"""
Restic Backup Monitor (Lightweight)

Checks last backup snapshot age by examining file modification times.
Uses: filesystem checks only (no restic command)

Repository: /mnt/backup-hdd/flotta-backup
"""

from pathlib import Path
from datetime import datetime, timezone
from typing import Dict


class BackupMonitor:
    """Monitor Restic backup status (lightweight file-based check)"""

    SNAPSHOT_DIR = Path('/mnt/backup-hdd/flotta-backup/snapshots')

    def check(self) -> Dict:
        """
        Check backup status by examining snapshot files.

        Tests:
        1. Snapshot directory accessible
        2. Last snapshot file < 30h old (daily at 3 AM, allow margin)
        3. Snapshot file count reasonable

        Returns:
            {
                'status': 'healthy' | 'warning' | 'critical',
                'last_snapshot_age_hours': X,
                'snapshot_count': Y,
                'last_snapshot_date': '...',
                'message': '...'
            }
        """
        try:
            # Check directory exists and is accessible
            if not self.SNAPSHOT_DIR.exists():
                return {
                    'status': 'critical',
                    'message': 'Snapshot directory not found'
                }

            if not self.SNAPSHOT_DIR.is_dir():
                return {
                    'status': 'critical',
                    'message': 'Snapshot path is not a directory'
                }

            # List all snapshot files (exclude . and ..)
            snapshot_files = [
                f for f in self.SNAPSHOT_DIR.iterdir()
                if f.is_file() and not f.name.startswith('.')
            ]

            if not snapshot_files:
                return {
                    'status': 'critical',
                    'snapshot_count': 0,
                    'message': 'No backup snapshots found'
                }

            # Find most recent snapshot by modification time
            latest_snapshot = max(snapshot_files, key=lambda f: f.stat().st_mtime)

            # Get modification time
            mtime = latest_snapshot.stat().st_mtime
            last_time = datetime.fromtimestamp(mtime, tz=timezone.utc)

            # Calculate age
            now = datetime.now(timezone.utc)
            age_hours = (now - last_time).total_seconds() / 3600

            # Determine status (daily backup at 3 AM, allow 30h margin)
            if age_hours < 30:
                status = 'healthy'
            elif age_hours < 48:
                status = 'warning'
            else:
                status = 'critical'

            return {
                'status': status,
                'last_snapshot_age_hours': round(age_hours, 1),
                'snapshot_count': len(snapshot_files),
                'last_snapshot_date': last_time.strftime('%Y-%m-%d %H:%M'),
                'message': f"Last backup {round(age_hours)}h ago ({len(snapshot_files)} snapshots)"
            }

        except PermissionError:
            return {
                'status': 'warning',
                'message': 'Permission denied accessing snapshots directory'
            }
        except Exception as e:
            return {
                'status': 'warning',
                'error': str(e),
                'message': f'Backup check error: {str(e)[:50]}'
            }