reader.py

import subprocess
import sys
import os
from typing import Optional, List


class JournalReader:
    def __init__(self):
        self._check_availability()

    def _check_availability(self):
        if not os.path.exists('/bin/systemctl') and not os.path.exists('/usr/bin/systemctl'):
            raise RuntimeError("systemd is not available on this system")

    def _is_journalctl_available(self) -> bool:
        for path in ['/bin/journalctl', '/usr/bin/journalctl', '/usr/sbin/journalctl']:
            if os.path.exists(path):
                return True
        result = subprocess.run(['which', 'journalctl'], capture_output=True)
        return result.returncode == 0

    def read_logs(self, boot: int = 0, service: Optional[str] = None) -> List[str]:
        if not self._is_journalctl_available():
            raise RuntimeError("journalctl is not available on this system")

        cmd = ['journalctl', '-b', '-o', 'short-iso', '--no-pager']
        
        if boot < 0:
            cmd[1] = f"-b{boot}"

        if service:
            service_name = service if service.endswith('.service') else f"{service}.service"
            cmd.extend(['-u', service_name])

        cmd.extend(['-p', '0..3'])

        try:
            result = subprocess.run(
                cmd,
                capture_output=True,
                text=True,
                timeout=30
            )
            if result.returncode != 0:
                if 'no entries' in result.stderr.lower():
                    return []
                raise RuntimeError(f"journalctl error: {result.stderr}")
            return result.stdout.splitlines()
        except subprocess.TimeoutExpired:
            raise RuntimeError("journalctl timed out")
        except Exception as e:
            raise RuntimeError(f"Failed to execute journalctl: {str(e)}")