import struct
f = open(r'd:\Users\TermiNexus\Desktop\TransPyC\ViperOS\disk.img', 'rb')
f.seek(0)
first_sector = f.read(512)
first_byte = first_sector[0]

if first_byte == 0xEB or first_byte == 0xE9:
    lba_start = 0
    bpb = first_sector
else:
    ptype = struct.unpack_from('<B', first_sector, 450)[0]
    lba_start = struct.unpack_from('<I', first_sector, 454)[0]
    f.seek(lba_start * 512)
    bpb = f.read(512)

bytes_per_sec = struct.unpack_from('<H', bpb, 11)[0]
sec_per_clus = struct.unpack_from('<B', bpb, 13)[0]
rsvd = struct.unpack_from('<H', bpb, 14)[0]
num_fats = struct.unpack_from('<B', bpb, 16)[0]
root_clus = struct.unpack_from('<I', bpb, 44)[0]
fat_size = struct.unpack_from('<I', bpb, 36)[0]
data_start = rsvd + num_fats * fat_size

print(f'BPS={bytes_per_sec} SPC={sec_per_clus} rsvd={rsvd} NF={num_fats} root_clus={root_clus} fat_size={fat_size} data_start={data_start}')

def read_dir(f, lba_start, data_start, sec_per_clus, bytes_per_sec, cluster, indent="  ", depth=0):
    if depth > 5:
        return
    cluster_sec = data_start + (cluster - 2) * sec_per_clus
    f.seek((lba_start + cluster_sec) * 512)
    dir_data = f.read(sec_per_clus * bytes_per_sec)
    off = 0
    lfn_parts = {}
    while off < len(dir_data):
        first = dir_data[off]
        if first == 0:
            break
        if first == 0xE5:
            off += 32
            lfn_parts = {}
            continue
        attr = dir_data[off + 11]
        if attr == 0x0F:  # LFN entry
            seq = first & 0x3F
            lfn_chars = []
            for i in range(5):
                c = struct.unpack_from('<H', dir_data, off + 2 + i * 2)[0]
                if c != 0xFFFF and c != 0:
                    lfn_chars.append(chr(c))
            for i in range(6):
                c = struct.unpack_from('<H', dir_data, off + 14 + i * 2)[0]
                if c != 0xFFFF and c != 0:
                    lfn_chars.append(chr(c))
            for i in range(2):
                c = struct.unpack_from('<H', dir_data, off + 28 + i * 2)[0]
                if c != 0xFFFF and c != 0:
                    lfn_chars.append(chr(c))
            lfn_parts[seq] = ''.join(lfn_chars)
            off += 32
            continue
        if attr == 8:  # Volume label
            off += 32
            lfn_parts = {}
            continue
        name_bytes = dir_data[off:off + 11]
        name_str = name_bytes.decode('ascii', errors='replace')
        nt_case = dir_data[off + 12]
        clus_hi = struct.unpack_from('<H', dir_data, off + 20)[0]
        clus_lo = struct.unpack_from('<H', dir_data, off + 26)[0]
        clus = (clus_hi << 16) | clus_lo
        fsize = struct.unpack_from('<I', dir_data, off + 28)[0]
        # Reconstruct LFN
        lfn = ''
        if lfn_parts:
            lfn = ''.join(lfn_parts.get(i, '') for i in sorted(lfn_parts.keys()))
        case_info = ""
        if nt_case & 0x08:
            case_info += " [base_lower]"
        if nt_case & 0x10:
            case_info += " [ext_lower]"
        print(f'{indent}SFN=[{name_str}] NT=0x{nt_case:02X}{case_info} LFN="{lfn}" attr=0x{attr:02X} clus={clus} size={fsize}')
        if attr & 0x10 and clus >= 2:
            # Skip . and .. entries
            sfn_name = name_str.rstrip()
            if sfn_name != '.' and sfn_name != '..':
                read_dir(f, lba_start, data_start, sec_per_clus, bytes_per_sec, clus, indent + "  ", depth + 1)
        off += 32
        lfn_parts = {}

read_dir(f, lba_start, data_start, sec_per_clus, bytes_per_sec, root_clus)
f.close()