#!/usr/bin/env python3
"""
Recursive ext4 directory dumper by inode number.
Bypasses all metadata validation - uses extent trees directly.
"""
import struct, os, sys, stat
from pathlib import Path

DEV        = '/dev/dm-0'
BLOCK      = 4096
BACKUP_SB_BLOCK = 32768

import ext4lib

# ── main ─────────────────────────────────────────────────────────────────────

import argparse

def main():
    parser = argparse.ArgumentParser(description='Recover ext4 directory tree by inode')
    parser.add_argument('inode', type=int, help='Root inode number')
    parser.add_argument('dest', help='Destination directory')
    parser.add_argument('--skip-existing', action='store_true',
                        help='Skip recovery if destination directory already exists and is non-empty')
    args = parser.parse_args()

    if args.skip_existing and os.path.isdir(args.dest) and os.listdir(args.dest):
        print(f"Skipping inode {args.inode} -> {args.dest} (already exists)")
        sys.exit(0)

    with open(DEV, 'rb') as f:
        sb_data = ext4lib.read_at(f, BACKUP_SB_BLOCK * BLOCK, 1024)
        sb      = ext4lib.parse_superblock(sb_data)
        assert sb['magic'] == 0xef53

        num_groups = (sb['blocks_count'] + sb['blocks_per_group'] - 1) \
                     // sb['blocks_per_group']
        gdt_data = ext4lib.read_at(f, (BACKUP_SB_BLOCK + 1) * BLOCK,
                           num_groups * sb['desc_size'])

        print(f"Dumping inode {args.inode} -> {args.dest}")
        ext4lib.dump_tree(f, sb, gdt_data, args.inode, args.dest)
        print(f"Done inode {args.inode}")

if __name__ == '__main__':
    main()