"""Some utilities for CubicWeb server/clients.

"""

__docformat__ = "restructuredtext en"

import os

import sys

import decimal

import datetime

import random

from itertools import repeat

from uuid import uuid4

from warnings import warn

from logilab.mtconverter import xml_escape

from logilab.common.deprecation import deprecated

_MARKER = object()

# initialize random seed from current time

random.seed()

def make_uid(key=None):

    """Return a unique identifier string.

    if specified, `key` is used to prefix the generated uid so it can be used

    for instance as a DOM id or as sql table names.

    See uuid.uuid4 documentation for the shape of the generated identifier, but

    this is basicallly a 32 bits hexadecimal string.

    """

    if key is None:

        return uuid4().hex

    return str(key) + uuid4().hex

def dump_class(cls, clsname):

    """create copy of a class by creating an empty class inheriting

    from the given cls.

    Those class will be used as place holder for attribute and relation

    description

    """

    # type doesn't accept unicode name

    # return type.__new__(type, str(clsname), (cls,), {})

    # __autogenerated__ attribute is just a marker

    return type(str(clsname), (cls,), {'__autogenerated__': True,

                                       '__doc__': cls.__doc__,

                                       '__module__': cls.__module__})

# use networkX instead ?

# http://networkx.lanl.gov/reference/algorithms.traversal.html#module-networkx.algorithms.traversal.astar

def transitive_closure_of(entity, relname, _seen=None):

    """return transitive closure *for the subgraph starting from the given

    entity* (eg 'parent' entities are not included in the results)

    """

    if _seen is None:

        _seen = set()

    _seen.add(entity.eid)

    yield entity

    for child in getattr(entity, relname):

        if child.eid in _seen:

            continue

        for subchild in transitive_closure_of(child, relname, _seen):

            yield subchild

class SizeConstrainedList(list):

    """simple list that makes sure the list does not get bigger

    than a given size.

    when the list is full and a new element is added, the first

    element of the list is removed before appending the new one

    >>> l = SizeConstrainedList(2)

    >>> l.append(1)

    >>> l.append(2)

    >>> l

    [1, 2]

    >>> l.append(3)

    [2, 3]

    """

    def __init__(self, maxsize):

        self.maxsize = maxsize

    def append(self, element):

        if len(self) == self.maxsize:

            del self[0]

        super(SizeConstrainedList, self).append(element)

    def extend(self, sequence):

        super(SizeConstrainedList, self).extend(sequence)

        keepafter = len(self) - self.maxsize

        if keepafter > 0:

            del self[:keepafter]

    __iadd__ = extend

class RepeatList(object):

    """fake a list with the same element in each row"""

    __slots__ = ('_size', '_item')

    def __init__(self, size, item):

        self._size = size

        self._item = item

    def __len__(self):

        return self._size

    def __nonzero__(self):

        return self._size

    def __iter__(self):

        return repeat(self._item, self._size)

    def __getitem__(self, index):

        return self._item

    def __getslice__(self, i, j):

        # XXX could be more efficient, but do we bother?

        return ([self._item] * self._size)[i:j]

    def __add__(self, other):

        if isinstance(other, RepeatList):

            if other._item == self._item:

                return RepeatList(self._size + other._size, self._item)

            return ([self._item] * self._size) + other[:]

        return ([self._item] * self._size) + other

    def __radd__(self, other):

        if isinstance(other, RepeatList):

            if other._item == self._item:

                return RepeatList(self._size + other._size, self._item)

            return other[:] + ([self._item] * self._size)

        return other[:] + ([self._item] * self._size)

    def __eq__(self, other):

        if isinstance(other, RepeatList):

            return other._size == self.size and other._item == self.item

        return self[:] == other

    def pop(self, i):

        self._size -= 1

class UStringIO(list):

    """a file wrapper which automatically encode unicode string to an encoding

    specifed in the constructor

    """

    def __nonzero__(self):

        return True

    def write(self, value):

        assert isinstance(value, unicode), u"unicode required not %s : %s"\

                                     % (type(value).__name__, repr(value))

        self.append(value)

    def getvalue(self):

        return u''.join(self)

    def __repr__(self):

        return '<%s at %#x>' % (self.__class__.__name__, id(self))

class HTMLHead(UStringIO):

    """wraps HTML header's stream

    Request objects use a HTMLHead instance to ease adding of

    javascripts and stylesheets

    """

    js_unload_code = u'jQuery(window).unload(unloadPageData);'

    def __init__(self):

        super(HTMLHead, self).__init__()

        self.jsvars = []

        self.jsfiles = []

        self.cssfiles = []

        self.ie_cssfiles = []

        self.post_inlined_scripts = []

        self.pagedata_unload = False

    def add_raw(self, rawheader):

        self.write(rawheader)

    def define_var(self, var, value, override=True):

        """adds a javascript var declaration / assginment in the header

        :param var: the variable name

        :param value: the variable value (as a raw python value,

                      it will be jsonized later)

        :param override: if False, don't set the variable value if the variable

                         is already defined. Default is True.

        """

        self.jsvars.append( (var, value, override) )

    def add_post_inline_script(self, content):

        self.post_inlined_scripts.append(content)

    def add_onload(self, jscode, jsoncall=_MARKER):

        if jsoncall is not _MARKER:

            warn('[3.7] specifying jsoncall is not needed anymore',

                 DeprecationWarning, stacklevel=2)

        self.add_post_inline_script(u"""jQuery(CubicWeb).one('server-response', function(event) {

%s});""" % jscode)

    def add_js(self, jsfile):

        """adds `jsfile` to the list of javascripts used in the webpage

        This function checks if the file has already been added

        :param jsfile: the script's URL

        """

        if jsfile not in self.jsfiles:

            self.jsfiles.append(jsfile)

    def add_css(self, cssfile, media):

        """adds `cssfile` to the list of javascripts used in the webpage

        This function checks if the file has already been added

        :param cssfile: the stylesheet's URL

        """

        if (cssfile, media) not in self.cssfiles:

            self.cssfiles.append( (cssfile, media) )

    def add_ie_css(self, cssfile, media='all', iespec=u'[if lt IE 8]'):

        """registers some IE specific CSS"""

        if (cssfile, media, iespec) not in self.ie_cssfiles:

            self.ie_cssfiles.append( (cssfile, media, iespec) )

    def add_unload_pagedata(self):

        """registers onunload callback to clean page data on server"""

        if not self.pagedata_unload:

            self.post_inlined_scripts.append(self.js_unload_code)

            self.pagedata_unload = True

    def getvalue(self, skiphead=False):

        """reimplement getvalue to provide a consistent (and somewhat browser

        optimzed cf. http://stevesouders.com/cuzillion) order in external

        resources declaration

        """

        w = self.write

        # 1/ variable declaration if any

        if self.jsvars:

            w(u'<script type="text/javascript"><!--//--><![CDATA[//><!--\n')

            for var, value, override in self.jsvars:

                vardecl = u'%s = %s;' % (var, json.dumps(value))

                if not override:

                    vardecl = (u'if (typeof %s == "undefined") {%s}' %

                               (var, vardecl))

                w(vardecl + u'\n')

            w(u'//--><!]]></script>\n')

        # 2/ css files

        for cssfile, media in self.cssfiles:

            w(u'<link rel="stylesheet" type="text/css" media="%s" href="%s"/>\n' %

              (media, xml_escape(cssfile)))

        # 3/ ie css if necessary

        if self.ie_cssfiles:

            for cssfile, media, iespec in self.ie_cssfiles:

                w(u'<!--%s>\n' % iespec)

                w(u'<link rel="stylesheet" type="text/css" media="%s" href="%s"/>\n' %

                  (media, xml_escape(cssfile)))

            w(u'<![endif]--> \n')

        # 4/ js files

        for jsfile in self.jsfiles:

            w(u'<script type="text/javascript" src="%s"></script>\n' %

              xml_escape(jsfile))

        # 5/ post inlined scripts (i.e. scripts depending on other JS files)

        if self.post_inlined_scripts:

            w(u'<script type="text/javascript">\n')

            w(u'\n\n'.join(self.post_inlined_scripts))

            w(u'\n</script>\n')

        header = super(HTMLHead, self).getvalue()

        if skiphead:

            return header

        return u'<head>\n%s</head>\n' % header

class HTMLStream(object):

    """represents a HTML page.

    This is used my main templates so that HTML headers can be added

    at any time during the page generation.

    HTMLStream uses the (U)StringIO interface to be compliant with

    existing code.

    """

    def __init__(self, req):

        # stream for <head>

        self.head = req.html_headers

        # main stream

        self.body = UStringIO()

        self.doctype = u''

        # xmldecl and html opening tag

        self.xmldecl = u'<?xml version="1.0" encoding="%s"?>\n' % req.encoding

        self.htmltag = u'<html xmlns="http://www.w3.org/1999/xhtml" ' \

                       'xmlns:cubicweb="http://www.logilab.org/2008/cubicweb" ' \

                       'xml:lang="%s" lang="%s">' % (req.lang, req.lang)

        # keep main_stream's reference on req for easier text/html demoting

        req.main_stream = self

    def write(self, data):

        """StringIO interface: this method will be assigned to self.w

        """

        self.body.write(data)

    def getvalue(self):

        """writes HTML headers, closes </head> tag and writes HTML body"""

        return u'%s\n%s\n%s\n%s\n%s\n</html>' % (self.xmldecl, self.doctype,

                                                 self.htmltag,

                                                 self.head.getvalue(),

                                                 self.body.getvalue())

def _pdf_conversion_availability():

    try:

        import pysixt

    except ImportError:

        return False

    from subprocess import Popen, STDOUT

    if not os.path.isfile('/usr/bin/fop'):

        return False

    try:

        Popen(['/usr/bin/fop', '-q'],

              stdout=open(os.devnull, 'w'),

              stderr=STDOUT)

    except OSError, e:

        getLogger('cubicweb').info('fop not usable (%s)', e)

        return False

    return True

def can_do_pdf_conversion(__answer_cache=[]):

    """pdf conversion depends on

    * pysixt (python package)

    * fop 0.9x

    NOTE: actual check is done by _pdf_conversion_availability and

    result is cached

    """

    if not __answer_cache: # first time, not in cache

        __answer_cache.append(_pdf_conversion_availability())

    return __answer_cache[0]

try:

    # may not be there if cubicweb-web not installed

    if sys.version_info < (2,6):

        import simplejson as json

    else:

        import json

except ImportError:

    pass

else:

    class CubicWebJsonEncoder(json.JSONEncoder):

        """define a json encoder to be able to encode yams std types"""

        # _iterencode is the only entry point I've found to use a custom encode

        # hook early enough: .default() is called if nothing else matched before,

        # .iterencode() is called once on the main structure to encode and then

        # never gets called again.

        # For the record, our main use case is in FormValidateController with:

        #   json.dumps((status, args, entity), cls=CubicWebJsonEncoder)

        # where we want all the entity attributes, including eid, to be part

        # of the json object dumped.

        # This would have once more been easier if Entity didn't extend dict.

        def _iterencode(self, obj, markers=None):

            if hasattr(obj, '__json_encode__'):

                obj = obj.__json_encode__()

            return json.JSONEncoder._iterencode(self, obj, markers)

        def default(self, obj):

            if isinstance(obj, datetime.datetime):

                return obj.strftime('%Y/%m/%d %H:%M:%S')

            elif isinstance(obj, datetime.date):

                return obj.strftime('%Y/%m/%d')

            elif isinstance(obj, datetime.time):

                return obj.strftime('%H:%M:%S')

            elif isinstance(obj, datetime.timedelta):

                return (obj.days * 24 * 60 * 60) + obj.seconds

            elif isinstance(obj, decimal.Decimal):

                return float(obj)

            try:

                return json.JSONEncoder.default(self, obj)

            except TypeError: