server: replace string literals in a bunch of places with consts

server/src/graphql.rs

@@ -23,6 +23,12 @@ pub type UnixTime = isize;
 /// # Thread ID, sans "thread:"
 pub type ThreadId = String;
 
+const TEXT_PLAIN: &'static str = "text/plain";
+const TEXT_HTML: &'static str = "text/html";
+const MULTIPART_ALTERNATIVE: &'static str = "multipart/alternative";
+const MULTIPART_MIXED: &'static str = "multipart/mixed";
+const MULTIPART_RELATED: &'static str = "multipart/related";
+
 #[derive(Debug, SimpleObject)]
 pub struct ThreadSummary {
     pub thread: ThreadId,
@@ -426,10 +432,10 @@ impl Mutation {
 fn extract_body(m: &ParsedMail) -> Result<Body, Error> {
     let body = m.get_body()?;
     let ret = match m.ctype.mimetype.as_str() {
-        "text/plain" => return Ok(Body::text(body)),
+        TEXT_PLAIN => return Ok(Body::text(body)),
-        "text/html" => return Ok(Body::html(body)),
+        TEXT_HTML => return Ok(Body::html(body)),
-        "multipart/mixed" => extract_mixed(m),
+        MULTIPART_MIXED => extract_mixed(m),
-        "multipart/alternative" => extract_alternative(m),
+        MULTIPART_ALTERNATIVE => extract_alternative(m),
         _ => extract_unhandled(m),
     };
     if let Err(err) = ret {
@@ -444,7 +450,6 @@ fn extract_unhandled(m: &ParsedMail) -> Result<Body, Error> {
         "Unhandled body content type:\n{}",
         render_content_type_tree(m)
     );
-    warn!("{}", msg);
     Ok(Body::UnhandledContentType(UnhandledContentType {
         text: msg,
     }))
@@ -455,59 +460,81 @@ fn extract_unhandled(m: &ParsedMail) -> Result<Body, Error> {
 // then give up.
 fn extract_alternative(m: &ParsedMail) -> Result<Body, Error> {
     for sp in &m.subparts {
-        if sp.ctype.mimetype == "text/html" {
+        if sp.ctype.mimetype.as_str() == TEXT_HTML {
             let body = sp.get_body()?;
             return Ok(Body::html(body));
         }
     }
     for sp in &m.subparts {
-        if sp.ctype.mimetype == "text/plain" {
+        if sp.ctype.mimetype.as_str() == TEXT_PLAIN {
             let body = sp.get_body()?;
             return Ok(Body::text(body));
         }
     }
-    Err("extract_alternative".into())
+    for sp in &m.subparts {
+        if sp.ctype.mimetype.as_str() == MULTIPART_RELATED {
+            return extract_related(sp);
+        }
+    }
+    Err(format!(
+        "extract_alternative failed to find suitable subpart, searched: {:?}",
+        vec![TEXT_HTML, TEXT_PLAIN]
+    )
+    .into())
 }
 
 // multipart/mixed defines multiple types of context all of which should be presented to the user
 // 'serially'.
 fn extract_mixed(m: &ParsedMail) -> Result<Body, Error> {
     for sp in &m.subparts {
-        if sp.ctype.mimetype == "multipart/alternative" {
+        if sp.ctype.mimetype.as_str() == MULTIPART_ALTERNATIVE {
             return extract_alternative(sp);
         }
     }
     for sp in &m.subparts {
-        if sp.ctype.mimetype == "multipart/related" {
+        if sp.ctype.mimetype == MULTIPART_RELATED {
             return extract_related(sp);
         }
     }
     for sp in &m.subparts {
         let body = sp.get_body()?;
         match sp.ctype.mimetype.as_str() {
-            "text/plain" => return Ok(Body::text(body)),
+            TEXT_PLAIN => return Ok(Body::text(body)),
-            "text/html" => return Ok(Body::html(body)),
+            TEXT_HTML => return Ok(Body::html(body)),
             _ => (),
         }
     }
-    Err("extract_mixed".into())
+    Err(format!(
+        "extract_mixed failed to find suitable subpart, searched: {:?}",
+        vec![
+            MULTIPART_ALTERNATIVE,
+            MULTIPART_RELATED,
+            TEXT_HTML,
+            TEXT_PLAIN
+        ]
+    )
+    .into())
 }
 
 fn extract_related(m: &ParsedMail) -> Result<Body, Error> {
     // TODO(wathiede): collect related things and change return type to new Body arm.
     for sp in &m.subparts {
-        if sp.ctype.mimetype == "text/html" {
+        if sp.ctype.mimetype == TEXT_HTML {
             let body = sp.get_body()?;
             return Ok(Body::html(body));
         }
     }
     for sp in &m.subparts {
-        if sp.ctype.mimetype == "text/plain" {
+        if sp.ctype.mimetype == TEXT_PLAIN {
             let body = sp.get_body()?;
             return Ok(Body::text(body));
         }
     }
-    Err("extract_related".into())
+    Err(format!(
+        "extract_related failed to find suitable subpart, searched: {:?}",
+        vec![TEXT_HTML, TEXT_PLAIN]
+    )
+    .into())
 }
 
 // TODO(wathiede): make this walk_attachments that takes a closure.