import re
from HTMLParser import HTMLParser
from postmarkup import render_bbcode
try:
    import markdown
except ImportError:
    pass

from django.shortcuts import render_to_response
from django.template import RequestContext
from django.http import HttpResponse, Http404
from django.utils.functional import Promise
from django.utils.translation import force_unicode, check_for_language
from django.utils.simplejson import JSONEncoder
from django.template.defaultfilters import urlize as django_urlize
from django.core.paginator import Paginator, EmptyPage, InvalidPage
from django.contrib.sites.models import Site

from djangobb_forum import settings as forum_settings


#compile smiles regexp
_SMILES = [(re.compile(smile_re), path) for smile_re, path in forum_settings.SMILES]


def absolute_url(path):
    return 'http://%s%s' % (Site.objects.get_current().domain, path)


def paged(paged_list_name, per_page):
    """
    Parse page from GET data and pass it to view. Split the
    query set returned from view.
    """

    def decorator(func):
        def wrapper(request, *args, **kwargs):
            result = func(request, *args, **kwargs)
            if not isinstance(result, dict) or 'paged_qs' not in result:
                return result
            try:
                page = int(request.GET.get('page', 1))
            except ValueError:
                page = 1

            real_per_page = per_page

            #if per_page_var:
                #try:
                    #value = int(request.GET[per_page_var])
                #except (ValueError, KeyError):
                    #pass
                #else:
                    #if value > 0:
                        #real_per_page = value

            from django.core.paginator import Paginator
            paginator = Paginator(result['paged_qs'], real_per_page)
            try:
                page_obj = paginator.page(page)
            except (InvalidPage, EmptyPage):
                raise Http404
            result[paged_list_name] = page_obj.object_list
            result['is_paginated'] = page_obj.has_other_pages(),
            result['page_obj'] = page_obj,
            result['page'] = page
            result['page_range'] = paginator.page_range,
            result['pages'] = paginator.num_pages
            result['results_per_page'] = paginator.per_page,
            result['request'] = request
            return result
        return wrapper

    return decorator


class LazyJSONEncoder(JSONEncoder):
    """
    This fing need to save django from crashing.
    """

    def default(self, o):
        if isinstance(o, Promise):
            return force_unicode(o)
        else:
            return super(LazyJSONEncoder, self).default(o)


class JsonResponse(HttpResponse):
    """
    HttpResponse subclass that serialize data into JSON format.
    """

    def __init__(self, data, mimetype='application/json'):
        json_data = LazyJSONEncoder().encode(data)
        super(JsonResponse, self).__init__(
            content=json_data, mimetype=mimetype)


def build_form(Form, _request, GET=False, *args, **kwargs):
    """
    Shorcut for building the form instance of given form class
    """

    if not GET and 'POST' == _request.method:
        form = Form(_request.POST, _request.FILES, *args, **kwargs)
    elif GET and 'GET' == _request.method:
        form = Form(_request.GET, _request.FILES, *args, **kwargs)
    else:
        form = Form(*args, **kwargs)
    return form


class ExcludeTagsHTMLParser(HTMLParser):
        """
        Class for html parsing with excluding specified tags.
        """

        def __init__(self, func, tags=('a', 'pre', 'span')):
            HTMLParser.__init__(self)
            self.func = func
            self.is_ignored = False
            self.tags = tags
            self.html = []

        def handle_starttag(self, tag, attrs):
            self.html.append('<%s%s>' % (tag, self.__html_attrs(attrs)))
            if tag in self.tags:
                self.is_ignored = True

        def handle_data(self, data):
            if not self.is_ignored:
                data = self.func(data)
            self.html.append(data)

        def handle_startendtag(self, tag, attrs):
            self.html.append('<%s%s/>' % (tag, self.__html_attrs(attrs))) 

        def handle_endtag(self, tag):
            self.is_ignored = False
            self.html.append('</%s>' % (tag))

        def handle_entityref(self, name):
            self.html.append('&%s;' % name)

        def handle_charref(self, name):
            self.html.append('&#%s;' % name)

        def unescape(self, s):
            #we don't need unescape data (without this possible XSS-attack)
            return s

        def __html_attrs(self, attrs):
            _attrs = ''
            if attrs:
                _attrs = ' %s' % (' '.join([('%s="%s"' % (k,v)) for k,v in attrs]))
            return _attrs

        def feed(self, data):
            HTMLParser.feed(self, data)
            self.html = ''.join(self.html)


def urlize(data):
    """
    Urlize plain text links in the HTML contents.
   
    Do not urlize content of A and CODE tags.
    """

    parser = ExcludeTagsHTMLParser(django_urlize)
    parser.feed(data)
    urlized_html = parser.html
    parser.close()
    return urlized_html

def _smile_replacer(data):
    for smile, path in _SMILES:
        data = smile.sub(path, data)
    return data

def smiles(data):
    """
    Replace text smiles.
    """

    parser = ExcludeTagsHTMLParser(_smile_replacer)
    parser.feed(data)
    smiled_html = parser.html
    parser.close()
    return smiled_html

def paginate(items, request, per_page, total_count=None):
    try:
        page_number = int(request.GET.get('page', 1))
    except ValueError:
        page_number = 1

    paginator = Paginator(items, per_page)
    pages = paginator.num_pages
    try:
        paged_list_name = paginator.page(page_number).object_list
    except (InvalidPage, EmptyPage):
        raise Http404
    return pages, paginator, paged_list_name 

def set_language(request, language):
    """
    Change the language of session of authenticated user.
    """

    if check_for_language(language):
        request.session['django_language'] = language


def convert_text_to_html(text, markup):
    if markup == 'bbcode':
        text = render_bbcode(text)
    elif markup == 'markdown':
        text = markdown.markdown(text, safe_mode='escape')
    else:
        raise Exception('Invalid markup property: %s' % markup)
    return urlize(text)


class TopicFromPostResult(object):
    """
    Custom Result object to return topics from a post search.

    This function uses a generator to return topic objects from
    results given by haystack on a post query. This eliminates
    loading a large array of topic objects into memory.
    """

    def __init__(self, posts):
        self.posts = posts

    def __len__(self):
        return len(self.posts)

    def __getitem__(self, key):
        if isinstance(key, slice):
            return (self.posts[i].object.topic
                        for i in xrange(*key.indices(len(self))))
        elif isinstance(key, int):
            return self.posts[key].object.topic

        raise TypeError('unknown type in key for __getitem__')