Initial code dump: matrix feedbot, aka bender

This is a rewrite of our old feedbot in rust, heavily inspired from
rek2's INN matrix bot and making use of some bits from matrix-rust-sdk

This is an asynchronous tokio-based matrix client using a stateless feed
fetcher implementation based on reqwest, it uses feed_rs for parsing RSS
and Atom feeds. State persistence is achieved using a simple file-backed
datastore with serde_yaml as a serialization format.

Published under the GNU General Public License version 3 or later.

src/feedreader.rs

@@ -0,0 +1,112 @@
+/**
+ * matrix-feedbot v0.1.0
+ *
+ * Copyright (C) 2024 The 1312 Media Collective
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ * 
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+use reqwest::header::{ HeaderMap, ACCEPT, USER_AGENT };
+use tracing::{ info, debug };
+use feed_rs::{ model, parser };
+use chrono::{ DateTime, Utc };
+use std::error::Error;
+
+#[derive(Clone, Debug)]
+pub struct Feed {
+    pub uri: String,
+    pub title: String,
+    pub model: model::Feed
+}
+
+#[derive(Clone, Debug)]
+pub struct Entry {
+    pub ts: DateTime<Utc>,
+    pub title: String,
+    pub link: String,
+    pub content: String,
+    pub feed: Feed,
+    #[allow(dead_code)]
+    pub model: model::Entry,
+    pub formatted: Option<String>
+}
+
+pub async fn fetch_and_parse_feed(uri: &str) -> Result<Feed, Box<dyn Error>> {
+    info!("Fetching feed at {}", uri);
+    let mut headers = HeaderMap::new();
+    headers.insert(USER_AGENT,
+        "matrix-feedbot/0.1.0 (compatible; Mozilla/5.0; +https://1312.media/)"
+        .parse().unwrap());
+
+    headers.insert(ACCEPT,
+        "application/rss+xml, application/rdf+xml;q=0.8, application/atom+xml;q=0.6, application/xml;q=0.4, text/xml;q=0.4"
+        .parse().unwrap());
+
+    let http_client = reqwest::Client::builder().default_headers(headers).build()?;
+    let response = http_client.get(uri).send().await?.text().await?;
+
+    info!("Got response, parsing feed");
+    let feed = parser::parse(response.as_bytes())?;
+
+    let feed_title = match feed.title.clone() {
+        Some(t) => t.content,
+        None => String::from("Untitled")
+    };
+
+    info!("Got feed with title \"{}\"", feed_title);
+
+    Ok(Feed {
+        uri: String::from(uri),
+        title: feed_title,
+        model: feed
+    })
+}
+
+pub fn format_entry(feed: Feed, entry: model::Entry) -> Result<Entry, Box<dyn Error>> {
+    debug!("Formatting entry {}", entry.id);
+
+    let mut e = Entry {
+        feed: feed,
+        title: match entry.title.clone() {
+            Some(t) => t.content,
+            None    => String::from("Untitled")
+        },
+        link: entry.links[0].href.clone(),
+        ts: match entry.updated {
+            Some(d) => d,
+            None    => entry.published.unwrap_or(Utc::now())
+        },
+        content: match entry.content.clone() {
+            Some(c) => c.body.unwrap_or(String::from("")),
+            None    => match entry.summary.clone() {
+                Some(s) => s.content,
+                None    => String::from("")
+            }
+        },
+        model: entry,
+        formatted: None
+    };
+
+    e.formatted = Some(format!(
+        "<b>{feed_title}: <a href=\"{link}\">{title}</a> on {date}</b>{content}",
+
+        feed_title=e.feed.title,
+        link=e.link,
+        title=e.title,
+        date=e.ts.to_rfc2822(),
+        content=e.content
+    ));
+
+    Ok(e)
+}