server: set filename when downloading attachment.

server/src/main.rs

@@ -1,16 +1,18 @@
 #[macro_use]
 extern crate rocket;
 
-use std::{error::Error, process::Command, str::FromStr};
+use std::{error::Error, io::Cursor, str::FromStr};
 
 use rocket::{
-    response::{content::Plain, Debug},
+    http::{ContentType, Header},
+    request::Request,
+    response::{content::Plain, Debug, Responder},
     serde::json::Json,
-    State,
+    Response, State,
 };
 use rocket_cors::{AllowedHeaders, AllowedOrigins};
 
-use notmuch::{MessageId, Notmuch, NotmuchError, SearchSummary, ThreadSet};
+use notmuch::{Notmuch, NotmuchError, SearchSummary, ThreadSet};
 
 #[get("/")]
 fn hello() -> &'static str {
@@ -32,19 +34,44 @@ async fn show(nm: &State<Notmuch>, query: &str) -> Result<Json<ThreadSet>, Debug
     Ok(Json(res))
 }
 
+struct PartResponder {
+    bytes: Vec<u8>,
+    filename: Option<String>,
+}
+
+impl<'r, 'o: 'r> Responder<'r, 'o> for PartResponder {
+    fn respond_to(self, _: &'r Request<'_>) -> rocket::response::Result<'o> {
+        let mut resp = Response::build();
+        if let Some(filename) = self.filename {
+            info!("filename {:?}", filename);
+            resp.header(Header::new(
+                "Content-Disposition",
+                format!(r#"attachment; filename="{}""#, filename),
+            ))
+            .header(ContentType::Binary);
+        }
+        resp.sized_body(self.bytes.len(), Cursor::new(self.bytes))
+            .ok()
+    }
+}
+
 #[get("/original/<id>/part/<part>")]
 async fn original_part(
     nm: &State<Notmuch>,
     id: &str,
     part: usize,
-) -> Result<Vec<u8>, Debug<NotmuchError>> {
+) -> Result<PartResponder, Debug<NotmuchError>> {
     let mid = if id.starts_with("id:") {
         id.to_string()
     } else {
         format!("id:{}", id)
     };
+    let meta = nm.show_part(&mid, part)?;
     let res = nm.show_original_part(&mid, part)?;
-    Ok(res)
+    Ok(PartResponder {
+        bytes: res,
+        filename: meta.filename,
+    })
 }
 
 #[get("/original/<id>")]