from __future__ import with_statement
import argparse
from datetime import datetime, timedelta
from fnmatch import fnmatchcase
import grp
import os
import pwd
import re
import stat
import struct
import sys
import time
import urllib


def day_of_year(d):
    """Calculate the "day of year" from a date object"""
    return int(d.strftime('%j'))


# OSX filenames are UTF-8 Only so any non-utf8 filenames are url encoded
if sys.platform == 'darwin':
    def encode_filename(name):
        try:
            name.decode('utf-8')
            return name
        except UnicodeDecodeError:
            return urllib.quote(name)
else:
    encode_filename = str


class Counter(object):

    __slots__ = ('v',)

    def __init__(self, value=0):
        self.v = value

    def inc(self, amount=1):
        self.v += amount

    def dec(self, amount=1):
        self.v -= amount

    def __cmp__(self, x):
        return cmp(self.v, x)

    def __repr__(self):
        return '<Counter(%r)>' % self.v


def get_keys_dir():
    """Determine where to store keys and cache"""
    return os.environ.get('DARC_KEYS_DIR',
                          os.path.join(os.path.expanduser('~'), '.darc', 'keys'))


def get_cache_dir():
    """Determine where to store keys and cache"""
    return os.environ.get('DARC_CACHE_DIR',
                          os.path.join(os.path.expanduser('~'), '.darc', 'cache'))


def deferrable(f):
    def wrapper(*args, **kw):
        callback = kw.pop('callback', None)
        if callback:
            data = kw.pop('callback_data', None)
            try:
                res = f(*args, **kw)
            except Exception, e:
                callback(None, e, data)
            else:
                callback(res, None, data)
        else:
            return f(*args, **kw)
    return wrapper


def error_callback(res, error, data):
    if res:
        raise res


def to_localtime(ts):
    """Convert datetime object from UTC to local time zone"""
    return ts - timedelta(seconds=time.altzone)


def read_set(path):
    """Read set from disk (as int32s)
    """
    with open(path, 'rb') as fd:
        data = fd.read()
        return set(struct.unpack('<%di' % (len(data) / 4), data))


def write_set(s, path):
    """Write set to disk (as int32s)
    """
    with open(path, 'wb') as fd:
        fd.write(struct.pack('<%di' % len(s), *s))


def encode_long(v):
    bytes = []
    while True:
        if v > 0x7f:
            bytes.append(0x80 | (v % 0x80))
            v >>= 7
        else:
            bytes.append(v)
            return ''.join(chr(x) for x in bytes)


def decode_long(bytes):
    v = 0
    base = 0
    for x in bytes:
        b = ord(x)
        if b & 0x80:
            v += (b & 0x7f) << base
            base += 7
        else:
            return v + (b << base)


def exclude_path(path, patterns):
    """Used by create and extract sub-commands to determine
    if an item should be processed or not
    """
    for pattern in (patterns or []):
        if pattern.match(path):
            return isinstance(pattern, ExcludePattern)
    return False


class IncludePattern(object):
    """--include PATTERN

    >>> py = IncludePattern('*.py')
    >>> foo = IncludePattern('/foo')
    >>> py.match('/foo/foo.py')
    True
    >>> py.match('/bar/foo.java')
    False
    >>> foo.match('/foo/foo.py')
    True
    >>> foo.match('/bar/foo.java')
    False
    >>> foo.match('/foobar/foo.py')
    False
    >>> foo.match('/foo')
    True
    """
    def __init__(self, pattern):
        self.pattern = self.dirpattern = pattern
        if not pattern.endswith(os.path.sep):
            self.dirpattern += os.path.sep

    def match(self, path):
        dir, name = os.path.split(path)
        return (path == self.pattern
                or (dir + os.path.sep).startswith(self.dirpattern)
                or fnmatchcase(name, self.pattern))

    def __repr__(self):
        return '%s(%s)' % (type(self), self.pattern)


class ExcludePattern(IncludePattern):
    """
    """


def walk_path(path, skip_inodes=None):
    st = os.lstat(path)
    if skip_inodes and (st.st_ino, st.st_dev) in skip_inodes:
        return
    yield path, st
    if stat.S_ISDIR(st.st_mode):
        for f in os.listdir(path):
            for x in walk_path(os.path.join(path, f), skip_inodes):
                yield x


def format_time(t):
    """Format datetime suitable for fixed length list output
    """
    if (datetime.now() - t).days < 365:
        return t.strftime('%b %d %H:%M')
    else:
        return t.strftime('%b %d  %Y')


def format_file_mode(mod):
    """Format file mode bits for list output
    """
    def x(v):
        return ''.join(v & m and s or '-'
                       for m, s in ((4, 'r'), (2, 'w'), (1, 'x')))
    return '%s%s%s' % (x(mod / 64), x(mod / 8), x(mod))

def format_file_size(v):
    """Format file size into a human friendly format
    """
    if v > 1024 * 1024 * 1024:
        return '%.2f GB' % (v / 1024. / 1024. / 1024.)
    elif v > 1024 * 1024:
        return '%.2f MB' % (v / 1024. / 1024.)
    elif v > 1024:
        return '%.2f kB' % (v / 1024.)
    else:
        return str(v)

class IntegrityError(Exception):
    """
    """

def memoize(function):
    cache = {}
    def decorated_function(*args):
        try:
            return cache[args]
        except KeyError:
            val = function(*args)
            cache[args] = val
            return val
    return decorated_function

@memoize
def uid2user(uid):
    try:
        return pwd.getpwuid(uid).pw_name
    except KeyError:
        return None

@memoize
def user2uid(user):
    try:
        return pwd.getpwnam(user).pw_uid
    except KeyError:
        return None

@memoize
def gid2group(gid):
    try:
        return grp.getgrgid(gid).gr_name
    except KeyError:
        return None

@memoize
def group2gid(group):
    try:
        return grp.getgrnam(group).gr_gid
    except KeyError:
        return None


class Location(object):
    """Object representing a store / archive location

    >>> Location('ssh://user@host:1234/some/path::archive')
    Location(proto='ssh', user='user', host='host', port=1234, path='/some/path', archive='archive')
    >>> Location('file:///some/path::archive')
    Location(proto='file', user=None, host=None, port=None, path='/some/path', archive='archive')
    >>> Location('user@host:/some/path::archive')
    Location(proto='ssh', user='user', host='host', port=22, path='/some/path', archive='archive')
    >>> Location('/some/path::archive')
    Location(proto='file', user=None, host=None, port=None, path='/some/path', archive='archive')
    """
    proto = user = host = port = path = archive = None
    ssh_re = re.compile(r'(?P<proto>ssh)://(?:(?P<user>[^@]+)@)?'
                        r'(?P<host>[^:/#]+)(?::(?P<port>\d+))?'
                        r'(?P<path>[^:]*)(?:::(?P<archive>.+))?')
    file_re = re.compile(r'(?P<proto>file)://'
                         r'(?P<path>[^:]*)(?:::(?P<archive>.+))?')
    scp_re = re.compile(r'((?:(?P<user>[^@]+)@)?(?P<host>[^:/]+):)?'
                        r'(?P<path>[^:]*)(?:::(?P<archive>.+))?')

    def __init__(self, text):
        if not self.parse(text):
            raise ValueError

    def parse(self, text):
        m = self.ssh_re.match(text)
        if m:
            self.proto = m.group('proto')
            self.user = m.group('user')
            self.host = m.group('host')
            self.port = m.group('port') and int(m.group('port')) or 22
            self.path = m.group('path')
            self.archive = m.group('archive')
            return True
        m = self.file_re.match(text)
        if m:
            self.proto = m.group('proto')
            self.path = m.group('path')
            self.archive = m.group('archive')
            return True
        m = self.scp_re.match(text)
        if m:
            self.user = m.group('user')
            self.host = m.group('host')
            self.path = m.group('path')
            self.archive = m.group('archive')
            self.proto = self.host and 'ssh' or 'file'
            if self.proto == 'ssh':
                self.port = 22
            return True
        return False

    def __str__(self):
        items = []
        items.append('proto=%r' % self.proto)
        items.append('user=%r' % self.user)
        items.append('host=%r' % self.host)
        items.append('port=%r' % self.port)
        items.append('path=%r'% self.path)
        items.append('archive=%r' % self.archive)
        return ', '.join(items)

    def to_key_filename(self):
        name = re.sub('[^\w]', '_', self.path).strip('_')
        if self.proto != 'file':
            name = self.host + '__' + name
        return os.path.join(get_keys_dir(), name)

    def __repr__(self):
        return "Location(%s)" % self


def location_validator(archive=None):
    def validator(text):
        try:
            loc = Location(text)
        except ValueError:
            raise argparse.ArgumentTypeError('Invalid location format: "%s"' % text)
        if archive is True and not loc.archive:
            raise argparse.ArgumentTypeError('"%s": No archive specified' % text)
        elif archive is False and loc.archive:
            raise argparse.ArgumentTypeError('"%s" No archive can be specified' % text)
        return loc
    return validator