added some utility structures

1 files changed, 81 insertions, 0 deletions

diff --git a/src/mail/query.rs b/src/mail/query.rs
index e69de29..631ad56 100644
--- a/src/mail/query.rs
+++ b/src/mail/query.rs
@@ -0,0 +1,81 @@
+use anyhow::{Result, anyhow};
+use super::mailbox::MailMeta;
+use super::snapshot::FrozenMailbox;
+use super::unique_ident::UniqueIdent;
+use super::uidindex::IndexEntry;
+use futures::stream::{FuturesUnordered, StreamExt};
+
+/// Query is in charge of fetching efficiently
+/// requested data for a list of emails
+pub struct Query<'a,'b> {
+    pub frozen: &'a FrozenMailbox,
+    pub emails: &'b [UniqueIdent],
+}
+
+impl<'a,'b> Query<'a,'b> {
+    pub fn index(&self) -> Result<Vec<IndexResult>> {
+        self
+            .emails
+            .iter()
+            .map(|uuid| {
+                self
+                    .frozen
+                    .snapshot
+                    .table
+                    .get(uuid)
+                    .map(|index| IndexResult { uuid: *uuid, index })
+                    .ok_or(anyhow!("missing email in index"))
+            })
+            .collect::<Result<Vec<_>, _>>()
+    }
+
+    pub async fn partial(&self) -> Result<Vec<PartialResult>> {
+        let meta = self.frozen.mailbox.fetch_meta(self.emails).await?;
+        let result = meta
+            .into_iter()
+            .zip(self.index()?)
+            .map(|(metadata, index)| PartialResult { uuid: index.uuid, index: index.index, metadata })
+            .collect::<Vec<_>>();
+        Ok(result)
+    }
+
+    /// @FIXME WARNING: THIS CAN ALLOCATE A LOT OF MEMORY
+    /// AND GENERATE SO MUCH NETWORK TRAFFIC.
+    /// THIS FUNCTION SHOULD BE REWRITTEN, FOR EXAMPLE WITH
+    /// SOMETHING LIKE AN ITERATOR
+    pub async fn full(&self) -> Result<Vec<FullResult>> {
+        let meta_list = self.partial().await?;
+        meta_list
+            .into_iter()
+            .map(|meta| async move  {
+                let content = self.frozen.mailbox.fetch_full(meta.uuid, &meta.metadata.message_key).await?;
+                Ok(FullResult {
+                    uuid: meta.uuid,
+                    index: meta.index,
+                    metadata: meta.metadata,
+                    content,
+                })
+            })
+            .collect::<FuturesUnordered<_>>()
+            .collect::<Vec<_>>()
+            .await
+            .into_iter()
+            .collect::<Result<Vec<_>, _>>()
+    }
+}
+
+pub struct IndexResult<'a> {
+    pub uuid: UniqueIdent,
+    pub index: &'a IndexEntry,
+}
+pub struct PartialResult<'a> {
+    pub uuid: UniqueIdent,
+    pub index: &'a IndexEntry,
+    pub metadata: MailMeta,
+}
+pub struct FullResult<'a> {
+    pub uuid: UniqueIdent,
+    pub index: &'a IndexEntry,
+    pub metadata: MailMeta,
+    pub content: Vec<u8>,
+}