//go:build linux
// +build linux

package utils

import (
	"errors"
	"os"
	"time"

	teaconst "github.com/TeaOSLab/EdgeHttpDNS/internal/const"
	executils "github.com/TeaOSLab/EdgeHttpDNS/internal/utils/exec"
	"github.com/iwind/TeaGo/Tea"
)

var systemdServiceFile = "/etc/systemd/system/" + teaconst.SystemdServiceName + ".service"
var initServiceFile = "/etc/init.d/" + teaconst.SystemdServiceName

// Install 安装系统服务
func (m *ServiceManager) Install(exePath string, args []string) error {
	if os.Getgid() != 0 {
		return errors.New("only root users can install the service")
	}

	systemd, err := executils.LookPath("systemctl")
	if err != nil {
		// systemd 不可用，降级到 init.d
		return m.installInitService(exePath, args)
	}

	return m.installSystemdService(systemd, exePath, args)
}

// Start 启动服务
func (m *ServiceManager) Start() error {
	if os.Getgid() != 0 {
		return errors.New("only root users can start the service")
	}

	// 优先检查 systemd
	if fileExists(systemdServiceFile) {
		systemd, err := executils.LookPath("systemctl")
		if err != nil {
			return err
		}
		return executils.NewTimeoutCmd(10*time.Second, systemd, "start", teaconst.SystemdServiceName+".service").Start()
	}

	// 降级到 init.d
	if fileExists(initServiceFile) {
		return executils.NewTimeoutCmd(10*time.Second, "service", teaconst.ProcessName, "start").Start()
	}

	return errors.New("no service file found, please install the service first")
}

// Uninstall 删除服务
func (m *ServiceManager) Uninstall() error {
	if os.Getgid() != 0 {
		return errors.New("only root users can uninstall the service")
	}

	// systemd
	if fileExists(systemdServiceFile) {
		systemd, err := executils.LookPath("systemctl")
		if err == nil {
			_ = executils.NewTimeoutCmd(10*time.Second, systemd, "stop", teaconst.SystemdServiceName+".service").Run()
			_ = executils.NewTimeoutCmd(10*time.Second, systemd, "disable", teaconst.SystemdServiceName+".service").Run()
			_ = executils.NewTimeoutCmd(10*time.Second, systemd, "daemon-reload").Run()
		}
		return os.Remove(systemdServiceFile)
	}

	// init.d
	if fileExists(initServiceFile) {
		_ = executils.NewTimeoutCmd(10*time.Second, "service", teaconst.ProcessName, "stop").Run()
		chkCmd, err := executils.LookPath("chkconfig")
		if err == nil {
			_ = executils.NewTimeoutCmd(10*time.Second, chkCmd, "--del", teaconst.ProcessName).Run()
		}
		return os.Remove(initServiceFile)
	}

	return nil
}

// installSystemdService 安装 systemd 服务
func (m *ServiceManager) installSystemdService(systemd, exePath string, args []string) error {
	shortName := teaconst.SystemdServiceName
	longName := "GoEdge HTTPDNS"

	// 用 bash 包装启动命令，兼容路径含空格的场景
	var startCmd = exePath + " daemon"
	bashPath, _ := executils.LookPath("bash")
	if len(bashPath) > 0 {
		startCmd = bashPath + " -c \"" + startCmd + "\""
	}

	desc := `### BEGIN INIT INFO
# Provides:          ` + shortName + `
# Required-Start:    $all
# Required-Stop:
# Default-Start:     2 3 4 5
# Default-Stop:
# Short-Description: ` + longName + ` Service
### END INIT INFO

[Unit]
Description=` + longName + ` Node Service
Before=shutdown.target
After=network-online.target

[Service]
Type=simple
Restart=always
RestartSec=1s
ExecStart=` + startCmd + `
ExecStop=` + exePath + ` stop
ExecReload=` + exePath + ` restart

[Install]
WantedBy=multi-user.target`

	// 权限 0644，systemd 单元文件不需要执行权限
	err := os.WriteFile(systemdServiceFile, []byte(desc), 0644)
	if err != nil {
		return err
	}

	// 停止已有服务
	_ = executils.NewTimeoutCmd(10*time.Second, systemd, "stop", shortName+".service").Run()

	// 重新加载
	_ = executils.NewTimeoutCmd(10*time.Second, systemd, "daemon-reload").Run()

	// 启用开机自启
	return executils.NewTimeoutCmd(10*time.Second, systemd, "enable", shortName+".service").Run()
}

// installInitService 安装 init.d 服务（降级方案，适用于无 systemd 的旧系统）
func (m *ServiceManager) installInitService(exePath string, args []string) error {
	shortName := teaconst.SystemdServiceName
	longName := "GoEdge HTTPDNS"

	// 生成 init.d 脚本
	script := `#!/bin/bash
### BEGIN INIT INFO
# Provides:          ` + shortName + `
# Required-Start:    $all
# Required-Stop:
# Default-Start:     2 3 4 5
# Default-Stop:      0 1 6
# Short-Description: ` + longName + ` Service
### END INIT INFO

INSTALL_DIR=` + Tea.Root + `

case "$1" in
start)
    cd "${INSTALL_DIR}"
    ` + exePath + ` daemon &
    echo "` + longName + ` started"
    ;;
stop)
    cd "${INSTALL_DIR}"
    ` + exePath + ` stop
    echo "` + longName + ` stopped"
    ;;
restart)
    cd "${INSTALL_DIR}"
    ` + exePath + ` stop
    sleep 1
    ` + exePath + ` daemon &
    echo "` + longName + ` restarted"
    ;;
status)
    cd "${INSTALL_DIR}"
    ` + exePath + ` status
    ;;
*)
    echo "Usage: $0 {start|stop|restart|status}"
    exit 1
    ;;
esac
exit 0
`

	// init.d 脚本需要执行权限
	err := os.WriteFile(initServiceFile, []byte(script), 0755)
	if err != nil {
		return err
	}

	// 尝试用 chkconfig 注册（CentOS/RHEL）
	chkCmd, err := executils.LookPath("chkconfig")
	if err == nil {
		_ = executils.NewTimeoutCmd(10*time.Second, chkCmd, "--add", teaconst.ProcessName).Run()
		return nil
	}

	// 尝试用 update-rc.d 注册（Debian/Ubuntu）
	updateRcCmd, err := executils.LookPath("update-rc.d")
	if err == nil {
		_ = executils.NewTimeoutCmd(10*time.Second, updateRcCmd, teaconst.ProcessName, "defaults").Run()
		return nil
	}

	return nil
}

// fileExists 检查文件是否存在
func fileExists(path string) bool {
	_, err := os.Stat(path)
	return err == nil
}