implement option to export index collected as the static rss feed, set save_torrents as false by default

src/rss.rs

@@ -0,0 +1,102 @@
+use anyhow::{Result, bail};
+use std::{collections::HashSet, fs::File, io::Write, path::PathBuf, str::FromStr};
+use url::Url;
+
+/// Export crawl index to the RSS file
+pub struct Rss {
+    file: File,
+    target: PathBuf,
+    tmp: PathBuf,
+    trackers: Option<HashSet<Url>>,
+}
+
+impl Rss {
+    /// Create writable file for given `filepath`
+    pub fn new(
+        filepath: &str,
+        title: &str,
+        link: &Option<String>,
+        description: &Option<String>,
+        trackers: Option<HashSet<Url>>,
+    ) -> Result<Self> {
+        // prevent from reading of the incomplete file
+        let tmp = PathBuf::from_str(&format!("{filepath}.tmp"))?;
+
+        // init public destination
+        let target = PathBuf::from_str(filepath)?;
+        if target.is_dir() {
+            bail!("RSS path `{}` is directory", target.to_string_lossy())
+        }
+        // init temporary file to write
+        let mut file = File::create(&tmp)?;
+        file.write_all(
+            b"<?xml version=\"1.0\" encoding=\"UTF-8\"?><rss version=\"2.0\"><channel><title>",
+        )?;
+        file.write_all(escape(title).as_bytes())?;
+        file.write_all(b"</title>")?;
+
+        if let Some(s) = link {
+            file.write_all(b"<link>")?;
+            file.write_all(escape(s).as_bytes())?;
+            file.write_all(b"</link>")?
+        }
+        if let Some(s) = description {
+            file.write_all(b"<description>")?;
+            file.write_all(escape(s).as_bytes())?;
+            file.write_all(b"</description>")?
+        }
+
+        Ok(Self {
+            file,
+            target,
+            trackers,
+            tmp,
+        })
+    }
+
+    /// Append `item` to the feed `channel`
+    pub fn push(
+        &mut self,
+        infohash: &str,
+        title: &str,
+        description: Option<&str>,
+        pub_date: Option<&str>,
+    ) -> Result<()> {
+        self.file.write_all(
+            format!(
+                "<item><guid>{infohash}</guid><title>{}</title><link>{}</link>",
+                escape(title),
+                escape(&crate::magnet(infohash, self.trackers.as_ref()))
+            )
+            .as_bytes(),
+        )?;
+        if let Some(s) = description {
+            self.file.write_all(b"<description>")?;
+            self.file.write_all(escape(s).as_bytes())?;
+            self.file.write_all(b"</description>")?
+        }
+        if let Some(s) = pub_date {
+            self.file.write_all(b"<pubDate>")?;
+            self.file.write_all(escape(s).as_bytes())?;
+            self.file.write_all(b"</pubDate>")?
+        }
+        self.file.write_all(b"</item>")?;
+        Ok(())
+    }
+
+    /// Write final bytes, replace public file with temporary one
+    pub fn commit(mut self) -> Result<()> {
+        self.file.write_all(b"</channel></rss>")?;
+        std::fs::rename(self.tmp, self.target)?;
+        Ok(())
+    }
+}
+
+fn escape(subject: &str) -> String {
+    subject
+        .replace('&', "&amp;")
+        .replace('<', "&lt;")
+        .replace('>', "&gt;")
+        .replace('"', "&quot;")
+        .replace("'", "&apos;")
+}