = strings.Split(serviceStartModeInclude, ",")

		return nil
	})

	return c
}

func (c *Collector) GetName() string {
	return Name
}

// ScrapeCaches returns the caches that the collection resets and begins a scrape of around Collect.
func (c *Collector) ScrapeCaches() []scrapecache.Cache {
	return []scrapecache.Cache{&c.metricCache}
}

func (c *Collector) Build(logger *slog.Logger, _ *mi.Session) error {
	c.logger = logger.With(slog.String("collector", Name))

	c.serviceConfigPoolBytes = sync.Pool{
		New: func() any {
			buf := make([]byte, 1024)

			return &buf
		},
	}

	c.queryAllServicesBuffer = make([]byte, 1024*200)

	c.info = prometheus.NewDesc(
		prometheus.BuildFQName(types.Namespace, Name, "info"),
		"A metric with a constant '1' value labeled with service information",
		[]string{"service", "display_name", "run_as", "path_name", "delayed_start", "trigger_start"},
		nil,
	)
	c.state = prometheus.NewDesc(
		prometheus.BuildFQName(types.Namespace, Name, "state"),
		"The state of the service (State)",
		[]string{"service", "state"},
		nil,
	)
	c.startMode = prometheus.NewDesc(
		prometheus.BuildFQName(types.Namespace, Name, "start_mode"),
		"The start mode of the service (StartMode)",
		[]string{"service", "start_mode"},
		nil,
	)
	c.processID = prometheus.NewDesc(
		prometheus.BuildFQName(types.Namespace, Name, "process"),
		"Process of started service. The value is the creation time of the process as a unix timestamp.",
		[]string{"service", "process_id"},
		nil,
	)

	c.apiStateValues = map[uint32]string{
		windows.SERVICE_CONTINUE_PENDING: "continue pending",
		windows.SERVICE_PAUSE_PENDING:    "pause pending",
		windows.SERVICE_PAUSED:           "paused",
		windows.SERVICE_RUNNING:          "running",
		windows.SERVICE_START_PENDING:    "start pending",
		windows.SERVICE_STOP_PENDING:     "stop pending",
		windows.SERVICE_STOPPED:          "stopped",
	}

	c.apiStartModeValues = map[uint32]string{
		windows.SERVICE_AUTO_START:   "auto",
		windows.SERVICE_BOOT_START:   "boot",
		windows.SERVICE_DEMAND_START: "manual",
		windows.SERVICE_DISABLED:     "disabled",
		windows.SERVICE_SYSTEM_START: "system",
	}

	startModes := slices.Sorted(maps.Values(c.apiStartModeValues))

	for _, startMode := range c.config.ServiceStartModeInclude {
		if !slices.Contains(startModes, startMode) {
			return fmt.Errorf("unknown start mode: %s. Possible values: %s", startMode,
				strings.Join(startModes, ", "),
			)
		}
	}

	c.allStartModesIncluded = true

	for _, startMode := range startModes {
		if !slices.Contains(c.config.ServiceStartModeInclude, startMode) {
			c.allStartModesIncluded = false
		}
	}

	// EnumServiceStatusEx requires only SC_MANAGER_ENUM_SERVICE.
	handle, err := windows.OpenSCManager(nil, nil, windows.SC_MANAGER_ENUMERATE_SERVICE)
	if err != nil {
		return fmt.Errorf("failed to open scm: %w", err)
	}

	c.serviceManagerHandle = &mgr.Mgr{Handle: handle}

	if err := c.configCache.init(registry.LOCAL_MACHINE, servicesKeyPath); err != nil {
		c.logger.Warn("Failed to watch the service configurations for changes. Service configurations are queried on every scrape",
			slog.Any("err", err),
		)
	}

	return nil
}

func (c *Collector) Close() error {
	if err := c.configCache.close(); err != nil {
		c.logger.Warn("Failed to close the service configuration cache",
			slog.Any("err", err),
		)
	}

	if c.serviceManagerHandle == nil {
		return nil
	}

	if err := c.serviceManagerHandle.Disconnect(); err != nil {
		c.logger.Warn("Failed to disconnect from scm",
			slog.Any("err", err),
		)
	}

	c.serviceManagerHandle = nil

	return nil
}

// Collect sends the metric values for each metric
// to the provided prometheus Metric channel.
func (c *Collector) Collect(ch chan<- prometheus.Metric, _ time.Duration) error {
	services, err := c.queryAllServices()
	if err != nil {
		return fmt.Errorf("failed to query all services: %w", err)
	}

	switch dropped, expired, err := c.configCache.refresh(); {
	case err != nil:
		c.logger.Warn("Failed to watch the service configurations for changes. Service configurations are queried on every scrape",
			slog.Any("err", err),
		)
	case expired:
		c.logger.Debug("Service configuration cache expired",
			slog.Int("count", dropped),
		)
	case dropped > 0:
		c.logger.Debug("Dropped changed service configurations from the cache",
			slog.Int("count", dropped),
		)
	}

	scrape := c.metricCache.Scrape()

	servicesCh := make(chan serviceEntry, len(services))

	for _, service := range services {
		servicesCh <- service
	}

	close(servicesCh)

	// If a worker panics, the remaining workers collect the remaining services.
	var g recovery.Group

	for range 4 {
		g.Go(func() error {
			for service := range servicesCh {
				c.collectWorker(ch, scrape, service)
			}

			return nil
		})
	}

	err = g.Wait()

	return err
}

func (c *Collector) collectWorker(ch chan<- prometheus.Metric, scrape *metriccache.Scrape[string, serviceValues], service serviceEntry) {
	if c.config.ServiceExclude.MatchString(service.name) || !c.config.ServiceInclude.MatchString(service.name) {
		return
	}

	if err := c.collectService(ch, scrape, service); err != nil {
		c.logger.Log(context.Background(), slog.LevelWarn, "failed collecting service info",
			slog.Any("err", err),
			slog.String("service", service.name),
		)
	}
}

func (c *Collector) collectService(ch chan<- prometheus.Metric, scrape *metriccache.Scrape[string, serviceValues], service serviceEntry) error {
	serviceName := service.name

	serviceConfig, configAvailable, err := c.getCachedServiceConfig(serviceName)
	if err != nil {
		return err
	}

	// serviceStartMode stays empty if the service configuration is not available.
	// The zero StartType of the empty configuration must not be reported as "boot".
	var serviceStartMode string

	if configAvailable {
		var ok bool

		serviceStartMode, ok = c.apiStartModeValues[serviceConfig.StartType]
		if !ok {
			c.logger.Log(context.Background(), slog.LevelWarn, "unknown service start mode",
				slog.String("service", serviceName),
				slog.Uint64("start_mode", uint64(serviceConfig.StartType)),
			)

			return nil
		}

		if !slices.Contains(c.config.ServiceStartModeInclude, serviceStartMode) {
			c.logger.Log(context.Background(), slog.LevelDebug, "service start mode excluded by config",
				slog.String("service", serviceName),
				slog.String("start_mode", serviceStartMode),
			)

			return nil
		}
	} else if !c.allStartModesIncluded {
		// A service with an unknown start mode can't match a start mode filter.
		c.logger.Log(context.Background(), slog.LevelDebug, "service with unknown start mode excluded by config",
			slog.String("service", serviceName),
		)

		return nil
	}

	values := serviceValues{
		state:       service.status.CurrentState,
		startMode:   serviceStartMode,
		displayName: serviceConfig.DisplayName,
		runAs:       serviceConfig.ServiceStartName,
		pathName:    serviceConfig.BinaryPathName,
		processID:   service.status.ProcessId,
	}

	// The labels stay empty if the service configuration or the delayed
	// auto-start flag and triggers are not available.
	if configAvailable && serviceConfig.extendedAvailable {
		values.delayedStart = strconv.FormatBool(serviceConfig.DelayedAutoStart)
		values.triggerStart = strconv.FormatBool(serviceConfig.triggerStart)
	}

	if values.processID != 0 {
		values.processStartTime = c.processStartTime(serviceName, values.processID)
	}

	metrics := scrape.Get(serviceName, values, func() []prometheus.Metric {
		return c.serviceMetrics(serviceName, values)
	})

	for _, metric := range metrics {
		ch <- metric
	}

	return nil
}

// serviceMetrics builds the metrics of a service.
func (c *Collector) serviceMetrics(serviceName string, values serviceValues) []prometheus.Metric {
	metrics := make([]prometheus.Metric, 0, 2+len(c.apiStartModeValues)+len(c.apiStateValues))

	metrics = append(metrics, prometheus.MustNewConstMetric(
		c.info,
		prometheus.GaugeValue,
		1.0,
		serviceName,
		values.displayName,
		values.runAs,
		values.pathName,
		values.delayedStart,
		values.triggerStart,
	))

	var (
		isCurrentStartMode float64
		isCurrentState     float64
	)

	if values.startMode != "" {
		for _, startMode := range c.apiStartModeValues {
			isCurrentStartMode = 0.0
			if startMode == values.startMode {
				isCurrentStartMode = 1.0
			}

			metrics = append(metrics, prometheus.MustNewConstMetric(
				c.startMode,
				prometheus.GaugeValue,
				isCurrentStartMode,
				serviceName,
				startMode,
			))
		}
	}

	for state, stateValue := range c.apiStateValues {
		isCurrentState = 0.0
		if state == values.state {
			isCurrentState = 1.0
		}

		metrics = append(metrics, prometheus.MustNewConstMetric(
			c.state,
			prometheus.GaugeValue,
			isCurrentState,
			serviceName,
			stateValue,
		))
	}

	if values.processStartTime == 0 {
		return metrics
	}

	return append(metrics, prometheus.MustNewConstMetric(
		c.processID,
		prometheus.GaugeValue,
		float64(values.processStartTime/1_000_000_000),
		serviceName,
		strconv.FormatUint(uint64(values.processID), 10),
	))
}

// processStartTime returns the creation time of the process of a service in
// nanoseconds, or 0 if it can't be determined.
func (c *Collector) processStartTime(serviceName string, processID uint32) uint64 {
	processStartTime, err := c.getProcessStartTime(processID)
	if err == nil {
		return processStartTime
	}

	logLevel := slog.LevelWarn

	// ERROR_INVALID_PARAMETER returns when the process is not running. This can be happened
	// if the service terminated after query the service API.
	if errors.Is(err, windows.ERROR_ACCESS_DENIED) || errors.Is(err, windows.ERROR_INVALID_PARAMETER) {
		logLevel = slog.LevelDebug
	}

	c.logger.Log(context.Background(), logLevel, "failed to get process start time",
		slog.String("service", serviceName),
		slog.Any("err", err),
	)

	return 0
}

// queryAllServices returns all service states of the current Windows system
// This is realized by ask Service Manager directly.
func (c *Collector) queryAllServices() ([]serviceEntry, error) {
	var (
		additionalBytesNeeded uint32
		servicesReturned      uint32
		err                   error
	)

	// The buffer is reused across scrapes. Hold the lock until the services are copied
	// out of the buffer, so that an overlapping Collect can't overwrite it in the meantime.
	c.queryAllServicesMu.Lock()
	defer c.queryAllServicesMu.Unlock()

	clear(c.queryAllServicesBuffer)

	for {
		currentBufferSize := uint32(cap(c.queryAllServicesBuffer))

		err = windows.EnumServicesStatusEx(
			c.serviceManagerHandle.Handle,
			windows.SC_STATUS_PROCESS_INFO,
			windows.SERVICE_WIN32,
			windows.SERVICE_STATE_ALL,
			&c.queryAllServicesBuffer[0],
			currentBufferSize,
			&additionalBytesNeeded,
			&servicesReturned,
			nil,
			nil,
		)
		if err == nil {
			break
		}

		if !errors.Is(err, windows.ERROR_MORE_DATA) {
			return nil, err
		}

		/*
			Unlike other WIN32 API calls, additionalBytesNeeded is not returning the absolute amount bytes needed,
			but the additional bytes needed relative to the cbBufSize parameter.
			ref:
			https://stackoverflow.com/questions/14756347/when-calling-enumservicesstatusex-twice-i-still-get-eror-more-data-in-c
		*/

		c.queryAllServicesBuffer = make([]byte, currentBufferSize+additionalBytesNeeded)
	}

	if servicesReturned == 0 {
		return []serviceEntry{}, nil
	}

	services := unsafe.Slice((*windows.ENUM_SERVICE_STATUS_PROCESS)(unsafe.Pointer(&c.queryAllServicesBuffer[0])), int(servicesReturned))
	entries := make([]serviceEntry, 0, len(services))

	for _, service := range services {
		if uintptr(unsafe.Pointer(service.ServiceName)) == uintptr(windows.InvalidHandle) {
			c.logger.Log(context.Background(), slog.LevelWarn, "failed collecting service info",
				slog.String("err", "ServiceName is 0xffffffffffffffff"),
				slog.String("service", fmt.Sprintf("%+v", service)),
			)

			continue
		}

		entries = append(entries, serviceEntry{
			name:   windows.UTF16PtrToString(service.ServiceName),
			status: service.ServiceStatusProcess,
		})
	}

	return entries, nil
}

// queryServiceConfig opens the service and queries its configuration.
// configAvailable is false if the service has no readable configuration.
func (c *Collector) queryServiceConfig(serviceName string) (serviceConfig, bool, error) {
	serviceNamePtr, err := windows.UTF16PtrFromString(serviceName)
	if err != nil {
		return serviceConfig{}, false, fmt.Errorf("invalid service name: %w", err)
	}

	// Open connection for service handler.
	serviceHandle, err := windows.OpenService(c.serviceManagerHandle.Handle, serviceNamePtr, windows.SERVICE_QUERY_CONFIG)
	if err != nil {
		return serviceConfig{}, false, fmt.Errorf("failed to open service: %w", err)
	}

	// Create handle for each service.
	serviceManager := &mgr.Service{Name: serviceName, Handle: serviceHandle}
	defer func(serviceManager *mgr.Service) {
		if err := serviceManager.Close(); err != nil {
			c.logger.Log(context.Background(), slog.LevelWarn, "failed to close service handle",
				slog.Any("err", err),
				slog.String("service", serviceName),
			)
		}
	}(serviceManager)

	// Get Service Configuration.
	config, err := c.getServiceConfig(serviceManager)
	if err != nil {
		if !errors.Is(err, windows.ERROR_FILE_NOT_FOUND) && !errors.Is(err, windows.ERROR_MUI_FILE_NOT_FOUND) {
			return serviceConfig{}, false, fmt.Errorf("failed to get service configuration: %w", err)
		}

		c.logger.Log(context.Background(), slog.LevelDebug, "failed collecting service config",
			slog.Any("err", err),
			slog.String("service", serviceName),
		)

		return serviceConfig{}, false, nil
	}

	return config, true, nil
}

func (c *Collector) getProcessStartTime(pid uint32) (uint64, error) {
	handle, err := windows.OpenProcess(windows.PROCESS_QUERY_LIMITED_INFORMATION, false, pid)
	if err != nil {
		return 0, fmt.Errorf("failed to open process %w", err)
	}

	var (
		creation windows.Filetime
		exit     windows.Filetime
		krn      windows.Filetime
		user     windows.Filetime
	)

	err = windows.GetProcessTimes(handle, &creation, &exit, &krn, &user)
	if err := windows.CloseHandle(handle); err != nil {
		c.logger.LogAttrs(context.Background(), slog.LevelWarn, "failed to close process handle",
			slog.Any("err", err),
			slog.Uint64("pid", uint64(pid)),
		)
	}

	if err != nil {
		return 0, fmt.Errorf("failed to get process times %w", err)
	}

	return uint64(creation.Nanoseconds()), nil
}

// getServiceConfig is an optimized variant of [mgr.Service.Config] that only
// retrieves the necessary information.
func (c *Collector) getServiceConfig(service *mgr.Service) (serviceConfig, error) {
	buf := c.serviceConfigPoolBytes.Get().(*[]byte) //nolint:forcetypeassert // The pool only holds *[]byte.
	defer c.serviceConfigPoolBytes.Put(buf)

	err := queryServiceConfigBuffer(buf, func(data *byte, size uint32, bytesNeeded *uint32) error {
		return windows.QueryServiceConfig(service.Handle, (*windows.QUERY_SERVICE_CONFIG)(unsafe.Pointer(data)), size, bytesNeeded)
	})
	if err != nil {
		return serviceConfig{}, err
	}

	queryServiceConfig := (*windows.QUERY_SERVICE_CONFIG)(unsafe.Pointer(&(*buf)[0]))

	config := serviceConfig{
		BinaryPathName:   windows.UTF16PtrToString(queryServiceConfig.BinaryPathName),
		DisplayName:      windows.UTF16PtrToString(queryServiceConfig.DisplayName),
		StartType:        queryServiceConfig.StartType,
		ServiceStartName: windows.UTF16PtrToString(queryServiceConfig.ServiceStartName),
	}

	// A failure only leaves the delayed_start and trigger_start labels empty.
	// It must not hide the rest of the configuration.
	if err := queryExtendedServiceConfig(service.Handle, buf, &config); err != nil {
		c.logger.Log(context.Background(), slog.LevelDebug, "failed to query the delayed auto-start flag and triggers of the service",
			slog.Any("err", err),
			slog.String("service", service.Name),
		)

		config.DelayedAutoStart = false
		config.triggerStart = false

		return config, nil
	}

	config.extendedAvailable = true

	return config, nil
}

// queryExtendedServiceConfig queries the delayed auto-start flag and the
// triggers of a service with QueryServiceConfig2 into config. buf must not be
// empty; the configuration strings must already be copied out of it.
func queryExtendedServiceConfig(handle windows.Handle, buf *[]byte, config *serviceConfig) error {
	// The service control manager ignores the delayed auto-start flag of services
	// that don't start automatically, so it is only queried for them.
	if config.StartType == windows.SERVICE_AUTO_START {
		var (
			delayed     windows.SERVICE_DELAYED_AUTO_START_INFO
			bytesNeeded uint32
		)

		err := windows.QueryServiceConfig2(handle, windows.SERVICE_CONFIG_DELAYED_AUTO_START_INFO,
			(*byte)(unsafe.Pointer(&delayed)), uint32(unsafe.Sizeof(delayed)), &bytesNeeded)
		if err != nil {
			return fmt.Errorf("failed to query the delayed auto-start flag: %w", err)
		}

		config.DelayedAutoStart = delayed.IsDelayedAutoStartUp != 0
	}

	err := queryServiceConfigBuffer(buf, func(data *byte, size uint32, bytesNeeded *uint32) error {
		return windows.QueryServiceConfig2(handle, windows.SERVICE_CONFIG_TRIGGER_INFO, data, size, bytesNeeded)
	})
	if err != nil {
		return fmt.Errorf("failed to query the service triggers: %w", err)
	}

	config.triggerStart = (*serviceTriggerInfo)(unsafe.Pointer(&(*buf)[0])).triggers > 0

	return nil
}

// queryServiceConfigBuffer calls query with the buffer and grows the buffer
// until the result fits. query wraps QueryServiceConfig or QueryServiceConfig2.
// The buffer must not be empty.
func queryServiceConfigBuffer(buf *[]byte, query func(data *byte, size uint32, bytesNeeded *uint32) error) error {
	for {
		var bytesNeeded uint32

		err := query(&(*buf)[0], uint32(len(*buf)), &bytesNeeded)
		if err == nil {
			return nil
		}

		if !errors.Is(err, windows.ERROR_INSUFFICIENT_BUFFER) && !errors.Is(err, windows.ERROR_MORE_DATA) {
			return err
		}

		if bytesNeeded <= uint32(len(*buf)) {
			return fmt.Errorf("win32 reports the buffer as too small (%d bytes needed, %d available): %w", bytesNeeded, len(*buf), err)
		}

		*buf = make([]byte, bytesNeeded)
	}
}