basic subscriptions system

9 files changed, 1170 insertions, 0 deletions

diff --git a/python/atoma/__init__.py b/python/atoma/__init__.py
new file mode 100644
index 0000000..0768081
--- /dev/null
+++ b/python/atoma/__init__.py
@@ -0,0 +1,12 @@
+from .atom import parse_atom_file, parse_atom_bytes
+from .rss import parse_rss_file, parse_rss_bytes
+from .json_feed import (
+    parse_json_feed, parse_json_feed_file, parse_json_feed_bytes
+)
+from .opml import parse_opml_file, parse_opml_bytes
+from .exceptions import (
+    FeedParseError, FeedDocumentError, FeedXMLError, FeedJSONError
+)
+from .const import VERSION
+
+__version__ = VERSION
diff --git a/python/atoma/atom.py b/python/atoma/atom.py
new file mode 100644
index 0000000..d4e676c
--- /dev/null
+++ b/python/atoma/atom.py
@@ -0,0 +1,284 @@
+from datetime import datetime
+import enum
+from io import BytesIO
+from typing import Optional, List
+from xml.etree.ElementTree import Element
+
+import attr
+
+from .utils import (
+    parse_xml, get_child, get_text, get_datetime, FeedParseError, ns
+)
+
+
+class AtomTextType(enum.Enum):
+    text = "text"
+    html = "html"
+    xhtml = "xhtml"
+
+
+@attr.s
+class AtomTextConstruct:
+    text_type: str = attr.ib()
+    lang: Optional[str] = attr.ib()
+    value: str = attr.ib()
+
+
+@attr.s
+class AtomEntry:
+    title: AtomTextConstruct = attr.ib()
+    id_: str = attr.ib()
+
+    # Should be mandatory but many feeds use published instead
+    updated: Optional[datetime] = attr.ib()
+
+    authors: List['AtomPerson'] = attr.ib()
+    contributors: List['AtomPerson'] = attr.ib()
+    links: List['AtomLink'] = attr.ib()
+    categories: List['AtomCategory'] = attr.ib()
+    published: Optional[datetime] = attr.ib()
+    rights: Optional[AtomTextConstruct] = attr.ib()
+    summary: Optional[AtomTextConstruct] = attr.ib()
+    content: Optional[AtomTextConstruct] = attr.ib()
+    source: Optional['AtomFeed'] = attr.ib()
+
+
+@attr.s
+class AtomFeed:
+    title: Optional[AtomTextConstruct] = attr.ib()
+    id_: str = attr.ib()
+
+    # Should be mandatory but many feeds do not include it
+    updated: Optional[datetime] = attr.ib()
+
+    authors: List['AtomPerson'] = attr.ib()
+    contributors: List['AtomPerson'] = attr.ib()
+    links: List['AtomLink'] = attr.ib()
+    categories: List['AtomCategory'] = attr.ib()
+    generator: Optional['AtomGenerator'] = attr.ib()
+    subtitle: Optional[AtomTextConstruct] = attr.ib()
+    rights: Optional[AtomTextConstruct] = attr.ib()
+    icon: Optional[str] = attr.ib()
+    logo: Optional[str] = attr.ib()
+
+    entries: List[AtomEntry] = attr.ib()
+
+
+@attr.s
+class AtomPerson:
+    name: str = attr.ib()
+    uri: Optional[str] = attr.ib()
+    email: Optional[str] = attr.ib()
+
+
+@attr.s
+class AtomLink:
+    href: str = attr.ib()
+    rel: Optional[str] = attr.ib()
+    type_: Optional[str] = attr.ib()
+    hreflang: Optional[str] = attr.ib()
+    title: Optional[str] = attr.ib()
+    length: Optional[int] = attr.ib()
+
+
+@attr.s
+class AtomCategory:
+    term: str = attr.ib()
+    scheme: Optional[str] = attr.ib()
+    label: Optional[str] = attr.ib()
+
+
+@attr.s
+class AtomGenerator:
+    name: str = attr.ib()
+    uri: Optional[str] = attr.ib()
+    version: Optional[str] = attr.ib()
+
+
+def _get_generator(element: Element, name,
+                   optional: bool=True) -> Optional[AtomGenerator]:
+    child = get_child(element, name, optional)
+    if child is None:
+        return None
+
+    return AtomGenerator(
+        child.text.strip(),
+        child.attrib.get('uri'),
+        child.attrib.get('version'),
+    )
+
+
+def _get_text_construct(element: Element, name,
+                        optional: bool=True) -> Optional[AtomTextConstruct]:
+    child = get_child(element, name, optional)
+    if child is None:
+        return None
+
+    try:
+        text_type = AtomTextType(child.attrib['type'])
+    except KeyError:
+        text_type = AtomTextType.text
+
+    try:
+        lang = child.lang
+    except AttributeError:
+        lang = None
+
+    if child.text is None:
+        if optional:
+            return None
+
+        raise FeedParseError(
+            'Could not parse atom feed: "{}" text is required but is empty'
+            .format(name)
+        )
+
+    return AtomTextConstruct(
+        text_type,
+        lang,
+        child.text.strip()
+    )
+
+
+def _get_person(element: Element) -> Optional[AtomPerson]:
+    try:
+        return AtomPerson(
+            get_text(element, 'feed:name', optional=False),
+            get_text(element, 'feed:uri'),
+            get_text(element, 'feed:email')
+        )
+    except FeedParseError:
+        return None
+
+
+def _get_link(element: Element) -> AtomLink:
+    length = element.attrib.get('length')
+    length = int(length) if length else None
+    return AtomLink(
+        element.attrib['href'],
+        element.attrib.get('rel'),
+        element.attrib.get('type'),
+        element.attrib.get('hreflang'),
+        element.attrib.get('title'),
+        length
+    )
+
+
+def _get_category(element: Element) -> AtomCategory:
+    return AtomCategory(
+        element.attrib['term'],
+        element.attrib.get('scheme'),
+        element.attrib.get('label'),
+    )
+
+
+def _get_entry(element: Element,
+               default_authors: List[AtomPerson]) -> AtomEntry:
+    root = element
+
+    # Mandatory
+    title = _get_text_construct(root, 'feed:title')
+    id_ = get_text(root, 'feed:id')
+
+    # Optional
+    try:
+        source = _parse_atom(get_child(root, 'feed:source', optional=False),
+                             parse_entries=False)
+    except FeedParseError:
+        source = None
+        source_authors = []
+    else:
+        source_authors = source.authors
+
+    authors = [_get_person(e)
+               for e in root.findall('feed:author', ns)] or default_authors
+    authors = [a for a in authors if a is not None]
+    authors = authors or default_authors or source_authors
+
+    contributors = [_get_person(e)
+                    for e in root.findall('feed:contributor', ns) if e]
+    contributors = [c for c in contributors if c is not None]
+
+    links = [_get_link(e) for e in root.findall('feed:link', ns)]
+    categories = [_get_category(e) for e in root.findall('feed:category', ns)]
+
+    updated = get_datetime(root, 'feed:updated')
+    published = get_datetime(root, 'feed:published')
+    rights = _get_text_construct(root, 'feed:rights')
+    summary = _get_text_construct(root, 'feed:summary')
+    content = _get_text_construct(root, 'feed:content')
+
+    return AtomEntry(
+        title,
+        id_,
+        updated,
+        authors,
+        contributors,
+        links,
+        categories,
+        published,
+        rights,
+        summary,
+        content,
+        source
+    )
+
+
+def _parse_atom(root: Element, parse_entries: bool=True) -> AtomFeed:
+    # Mandatory
+    id_ = get_text(root, 'feed:id', optional=False)
+
+    # Optional
+    title = _get_text_construct(root, 'feed:title')
+    updated = get_datetime(root, 'feed:updated')
+    authors = [_get_person(e)
+               for e in root.findall('feed:author', ns) if e]
+    authors = [a for a in authors if a is not None]
+    contributors = [_get_person(e)
+                    for e in root.findall('feed:contributor', ns) if e]
+    contributors = [c for c in contributors if c is not None]
+    links = [_get_link(e)
+             for e in root.findall('feed:link', ns)]
+    categories = [_get_category(e)
+                  for e in root.findall('feed:category', ns)]
+
+    generator = _get_generator(root, 'feed:generator')
+    subtitle = _get_text_construct(root, 'feed:subtitle')
+    rights = _get_text_construct(root, 'feed:rights')
+    icon = get_text(root, 'feed:icon')
+    logo = get_text(root, 'feed:logo')
+
+    if parse_entries:
+        entries = [_get_entry(e, authors)
+                   for e in root.findall('feed:entry', ns)]
+    else:
+        entries = []
+
+    atom_feed = AtomFeed(
+        title,
+        id_,
+        updated,
+        authors,
+        contributors,
+        links,
+        categories,
+        generator,
+        subtitle,
+        rights,
+        icon,
+        logo,
+        entries
+    )
+    return atom_feed
+
+
+def parse_atom_file(filename: str) -> AtomFeed:
+    """Parse an Atom feed from a local XML file."""
+    root = parse_xml(filename).getroot()
+    return _parse_atom(root)
+
+
+def parse_atom_bytes(data: bytes) -> AtomFeed:
+    """Parse an Atom feed from a byte-string containing XML data."""
+    root = parse_xml(BytesIO(data)).getroot()
+    return _parse_atom(root)
diff --git a/python/atoma/const.py b/python/atoma/const.py
new file mode 100644
index 0000000..d52d0f6
--- /dev/null
+++ b/python/atoma/const.py
@@ -0,0 +1 @@
+VERSION = '0.0.13'
diff --git a/python/atoma/exceptions.py b/python/atoma/exceptions.py
new file mode 100644
index 0000000..88170c5
--- /dev/null
+++ b/python/atoma/exceptions.py
@@ -0,0 +1,14 @@
+class FeedParseError(Exception):
+    """Document is an invalid feed."""
+
+
+class FeedDocumentError(Exception):
+    """Document is not a supported file."""
+
+
+class FeedXMLError(FeedDocumentError):
+    """Document is not valid XML."""
+
+
+class FeedJSONError(FeedDocumentError):
+    """Document is not valid JSON."""
diff --git a/python/atoma/json_feed.py b/python/atoma/json_feed.py
new file mode 100644
index 0000000..410ff4a
--- /dev/null
+++ b/python/atoma/json_feed.py
@@ -0,0 +1,223 @@
+from datetime import datetime, timedelta
+import json
+from typing import Optional, List
+
+import attr
+
+from .exceptions import FeedParseError, FeedJSONError
+from .utils import try_parse_date
+
+
+@attr.s
+class JSONFeedAuthor:
+
+    name: Optional[str] = attr.ib()
+    url: Optional[str] = attr.ib()
+    avatar: Optional[str] = attr.ib()
+
+
+@attr.s
+class JSONFeedAttachment:
+
+    url: str = attr.ib()
+    mime_type: str = attr.ib()
+    title: Optional[str] = attr.ib()
+    size_in_bytes: Optional[int] = attr.ib()
+    duration: Optional[timedelta] = attr.ib()
+
+
+@attr.s
+class JSONFeedItem:
+
+    id_: str = attr.ib()
+    url: Optional[str] = attr.ib()
+    external_url: Optional[str] = attr.ib()
+    title: Optional[str] = attr.ib()
+    content_html: Optional[str] = attr.ib()
+    content_text: Optional[str] = attr.ib()
+    summary: Optional[str] = attr.ib()
+    image: Optional[str] = attr.ib()
+    banner_image: Optional[str] = attr.ib()
+    date_published: Optional[datetime] = attr.ib()
+    date_modified: Optional[datetime] = attr.ib()
+    author: Optional[JSONFeedAuthor] = attr.ib()
+
+    tags: List[str] = attr.ib()
+    attachments: List[JSONFeedAttachment] = attr.ib()
+
+
+@attr.s
+class JSONFeed:
+
+    version: str = attr.ib()
+    title: str = attr.ib()
+    home_page_url: Optional[str] = attr.ib()
+    feed_url: Optional[str] = attr.ib()
+    description: Optional[str] = attr.ib()
+    user_comment: Optional[str] = attr.ib()
+    next_url: Optional[str] = attr.ib()
+    icon: Optional[str] = attr.ib()
+    favicon: Optional[str] = attr.ib()
+    author: Optional[JSONFeedAuthor] = attr.ib()
+    expired: bool = attr.ib()
+
+    items: List[JSONFeedItem] = attr.ib()
+
+
+def _get_items(root: dict) -> List[JSONFeedItem]:
+    rv = []
+    items = root.get('items', [])
+    if not items:
+        return rv
+
+    for item in items:
+        rv.append(_get_item(item))
+
+    return rv
+
+
+def _get_item(item_dict: dict) -> JSONFeedItem:
+    return JSONFeedItem(
+        id_=_get_text(item_dict, 'id', optional=False),
+        url=_get_text(item_dict, 'url'),
+        external_url=_get_text(item_dict, 'external_url'),
+        title=_get_text(item_dict, 'title'),
+        content_html=_get_text(item_dict, 'content_html'),
+        content_text=_get_text(item_dict, 'content_text'),
+        summary=_get_text(item_dict, 'summary'),
+        image=_get_text(item_dict, 'image'),
+        banner_image=_get_text(item_dict, 'banner_image'),
+        date_published=_get_datetime(item_dict, 'date_published'),
+        date_modified=_get_datetime(item_dict, 'date_modified'),
+        author=_get_author(item_dict),
+        tags=_get_tags(item_dict, 'tags'),
+        attachments=_get_attachments(item_dict, 'attachments')
+    )
+
+
+def _get_attachments(root, name) -> List[JSONFeedAttachment]:
+    rv = list()
+    for attachment_dict in root.get(name, []):
+        rv.append(JSONFeedAttachment(
+            _get_text(attachment_dict, 'url', optional=False),
+            _get_text(attachment_dict, 'mime_type', optional=False),
+            _get_text(attachment_dict, 'title'),
+            _get_int(attachment_dict, 'size_in_bytes'),
+            _get_duration(attachment_dict, 'duration_in_seconds')
+        ))
+    return rv
+
+
+def _get_tags(root, name) -> List[str]:
+    tags = root.get(name, [])
+    return [tag for tag in tags if isinstance(tag, str)]
+
+
+def _get_datetime(root: dict, name, optional: bool=True) -> Optional[datetime]:
+    text = _get_text(root, name, optional)
+    if text is None:
+        return None
+
+    return try_parse_date(text)
+
+
+def _get_expired(root: dict) -> bool:
+    if root.get('expired') is True:
+        return True
+
+    return False
+
+
+def _get_author(root: dict) -> Optional[JSONFeedAuthor]:
+    author_dict = root.get('author')
+    if not author_dict:
+        return None
+
+    rv = JSONFeedAuthor(
+        name=_get_text(author_dict, 'name'),
+        url=_get_text(author_dict, 'url'),
+        avatar=_get_text(author_dict, 'avatar'),
+    )
+    if rv.name is None and rv.url is None and rv.avatar is None:
+        return None
+
+    return rv
+
+
+def _get_int(root: dict, name: str, optional: bool=True) -> Optional[int]:
+    rv = root.get(name)
+    if not optional and rv is None:
+        raise FeedParseError('Could not parse feed: "{}" int is required but '
+                             'is empty'.format(name))
+
+    if optional and rv is None:
+        return None
+
+    if not isinstance(rv, int):
+        raise FeedParseError('Could not parse feed: "{}" is not an int'
+                             .format(name))
+
+    return rv
+
+
+def _get_duration(root: dict, name: str,
+                  optional: bool=True) -> Optional[timedelta]:
+    duration = _get_int(root, name, optional)
+    if duration is None:
+        return None
+
+    return timedelta(seconds=duration)
+
+
+def _get_text(root: dict, name: str, optional: bool=True) -> Optional[str]:
+    rv = root.get(name)
+    if not optional and rv is None:
+        raise FeedParseError('Could not parse feed: "{}" text is required but '
+                             'is empty'.format(name))
+
+    if optional and rv is None:
+        return None
+
+    if not isinstance(rv, str):
+        raise FeedParseError('Could not parse feed: "{}" is not a string'
+                             .format(name))
+
+    return rv
+
+
+def parse_json_feed(root: dict) -> JSONFeed:
+    return JSONFeed(
+        version=_get_text(root, 'version', optional=False),
+        title=_get_text(root, 'title', optional=False),
+        home_page_url=_get_text(root, 'home_page_url'),
+        feed_url=_get_text(root, 'feed_url'),
+        description=_get_text(root, 'description'),
+        user_comment=_get_text(root, 'user_comment'),
+        next_url=_get_text(root, 'next_url'),
+        icon=_get_text(root, 'icon'),
+        favicon=_get_text(root, 'favicon'),
+        author=_get_author(root),
+        expired=_get_expired(root),
+        items=_get_items(root)
+    )
+
+
+def parse_json_feed_file(filename: str) -> JSONFeed:
+    """Parse a JSON feed from a local json file."""
+    with open(filename) as f:
+        try:
+            root = json.load(f)
+        except json.decoder.JSONDecodeError:
+            raise FeedJSONError('Not a valid JSON document')
+
+    return parse_json_feed(root)
+
+
+def parse_json_feed_bytes(data: bytes) -> JSONFeed:
+    """Parse a JSON feed from a byte-string containing JSON data."""
+    try:
+        root = json.loads(data)
+    except json.decoder.JSONDecodeError:
+        raise FeedJSONError('Not a valid JSON document')
+
+    return parse_json_feed(root)
diff --git a/python/atoma/opml.py b/python/atoma/opml.py
new file mode 100644
index 0000000..a73105e
--- /dev/null
+++ b/python/atoma/opml.py
@@ -0,0 +1,107 @@
+from datetime import datetime
+from io import BytesIO
+from typing import Optional, List
+from xml.etree.ElementTree import Element
+
+import attr
+
+from .utils import parse_xml, get_text, get_int, get_datetime
+
+
+@attr.s
+class OPMLOutline:
+    text: Optional[str] = attr.ib()
+    type: Optional[str] = attr.ib()
+    xml_url: Optional[str] = attr.ib()
+    description: Optional[str] = attr.ib()
+    html_url: Optional[str] = attr.ib()
+    language: Optional[str] = attr.ib()
+    title: Optional[str] = attr.ib()
+    version: Optional[str] = attr.ib()
+
+    outlines: List['OPMLOutline'] = attr.ib()
+
+
+@attr.s
+class OPML:
+    title: Optional[str] = attr.ib()
+    owner_name: Optional[str] = attr.ib()
+    owner_email: Optional[str] = attr.ib()
+    date_created: Optional[datetime] = attr.ib()
+    date_modified: Optional[datetime] = attr.ib()
+    expansion_state: Optional[str] = attr.ib()
+
+    vertical_scroll_state: Optional[int] = attr.ib()
+    window_top: Optional[int] = attr.ib()
+    window_left: Optional[int] = attr.ib()
+    window_bottom: Optional[int] = attr.ib()
+    window_right: Optional[int] = attr.ib()
+
+    outlines: List[OPMLOutline] = attr.ib()
+
+
+def _get_outlines(element: Element) -> List[OPMLOutline]:
+    rv = list()
+
+    for outline in element.findall('outline'):
+        rv.append(OPMLOutline(
+            outline.attrib.get('text'),
+            outline.attrib.get('type'),
+            outline.attrib.get('xmlUrl'),
+            outline.attrib.get('description'),
+            outline.attrib.get('htmlUrl'),
+            outline.attrib.get('language'),
+            outline.attrib.get('title'),
+            outline.attrib.get('version'),
+            _get_outlines(outline)
+        ))
+
+    return rv
+
+
+def _parse_opml(root: Element) -> OPML:
+    head = root.find('head')
+    body = root.find('body')
+
+    return OPML(
+        get_text(head, 'title'),
+        get_text(head, 'ownerName'),
+        get_text(head, 'ownerEmail'),
+        get_datetime(head, 'dateCreated'),
+        get_datetime(head, 'dateModified'),
+        get_text(head, 'expansionState'),
+        get_int(head, 'vertScrollState'),
+        get_int(head, 'windowTop'),
+        get_int(head, 'windowLeft'),
+        get_int(head, 'windowBottom'),
+        get_int(head, 'windowRight'),
+        outlines=_get_outlines(body)
+    )
+
+
+def parse_opml_file(filename: str) -> OPML:
+    """Parse an OPML document from a local XML file."""
+    root = parse_xml(filename).getroot()
+    return _parse_opml(root)
+
+
+def parse_opml_bytes(data: bytes) -> OPML:
+    """Parse an OPML document from a byte-string containing XML data."""
+    root = parse_xml(BytesIO(data)).getroot()
+    return _parse_opml(root)
+
+
+def get_feed_list(opml_obj: OPML) -> List[str]:
+    """Walk an OPML document to extract the list of feed it contains."""
+    rv = list()
+
+    def collect(obj):
+        for outline in obj.outlines:
+            if outline.type == 'rss' and outline.xml_url:
+                rv.append(outline.xml_url)
+
+            if outline.outlines:
+                collect(outline)
+
+    collect(opml_obj)
+    return rv
diff --git a/python/atoma/rss.py b/python/atoma/rss.py
new file mode 100644
index 0000000..f447a2f
--- /dev/null
+++ b/python/atoma/rss.py
@@ -0,0 +1,221 @@
+from datetime import datetime
+from io import BytesIO
+from typing import Optional, List
+from xml.etree.ElementTree import Element
+
+import attr
+
+from .utils import (
+    parse_xml, get_child, get_text, get_int, get_datetime, FeedParseError
+)
+
+
+@attr.s
+class RSSImage:
+    url: str = attr.ib()
+    title: Optional[str] = attr.ib()
+    link: str = attr.ib()
+    width: int = attr.ib()
+    height: int = attr.ib()
+    description: Optional[str] = attr.ib()
+
+
+@attr.s
+class RSSEnclosure:
+    url: str = attr.ib()
+    length: Optional[int] = attr.ib()
+    type: Optional[str] = attr.ib()
+
+
+@attr.s
+class RSSSource:
+    title: str = attr.ib()
+    url: Optional[str] = attr.ib()
+
+
+@attr.s
+class RSSItem:
+    title: Optional[str] = attr.ib()
+    link: Optional[str] = attr.ib()
+    description: Optional[str] = attr.ib()
+    author: Optional[str] = attr.ib()
+    categories: List[str] = attr.ib()
+    comments: Optional[str] = attr.ib()
+    enclosures: List[RSSEnclosure] = attr.ib()
+    guid: Optional[str] = attr.ib()
+    pub_date: Optional[datetime] = attr.ib()
+    source: Optional[RSSSource] = attr.ib()
+
+    # Extension
+    content_encoded: Optional[str] = attr.ib()
+
+
+@attr.s
+class RSSChannel:
+    title: Optional[str] = attr.ib()
+    link: Optional[str] = attr.ib()
+    description: Optional[str] = attr.ib()
+    language: Optional[str] = attr.ib()
+    copyright: Optional[str] = attr.ib()
+    managing_editor: Optional[str] = attr.ib()
+    web_master: Optional[str] = attr.ib()
+    pub_date: Optional[datetime] = attr.ib()
+    last_build_date: Optional[datetime] = attr.ib()
+    categories: List[str] = attr.ib()
+    generator: Optional[str] = attr.ib()
+    docs: Optional[str] = attr.ib()
+    ttl: Optional[int] = attr.ib()
+    image: Optional[RSSImage] = attr.ib()
+
+    items: List[RSSItem] = attr.ib()
+
+    # Extension
+    content_encoded: Optional[str] = attr.ib()
+
+
+def _get_image(element: Element, name,
+               optional: bool=True) -> Optional[RSSImage]:
+    child = get_child(element, name, optional)
+    if child is None:
+        return None
+
+    return RSSImage(
+        get_text(child, 'url', optional=False),
+        get_text(child, 'title'),
+        get_text(child, 'link', optional=False),
+        get_int(child, 'width') or 88,
+        get_int(child, 'height') or 31,
+        get_text(child, 'description')
+    )
+
+
+def _get_source(element: Element, name,
+                optional: bool=True) -> Optional[RSSSource]:
+    child = get_child(element, name, optional)
+    if child is None:
+        return None
+
+    return RSSSource(
+        child.text.strip(),
+        child.attrib.get('url'),
+    )
+
+
+def _get_enclosure(element: Element) -> RSSEnclosure:
+    length = element.attrib.get('length')
+    try:
+        length = int(length)
+    except (TypeError, ValueError):
+        length = None
+
+    return RSSEnclosure(
+        element.attrib['url'],
+        length,
+        element.attrib.get('type'),
+    )
+
+
+def _get_link(element: Element) -> Optional[str]:
+    """Attempt to retrieve item link.
+
+    Use the GUID as a fallback if it is a permalink.
+    """
+    link = get_text(element, 'link')
+    if link is not None:
+        return link
+
+    guid = get_child(element, 'guid')
+    if guid is not None and guid.attrib.get('isPermaLink') == 'true':
+        return get_text(element, 'guid')
+
+    return None
+
+
+def _get_item(element: Element) -> RSSItem:
+    root = element
+
+    title = get_text(root, 'title')
+    link = _get_link(root)
+    description = get_text(root, 'description')
+    author = get_text(root, 'author')
+    categories = [e.text for e in root.findall('category')]
+    comments = get_text(root, 'comments')
+    enclosure = [_get_enclosure(e) for e in root.findall('enclosure')]
+    guid = get_text(root, 'guid')
+    pub_date = get_datetime(root, 'pubDate')
+    source = _get_source(root, 'source')
+
+    content_encoded = get_text(root, 'content:encoded')
+
+    return RSSItem(
+        title,
+        link,
+        description,
+        author,
+        categories,
+        comments,
+        enclosure,
+        guid,
+        pub_date,
+        source,
+        content_encoded
+    )
+
+
+def _parse_rss(root: Element) -> RSSChannel:
+    rss_version = root.get('version')
+    if rss_version != '2.0':
+        raise FeedParseError('Cannot process RSS feed version "{}"'
+                             .format(rss_version))
+
+    root = root.find('channel')
+
+    title = get_text(root, 'title')
+    link = get_text(root, 'link')
+    description = get_text(root, 'description')
+    language = get_text(root, 'language')
+    copyright = get_text(root, 'copyright')
+    managing_editor = get_text(root, 'managingEditor')
+    web_master = get_text(root, 'webMaster')
+    pub_date = get_datetime(root, 'pubDate')
+    last_build_date = get_datetime(root, 'lastBuildDate')
+    categories = [e.text for e in root.findall('category')]
+    generator = get_text(root, 'generator')
+    docs = get_text(root, 'docs')
+    ttl = get_int(root, 'ttl')
+
+    image = _get_image(root, 'image')
+    items = [_get_item(e) for e in root.findall('item')]
+
+    content_encoded = get_text(root, 'content:encoded')
+
+    return RSSChannel(
+        title,
+        link,
+        description,
+        language,
+        copyright,
+        managing_editor,
+        web_master,
+        pub_date,
+        last_build_date,
+        categories,
+        generator,
+        docs,
+        ttl,
+        image,
+        items,
+        content_encoded
+    )
+
+
+def parse_rss_file(filename: str) -> RSSChannel:
+    """Parse an RSS feed from a local XML file."""
+    root = parse_xml(filename).getroot()
+    return _parse_rss(root)
+
+
+def parse_rss_bytes(data: bytes) -> RSSChannel:
+    """Parse an RSS feed from a byte-string containing XML data."""
+    root = parse_xml(BytesIO(data)).getroot()
+    return _parse_rss(root)
diff --git a/python/atoma/simple.py b/python/atoma/simple.py
new file mode 100644
index 0000000..98bb3e1
--- /dev/null
+++ b/python/atoma/simple.py
@@ -0,0 +1,224 @@
+"""Simple API that abstracts away the differences between feed types."""
+
+from datetime import datetime, timedelta
+import html
+import os
+from typing import Optional, List, Tuple
+import urllib.parse
+
+import attr
+
+from . import atom, rss, json_feed
+from .exceptions import (
+    FeedParseError, FeedDocumentError, FeedXMLError, FeedJSONError
+)
+
+
+@attr.s
+class Attachment:
+    link: str = attr.ib()
+    mime_type: Optional[str] = attr.ib()
+    title: Optional[str] = attr.ib()
+    size_in_bytes: Optional[int] = attr.ib()
+    duration: Optional[timedelta] = attr.ib()
+
+
+@attr.s
+class Article:
+    id: str = attr.ib()
+    title: Optional[str] = attr.ib()
+    link: Optional[str] = attr.ib()
+    content: str = attr.ib()
+    published_at: Optional[datetime] = attr.ib()
+    updated_at: Optional[datetime] = attr.ib()
+    attachments: List[Attachment] = attr.ib()
+
+
+@attr.s
+class Feed:
+    title: str = attr.ib()
+    subtitle: Optional[str] = attr.ib()
+    link: Optional[str] = attr.ib()
+    updated_at: Optional[datetime] = attr.ib()
+    articles: List[Article] = attr.ib()
+
+
+def _adapt_atom_feed(atom_feed: atom.AtomFeed) -> Feed:
+    articles = list()
+    for entry in atom_feed.entries:
+        if entry.content is not None:
+            content = entry.content.value
+        elif entry.summary is not None:
+            content = entry.summary.value
+        else:
+            content = ''
+        published_at, updated_at = _get_article_dates(entry.published,
+                                                      entry.updated)
+        # Find article link and attachments
+        article_link = None
+        attachments = list()
+        for candidate_link in entry.links:
+            if candidate_link.rel in ('alternate', None):
+                article_link = candidate_link.href
+            elif candidate_link.rel == 'enclosure':
+                attachments.append(Attachment(
+                    title=_get_attachment_title(candidate_link.title,
+                                                candidate_link.href),
+                    link=candidate_link.href,
+                    mime_type=candidate_link.type_,
+                    size_in_bytes=candidate_link.length,
+                    duration=None
+                ))
+
+        if entry.title is None:
+            entry_title = None
+        elif entry.title.text_type in (atom.AtomTextType.html,
+                                       atom.AtomTextType.xhtml):
+            entry_title = html.unescape(entry.title.value).strip()
+        else:
+            entry_title = entry.title.value
+
+        articles.append(Article(
+            entry.id_,
+            entry_title,
+            article_link,
+            content,
+            published_at,
+            updated_at,
+            attachments
+        ))
+
+    # Find feed link
+    link = None
+    for candidate_link in atom_feed.links:
+        if candidate_link.rel == 'self':
+            link = candidate_link.href
+            break
+
+    return Feed(
+        atom_feed.title.value if atom_feed.title else atom_feed.id_,
+        atom_feed.subtitle.value if atom_feed.subtitle else None,
+        link,
+        atom_feed.updated,
+        articles
+    )
+
+
+def _adapt_rss_channel(rss_channel: rss.RSSChannel) -> Feed:
+    articles = list()
+    for item in rss_channel.items:
+        attachments = [
+            Attachment(link=e.url, mime_type=e.type, size_in_bytes=e.length,
+                       title=_get_attachment_title(None, e.url), duration=None)
+            for e in item.enclosures
+        ]
+        articles.append(Article(
+            item.guid or item.link,
+            item.title,
+            item.link,
+            item.content_encoded or item.description or '',
+            item.pub_date,
+            None,
+            attachments
+        ))
+
+    if rss_channel.title is None and rss_channel.link is None:
+        raise FeedParseError('RSS feed does not have a title nor a link')
+
+    return Feed(
+        rss_channel.title if rss_channel.title else rss_channel.link,
+        rss_channel.description,
+        rss_channel.link,
+        rss_channel.pub_date,
+        articles
+    )
+
+
+def _adapt_json_feed(json_feed: json_feed.JSONFeed) -> Feed:
+    articles = list()
+    for item in json_feed.items:
+        attachments = [
+            Attachment(a.url, a.mime_type,
+                       _get_attachment_title(a.title, a.url),
+                       a.size_in_bytes, a.duration)
+            for a in item.attachments
+        ]
+        articles.append(Article(
+            item.id_,
+            item.title,
+            item.url,
+            item.content_html or item.content_text or '',
+            item.date_published,
+            item.date_modified,
+            attachments
+        ))
+
+    return Feed(
+        json_feed.title,
+        json_feed.description,
+        json_feed.feed_url,
+        None,
+        articles
+    )
+
+
+def _get_article_dates(published_at: Optional[datetime],
+                       updated_at: Optional[datetime]
+                       ) -> Tuple[Optional[datetime], Optional[datetime]]:
+    if published_at and updated_at:
+        return published_at, updated_at
+
+    if updated_at:
+        return updated_at, None
+
+    if published_at:
+        return published_at, None
+
+    raise FeedParseError('Article does not have proper dates')
+
+
+def _get_attachment_title(attachment_title: Optional[str], link: str) -> str:
+    if attachment_title:
+        return attachment_title
+
+    parsed_link = urllib.parse.urlparse(link)
+    return os.path.basename(parsed_link.path)
+
+
+def _simple_parse(pairs, content) -> Feed:
+    is_xml = True
+    is_json = True
+    for parser, adapter in pairs:
+        try:
+            return adapter(parser(content))
+        except FeedXMLError:
+            is_xml = False
+        except FeedJSONError:
+            is_json = False
+        except FeedParseError:
+            continue
+
+    if not is_xml and not is_json:
+        raise FeedDocumentError('File is not a supported feed type')
+
+    raise FeedParseError('File is not a valid supported feed')
+
+
+def simple_parse_file(filename: str) -> Feed:
+    """Parse an Atom, RSS or JSON feed from a local file."""
+    pairs = (
+        (rss.parse_rss_file, _adapt_rss_channel),
+        (atom.parse_atom_file, _adapt_atom_feed),
+        (json_feed.parse_json_feed_file, _adapt_json_feed)
+    )
+    return _simple_parse(pairs, filename)
+
+
+def simple_parse_bytes(data: bytes) -> Feed:
+    """Parse an Atom, RSS or JSON feed from a byte-string containing data."""
+    pairs = (
+        (rss.parse_rss_bytes, _adapt_rss_channel),
+        (atom.parse_atom_bytes, _adapt_atom_feed),
+        (json_feed.parse_json_feed_bytes, _adapt_json_feed)
+    )
+    return _simple_parse(pairs, data)
diff --git a/python/atoma/utils.py b/python/atoma/utils.py
new file mode 100644
index 0000000..4dc1ab5
--- /dev/null
+++ b/python/atoma/utils.py
@@ -0,0 +1,84 @@
+from datetime import datetime, timezone
+from xml.etree.ElementTree import Element
+from typing import Optional
+
+import dateutil.parser
+from defusedxml.ElementTree import parse as defused_xml_parse, ParseError
+
+from .exceptions import FeedXMLError, FeedParseError
+
+ns = {
+    'content': 'http://purl.org/rss/1.0/modules/content/',
+    'feed': 'http://www.w3.org/2005/Atom'
+}
+
+
+def parse_xml(xml_content):
+    try:
+        return defused_xml_parse(xml_content)
+    except ParseError:
+        raise FeedXMLError('Not a valid XML document')
+
+
+def get_child(element: Element, name,
+              optional: bool=True) -> Optional[Element]:
+    child = element.find(name, namespaces=ns)
+
+    if child is None and not optional:
+        raise FeedParseError(
+            'Could not parse feed: "{}" does not have a "{}"'
+            .format(element.tag, name)
+        )
+
+    elif child is None:
+        return None
+
+    return child
+
+
+def get_text(element: Element, name, optional: bool=True) -> Optional[str]:
+    child = get_child(element, name, optional)
+    if child is None:
+        return None
+
+    if child.text is None:
+        if optional:
+            return None
+
+        raise FeedParseError(
+            'Could not parse feed: "{}" text is required but is empty'
+            .format(name)
+        )
+
+    return child.text.strip()
+
+
+def get_int(element: Element, name, optional: bool=True) -> Optional[int]:
+    text = get_text(element, name, optional)
+    if text is None:
+        return None
+
+    return int(text)
+
+
+def get_datetime(element: Element, name,
+                 optional: bool=True) -> Optional[datetime]:
+    text = get_text(element, name, optional)
+    if text is None:
+        return None
+
+    return try_parse_date(text)
+
+
+def try_parse_date(date_str: str) -> Optional[datetime]:
+    try:
+        date = dateutil.parser.parse(date_str, fuzzy=True)
+    except (ValueError, OverflowError):
+        return None
+
+    if date.tzinfo is None:
+        # TZ naive datetime, make it a TZ aware datetime by assuming it
+        # contains UTC time
+        date = date.replace(tzinfo=timezone.utc)
+
+    return date