# -*- coding: UTF-8 -*-

# Copyright (c) 2010 - 2011, Pascal Volk

# See COPYING for distribution information.

"""

    VirtualMailManager.common

    ~~~~~~~~~~~~~~~~~~~~~~~~~

    Some common functions

"""

import os

import re

import stat

from VirtualMailManager import ENCODING

from VirtualMailManager.constants import NOT_EXECUTABLE, NO_SUCH_BINARY

from VirtualMailManager.errors import VMMError

VERSION_RE = re.compile(r'^(\d+)\.(\d+)\.(?:(\d+)|(alpha|beta|rc)(\d+))$')

_version_level = dict(alpha=0xA, beta=0xB, rc=0xC)

_version_cache = {}

_ = lambda msg: msg

def expand_path(path):

    """Expands paths, starting with ``.`` or ``~``, to an absolute path."""

    if path.startswith('.'):

        return os.path.abspath(path)

    if path.startswith('~'):

        return os.path.expanduser(path)

    return path

def get_unicode(string):

    """Converts `string` to `unicode`, if necessary."""

    if isinstance(string, unicode):

        return string

    return unicode(string, ENCODING, 'replace')

def lisdir(path):

    """Checks if `path` is a directory.  Doesn't follow symbolic links.

    Returns bool.

    """

    try:

        lstat = os.lstat(path)

    except OSError:

        return False

    return stat.S_ISDIR(lstat.st_mode)

def exec_ok(binary):

    """Checks if the `binary` exists and if it is executable.

    Throws a `VMMError` if the `binary` isn't a file or is not

    executable.

    """

    binary = expand_path(binary)

    if not os.path.isfile(binary):

        raise VMMError(_(u"No such file: '%s'") % get_unicode(binary),

                       NO_SUCH_BINARY)

    if not os.access(binary, os.X_OK):

        raise VMMError(_(u"File is not executable: '%s'") %

                       get_unicode(binary), NOT_EXECUTABLE)

    return binary

def human_size(size):

    """Converts the `size` in bytes in human readable format."""

    unit_limit = (('T', 1 << 40), ('G', 1 << 30), ('M', 1 << 20),

                  ('k', 1 << 10), ('b', 1))

    for unit, limit in unit_limit:

        if size >= limit:

            if unit != 'b':

                return '%.2f%s' % (size / float(limit), unit)

            else:

                return '%ub' % size

def size_in_bytes(size):

    """Converts the string `size` to a long (size in bytes).

    The string `size` can be suffixed with *b* (bytes), *k* (kilobytes),

    *M* (megabytes) or *G* (gigabytes).

    """

    if not isinstance(size, basestring) or not size:

        raise TypeError('size must be a non empty string.')

    if size[-1].upper() in ('B', 'K', 'M', 'G'):

        try:

            num = int(size[:-1])

        except ValueError:

            raise ValueError('Not a valid integer value: %r' % size[:-1])

        unit = size[-1].upper()

        if unit == 'B':

            return num

        elif unit == 'K':

            return num << 10L

        elif unit == 'M':

            return num << 20L

        else:

            return num << 30L

    else:

        try:

            num = int(size)

        except ValueError:

            raise ValueError('Not a valid size value: %r' % size)

        return num

def version_hex(version_string):

    """Converts a Dovecot version, e.g.: '1.2.3' or '2.0.beta4', to an int.

    Raises a `ValueError` if the *version_string* has the wrong™ format.

    version_hex('1.2.3') -> 270548736

    hex(version_hex('1.2.3')) -> '0x10203f00'

    """

    global _version_cache

    if version_string in _version_cache:

        return _version_cache[version_string]

    version = 0

    version_mo = VERSION_RE.match(version_string)

    if not version_mo:

        raise ValueError('Invalid version string: %r' % version_string)

    major, minor, patch, level, serial = version_mo.groups()

    major = int(major)

    minor = int(minor)

    if patch:

        patch = int(patch)

    if serial:

        serial = int(serial)

    if major > 0xFF or minor > 0xFF or \

      patch and patch > 0xFF or serial and serial > 0xFF:

        raise ValueError('Invalid version string: %r' % version_string)

    version += major << 28

    version += minor << 20

    if patch:

        version += patch << 12

    version += _version_level.get(level, 0xF) << 8

    if serial:

        version += serial

    _version_cache[version_string] = version

    return version

def version_str(version):

    """Converts a Dovecot version previously converted with version_hex back to

    a string.

    Raises a `TypeError` if *version* is not an int/long.

    Raises a `ValueError` if *version* is an incorrect int version.

    """

    global _version_cache

    if version in _version_cache:

        return _version_cache[version]

    if not isinstance(version, (int, long)):

        raise TypeError('Argument is not a int/long: %r', version)

    major = (version >> 28) & 0xFF

    minor = (version >> 20) & 0xFF

    patch = (version >> 12) & 0xFF

    level = (version >> 8) & 0x0F

    serial = version & 0xFF

    levels = dict(zip(_version_level.values(), _version_level.keys()))

    if level == 0xF and not serial:

        version_string = '%u.%u.%u' % (major, minor, patch)

    elif level in levels and not patch:

        version_string = '%u.%u.%s%u' % (major, minor, levels[level], serial)

    else:

        raise ValueError('Invalid version: %r' % hex(version))

    _version_cache[version] = version_string

    return version_string

del _