NewsBlur/utils/PyRSS2Gen.py

"""PyRSS2Gen - A Python library for generating RSS 2.0 feeds."""

__name__ = "PyRSS2Gen"
__version__ = (1, 0, 0)
__author__ = "Andrew Dalke <dalke@dalkescientific.com>"

_generator_name = __name__ + "-" + ".".join(map(str, __version__))

import datetime


# Could make this the base class; will need to add 'publish'
class WriteXmlMixin:
    def write_xml(self, outfile, encoding="iso-8859-1"):
        from xml.sax import saxutils

        handler = saxutils.XMLGenerator(outfile, encoding)
        handler.startDocument()
        self.publish(handler)
        handler.endDocument()

    def to_xml(self, encoding="iso-8859-1"):
        try:
            import io as StringIO
        except ImportError:
            import io
        f = io.StringIO()
        self.write_xml(f, encoding)
        return f.getvalue()


def _element(handler, name, obj, d={}):
    if isinstance(obj, str) or obj is None:
        # special-case handling to make the API easier
        # to use for the common case.
        handler.startElement(name, d)
        if obj is not None:
            handler.characters(obj)
        handler.endElement(name)
    else:
        # It better know how to emit the correct XML.
        obj.publish(handler)


def _opt_element(handler, name, obj):
    if obj is None:
        return
    _element(handler, name, obj)


def _format_date(dt):
    """convert a datetime into an RFC 822 formatted date

    Input date must be in GMT.
    """
    # Looks like:
    #   Sat, 07 Sep 2002 00:00:01 GMT
    # Can't use strftime because that's locale dependent
    #
    # Isn't there a standard way to do this for Python?  The
    # rfc822 and email.Utils modules assume a timestamp.  The
    # following is based on the rfc822 module.
    return "%s, %02d %s %04d %02d:%02d:%02d GMT" % (
        ["Mon", "Tue", "Wed", "Thu", "Fri", "Sat", "Sun"][dt.weekday()],
        dt.day,
        ["Jan", "Feb", "Mar", "Apr", "May", "Jun", "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"][dt.month - 1],
        dt.year,
        dt.hour,
        dt.minute,
        dt.second,
    )


##
# A couple simple wrapper objects for the fields which
# take a simple value other than a string.
class IntElement:
    """implements the 'publish' API for integers

    Takes the tag name and the integer value to publish.

    (Could be used for anything which uses str() to be published
    to text for XML.)
    """

    element_attrs = {}

    def __init__(self, name, val):
        self.name = name
        self.val = val

    def publish(self, handler):
        handler.startElement(self.name, self.element_attrs)
        handler.characters(str(self.val))
        handler.endElement(self.name)


class DateElement:
    """implements the 'publish' API for a datetime.datetime

    Takes the tag name and the datetime to publish.

    Converts the datetime to RFC 2822 timestamp (4-digit year).
    """

    def __init__(self, name, dt):
        self.name = name
        self.dt = dt

    def publish(self, handler):
        _element(handler, self.name, _format_date(self.dt))


####


class Category:
    """Publish a category element"""

    def __init__(self, category, domain=None):
        self.category = category
        self.domain = domain

    def publish(self, handler):
        d = {}
        if self.domain is not None:
            d["domain"] = self.domain
        _element(handler, "category", self.category, d)


class Cloud:
    """Publish a cloud"""

    def __init__(self, domain, port, path, registerProcedure, protocol):
        self.domain = domain
        self.port = port
        self.path = path
        self.registerProcedure = registerProcedure
        self.protocol = protocol

    def publish(self, handler):
        _element(
            handler,
            "cloud",
            None,
            {
                "domain": self.domain,
                "port": str(self.port),
                "path": self.path,
                "registerProcedure": self.registerProcedure,
                "protocol": self.protocol,
            },
        )


class Image:
    """Publish a channel Image"""

    element_attrs = {}

    def __init__(self, url, title, link, width=None, height=None, description=None):
        self.url = url
        self.title = title
        self.link = link
        self.width = width
        self.height = height
        self.description = description

    def publish(self, handler):
        handler.startElement("image", self.element_attrs)

        _element(handler, "url", self.url)
        _element(handler, "title", self.title)
        _element(handler, "link", self.link)

        width = self.width
        if isinstance(width, int):
            width = IntElement("width", width)
        _opt_element(handler, "width", width)

        height = self.height
        if isinstance(height, int):
            height = IntElement("height", height)
        _opt_element(handler, "height", height)

        _opt_element(handler, "description", self.description)

        handler.endElement("image")


class Guid:
    """Publish a guid

    Defaults to being a permalink, which is the assumption if it's
    omitted.  Hence strings are always permalinks.
    """

    def __init__(self, guid, isPermaLink=1):
        self.guid = guid
        self.isPermaLink = isPermaLink

    def publish(self, handler):
        d = {}
        if self.isPermaLink:
            d["isPermaLink"] = "true"
        else:
            d["isPermaLink"] = "false"
        _element(handler, "guid", self.guid, d)


class TextInput:
    """Publish a textInput

    Apparently this is rarely used.
    """

    element_attrs = {}

    def __init__(self, title, description, name, link):
        self.title = title
        self.description = description
        self.name = name
        self.link = link

    def publish(self, handler):
        handler.startElement("textInput", self.element_attrs)
        _element(handler, "title", self.title)
        _element(handler, "description", self.description)
        _element(handler, "name", self.name)
        _element(handler, "link", self.link)
        handler.endElement("textInput")


class Enclosure:
    """Publish an enclosure"""

    def __init__(self, url, length, type):
        self.url = url
        self.length = length
        self.type = type

    def publish(self, handler):
        _element(
            handler,
            "enclosure",
            None,
            {
                "url": self.url,
                "length": str(self.length),
                "type": self.type,
            },
        )


class Source:
    """Publish the item's original source, used by aggregators"""

    def __init__(self, name, url):
        self.name = name
        self.url = url

    def publish(self, handler):
        _element(handler, "source", self.name, {"url": self.url})


class SkipHours:
    """Publish the skipHours

    This takes a list of hours, as integers.
    """

    element_attrs = {}

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

    def publish(self, handler):
        if self.hours:
            handler.startElement("skipHours", self.element_attrs)
            for hour in self.hours:
                _element(handler, "hour", str(hour))
            handler.endElement("skipHours")


class SkipDays:
    """Publish the skipDays

    This takes a list of days as strings.
    """

    element_attrs = {}

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

    def publish(self, handler):
        if self.days:
            handler.startElement("skipDays", self.element_attrs)
            for day in self.days:
                _element(handler, "day", day)
            handler.endElement("skipDays")


class RSS2(WriteXmlMixin):
    """The main RSS class.

    Stores the channel attributes, with the "category" elements under
    ".categories" and the RSS items under ".items".
    """

    rss_attrs = {"version": "2.0"}
    element_attrs = {}

    def __init__(
        self,
        title,
        link,
        description,
        language=None,
        copyright=None,
        managingEditor=None,
        webMaster=None,
        pubDate=None,  # a datetime, *in* *GMT*
        lastBuildDate=None,  # a datetime
        categories=None,  # list of strings or Category
        generator=_generator_name,
        docs="http://blogs.law.harvard.edu/tech/rss",
        cloud=None,  # a Cloud
        ttl=None,  # integer number of minutes
        image=None,  # an Image
        rating=None,  # a string; I don't know how it's used
        textInput=None,  # a TextInput
        skipHours=None,  # a SkipHours with a list of integers
        skipDays=None,  # a SkipDays with a list of strings
        items=None,  # list of RSSItems
    ):
        self.title = title
        self.link = link
        self.description = description
        self.language = language
        self.copyright = copyright
        self.managingEditor = managingEditor

        self.webMaster = webMaster
        self.pubDate = pubDate
        self.lastBuildDate = lastBuildDate

        if categories is None:
            categories = []
        self.categories = categories
        self.generator = generator
        self.docs = docs
        self.cloud = cloud
        self.ttl = ttl
        self.image = image
        self.rating = rating
        self.textInput = textInput
        self.skipHours = skipHours
        self.skipDays = skipDays

        if items is None:
            items = []
        self.items = items

    def publish(self, handler):
        handler.startElement("rss", self.rss_attrs)
        handler.startElement("channel", self.element_attrs)
        _element(handler, "title", self.title)
        _element(handler, "link", self.link)
        _element(handler, "description", self.description)

        self.publish_extensions(handler)

        _opt_element(handler, "language", self.language)
        _opt_element(handler, "copyright", self.copyright)
        _opt_element(handler, "managingEditor", self.managingEditor)
        _opt_element(handler, "webMaster", self.webMaster)

        pubDate = self.pubDate
        if isinstance(pubDate, datetime.datetime):
            pubDate = DateElement("pubDate", pubDate)
        _opt_element(handler, "pubDate", pubDate)

        lastBuildDate = self.lastBuildDate
        if isinstance(lastBuildDate, datetime.datetime):
            lastBuildDate = DateElement("lastBuildDate", lastBuildDate)
        _opt_element(handler, "lastBuildDate", lastBuildDate)

        for category in self.categories:
            if isinstance(category, str):
                category = Category(category)
            category.publish(handler)

        _opt_element(handler, "generator", self.generator)
        _opt_element(handler, "docs", self.docs)

        if self.cloud is not None:
            self.cloud.publish(handler)

        ttl = self.ttl
        if isinstance(self.ttl, int):
            ttl = IntElement("ttl", ttl)
        _opt_element(handler, "tt", ttl)

        if self.image is not None:
            self.image.publish(handler)

        _opt_element(handler, "rating", self.rating)
        if self.textInput is not None:
            self.textInput.publish(handler)
        if self.skipHours is not None:
            self.skipHours.publish(handler)
        if self.skipDays is not None:
            self.skipDays.publish(handler)

        for item in self.items:
            item.publish(handler)

        handler.endElement("channel")
        handler.endElement("rss")

    def publish_extensions(self, handler):
        # Derived classes can hook into this to insert
        # output after the three required fields.
        pass


class RSSItem(WriteXmlMixin):
    """Publish an RSS Item"""

    element_attrs = {}

    def __init__(
        self,
        title=None,  # string
        link=None,  # url as string
        description=None,  # string
        author=None,  # email address as string
        categories=None,  # list of string or Category
        comments=None,  # url as string
        enclosure=None,  # an Enclosure
        guid=None,  # a unique string
        pubDate=None,  # a datetime
        source=None,  # a Source
    ):
        if title is None and description is None:
            raise TypeError("must define at least one of 'title' or 'description'")
        self.title = title
        self.link = link
        self.description = description
        self.author = author
        if categories is None:
            categories = []
        self.categories = categories
        self.comments = comments
        self.enclosure = enclosure
        self.guid = guid
        self.pubDate = pubDate
        self.source = source
        # It sure does get tedious typing these names three times...

    def publish(self, handler):
        handler.startElement("item", self.element_attrs)
        _opt_element(handler, "title", self.title)
        _opt_element(handler, "link", self.link)
        self.publish_extensions(handler)
        _opt_element(handler, "description", self.description)
        _opt_element(handler, "author", self.author)

        for category in self.categories:
            if isinstance(category, str):
                category = Category(category)
            category.publish(handler)

        _opt_element(handler, "comments", self.comments)
        if self.enclosure is not None:
            self.enclosure.publish(handler)
        _opt_element(handler, "guid", self.guid)

        pubDate = self.pubDate
        if isinstance(pubDate, datetime.datetime):
            pubDate = DateElement("pubDate", pubDate)
        _opt_element(handler, "pubDate", pubDate)

        if self.source is not None:
            self.source.publish(handler)

        handler.endElement("item")

    def publish_extensions(self, handler):
        # Derived classes can hook into this to insert
        # output after the title and link elements
        pass