Allow specifying how many items go into the feed

Signed-off-by: Jacob Kiers <code@kiers.eu>

src/cli.rs

@@ -31,6 +31,9 @@ pub(crate) struct FeedBuilderSettings {
     /// Create an HTML file for each message
     #[clap(short, long, value_parser, default_value_t = false)]
     pub include_html: bool,
+    /// Maximum number of items in the feed (default: unlimited)
+    #[clap(short = 'n', long, value_parser)]
+    pub max_items: Option<usize>,
 }
 
 #[derive(Subcommand)]

src/main.rs

@@ -41,6 +41,7 @@ fn main() -> Result<(), Box<dyn Error>> {
             &settings.filename,
             &settings.hostname,
             settings.include_html,
+            settings.max_items
         ),
 
         cli::Command::Update => command::update::self_update(),
@@ -63,6 +64,7 @@ fn build_feed(
     filename: &PathBuf,
     hostname: &String,
     include_html: bool,
+    max_items_in_feed: Option<usize>
 ) -> Result<(), Box<dyn Error>> {
     let dir = filename.parent().ok_or(format!(
         "Could not get parent directory of {}",
@@ -87,7 +89,9 @@ fn build_feed(
 
     let mut reader = DataDirectoryMessageReader::new(Path::new("data").to_path_buf());
 
-    for msg in reader.read_rfc822_messages() {
+    let max_items_in_feed = max_items_in_feed.unwrap_or_else(|| usize::MAX);
+
+    for msg in reader.read_rfc822_messages().take(max_items_in_feed) {
         let parsed = msg.get_parsed().expect("A parsed messsage.");
 
         let date = parsed.date().ok_or(format!(