"""

Syndication feed generation library -- used for generating RSS, etc.

Sample usage:

>>> from django.utils import feedgenerator

>>> feed = feedgenerator.Rss201rev2Feed(

...     title=u"Poynter E-Media Tidbits",

...     link=u"http://www.poynter.org/column.asp?id=31",

...     description=u"A group weblog by the sharpest minds in online media/journalism/publishing.",

...     language=u"en",

... )

>>> feed.add_item(title="Hello", link=u"http://www.holovaty.com/test/", description="Testing.")

>>> fp = open('test.rss', 'w')

>>> feed.write(fp, 'utf-8')

>>> fp.close()

For definitions of the different versions of RSS, see:

http://diveintomark.org/archives/2004/02/04/incompatible-rss

"""

import re

import datetime

from django.utils.xmlutils import SimplerXMLGenerator

from django.utils.encoding import force_unicode, iri_to_uri

def rfc2822_date(date):

    # We do this ourselves to be timezone aware, email.Utils is not tz aware.

    if date.tzinfo:

        time_str = date.strftime('%a, %d %b %Y %H:%M:%S ')

        offset = date.tzinfo.utcoffset(date)

        timezone = (offset.days * 24 * 60) + (offset.seconds / 60)

        hour, minute = divmod(timezone, 60)

        return time_str + "%+03d%02d" % (hour, minute)

    else:

        return date.strftime('%a, %d %b %Y %H:%M:%S -0000')

def rfc3339_date(date):

    if date.tzinfo:

        time_str = date.strftime('%Y-%m-%dT%H:%M:%S')

        offset = date.tzinfo.utcoffset(date)

        timezone = (offset.days * 24 * 60) + (offset.seconds / 60)

        hour, minute = divmod(timezone, 60)

        return time_str + "%+03d:%02d" % (hour, minute)

    else:

        return date.strftime('%Y-%m-%dT%H:%M:%SZ')

def get_tag_uri(url, date):

    "Creates a TagURI. See http://diveintomark.org/archives/2004/05/28/howto-atom-id"

    tag = re.sub('^http://', '', url)

    if date is not None:

        tag = re.sub('/', ',%s:/' % date.strftime('%Y-%m-%d'), tag, 1)

    tag = re.sub('#', '/', tag)

    return u'tag:' + tag

class SyndicationFeed(object):

    "Base class for all syndication feeds. Subclasses should provide write()"

    def __init__(self, title, link, description, language=None, author_email=None,

            author_name=None, author_link=None, subtitle=None, categories=None,

            feed_url=None, feed_copyright=None, feed_guid=None, ttl=None, **kwargs):

        to_unicode = lambda s: force_unicode(s, strings_only=True)

        if categories:

            categories = [force_unicode(c) for c in categories]

        self.feed = {

            'title': to_unicode(title),

            'link': iri_to_uri(link),

            'description': to_unicode(description),

            'language': to_unicode(language),

            'author_email': to_unicode(author_email),

            'author_name': to_unicode(author_name),

            'author_link': iri_to_uri(author_link),

            'subtitle': to_unicode(subtitle),

            'categories': categories or (),

            'feed_url': iri_to_uri(feed_url),

            'feed_copyright': to_unicode(feed_copyright),

            'id': feed_guid or link,

            'ttl': ttl,

        }

        self.feed.update(kwargs)

        self.items = []

    def add_item(self, title, link, description, author_email=None,

        author_name=None, author_link=None, pubdate=None, comments=None,

        unique_id=None, enclosure=None, categories=(), item_copyright=None,

        ttl=None, **kwargs):

        """

        Adds an item to the feed. All args are expected to be Python Unicode

        objects except pubdate, which is a datetime.datetime object, and

        enclosure, which is an instance of the Enclosure class.

        """

        to_unicode = lambda s: force_unicode(s, strings_only=True)

        if categories:

            categories = [to_unicode(c) for c in categories]

        item = {

            'title': to_unicode(title),

            'link': iri_to_uri(link),

            'description': to_unicode(description),

            'author_email': to_unicode(author_email),

            'author_name': to_unicode(author_name),

            'author_link': iri_to_uri(author_link),

            'pubdate': pubdate,

            'comments': to_unicode(comments),

            'unique_id': to_unicode(unique_id),

            'enclosure': enclosure,

            'categories': categories or (),

            'item_copyright': to_unicode(item_copyright),

            'ttl': ttl,

        }

        item.update(kwargs)

        self.items.append(item)

    def num_items(self):

        return len(self.items)

    def root_attributes(self):

        """

        Return extra attributes to place on the root (i.e. feed/channel) element.

        Called from write().

        """

        return {}

    def add_root_elements(self, handler):

        """

        Add elements in the the root (i.e. feed/channel) element. Called

        from write().

        """

        pass

    def item_attributes(self, item):

        """

        Return extra attributes to place on each item (i.e. item/entry) element.

        """

        return {}

    def add_item_elements(self, handler, item):

        """

        Add elements on each item (i.e. item/entry) element.

        """

        pass

    def write(self, outfile, encoding):

        """

        Outputs the feed in the given encoding to outfile, which is a file-like

        object. Subclasses should override this.

        """

        raise NotImplementedError

    def writeString(self, encoding):

        """

        Returns the feed in the given encoding as a string.

        """

        from StringIO import StringIO

        s = StringIO()

        self.write(s, encoding)

        return s.getvalue()

    def latest_post_date(self):

        """

        Returns the latest item's pubdate. If none of them have a pubdate,

        this returns the current date/time.

        """

        updates = [i['pubdate'] for i in self.items if i['pubdate'] is not None]

        if len(updates) > 0:

            updates.sort()

            return updates[-1]

        else:

            return datetime.datetime.now()

class Enclosure(object):

    "Represents an RSS enclosure"

    def __init__(self, url, length, mime_type):

        "All args are expected to be Python Unicode objects"

        self.length, self.mime_type = length, mime_type

        self.url = iri_to_uri(url)

class RssFeed(SyndicationFeed):

    mime_type = 'application/rss+xml'

    def write(self, outfile, encoding):

        handler = SimplerXMLGenerator(outfile, encoding)

        handler.startDocument()

        handler.startElement(u"rss", self.rss_attributes())

        handler.startElement(u"channel", self.root_attributes())

        self.add_root_elements(handler)

        self.write_items(handler)

        self.endChannelElement(handler)

        handler.endElement(u"rss")

    def rss_attributes(self):

        return {u"version": self._version}

    def write_items(self, handler):

        for item in self.items:

            handler.startElement(u'item', self.item_attributes(item))

            self.add_item_elements(handler, item)

            handler.endElement(u"item")

    def add_root_elements(self, handler):

        handler.addQuickElement(u"title", self.feed['title'])

        handler.addQuickElement(u"link", self.feed['link'])

        handler.addQuickElement(u"description", self.feed['description'])

        if self.feed['language'] is not None:

            handler.addQuickElement(u"language", self.feed['language'])

        for cat in self.feed['categories']:

            handler.addQuickElement(u"category", cat)

        if self.feed['feed_copyright'] is not None:

            handler.addQuickElement(u"copyright", self.feed['feed_copyright'])

        handler.addQuickElement(u"lastBuildDate", rfc2822_date(self.latest_post_date()).decode('utf-8'))

        if self.feed['ttl'] is not None:

            handler.addQuickElement(u"ttl", self.feed['ttl'])

    def endChannelElement(self, handler):

        handler.endElement(u"channel")

class RssUserland091Feed(RssFeed):

    _version = u"0.91"

    def add_item_elements(self, handler, item):

        handler.addQuickElement(u"title", item['title'])

        handler.addQuickElement(u"link", item['link'])

        if item['description'] is not None:

            handler.addQuickElement(u"description", item['description'])

class Rss201rev2Feed(RssFeed):

    # Spec: http://blogs.law.harvard.edu/tech/rss

    _version = u"2.0"

    def add_item_elements(self, handler, item):

        handler.addQuickElement(u"title", item['title'])

        handler.addQuickElement(u"link", item['link'])

        if item['description'] is not None:

            handler.addQuickElement(u"description", item['description'])

        # Author information.

        if item["author_name"] and item["author_email"]:

            handler.addQuickElement(u"author", "%s (%s)" % \

                (item['author_email'], item['author_name']))

        elif item["author_email"]:

            handler.addQuickElement(u"author", item["author_email"])

        elif item["author_name"]:

            handler.addQuickElement(u"dc:creator", item["author_name"], {"xmlns:dc": u"http://purl.org/dc/elements/1.1/"})

        if item['pubdate'] is not None:

            handler.addQuickElement(u"pubDate", rfc2822_date(item['pubdate']).decode('utf-8'))

        if item['comments'] is not None:

            handler.addQuickElement(u"comments", item['comments'])

        if item['unique_id'] is not None:

            handler.addQuickElement(u"guid", item['unique_id'])

        if item['ttl'] is not None:

            handler.addQuickElement(u"ttl", item['ttl'])

        # Enclosure.

        if item['enclosure'] is not None:

            handler.addQuickElement(u"enclosure", '',

                {u"url": item['enclosure'].url, u"length": item['enclosure'].length,

                    u"type": item['enclosure'].mime_type})

        # Categories.

        for cat in item['categories']:

            handler.addQuickElement(u"category", cat)

class Atom1Feed(SyndicationFeed):

    # Spec: http://atompub.org/2005/07/11/draft-ietf-atompub-format-10.html

    mime_type = 'application/atom+xml'

    ns = u"http://www.w3.org/2005/Atom"

    def write(self, outfile, encoding):

        handler = SimplerXMLGenerator(outfile, encoding)

        handler.startDocument()

        handler.startElement(u'feed', self.root_attributes())

        self.add_root_elements(handler)

        self.write_items(handler)

        handler.endElement(u"feed")

    def root_attributes(self):

        if self.feed['language'] is not None:

            return {u"xmlns": self.ns, u"xml:lang": self.feed['language']}

        else:

            return {u"xmlns": self.ns}

    def add_root_elements(self, handler):

        handler.addQuickElement(u"title", self.feed['title'])

        handler.addQuickElement(u"link", "", {u"rel": u"alternate", u"href": self.feed['link']})

        if self.feed['feed_url'] is not None:

            handler.addQuickElement(u"link", "", {u"rel": u"self", u"href": self.feed['feed_url']})

        handler.addQuickElement(u"id", self.feed['id'])

        handler.addQuickElement(u"updated", rfc3339_date(self.latest_post_date()).decode('utf-8'))

        if self.feed['author_name'] is not None:

            handler.startElement(u"author", {})

            handler.addQuickElement(u"name", self.feed['author_name'])

            if self.feed['author_email'] is not None:

                handler.addQuickElement(u"email", self.feed['author_email'])

            if self.feed['author_link'] is not None:

                handler.addQuickElement(u"uri", self.feed['author_link'])

            handler.endElement(u"author")

        if self.feed['subtitle'] is not None:

            handler.addQuickElement(u"subtitle", self.feed['subtitle'])

        for cat in self.feed['categories']:

            handler.addQuickElement(u"category", "", {u"term": cat})

        if self.feed['feed_copyright'] is not None:

            handler.addQuickElement(u"rights", self.feed['feed_copyright'])

    def write_items(self, handler):

        for item in self.items:

            handler.startElement(u"entry", self.item_attributes(item))

            self.add_item_elements(handler, item)

            handler.endElement(u"entry")

    def add_item_elements(self, handler, item):

        handler.addQuickElement(u"title", item['title'])

        handler.addQuickElement(u"link", u"", {u"href": item['link'], u"rel": u"alternate"})

        if item['pubdate'] is not None:

            handler.addQuickElement(u"updated", rfc3339_date(item['pubdate']).decode('utf-8'))

        # Author information.

        if item['author_name'] is not None:

            handler.startElement(u"author", {})

            handler.addQuickElement(u"name", item['author_name'])

            if item['author_email'] is not None:

                handler.addQuickElement(u"email", item['author_email'])

            if item['author_link'] is not None:

                handler.addQuickElement(u"uri", item['author_link'])

            handler.endElement(u"author")

        # Unique ID.

        if item['unique_id'] is not None:

            unique_id = item['unique_id']

        else:

            unique_id = get_tag_uri(item['link'], item['pubdate'])

        handler.addQuickElement(u"id", unique_id)

        # Summary.

        if item['description'] is not None:

            handler.addQuickElement(u"summary", item['description'], {u"type": u"html"})

        # Enclosure.

        if item['enclosure'] is not None:

            handler.addQuickElement(u"link", '',

                {u"rel": u"enclosure",

                 u"href": item['enclosure'].url,

                 u"length": item['enclosure'].length,

                 u"type": item['enclosure'].mime_type})

        # Categories.

        for cat in item['categories']:

            handler.addQuickElement(u"category", u"", {u"term": cat})

        # Rights.

        if item['item_copyright'] is not None:

            handler.addQuickElement(u"rights", item['item_copyright'])

# This isolates the decision of what the system default is, so calling code can

# do "feedgenerator.DefaultFeed" instead of "feedgenerator.Rss201rev2Feed".

DefaultFeed = Rss201rev2Feed