initial commit

src/feed.rs

@@ -0,0 +1,88 @@
+mod link;
+
+use chrono::{DateTime, Utc};
+use link::Link;
+use url::Url;
+
+/// Export crawl index to the RSS file
+pub struct Feed {
+    buffer: String,
+    canonical: Link,
+}
+
+impl Feed {
+    pub fn new(
+        title: &str,
+        description: Option<&str>,
+        canonical: Option<Url>,
+        capacity: usize,
+    ) -> Self {
+        let t = chrono::Utc::now().to_rfc2822();
+        let mut buffer = String::with_capacity(capacity);
+
+        buffer.push_str("<?xml version=\"1.0\" encoding=\"UTF-8\"?><rss version=\"2.0\"><channel>");
+
+        buffer.push_str("<pubDate>");
+        buffer.push_str(&t);
+        buffer.push_str("</pubDate>");
+
+        buffer.push_str("<lastBuildDate>");
+        buffer.push_str(&t);
+        buffer.push_str("</lastBuildDate>");
+
+        buffer.push_str("<title>");
+        buffer.push_str(title);
+        buffer.push_str("</title>");
+
+        if let Some(d) = description {
+            buffer.push_str("<description>");
+            buffer.push_str(d);
+            buffer.push_str("</description>")
+        }
+
+        if let Some(ref c) = canonical {
+            // @TODO required the RSS specification!
+            buffer.push_str("<link>");
+            buffer.push_str(c.as_str());
+            buffer.push_str("</link>")
+        }
+
+        Self {
+            buffer,
+            canonical: Link::from_url(canonical),
+        }
+    }
+
+    /// Append `item` to the feed `channel`
+    pub fn push(&mut self, guid: i64, time: DateTime<Utc>, title: String, message: &str) {
+        self.buffer.push_str(&format!(
+            "<item><guid>{guid}</guid><title>{title}</title><link>{}</link>",
+            self.canonical.link(guid)
+        ));
+
+        self.buffer.push_str("<description>");
+        self.buffer.push_str(&escape(message));
+        self.buffer.push_str("</description>");
+
+        self.buffer.push_str("<pubDate>");
+        self.buffer.push_str(&time.to_rfc2822());
+        self.buffer.push_str("</pubDate>");
+
+        self.buffer.push_str("</item>")
+    }
+
+    /// Write final bytes
+    pub fn commit(mut self) -> String {
+        self.buffer.push_str("</channel></rss>");
+        self.buffer
+    }
+}
+
+fn escape(value: &str) -> String {
+    value
+        .replace('&', "&amp;")
+        .replace('<', "&lt;")
+        .replace('>', "&gt;")
+        .replace('"', "&quot;")
+        .replace("'", "&apos;")
+}