1 files changed, 345 insertions, 0 deletions
diff --git a/src/mail/uidindex.rs b/src/mail/uidindex.rs
new file mode 100644
index 0000000..49dbba5
--- /dev/null
+++ b/src/mail/uidindex.rs
@@ -0,0 +1,345 @@
+use std::num::NonZeroU32;
+
+use im::{HashMap, HashSet, OrdMap, OrdSet};
+use serde::{de::Error, Deserialize, Deserializer, Serialize, Serializer};
+
+use crate::bayou::*;
+use crate::mail::mail_ident::MailIdent;
+
+pub type ImapUid = NonZeroU32;
+pub type ImapUidvalidity = NonZeroU32;
+pub type Flag = String;
+
+#[derive(Clone)]
+/// A UidIndex handles the mutable part of a mailbox
+/// It is built by running the event log on it
+/// Each applied log generates a new UidIndex by cloning the previous one
+/// and applying the event. This is why we use immutable datastructures:
+/// they are cheap to clone.
+pub struct UidIndex {
+    // Source of trust
+    pub table: OrdMap<MailIdent, (ImapUid, Vec<Flag>)>,
+
+    // Indexes optimized for queries
+    pub idx_by_uid: OrdMap<ImapUid, MailIdent>,
+    pub idx_by_flag: FlagIndex,
+
+    // Counters
+    pub uidvalidity: ImapUidvalidity,
+    pub uidnext: ImapUid,
+    pub internalseq: ImapUid,
+}
+
+#[derive(Clone, Serialize, Deserialize, Debug)]
+pub enum UidIndexOp {
+    MailAdd(MailIdent, ImapUid, Vec<Flag>),
+    MailDel(MailIdent),
+    FlagAdd(MailIdent, Vec<Flag>),
+    FlagDel(MailIdent, Vec<Flag>),
+}
+
+impl UidIndex {
+    #[must_use]
+    pub fn op_mail_add(&self, ident: MailIdent, flags: Vec<Flag>) -> UidIndexOp {
+        UidIndexOp::MailAdd(ident, self.internalseq, flags)
+    }
+
+    #[must_use]
+    pub fn op_mail_del(&self, ident: MailIdent) -> UidIndexOp {
+        UidIndexOp::MailDel(ident)
+    }
+
+    #[must_use]
+    pub fn op_flag_add(&self, ident: MailIdent, flags: Vec<Flag>) -> UidIndexOp {
+        UidIndexOp::FlagAdd(ident, flags)
+    }
+
+    #[must_use]
+    pub fn op_flag_del(&self, ident: MailIdent, flags: Vec<Flag>) -> UidIndexOp {
+        UidIndexOp::FlagDel(ident, flags)
+    }
+
+    // INTERNAL functions to keep state consistent
+
+    fn reg_email(&mut self, ident: MailIdent, uid: ImapUid, flags: &Vec<Flag>) {
+        // Insert the email in our table
+        self.table.insert(ident, (uid, flags.clone()));
+
+        // Update the indexes/caches
+        self.idx_by_uid.insert(uid, ident);
+        self.idx_by_flag.insert(uid, flags);
+    }
+
+    fn unreg_email(&mut self, ident: &MailIdent) {
+        // We do nothing if the mail does not exist
+        let (uid, flags) = match self.table.get(ident) {
+            Some(v) => v,
+            None => return,
+        };
+
+        // Delete all cache entries
+        self.idx_by_uid.remove(uid);
+        self.idx_by_flag.remove(*uid, flags);
+
+        // Remove from source of trust
+        self.table.remove(ident);
+    }
+}
+
+impl Default for UidIndex {
+    fn default() -> Self {
+        Self {
+            table: OrdMap::new(),
+            idx_by_uid: OrdMap::new(),
+            idx_by_flag: FlagIndex::new(),
+            uidvalidity: NonZeroU32::new(1).unwrap(),
+            uidnext: NonZeroU32::new(1).unwrap(),
+            internalseq: NonZeroU32::new(1).unwrap(),
+        }
+    }
+}
+
+impl BayouState for UidIndex {
+    type Op = UidIndexOp;
+
+    fn apply(&self, op: &UidIndexOp) -> Self {
+        let mut new = self.clone();
+        match op {
+            UidIndexOp::MailAdd(ident, uid, flags) => {
+                // Change UIDValidity if there is a conflict
+                if *uid < new.internalseq {
+                    new.uidvalidity =
+                        NonZeroU32::new(new.uidvalidity.get() + new.internalseq.get() - uid.get())
+                            .unwrap();
+                }
+
+                // Assign the real uid of the email
+                let new_uid = new.internalseq;
+
+                // Delete the previous entry if any.
+                // Our proof has no assumption on `ident` uniqueness,
+                // so we must handle this case even it is very unlikely
+                // In this case, we overwrite the email.
+                // Note: assigning a new UID is mandatory.
+                new.unreg_email(ident);
+
+                // We record our email and update ou caches
+                new.reg_email(*ident, new_uid, flags);
+
+                // Update counters
+                new.internalseq = NonZeroU32::new(new.internalseq.get() + 1).unwrap();
+                new.uidnext = new.internalseq;
+            }
+            UidIndexOp::MailDel(ident) => {
+                // If the email is known locally, we remove its references in all our indexes
+                new.unreg_email(ident);
+
+                // We update the counter
+                new.internalseq = NonZeroU32::new(new.internalseq.get() + 1).unwrap();
+            }
+            UidIndexOp::FlagAdd(ident, new_flags) => {
+                if let Some((uid, existing_flags)) = new.table.get_mut(ident) {
+                    // Add flags to the source of trust and the cache
+                    let mut to_add: Vec<Flag> = new_flags
+                        .iter()
+                        .filter(|f| !existing_flags.contains(f))
+                        .cloned()
+                        .collect();
+                    new.idx_by_flag.insert(*uid, &to_add);
+                    existing_flags.append(&mut to_add);
+                }
+            }
+            UidIndexOp::FlagDel(ident, rm_flags) => {
+                if let Some((uid, existing_flags)) = new.table.get_mut(ident) {
+                    // Remove flags from the source of trust and the cache
+                    existing_flags.retain(|x| !rm_flags.contains(x));
+                    new.idx_by_flag.remove(*uid, rm_flags);
+                }
+            }
+        }
+        new
+    }
+}
+
+// ---- FlagIndex implementation ----
+#[derive(Clone)]
+pub struct FlagIndex(HashMap<Flag, OrdSet<ImapUid>>);
+pub type FlagIter<'a> = im::hashmap::Keys<'a, Flag, OrdSet<ImapUid>>;
+
+impl FlagIndex {
+    fn new() -> Self {
+        Self(HashMap::new())
+    }
+    fn insert(&mut self, uid: ImapUid, flags: &Vec<Flag>) {
+        flags.iter().for_each(|flag| {
+            self.0
+                .entry(flag.clone())
+                .or_insert(OrdSet::new())
+                .insert(uid);
+        });
+    }
+    fn remove(&mut self, uid: ImapUid, flags: &Vec<Flag>) -> () {
+        flags.iter().for_each(|flag| {
+            self.0.get_mut(flag).and_then(|set| set.remove(&uid));
+        });
+    }
+
+    pub fn get(&self, f: &Flag) -> Option<&OrdSet<ImapUid>> {
+        self.0.get(f)
+    } 
+
+    pub fn flags(&self) -> FlagIter {
+        self.0.keys()
+    }
+}
+
+// ---- CUSTOM SERIALIZATION AND DESERIALIZATION ----
+
+#[derive(Serialize, Deserialize)]
+struct UidIndexSerializedRepr {
+    mails: Vec<(ImapUid, MailIdent, Vec<Flag>)>,
+    uidvalidity: ImapUidvalidity,
+    uidnext: ImapUid,
+    internalseq: ImapUid,
+}
+
+impl<'de> Deserialize<'de> for UidIndex {
+    fn deserialize<D>(d: D) -> Result<Self, D::Error>
+    where
+        D: Deserializer<'de>,
+    {
+        let val: UidIndexSerializedRepr = UidIndexSerializedRepr::deserialize(d)?;
+
+        let mut uidindex = UidIndex {
+            table: OrdMap::new(),
+            idx_by_uid: OrdMap::new(),
+            idx_by_flag: FlagIndex::new(),
+            uidvalidity: val.uidvalidity,
+            uidnext: val.uidnext,
+            internalseq: val.internalseq,
+        };
+
+        val.mails
+            .iter()
+            .for_each(|(u, i, f)| uidindex.reg_email(*i, *u, f));
+
+        Ok(uidindex)
+    }
+}
+
+impl Serialize for UidIndex {
+    fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
+    where
+        S: Serializer,
+    {
+        let mut mails = vec![];
+        for (ident, (uid, flags)) in self.table.iter() {
+            mails.push((*uid, *ident, flags.clone()));
+        }
+
+        let val = UidIndexSerializedRepr {
+            mails,
+            uidvalidity: self.uidvalidity,
+            uidnext: self.uidnext,
+            internalseq: self.internalseq,
+        };
+
+        val.serialize(serializer)
+    }
+}
+
+// ---- TESTS ----
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_uidindex() {
+        let mut state = UidIndex::default();
+
+        // Add message 1
+        {
+            let m = MailIdent([0x01; 24]);
+            let f = vec!["\\Recent".to_string(), "\\Archive".to_string()];
+            let ev = state.op_mail_add(m, f);
+            state = state.apply(&ev);
+
+            // Early checks
+            assert_eq!(state.table.len(), 1);
+            let (uid, flags) = state.table.get(&m).unwrap();
+            assert_eq!(*uid, 1);
+            assert_eq!(flags.len(), 2);
+            let ident = state.idx_by_uid.get(&1).unwrap();
+            assert_eq!(&m, ident);
+            let recent = state.idx_by_flag.0.get("\\Recent").unwrap();
+            assert_eq!(recent.len(), 1);
+            assert_eq!(recent.iter().next().unwrap(), &1);
+            assert_eq!(state.uidnext, 2);
+            assert_eq!(state.uidvalidity, 1);
+        }
+
+        // Add message 2
+        {
+            let m = MailIdent([0x02; 24]);
+            let f = vec!["\\Seen".to_string(), "\\Archive".to_string()];
+            let ev = state.op_mail_add(m, f);
+            state = state.apply(&ev);
+
+            let archive = state.idx_by_flag.0.get("\\Archive").unwrap();
+            assert_eq!(archive.len(), 2);
+        }
+
+        // Add flags to message 1
+        {
+            let m = MailIdent([0x01; 24]);
+            let f = vec!["Important".to_string(), "$cl_1".to_string()];
+            let ev = state.op_flag_add(m, f);
+            state = state.apply(&ev);
+        }
+
+        // Delete flags from message 1
+        {
+            let m = MailIdent([0x01; 24]);
+            let f = vec!["\\Recent".to_string()];
+            let ev = state.op_flag_del(m, f);
+            state = state.apply(&ev);
+
+            let archive = state.idx_by_flag.0.get("\\Archive").unwrap();
+            assert_eq!(archive.len(), 2);
+        }
+
+        // Delete message 2
+        {
+            let m = MailIdent([0x02; 24]);
+            let ev = state.op_mail_del(m);
+            state = state.apply(&ev);
+
+            let archive = state.idx_by_flag.0.get("\\Archive").unwrap();
+            assert_eq!(archive.len(), 1);
+        }
+
+        // Add a message 3 concurrent to message 1 (trigger a uid validity change)
+        {
+            let m = MailIdent([0x03; 24]);
+            let f = vec!["\\Archive".to_string(), "\\Recent".to_string()];
+            let ev = UidIndexOp::MailAdd(m, 1, f);
+            state = state.apply(&ev);
+        }
+
+        // Checks
+        {
+            assert_eq!(state.table.len(), 2);
+            assert!(state.uidvalidity > 1);
+
+            let (last_uid, ident) = state.idx_by_uid.get_max().unwrap();
+            assert_eq!(ident, &MailIdent([0x03; 24]));
+
+            let archive = state.idx_by_flag.0.get("\\Archive").unwrap();
+            assert_eq!(archive.len(), 2);
+            let mut iter = archive.iter();
+            assert_eq!(iter.next().unwrap(), &1);
+            assert_eq!(iter.next().unwrap(), last_uid);
+        }
+    }
+}