implement index file option

src/config.rs

@@ -16,4 +16,8 @@ pub struct Config {
     /// * keep empty to export all
     #[arg(short, long)]
     pub filter_tag: Vec<String>,
+
+    /// Generate index file with given name
+    #[arg(short, long)]
+    pub index: Option<String>,
 }

src/main.rs

@@ -96,6 +96,17 @@ fn main() -> Result<()> {
         })
     }
 
+    if let Some(index) = config.index {
+        let mut file = File::create_new({
+            let mut path = PathBuf::from(&config.target);
+            path.push(format!("{}.md", index.trim_end_matches(".md")));
+            path
+        })?;
+        for discussion in &discussions {
+            file.write_all(format!("* [{}]({}.md)\n", discussion.title, discussion.id).as_bytes())?;
+        }
+    }
+
     for discussion in discussions {
         let mut file = File::create_new({
             let mut path = PathBuf::from(&config.target);