// MsgSyncReq: enable and start services on the remote host (systemd)

// Copyright (C) 2021  Simon Ruderich
//
// 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.
//
// 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 sync

import (
	"fmt"
	"strings"

	"ruderich.org/simon/safcm"
)

func (s *Sync) syncServicesSystemd() error {
	s.log.Debugf("services: checking %s (systemd detected)",
		strings.Join(s.req.Services, " "))
	services, err := s.systemdServiceState(s.req.Services)
	if err != nil {
		return err
	}

	var start, enable []string
	for _, name := range s.req.Services {
		var change safcm.ServiceChange

		x := services[name]
		if x.ActiveState != "active" {
			start = append(start, name)
			change.Started = true
		}
		if x.UnitFileState != "enabled" {
			enable = append(enable, name)
			change.Enabled = true
		}

		if change.Started || change.Enabled {
			change.Name = name
			s.resp.ServiceChanges = append(s.resp.ServiceChanges,
				change)
		}
	}
	if len(start) == 0 && len(enable) == 0 {
		return nil
	}

	if s.req.DryRun {
		return nil
	}

	// Reload service files which were possibly changed during file sync
	// or package installation
	_, _, err = s.cmd.Run("services", "/bin/systemctl", "daemon-reload")
	if err != nil {
		return err
	}
	if len(start) != 0 {
		s.log.Verbosef("services: starting %s",
			strings.Join(start, " "))
		_, _, err := s.cmd.Run("services", append([]string{
			"/bin/systemctl", "start", "--",
		}, start...)...)
		if err != nil {
			return err
		}
	}
	if len(enable) != 0 {
		s.log.Verbosef("services: enabling %s",
			strings.Join(enable, " "))
		_, _, err := s.cmd.Run("services", append([]string{
			"/bin/systemctl", "enable", "--",
		}, enable...)...)
		if err != nil {
			return err
		}
	}

	return nil
}

type SystemdService struct {
	ActiveState   string
	UnitFileState string
}

func (s *Sync) systemdServiceState(services []string) (
	map[string]SystemdService, error) {

	out, _, err := s.cmd.Run("services", append([]string{
		"/bin/systemctl",
		"show",
		"--property=ActiveState,UnitFileState,LoadError",
		"--",
	}, services...)...)
	if err != nil {
		return nil, err
	}

	i := 0

	res := make(map[string]SystemdService)
	for _, block := range strings.Split(string(out), "\n\n") {
		lines := strings.Split(strings.TrimSpace(block), "\n")
		if len(lines) != 3 {
			return nil, fmt.Errorf("invalid systemctl output: %q",
				block)
		}

		var service SystemdService
		for _, x := range lines {
			const (
				activePrefix = "ActiveState="
				unitPrefix   = "UnitFileState="
				errorPrefix  = "LoadError="
			)

			if strings.HasPrefix(x, activePrefix) {
				service.ActiveState = strings.TrimPrefix(x,
					activePrefix)
			} else if strings.HasPrefix(x, unitPrefix) {
				service.UnitFileState = strings.TrimPrefix(x,
					unitPrefix)
			} else if strings.HasPrefix(x, errorPrefix) {
				x := strings.TrimPrefix(x, errorPrefix)
				// Older systemd versions (e.g. 237) add empty
				// quotes even if there is no error
				if x != "" && x != ` ""` {
					return nil, fmt.Errorf(
						"systemd unit %q not found",
						services[i])
				}
			} else {
				return nil, fmt.Errorf(
					"invalid systemctl show line %q", x)
			}
		}
		res[services[i]] = service

		i++
	}

	return res, nil
}