entry.py

# -*- coding: utf-8 -*-
'''
    feedgen.entry
    ~~~~~~~~~~~~~

    :copyright: 2013, Lars Kiesow <lkiesow@uos.de>

    :license: FreeBSD and LGPL, see license.* for more details.
'''

from lxml import etree
from datetime import datetime
import dateutil.parser
import dateutil.tz
from feedgen.util import ensure_format, formatRFC2822
from feedgen.compat import string_types


class FeedEntry(object):
    '''FeedEntry call representing an ATOM feeds entry node or an RSS feeds item
    node.
    '''

    def __init__(self):
        # ATOM
        # required
        self.__atom_id = None
        self.__atom_title = None
        self.__atom_updated = datetime.now(dateutil.tz.tzutc())

        # recommended
        self.__atom_author = None
        self.__atom_content = None
        self.__atom_link = None
        self.__atom_summary = None

        # optional
        self.__atom_category = None
        self.__atom_contributor = None
        self.__atom_published = None
        self.__atom_source = None
        self.__atom_rights = None

        # RSS
        self.__rss_author = None
        self.__rss_category = None
        self.__rss_comments = None
        self.__rss_description = None
        self.__rss_content = None
        self.__rss_enclosure = None
        self.__rss_guid = None
        self.__rss_link = None
        self.__rss_pubDate = None
        self.__rss_source = None
        self.__rss_title = None

        # Extension list:
        self.__extensions = {}
        self.__extensions_register = {}

    def atom_entry(self, extensions=True):
        '''Create an ATOM entry and return it.'''
        entry = etree.Element('entry')
        if not (self.__atom_id and self.__atom_title and self.__atom_updated):
            raise ValueError('Required fields not set')
        id = etree.SubElement(entry, 'id')
        id.text = self.__atom_id
        title = etree.SubElement(entry, 'title')
        title.text = self.__atom_title
        updated = etree.SubElement(entry, 'updated')
        updated.text = self.__atom_updated.isoformat()

        # An entry must contain an alternate link if there is no content
        # element.
        if not self.__atom_content:
            links = self.__atom_link or []
            if not [l for l in links if l.get('rel') == 'alternate']:
                raise ValueError('Entry must contain an alternate link or ' +
                                 'a content element.')

        # Add author elements
        for a in self.__atom_author or []:
            # Atom requires a name. Skip elements without.
            if not a.get('name'):
                continue
            author = etree.SubElement(entry, 'author')
            name = etree.SubElement(author, 'name')
            name.text = a.get('name')
            if a.get('email'):
                email = etree.SubElement(author, 'email')
                email.text = a.get('email')
            if a.get('uri'):
                uri = etree.SubElement(author, 'uri')
                uri.text = a.get('uri')

        if self.__atom_content:
            content = etree.SubElement(entry, 'content')
            type = self.__atom_content.get('type')
            if self.__atom_content.get('src'):
                content.attrib['src'] = self.__atom_content['src']
            elif self.__atom_content.get('content'):
                # Surround xhtml with a div tag, parse it and embed it
                if type == 'xhtml':
                    content.append(etree.fromstring(
                        '<div xmlns="http://www.w3.org/1999/xhtml">' +
                        self.__atom_content.get('content') + '</div>'))
                elif type == 'CDATA':
                    content.text = etree.CDATA(
                            self.__atom_content.get('content'))
                # Emed the text in escaped form
                elif not type or type.startswith('text') or type == 'html':
                    content.text = self.__atom_content.get('content')
                # Parse XML and embed it
                elif type.endswith('/xml') or type.endswith('+xml'):
                    content.append(etree.fromstring(
                        self.__atom_content['content']))
                # Everything else should be included base64 encoded
                else:
                    raise ValueError('base64 encoded content is not ' +
                                     'supported at the moment. Pull requests' +
                                     ' adding support are welcome.')
            # Add type description of the content
            if type:
                content.attrib['type'] = type

        for l in self.__atom_link or []:
            link = etree.SubElement(entry, 'link', href=l['href'])
            if l.get('rel'):
                link.attrib['rel'] = l['rel']
            if l.get('type'):
                link.attrib['type'] = l['type']
            if l.get('hreflang'):
                link.attrib['hreflang'] = l['hreflang']
            if l.get('title'):
                link.attrib['title'] = l['title']
            if l.get('length'):
                link.attrib['length'] = l['length']

        if self.__atom_summary:
            summary = etree.SubElement(entry, 'summary')
            summary.text = self.__atom_summary

        for c in self.__atom_category or []:
            cat = etree.SubElement(entry, 'category', term=c['term'])
            if c.get('scheme'):
                cat.attrib['scheme'] = c['scheme']
            if c.get('label'):
                cat.attrib['label'] = c['label']

        # Add author elements
        for c in self.__atom_contributor or []:
            # Atom requires a name. Skip elements without.
            if not c.get('name'):
                continue
            contrib = etree.SubElement(entry, 'contributor')
            name = etree.SubElement(contrib, 'name')
            name.text = c.get('name')
            if c.get('email'):
                email = etree.SubElement(contrib, 'email')
                email.text = c.get('email')
            if c.get('uri'):
                uri = etree.SubElement(contrib, 'uri')
                uri.text = c.get('uri')

        if self.__atom_published:
            published = etree.SubElement(entry, 'published')
            published.text = self.__atom_published.isoformat()

        if self.__atom_rights:
            rights = etree.SubElement(entry, 'rights')
            rights.text = self.__atom_rights

        if extensions:
            for ext in self.__extensions.values() or []:
                if ext.get('atom'):
                    ext['inst'].extend_atom(entry)

        return entry

    def rss_entry(self, extensions=True):
        '''Create a RSS item and return it.'''
        entry = etree.Element('item')
        if not (self.__rss_title or
                self.__rss_description or
                self.__rss_content):
            raise ValueError('Required fields not set')
        if self.__rss_title:
            title = etree.SubElement(entry, 'title')
            title.text = self.__rss_title
        if self.__rss_link:
            link = etree.SubElement(entry, 'link')
            link.text = self.__rss_link
        if self.__rss_description and self.__rss_content:
            description = etree.SubElement(entry, 'description')
            description.text = self.__rss_description
            XMLNS_CONTENT = 'http://purl.org/rss/1.0/modules/content/'
            content = etree.SubElement(entry, '{%s}encoded' % XMLNS_CONTENT)
            content.text = etree.CDATA(self.__rss_content['content']) \
                if self.__rss_content.get('type', '') == 'CDATA' \
                else self.__rss_content['content']
        elif self.__rss_description:
            description = etree.SubElement(entry, 'description')
            description.text = self.__rss_description
        elif self.__rss_content:
            description = etree.SubElement(entry, 'description')
            description.text = self.__rss_content['content']
        for a in self.__rss_author or []:
            author = etree.SubElement(entry, 'author')
            author.text = a
        if self.__rss_guid:
            guid = etree.SubElement(entry, 'guid')
            guid.text = self.__rss_guid
            guid.attrib['isPermaLink'] = 'false'
        for cat in self.__rss_category or []:
            category = etree.SubElement(entry, 'category')
            category.text = cat['value']
            if cat.get('domain'):
                category.attrib['domain'] = cat['domain']
        if self.__rss_comments:
            comments = etree.SubElement(entry, 'comments')
            comments.text = self.__rss_comments
        if self.__rss_enclosure:
            enclosure = etree.SubElement(entry, 'enclosure')
            enclosure.attrib['url'] = self.__rss_enclosure['url']
            enclosure.attrib['length'] = self.__rss_enclosure['length']
            enclosure.attrib['type'] = self.__rss_enclosure['type']
        if self.__rss_pubDate:
            pubDate = etree.SubElement(entry, 'pubDate')
            pubDate.text = formatRFC2822(self.__rss_pubDate)

        if extensions:
            for ext in self.__extensions.values() or []:
                if ext.get('rss'):
                    ext['inst'].extend_rss(entry)

        return entry

    def title(self, title=None):
        '''Get or set the title value of the entry. It should contain a human
        readable title for the entry. Title is mandatory for both ATOM and RSS
        and should not be blank.

        :param title: The new title of the entry.
        :returns: The entriess title.
        '''
        if title is not None:
            self.__atom_title = title
            self.__rss_title = title
        return self.__atom_title

    def id(self, id=None):
        '''Get or set the entry id which identifies the entry using a
        universally unique and permanent URI. Two entries in a feed can have
        the same value for id if they represent the same entry at different
        points in time. This method will also set rss:guid.  Id is mandatory
        for an ATOM entry.

        :param id: New Id of the entry.
        :returns: Id of the entry.
        '''
        if id is not None:
            self.__atom_id = id
            self.__rss_guid = id
        return self.__atom_id

    def guid(self, guid=None):
        '''Get or set the entries guid which is a string that uniquely
        identifies the item. This will also set atom:id.

        :param guid: Id of the entry.
        :returns: Id of the entry.
        '''
        return self.id(guid)

    def updated(self, updated=None):
        '''Set or get the updated value which indicates the last time the entry
        was modified in a significant way.

        The value can either be a string which will automatically be parsed or
        a datetime.datetime object. In any case it is necessary that the value
        include timezone information.

        :param updated: The modification date.
        :returns: Modification date as datetime.datetime
        '''
        if updated is not None:
            if isinstance(updated, string_types):
                updated = dateutil.parser.parse(updated)
            if not isinstance(updated, datetime):
                raise ValueError('Invalid datetime format')
            if updated.tzinfo is None:
                raise ValueError('Datetime object has no timezone info')
            self.__atom_updated = updated
            self.__rss_lastBuildDate = updated

        return self.__atom_updated

    def author(self, author=None, replace=False, **kwargs):
        '''Get or set autor data. An author element is a dict containing a
        name, an email adress and a uri. Name is mandatory for ATOM, email is
        mandatory for RSS.

        This method can be called with:
        - the fields of an author as keyword arguments
        - the fields of an author as a dictionary
        - a list of dictionaries containing the author fields

        An author has the following fields:
        - *name* conveys a human-readable name for the person.
        - *uri* contains a home page for the person.
        - *email* contains an email address for the person.

        :param author:  Dict or list of dicts with author data.
        :param replace: Add or replace old data.

        Example::

            >>> author({'name':'John Doe', 'email':'jdoe@example.com'})
            [{'name':'John Doe','email':'jdoe@example.com'}]

            >>> author([{'name': 'Mr. X'}, {'name': 'Max'}])
            [{'name':'John Doe','email':'jdoe@example.com'},
                    {'name':'John Doe'}, {'name':'Max'}]

            >>> author(name='John Doe', email='jdoe@example.com', replace=True)
            [{'name':'John Doe','email':'jdoe@example.com'}]

        '''
        if author is None and kwargs:
            author = kwargs
        if author is not None:
            if replace or self.__atom_author is None:
                self.__atom_author = []
            self.__atom_author += ensure_format(author,
                                                set(['name', 'email', 'uri']),
                                                set(['name']))
            self.__rss_author = []
            for a in self.__atom_author:
                if a.get('email'):
                    self.__rss_author.append('%(email)s (%(name)s)' % a)
        return self.__atom_author

    def content(self, content=None, src=None, type=None):
        '''Get or set the cntent of the entry which contains or links to the
        complete content of the entry. Content must be provided for ATOM
        entries if there is no alternate link, and should be provided if there
        is no summary. If the content is set (not linked) it will also set
        rss:description.

        :param content: The content of the feed entry.
        :param src: Link to the entries content.
        :param type: If type is CDATA content would not be escaped.
        :returns: Content element of the entry.
        '''
        if src is not None:
            self.__atom_content = {'src': src}
        elif content is not None:
            self.__atom_content = {'content': content}
            self.__rss_content = {'content': content}
            if type is not None:
                self.__atom_content['type'] = type
                self.__rss_content['type'] = type
        return self.__atom_content

    def link(self, link=None, replace=False, **kwargs):
        '''Get or set link data. An link element is a dict with the fields
        href, rel, type, hreflang, title, and length. Href is mandatory for
        ATOM.

        This method can be called with:
        - the fields of a link as keyword arguments
        - the fields of a link as a dictionary
        - a list of dictionaries containing the link fields

        A link has the following fields:

        - *href* is the URI of the referenced resource (typically a Web page)
        - *rel* contains a single link relationship type. It can be a full URI,
          or one of the following predefined values (default=alternate):

            - *alternate* an alternate representation of the entry or feed, for
              example a permalink to the html version of the entry, or the
              front page of the weblog.
            - *enclosure* a related resource which is potentially large in size
              and might require special handling, for example an audio or video
              recording.
            - *related* an document related to the entry or feed.
            - *self* the feed itself.
            - *via* the source of the information provided in the entry.

        - *type* indicates the media type of the resource.
        - *hreflang* indicates the language of the referenced resource.
        - *title* human readable information about the link, typically for
          display purposes.
        - *length* the length of the resource, in bytes.

        RSS only supports one link with nothing but a URL. So for the RSS link
        element the last link with rel=alternate is used.

        RSS also supports one enclusure element per entry which is covered by
        the link element in ATOM feed entries. So for the RSS enclusure element
        the last link with rel=enclosure is used.

        :param link:    Dict or list of dicts with data.
        :param replace: Add or replace old data.
        :returns: List of link data.
        '''
        if link is None and kwargs:
            link = kwargs
        if link is not None:
            if replace or self.__atom_link is None:
                self.__atom_link = []
            self.__atom_link += ensure_format(
                link,
                set(['href', 'rel', 'type', 'hreflang', 'title', 'length']),
                set(['href']),
                {'rel': ['alternate', 'enclosure', 'related', 'self', 'via']},
                {'rel': 'alternate'})
            # RSS only needs one URL. We use the first link for RSS:
            for l in self.__atom_link:
                if l.get('rel') == 'alternate':
                    self.__rss_link = l['href']
                elif l.get('rel') == 'enclosure':
                    self.__rss_enclosure = {'url': l['href']}
                    self.__rss_enclosure['type'] = l.get('type')
                    self.__rss_enclosure['length'] = l.get('length') or '0'
        # return the set with more information (atom)
        return self.__atom_link

    def summary(self, summary=None):
        '''Get or set the summary element of an entry which conveys a short
        summary, abstract, or excerpt of the entry. Summary is an ATOM only
        element and should be provided if there either is no content provided
        for the entry, or that content is not inline (i.e., contains a src
        attribute), or if the content is encoded in base64.  This method will
        also set the rss:description field if it wasn't previously set or
        contains the old value of summary.

        :param summary: Summary of the entries contents.
        :returns: Summary of the entries contents.
        '''
        if summary is not None:
            # Replace the RSS description with the summary if it was the
            # summary before. Not if is the description.
            if not self.__rss_description or \
                    self.__rss_description == self.__atom_summary:
                self.__rss_description = summary
            self.__atom_summary = summary
        return self.__atom_summary

    def description(self, description=None, isSummary=False):
        '''Get or set the description value which is the item synopsis.
        Description is an RSS only element. For ATOM feeds it is split in
        summary and content. The isSummary parameter can be used to control
        which ATOM value is set when setting description.

        :param description: Description of the entry.
        :param isSummary: If the description should be used as content or
                          summary.
        :returns: The entries description.
        '''
        if description is not None:
            self.__rss_description = description
            if isSummary:
                self.__atom_summary = description
            else:
                self.__atom_content = description
        return self.__rss_description

    def category(self, category=None, replace=False, **kwargs):
        '''Get or set categories that the entry belongs to.

        This method can be called with:
        - the fields of a category as keyword arguments
        - the fields of a category as a dictionary
        - a list of dictionaries containing the category fields

        A categories has the following fields:
        - *term* identifies the category
        - *scheme* identifies the categorization scheme via a URI.
        - *label* provides a human-readable label for display

        If a label is present it is used for the RSS feeds. Otherwise the term
        is used. The scheme is used for the domain attribute in RSS.

        :param category:    Dict or list of dicts with data.
        :param replace: Add or replace old data.
        :returns: List of category data.
        '''
        if category is None and kwargs:
            category = kwargs
        if category is not None:
            if replace or self.__atom_category is None:
                self.__atom_category = []
            self.__atom_category += ensure_format(
                    category,
                    set(['term', 'scheme', 'label']),
                    set(['term']))
            # Map the ATOM categories to RSS categories. Use the atom:label as
            # name or if not present the atom:term. The atom:scheme is the
            # rss:domain.
            self.__rss_category = []
            for cat in self.__atom_category:
                rss_cat = {}
                rss_cat['value'] = cat.get('label', cat['term'])
                if cat.get('scheme'):
                    rss_cat['domain'] = cat['scheme']
                self.__rss_category.append(rss_cat)
        return self.__atom_category

    def contributor(self, contributor=None, replace=False, **kwargs):
        '''Get or set the contributor data of the feed. This is an ATOM only
        value.

        This method can be called with:
        - the fields of an contributor as keyword arguments
        - the fields of an contributor as a dictionary
        - a list of dictionaries containing the contributor fields

        An contributor has the following fields:
        - *name* conveys a human-readable name for the person.
        - *uri* contains a home page for the person.
        - *email* contains an email address for the person.

        :param contributor: Dictionary or list of dictionaries with contributor
                            data.
        :param replace: Add or replace old data.
        :returns: List of contributors as dictionaries.
        '''
        if contributor is None and kwargs:
            contributor = kwargs
        if contributor is not None:
            if replace or self.__atom_contributor is None:
                self.__atom_contributor = []
            self.__atom_contributor += ensure_format(
                    contributor, set(['name', 'email', 'uri']), set(['name']))
        return self.__atom_contributor

    def published(self, published=None):
        '''Set or get the published value which contains the time of the initial
        creation or first availability of the entry.

        The value can either be a string which will automatically be parsed or
        a datetime.datetime object. In any case it is necessary that the value
        include timezone information.

        :param published: The creation date.
        :returns: Creation date as datetime.datetime
        '''
        if published is not None:
            if isinstance(published, string_types):
                published = dateutil.parser.parse(published)
            if not isinstance(published, datetime):
                raise ValueError('Invalid datetime format')
            if published.tzinfo is None:
                raise ValueError('Datetime object has no timezone info')
            self.__atom_published = published
            self.__rss_pubDate = published

        return self.__atom_published

    def pubdate(self, pubDate=None):
        '''Get or set the pubDate of the entry which indicates when the entry
        was published. This method is just another name for the published(...)
        method.
        '''
        return self.published(pubDate)

    def rights(self, rights=None):
        '''Get or set the rights value of the entry which conveys information
        about rights, e.g. copyrights, held in and over the entry. This ATOM
        value will also set rss:copyright.

        :param rights: Rights information of the feed.
        :returns: Rights information of the feed.
        '''
        if rights is not None:
            self.__atom_rights = rights
        return self.__atom_rights

    def comments(self, comments=None):
        '''Get or set the the value of comments which is the url of the
        comments page for the item. This is a RSS only value.

        :param comments: URL to the comments page.
        :returns: URL to the comments page.
        '''
        if comments is not None:
            self.__rss_comments = comments
        return self.__rss_comments

    def enclosure(self, url=None, length=None, type=None):
        '''Get or set the value of enclosure which describes a media object
        that is attached to the item. This is a RSS only value which is
        represented by link(rel=enclosure) in ATOM. ATOM feeds can furthermore
        contain several enclosures while RSS may contain only one. That is why
        this method, if repeatedly called, will add more than one enclosures to
        the feed.  However, only the last one is used for RSS.

        :param url: URL of the media object.
        :param length: Size of the media in bytes.
        :param type: Mimetype of the linked media.
        :returns: Data of the enclosure element.
        '''
        if url is not None:
            self.link(href=url, rel='enclosure', type=type, length=length)
        return self.__rss_enclosure

    def ttl(self, ttl=None):
        '''Get or set the ttl value. It is an RSS only element. ttl stands for
        time to live. It's a number of minutes that indicates how long a
        channel can be cached before refreshing from the source.

        :param ttl: Integer value representing the time to live.
        :returns: Time to live of of the entry.
        '''
        if ttl is not None:
            self.__rss_ttl = int(ttl)
        return self.__rss_ttl

    def load_extension(self, name, atom=True, rss=True):
        '''Load a specific extension by name.

        :param name: Name of the extension to load.
        :param atom: If the extension should be used for ATOM feeds.
        :param rss: If the extension should be used for RSS feeds.
        '''
        # Check loaded extensions
        if not isinstance(self.__extensions, dict):
            self.__extensions = {}
        if name in self.__extensions.keys():
            raise ImportError('Extension already loaded')

        # Load extension
        extname = name[0].upper() + name[1:] + 'EntryExtension'
        try:
            supmod = __import__('feedgen.ext.%s_entry' % name)
            extmod = getattr(supmod.ext, name + '_entry')
        except ImportError:
            # Use FeedExtension module instead
            supmod = __import__('feedgen.ext.%s' % name)
            extmod = getattr(supmod.ext, name)
        ext = getattr(extmod, extname)
        self.register_extension(name, ext, atom, rss)

    def register_extension(self, namespace, extension_class_entry=None,
                           atom=True, rss=True):
        '''Register a specific extension by classes to a namespace.

        :param namespace: namespace for the extension
        :param extension_class_entry: Class of the entry extension to load.
        :param atom: If the extension should be used for ATOM feeds.
        :param rss: If the extension should be used for RSS feeds.
        '''
        # Check loaded extensions
        # `load_extension` ignores the "Extension" suffix.
        if not isinstance(self.__extensions, dict):
            self.__extensions = {}
        if namespace in self.__extensions.keys():
            raise ImportError('Extension already loaded')
        if not extension_class_entry:
            raise ImportError('No extension class')

        extinst = extension_class_entry()
        setattr(self, namespace, extinst)

        # `load_extension` registry
        self.__extensions[namespace] = {
                'inst': extinst,
                'extension_class_entry': extension_class_entry,
                'atom': atom,
                'rss': rss
                }