package journald

import (
	"bufio"
	"fmt"
	"io"
	"os/exec"
	"syscall"

	"gitea.d3m0k1d.ru/d3m0k1d/HellreigN/agent/internal/config"
	"gitea.d3m0k1d.ru/d3m0k1d/HellreigN/agent/internal/logsource"
)

var _ logsource.LogSource = new(JournaldLogSource)

type JournaldLogSource struct {
	cmd           *exec.Cmd
	stdout        io.ReadCloser
	stdoutscanner *bufio.Scanner
}

// ReadLine implements logsource.LogSource.
func (j *JournaldLogSource) ReadLine() (string, error) {
	if j.stdoutscanner.Scan() {
		return j.stdoutscanner.Text(), nil
	} else {
		if j.stdoutscanner.Err() == nil {
			return "", fmt.Errorf("%w: %s", logsource.ErrDead, io.EOF)
		}
		return "", j.stdoutscanner.Err()
	}
}
func (j *JournaldLogSource) Close() error {
	_ = j.cmd.Process.Signal(syscall.SIGTERM)
	return j.cmd.Wait()
}

func New(cfg config.ServiceConfig, logdir string) (*JournaldLogSource, error) {
	args := make([]string, 0)
	if cfg.Path != nil {
		args = append(args, "-u", *cfg.Path)
	}
	args = append(args, "-f", "-n", "0", "-o", "short", "--no-pager", "--directory", logdir)
	cmd := exec.Command("journalctl", args...) //nolint:gosec
	stdout, err := cmd.StdoutPipe()
	if err != nil {
		return nil, err
	}
	err = cmd.Start()
	if err != nil {
		return nil, err
	}
	stdoutscanner := bufio.NewScanner(stdout)
	return &JournaldLogSource{cmd, stdout, stdoutscanner}, nil
}