#!/usr/bin/env python3
"""
UADF Virtual filesystem

This extfs provides quick and dirty read-only access to disk image files for
the Commodore Amiga adf or adz (gzipped adfs) and dms.

It requires the unadf utility, unfortunately there is no original sources,
since authors page doesn't exists anymore. Luckily, there is a copy of the
source (and useful patches) in Debian repository:
http://packages.debian.org/sid/unadf

There should be one change made to the source of unadf, though. While using
"-lr" switch it by default also displays comments, separated by the comma.
However there is no way to distinguish where filename ends and comment starts,
if comment or filename already contains any comma.

The patched sources are available from: https://github.com/lclevy/ADFlib

It also requires xdms utility, for optional dms support.

Changelog:
    1.3 Switch to Python3
    1.2 Added failsafe for filenames in archive with spaces and nodos message.
    1.1 Moved common code into extfslib library
    1.0 Initial release

Author: Roman 'gryf' Dobosz <gryf73@gmail.com>
Date: 2019-06-30
Version: 1.3
Licence: BSD
"""

import sys
import re
import os
import gzip
from subprocess import check_output, check_call, CalledProcessError
from tempfile import mkstemp, mkdtemp
import shutil

from extfslib import Archive, parse_args


class UAdf(Archive):
    """
    Class for interact with c1541 program and MC
    """
    LINE_PAT = re.compile(b'\s*(?P<size>\d+)?'
                          b'\s{2}(?P<date>\d{4}/\d{2}/\d{2})'
                          b'\s{2}\s?(?P<time>\d+:\d{2}:\d{2})'
                          b'\s{2}(?P<fpath>.*)')
    ARCHIVER = b"unadf"
    DMS = b"xdms"
    CMDS = {"list": b"-lr",
            "read": b"r",
            "write": b"w",
            "delete": b"d"}
    DATETIME = b"%s-%s-%s %02d:%s"

    def __init__(self, fname):
        """Prepare archive content for operations"""
        self._clean = True
        self._arch = fname

        if fname.lower().endswith(".adz"):
            self._ungzip()

        if fname.lower().endswith(".dms"):
            self._undms()

        super(UAdf, self).__init__(self._arch)

    def __del__(self):
        """Cleanup"""
        if not self._clean:
            try:
                os.unlink(self._arch)
            except OSError:
                pass

    def _parse_dt(self, date, time):
        """Return parsed datetime which fulfill extfs standards date."""
        year, month, day = date.split(b"/")
        hours, minutes, _unused = time.split(b":")
        return self.DATETIME % (month, day, year, int(hours), minutes)

    def _ungzip(self):
        """Create temporary file for ungzipped adf file since unadf does not
        accept gzipped content in any way including reading from stdin."""
        fdesc, tmp_fname = mkstemp(suffix=".adf")
        os.close(fdesc)

        with gzip.open(self._arch) as gobj:
            with open(tmp_fname, "wb") as fobj:
                fobj.write(gobj.read())
        self._arch = tmp_fname
        self._clean = False

    def _undms(self):
        """Create temporary adf file extracted from dms."""
        fdesc, tmp_fname = mkstemp(suffix=".adf")
        os.close(fdesc)

        try:
            check_call([self.DMS, b'-q', b'u', self._arch, "+" + tmp_fname])
            self._arch = tmp_fname
            self._clean = False
        except (CalledProcessError, OSError):
            pass

    def _get_dir(self):
        """Retrieve directory"""
        contents = []
        with open(os.devnull, "w") as fnull:
            try:
                out = check_output([self.ARCHIVER, self.CMDS['list'],
                                    self._arch], stderr=fnull)
            except CalledProcessError:
                return contents

        for line in out.split(b"\n"):
            match = self.LINE_PAT.match(line)
            if not match:
                continue

            match_entry = match.groupdict()
            entry = {}
            for key in match_entry:
                entry[bytes(key, 'utf-8')] = match_entry[key]
            del match_entry

            entry[b'perms'] = b"-rw-r--r--"
            if not entry[b'size']:
                entry[b'perms'] = b"drwxr-xr-x"
                entry[b'size'] = b"0"
            entry[b'display_name'] = self._map_name(entry[b'fpath'])
            entry[b'datetime'] = self._parse_dt(entry[b'date'], entry[b'time'])
            entry[b'uid'] = bytes(str(self._uid), 'utf-8')
            entry[b'gid'] = bytes(str(self._gid), 'utf-8')
            contents.append(entry)

        return contents

    def list(self):
        """
        Output list contents of adf image.
        Convert filenames to be Unix filesystem friendly
        Add suffix to show user what kind of file do he dealing with.
        """
        if not self._contents:
            sys.stderr.write("Nodos or archive error\n")
            return 1

        for entry in self._contents:
            sys.stdout.buffer.write(self.ITEM % entry)
        return 0

    def copyout(self, src, dst):
        """Copy file form the adf image."""
        real_src = self._get_real_name(src)
        if not real_src:
            raise IOError("No such file or directory")

        if b" " in real_src:
            sys.stderr.write("unadf is unable to operate on filepath with "
                             "space inside.\nUse affs to mount image and than"
                             " extract desired files.\n")
            return 1

        extract_dir = mkdtemp()
        cmd = [self.ARCHIVER, self._arch, real_src, b"-d", extract_dir]
        if check_call(cmd, stdout=open(os.devnull, 'wb'),
                      stderr=open(os.devnull, 'wb')) != 0:
            shutil.rmtree(extract_dir)
            sys.stderr.write("unadf returned with nonzero exit code\n")
            return 1

        shutil.move(os.path.join(bytes(extract_dir, "utf8"), real_src),
                    bytes(dst, "utf8"))
        shutil.rmtree(extract_dir)

        return 0


if __name__ == "__main__":
    sys.exit(parse_args(UAdf))