package display

import (
	"bufio"
	"bytes"
	"errors"
	"os"
	"os/exec"
	"strconv"
	"sync"
	"time"

	"github.com/godbus/dbus"
	geoclue2 "github.com/linuxdeepin/go-dbus-factory/org.freedesktop.geoclue2"
	"github.com/linuxdeepin/go-lib/dbusutil"
)

const (
	// ColorTemperatureModeNone 不调整色温
	ColorTemperatureModeNone int32 = iota
	// ColorTemperatureModeAuto 自动调整色温
	ColorTemperatureModeAuto
	// ColorTemperatureModeManual 手动调整色温
	ColorTemperatureModeManual
)

func isValidColorTempMode(mode int32) bool {
	return mode >= ColorTemperatureModeNone && mode <= ColorTemperatureModeManual
}

// dbus 上导出的方法
func (m *Manager) setColorTempMode(mode int32) error {
	if !isValidColorTempMode(mode) {
		return errors.New("mode out of range, not 0 or 1 or 2")
	}
	m.setPropColorTemperatureMode(mode)
	m.setColorTempModeReal(mode)
	m.saveColorTempModeInCfg(mode)
	return nil
}

func (m *Manager) setColorTempModeReal(mode int32) {
	if _greeterMode {
		return
	}
	switch mode {
	case ColorTemperatureModeAuto: // 自动模式调节色温 启动服务
		m.redshiftRunner.start()

	case ColorTemperatureModeManual, ColorTemperatureModeNone:
		// manual 手动调节色温
		// none 恢复正常色温
		m.redshiftRunner.stop()
	}
	// 对于自动模式，也要先把色温设置为正常。
	m.setColorTempOneShot()
}

const (
	redshiftStateRunning = iota + 1
	redshiftStateStopped
)

type redshiftRunner struct {
	mu                 sync.Mutex
	state              int
	timer              *time.Timer
	process            *os.Process
	value              int
	cb                 func(value int)
	sysService         *dbusutil.Service
	geoAgentRegistered bool
}

func newRedshiftRunner() *redshiftRunner {
	sysService, err := dbusutil.NewSystemService()
	if err != nil {
		logger.Warning("new sys service failed:", err)
	}
	return &redshiftRunner{
		sysService: sysService,
	}
}

func (r *redshiftRunner) start() {
	r.mu.Lock()
	defer r.mu.Unlock()
	logger.Debugf("redshiftRunner.start")

	if r.state == redshiftStateRunning {
		return
	}
	r.state = redshiftStateRunning

	err := r.registerGeoClueAgent()
	if err != nil {
		logger.Warning("register geoClue agent failed:", err)
	}

	cmd := exec.Command("redshift", "-m", "dummy", "-t", "6500:3500", "-r")
	cmd.Env = append(os.Environ(), "LC_ALL=C")
	var errBuf bytes.Buffer
	cmd.Stderr = &errBuf
	stdout, err := cmd.StdoutPipe()
	if err != nil {
		logger.Warning("get stdout pipe failed:", err)
		r.state = redshiftStateStopped
		return
	}
	err = cmd.Start()
	if err != nil {
		logger.Warning("start redshift failed:", err)
		r.state = redshiftStateStopped
		return
	}

	r.process = cmd.Process
	r.value = 0

	go func() {
		logger.Debugf("redshift is running, pid: %v", r.process.Pid)
		scanner := bufio.NewScanner(stdout)
		for scanner.Scan() {
			line := scanner.Bytes()
			logger.Debugf("line: %s", line)
			temp, ok := getTemperatureWithLine(line)
			if ok {
				logger.Debug("temp:", temp)
				r.updateValue(temp)
			}
		}
		err := scanner.Err()
		if err != nil {
			logger.Warning("scanner err:", err)
		}

		err = cmd.Wait()
		if err != nil {
			logger.Debugf("redshift cmd wait err: %v, errBuf: %s", err, errBuf.Bytes())
		}
		logger.Debug("redshift stopped")

		r.mu.Lock()
		r.state = redshiftStateStopped
		r.process = nil
		r.mu.Unlock()
	}()

	return
}

func (r *redshiftRunner) stop() {
	r.mu.Lock()
	defer r.mu.Unlock()

	if r.state == redshiftStateStopped {
		return
	}

	logger.Debug("redshiftRunner.stop")
	if r.process != nil {
		err := r.process.Signal(os.Interrupt)
		if err != nil {
			logger.Warning("send signal interrupt to redshift process failed:", err)
		}
	}
	r.value = 0
}

func (r *redshiftRunner) updateValue(value int) {
	r.mu.Lock()
	if r.value == value {
		// no change
		r.mu.Unlock()
		return
	}
	r.value = value
	r.mu.Unlock()

	if r.cb != nil {
		r.cb(value)
	}
}

func (r *redshiftRunner) getValue() int {
	r.mu.Lock()
	defer r.mu.Unlock()
	return r.value
}

func getTemperatureWithLine(line []byte) (int, bool) {
	const prefix = "Temperature: "
	if bytes.HasPrefix(line, []byte(prefix)) {
		numStr := string(line[len(prefix):])
		num, err := strconv.Atoi(numStr)
		return num, err == nil
	}
	return 0, false
}

// dbus 上导出的方法
func (m *Manager) setColorTempValue(value int32) error {
	if m.ColorTemperatureMode != ColorTemperatureModeManual {
		return errors.New("current not manual mode, can not adjust color temperature by manual")
	}
	if !isValidColorTempValue(value) {
		return errors.New("value out of range")
	}
	m.PropsMu.Lock()
	m.setPropColorTemperatureManual(value)
	m.PropsMu.Unlock()
	m.setColorTempOneShot()
	m.saveColorTempValueInCfg(value)
	return nil
}

func isValidColorTempValue(value int32) bool {
	return value >= 1000 && value <= 25000
}

// saveColorTempValueInCfg 保存手动色温值到用户配置
func (m *Manager) saveColorTempValueInCfg(value int32) {
	m.modifySuitableUserMonitorModeConfig(func(cfg *UserMonitorModeConfig) {
		cfg.ColorTemperatureManual = value
	})
	err := m.saveUserConfig()
	if err != nil {
		logger.Warning(err)
	}
}

// saveColorTempModeInCfg 保存色温模式到用户配置
func (m *Manager) saveColorTempModeInCfg(mode int32) {
	m.modifySuitableUserMonitorModeConfig(func(cfg *UserMonitorModeConfig) {
		cfg.ColorTemperatureMode = mode
	})
	err := m.saveUserConfig()
	if err != nil {
		logger.Warning(err)
	}
}

func (m *Manager) getColorTemperatureValue() int {
	m.PropsMu.RLock()
	mode := m.ColorTemperatureMode
	manual := m.ColorTemperatureManual
	m.PropsMu.RUnlock()

	switch mode {
	case ColorTemperatureModeNone:
		return defaultTemperatureManual
	case ColorTemperatureModeManual:
		return int(manual)
	case ColorTemperatureModeAuto:
		return m.redshiftRunner.getValue()
	}

	return defaultTemperatureManual
}

// applyColorTempConfig 应用色温设置
func (m *Manager) applyColorTempConfig(displayMode byte) {
	cfg := m.getSuitableUserMonitorModeConfig(displayMode)
	if cfg == nil {
		cfg = getDefaultUserMonitorModeConfig()
	}
	m.setPropColorTemperatureMode(cfg.ColorTemperatureMode)
	m.setPropColorTemperatureManual(cfg.ColorTemperatureManual)
	m.setColorTempModeReal(m.ColorTemperatureMode)
}

func controlRedshift(action string) {
	// #nosec G204
	_, err := exec.Command("systemctl", "--user", action, "redshift.service").Output()
	if err != nil {
		logger.Warning("failed to ", action, " redshift.service:", err)
	} else {
		logger.Info("success to ", action, " redshift.service")
	}
}

var _setColorTempMu sync.Mutex

func (m *Manager) setColorTempOneShot() {
	_setColorTempMu.Lock()
	defer _setColorTempMu.Unlock()

	monitors := m.getConnectedMonitors()
	for _, monitor := range monitors {
		monitor.PropsMu.RLock()
		br := monitor.Brightness
		name := monitor.Name
		monitor.PropsMu.RUnlock()

		if m.canSetBrightness(name) {
			err := m.setBrightness(name, br)
			if err != nil {
				logger.Warning(err)
			}
		}
	}
}

const (
	dbusIfcGeoClueAgent  = "org.freedesktop.GeoClue2.Agent"
	dbusPathGeoClueAgent = "/org/freedesktop/GeoClue2/Agent"
)

type geoClueAgent struct {
	MaxAccuracyLevel uint32
}

const (
	AccuracyLevelNone         = 0
	AccuracyLevelCountry      = 1
	AccuracyLevelCity         = 4
	AccuracyLevelNeighborhood = 5
	AccuracyLevelStreet       = 6
	AccuracyLevelExact        = 8
)

func (a *geoClueAgent) GetInterfaceName() string {
	return dbusIfcGeoClueAgent
}

func (a *geoClueAgent) AuthorizeApp(desktopId string, reqAccuracyLevel uint32) (authorized bool, allowedAccuracyLevel uint32, busErr *dbus.Error) {
	// 目前发现这个方法不会被调用。
	logger.Debugf("AuthorizeApp desktopId: %q, reqAccuracyLevel: %v", desktopId, reqAccuracyLevel)
	return true, reqAccuracyLevel, nil
}

func (a *geoClueAgent) GetExportedMethods() dbusutil.ExportedMethods {
	return dbusutil.ExportedMethods{
		{
			Name:    "AuthorizeApp",
			Fn:      a.AuthorizeApp,
			InArgs:  []string{"desktopId", "reqAccuracyLevel"},
			OutArgs: []string{"authorized", "allowedAccuracyLevel"},
		},
	}
}

func (r *redshiftRunner) registerGeoClueAgent() error {
	if r.geoAgentRegistered {
		return nil
	}
	if r.sysService == nil {
		return errors.New("sys service is nil")
	}

	sysBus := r.sysService.Conn()
	agent := &geoClueAgent{
		MaxAccuracyLevel: AccuracyLevelStreet,
	}
	err := r.sysService.Export(dbusPathGeoClueAgent, agent)
	if err != nil {
		return err
	}

	geoManager := geoclue2.NewManager(sysBus)
	err = geoManager.AddAgent(0, "geoclue-demo-agent")
	if err != nil {
		return err
	}

	r.geoAgentRegistered = true
	return nil
}
