Add support for atom / rss feedHEADmaster

Date format was changed to support `updated` in ISO format. Now every
post will require date and time, which might be a usability regression,
but we'll see. Also, `updated` field was introduced in metadata. If
there is no such field, them date field will be used instead.

12 files changed, 111 insertions, 40 deletions

diff --git a/README.md b/README.md
index 7ac9d4a..94afe61 100644
--- a/README.md
+++ b/README.md
@@ -13,7 +13,7 @@ $ pip3 install -r requirements.txt
 ```
 $ mkdir posts/hello-world
 $ echo 'Title: Hello, World!' > posts/hello-world/metadata.txt
-$ echo 'Date: 2022-12-23' >> posts/hello-world/metadata.txt
+$ echo "Date: `date +"%Y-%m-%dT%H:%M:%S%z"`" >> posts/hello-world/metadata.txt
 $ echo 'Hello, world!' > posts/hello-world/hello-world.md
 $ make deploy
 ```
diff --git a/blog/atom.py b/blog/atom.py
new file mode 100644
index 0000000..e6d836c
--- /dev/null
+++ b/blog/atom.py
@@ -0,0 +1,34 @@
+import os
+import datetime
+import functools
+from typing import List
+
+from jinja2 import Template
+
+import render
+from post import Post, remove_drafts
+
+
+class Atom(object):
+    template: Template
+    posts: List[Post]
+
+    def __init__(self, template: Template, posts: List[Post]) -> None:
+        self.template = template
+        self.posts = remove_drafts(posts)
+
+    @staticmethod
+    def _now() -> datetime.datetime:
+        now = datetime.datetime.now(datetime.timezone.utc)
+        return now.replace(microsecond=0)
+
+    @functools.cached_property
+    def updated(self) -> datetime.datetime:
+        if not self.posts:
+            return self._now()
+        return self.posts[0].metadata.updated
+
+    def generate(self, basedir: str) -> None:
+        atom = os.path.join(basedir, "atom.xml")
+        rendered = self.template.render(updated=self.updated, posts=self.posts)
+        render.write_file_content(atom, rendered)
diff --git a/blog/blog.py b/blog/blog.py
index 27845bc..4b9a345 100644
--- a/blog/blog.py
+++ b/blog/blog.py
@@ -10,6 +10,7 @@ from jinja2 import Template, Environment, FileSystemLoader, select_autoescape
 
 from post import Post
 from feed import Feed
+from atom import Atom
 
 
 def recreate_workdir(basedir: str) -> None:
@@ -49,6 +50,9 @@ def generate_blog() -> None:
     feed = Feed(env.get_template("feed.html"), posts)
     feed.generate(workdir)
 
+    atom = Atom(env.get_template("atom.xml"), posts)
+    atom.generate(workdir)
+
     copy_share(workdir)
 
 
diff --git a/blog/feed.py b/blog/feed.py
index 3e5b2e0..381aab6 100644
--- a/blog/feed.py
+++ b/blog/feed.py
@@ -1,10 +1,11 @@
 import os
+import datetime
 from typing import List
 
 from jinja2 import Template
 
 import render
-from post import Post
+from post import Post, remove_drafts
 
 
 class Feed(object):
@@ -13,11 +14,7 @@ class Feed(object):
 
     def __init__(self, template: Template, posts: List[Post]) -> None:
         self.template = template
-        self.posts = Feed._remove_drafts(posts)
-
-    @staticmethod
-    def _remove_drafts(posts: List[Post]) -> List[Post]:
-        return list(filter(lambda x: x.metadata.status != "draft", posts))
+        self.posts = remove_drafts(posts)
 
     def generate(self, basedir: str) -> None:
         index = os.path.join(basedir, "index.html")
diff --git a/blog/post.py b/blog/post.py
index 8a7c880..955724a 100644
--- a/blog/post.py
+++ b/blog/post.py
@@ -2,27 +2,23 @@ import os
 import shutil
 import datetime
 import functools
-from typing import Dict
+from typing import Dict, List
 
 from jinja2 import Template
 
+from dataclasses import dataclass
+
 import render
 
 
+@dataclass(slots=True)
 class Metadata(object):
-    __slots__ = ("title", "author", "date", "status")
     title: str
     author: str
-    date: str
+    date: datetime.datetime
+    updated: datetime.datetime
     status: str
 
-    def __init__(self, title: str, author: str,
-                 date: str, status: str) -> None:
-        self.title = title
-        self.author = author
-        self.date = date
-        self.status = status
-
 
 class Post(object):
     template: Template
@@ -52,33 +48,45 @@ class Post(object):
 
         title = raw["Title"]
         author = raw["Author"]
-        date = raw.get("Date", datetime.date.today().strftime("%Y-%m-%d"))
+        date = raw["Date"]
+        updated = raw.get("Updated", date)
         status = raw.get("Status", "draft")
 
-        return Metadata(title, author, date, status)
+        return Metadata(
+                title,
+                author,
+                datetime.datetime.fromisoformat(date),
+                datetime.datetime.fromisoformat(updated),
+                status
+        )
+
+    @functools.cached_property
+    def content(self) -> str:
+        md = None
+        for filename in os.listdir(self.directory):
+            if filename.endswith(".md"):
+                return render.to_html(os.path.join(self.directory, filename))
+        assert False, f"There is no markdown file in `{self.directory}`"
 
     def generate(self, basedir: str) -> None:
         postdir = os.path.basename(self.directory)
         workdir = os.path.join(basedir, postdir)
         os.makedirs(workdir)
 
-        md = None
         for filename in os.listdir(self.directory):
             source = os.path.join(self.directory, filename)
             destination = os.path.join(workdir, filename)
-
             shutil.copy(source, destination)
 
-            if filename.endswith(".md"):
-                md = source
-
-        assert md, f"There is no markdown file in `{self.directory}`"
-
-        content = render.to_html(md)
         rendered = self.template.render(title=self.metadata.title,
                                         author=self.metadata.author,
                                         date=self.metadata.date,
+                                        updated=self.metadata.updated,
                                         status=self.metadata.status,
-                                        content=content)
+                                        content=self.content)
         render.write_file_content(os.path.join(workdir, "index.html"),
                                   rendered)
+
+
+def remove_drafts(posts: List[Post]) -> List[Post]:
+    return list(filter(lambda x: x.metadata.status != "draft", posts))
diff --git a/posts/hello-world/metadata.txt b/posts/hello-world/metadata.txt
index 4c57cf0..6a41b6b 100644
--- a/posts/hello-world/metadata.txt
+++ b/posts/hello-world/metadata.txt
@@ -1,4 +1,4 @@
 Title: Hello, World!
 Author: Dmitry Ilvokhin
-Date: 2022-12-23
+Date: 2022-12-23T17:34:00+00:00
 Status: published
diff --git a/posts/jemalloc-hpa-reference/metadata.txt b/posts/jemalloc-hpa-reference/metadata.txt
index 0a84976..44feafe 100644
--- a/posts/jemalloc-hpa-reference/metadata.txt
+++ b/posts/jemalloc-hpa-reference/metadata.txt
@@ -1,4 +1,4 @@
 Title: Jemalloc HPA Reference
 Author: Dmitry Ilvokhin
-Date: 2025-03-23
+Date: 2025-03-23T12:58:00+00:00
 Status: published
diff --git a/posts/libstdc++-std-unordered-map/metadata.txt b/posts/libstdc++-std-unordered-map/metadata.txt
index 24b3750..603d518 100644
--- a/posts/libstdc++-std-unordered-map/metadata.txt
+++ b/posts/libstdc++-std-unordered-map/metadata.txt
@@ -1,4 +1,4 @@
 Title: How libstdc++ `std::unordered_map` implemented?
 Author: Dmitry Ilvokhin
-Date: 2023-07-02
+Date: 2023-07-02T13:08:00+01:00
 Status: published
diff --git a/share/style.css b/share/style.css
index 592e612..a6b2576 100644
--- a/share/style.css
+++ b/share/style.css
@@ -112,10 +112,6 @@ ul.posts li span {
 ul.posts time {
 }
 
-ul.posts li a:visited {
-    color: #8b6fcb;
-}
-
 .toclink {
     color: #222;
 }
diff --git a/templates/atom.xml b/templates/atom.xml
new file mode 100644
index 0000000..ba7fbda
--- /dev/null
+++ b/templates/atom.xml
@@ -0,0 +1,24 @@
+<feed xmlns="http://www.w3.org/2005/Atom">
+    <title>blog.ilvokhin.com</title>
+    <id>tag:blog.ilvokhin.com,2022:blog.ilvokhin.com</id>
+    <link rel="alternate" href="https://blog.ilvokhin.com"></link>
+    <link rel="self" href="https://blog.ilvokhin.com/atom.xml"></link>
+    <updated>{{ updated.isoformat() }}</updated>
+    <author>
+        <name>Dmitry Ilvokhin</name>
+        <uri>https://ilvokhin.com/</uri>
+        <email>d@ilvokhin.com</email>
+    </author>
+{% if posts %}
+    {% for post in posts %}
+    <entry>
+        <title>{{ post.metadata.title }}</title>
+        <id>tag:blog.ilvokhin.com,2022:blog.ilvokhin.com/{{ post.name }}</id>
+        <link rel="alternate" href="https://blog.ilvokhin.com/{{ post.name }}"></link>
+        <published>{{ post.metadata.date.isoformat() }}</published>
+        <updated>{{ post.metadata.updated.isoformat() }}</updated>
+        <content type="html">{{ post.content }}</content>
+    </entry>
+    {% endfor %}
+{% endif %}
+</feed>
diff --git a/templates/feed.html b/templates/feed.html
index deb89c5..e17d3d0 100644
--- a/templates/feed.html
+++ b/templates/feed.html
@@ -28,8 +28,8 @@
         <li>
             <span>
             <i>
-            <time datetime="{{ post.metadata.date }}" pubdate>
-            {{ post.metadata.date }}
+            <time datetime="{{ post.metadata.date.strftime('%Y-%m-%d') }}" pubdate>
+            {{ post.metadata.date.strftime('%Y-%m-%d') }}
             </time>
             </i>
             </span>
@@ -41,6 +41,9 @@
 
 </content>
 </main>
+<footer>
+    <small><p><a class="rss" href="/atom.xml">Atom / RSS</a></p><small>
+</footer>
 </body>
 
 </html>
diff --git a/templates/post.html b/templates/post.html
index 20c3ac2..f61a2bd 100644
--- a/templates/post.html
+++ b/templates/post.html
@@ -22,9 +22,14 @@
 <main>
 <h1>{{ title }}</h1>
 <p>
-    <i><time datetime="{{ date }}" pubdate>
-    {{ date }}
-    </time></i>
+    <i>
+    <time datetime="{{ date.strftime('%Y-%m-%d') }}" pubdate>
+        {{ date.strftime('%Y-%m-%d') }}
+    </time>
+    {% if date != updated %}
+    (updated <time datetime="{{ updated.strftime('%Y-%m-%d') }}">{{ updated.strftime('%Y-%m-%d') }}</time>)
+    {% endif %}
+    </i>
 {% if status == "draft" %}
 • {{ status }}
 {% endif %}