Select what to fecth for search

2 files changed, 34 insertions, 5 deletions

diff --git a/src/imap/mailbox_view.rs b/src/imap/mailbox_view.rs
index 5311635..4d0858f 100644
--- a/src/imap/mailbox_view.rs
+++ b/src/imap/mailbox_view.rs
@@ -344,12 +344,19 @@ impl MailboxView {
         search_key: &SearchKey<'a>,
         uid: bool,
     ) -> Result<Vec<Body<'static>>> {
-        let (seq_set, seq_type) = search::Criteria(search_key).to_sequence_set();
+        // 1. Compute the subset of sequence identifiers we need to fetch
+        let query = search::Criteria(search_key);
+        let (seq_set, seq_type) = query.to_sequence_set();
         let mailids = MailIdentifiersList(self.get_mail_ids(&seq_set, seq_type.is_uid())?);
         let mail_u32 = match uid {
             true => mailids.uids(),
             _ => mailids.ids(),
         };
+
+        // 2. Compute wether we will need to fetch the mail meta and/or the body
+        let _need_meta = query.need_meta();
+        let _need_body = query.need_body();
+
         Ok(vec![Body::Data(Data::Search(mail_u32))])
     }
 
diff --git a/src/imap/search.rs b/src/imap/search.rs
index bf1d30e..ef89288 100644
--- a/src/imap/search.rs
+++ b/src/imap/search.rs
@@ -69,12 +69,34 @@ impl<'a> Criteria<'a> {
         }
     }
 
-    fn need_meta(&self) {
-        unimplemented!();
+    /// Not really clever as we can have cases where we filter out
+    /// the email before needing to inspect its meta.
+    /// But for now we are seeking the most basic/stupid algorithm.
+    pub fn need_meta(&self) -> bool {
+        use SearchKey::*;
+        match self.0 {
+            // IMF Headers
+            Bcc(_) | Cc(_) | From(_) | Header(..) | SentBefore(_) | SentOn(_) | SentSince(_) | Subject(_) | To(_) => true,
+            // Internal Date is also stored in MailMeta
+            Before(_) | On(_) | Since(_) => true,
+            // Message size is also stored in MailMeta
+            Larger(_) | Smaller(_) => true,
+            And(and_list) => and_list.as_ref().iter().any(|sk| Criteria(sk).need_meta()),
+            Not(inner) => Criteria(inner).need_meta(),
+            Or(left, right) => Criteria(left).need_meta() || Criteria(right).need_meta(),
+            _ => false,
+        }
     }
 
-    fn need_body(&self) {
-        unimplemented!();
+    pub fn need_body(&self) -> bool {
+        use SearchKey::*;
+        match self.0 {
+            Text(_) | Body(_) => true,
+            And(and_list) => and_list.as_ref().iter().any(|sk| Criteria(sk).need_body()),
+            Not(inner) => Criteria(inner).need_body(),
+            Or(left, right) => Criteria(left).need_body() || Criteria(right).need_body(),
+            _ => false,
+        }
     }
 }