separate torrent storage features

src/torrent.rs

@@ -0,0 +1,32 @@
+use anyhow::Result;
+use std::{fs, io::Write, path::PathBuf, str::FromStr};
+
+pub struct Torrent {
+    storage: PathBuf,
+}
+
+impl Torrent {
+    pub fn init(path: &str) -> Result<Self> {
+        Ok(Self {
+            storage: PathBuf::from_str(path)?.canonicalize()?,
+        })
+    }
+
+    pub fn persist(&self, infohash: &str, data: &[u8]) -> Result<Option<PathBuf>> {
+        Ok(if self.path(infohash).exists() {
+            None
+        } else {
+            let p = self.path(infohash);
+            let mut f = fs::File::create(&p)?;
+            f.write_all(data)?;
+            Some(p)
+        })
+    }
+
+    fn path(&self, infohash: &str) -> PathBuf {
+        let mut p = PathBuf::new();
+        p.push(&self.storage);
+        p.push(format!("{infohash}.torrent"));
+        p
+    }
+}