added some utility structures

1 files changed, 43 insertions, 2 deletions

diff --git a/src/mail/snapshot.rs b/src/mail/snapshot.rs
index 7256d50..54bec64 100644
--- a/src/mail/snapshot.rs
+++ b/src/mail/snapshot.rs
@@ -1,11 +1,52 @@
 use std::sync::Arc;
+
+use anyhow::Result;
+
 use super::mailbox::Mailbox;
 use super::uidindex::UidIndex;
 
-pub struct Snapshot {
+/// A Frozen Mailbox has a snapshot of the current mailbox
+/// state that is desynchronized with the real mailbox state.
+/// It's up to the user to choose when their snapshot must be updated
+/// to give useful information to their clients
+///
+/// 
+pub struct FrozenMailbox {
     pub mailbox: Arc<Mailbox>,
     pub snapshot: UidIndex,
 }
 
-impl Snapshot {
+impl FrozenMailbox {
+    /// Create a snapshot from a mailbox, the mailbox + the snapshot
+    /// becomes the "Frozen Mailbox".
+    pub async fn new(mailbox: Arc<Mailbox>) -> Self {
+        let state = mailbox.current_uid_index().await;
+
+        Self {
+            mailbox,
+            snapshot: state,
+        }
+    }
+
+    /// Force the synchronization of the inner mailbox
+    /// but do not update the local snapshot
+    pub async fn sync(&self) -> Result<()> {
+        self.mailbox.opportunistic_sync().await
+    }
+
+    /// Peek snapshot without updating the frozen mailbox
+    /// Can be useful if you want to plan some writes
+    /// while sending a diff to the client later
+    pub async fn peek(&self) -> UidIndex {
+        self.mailbox.current_uid_index().await
+    }
+
+    /// Update the FrozenMailbox local snapshot.
+    /// Returns the old snapshot, so you can build a diff
+    pub async fn update(&mut self) -> UidIndex {
+       let old_snapshot = self.snapshot.clone();
+       self.snapshot = self.mailbox.current_uid_index().await;
+
+       old_snapshot
+    }
 }