1 files changed, 324 insertions, 0 deletions
diff --git a/aero-collections/src/calendar/namespace.rs b/aero-collections/src/calendar/namespace.rs
new file mode 100644
index 0000000..db65703
--- /dev/null
+++ b/aero-collections/src/calendar/namespace.rs
@@ -0,0 +1,324 @@
+use anyhow::{bail, Result};
+use std::collections::{BTreeMap, HashMap};
+use std::sync::{Arc, Weak};
+
+use serde::{Deserialize, Serialize};
+
+use aero_bayou::timestamp::now_msec;
+use aero_user::cryptoblob::{open_deserialize, seal_serialize};
+use aero_user::storage;
+
+use super::Calendar;
+use crate::unique_ident::{gen_ident, UniqueIdent};
+use crate::user::User;
+
+pub(crate) const CAL_LIST_PK: &str = "calendars";
+pub(crate) const CAL_LIST_SK: &str = "list";
+pub(crate) const MAIN_CAL: &str = "Personal";
+pub(crate) const MAX_CALNAME_CHARS: usize = 32;
+
+pub struct CalendarNs(std::sync::Mutex<HashMap<UniqueIdent, Weak<Calendar>>>);
+
+impl CalendarNs {
+    /// Create a new calendar namespace
+    pub fn new() -> Self {
+        Self(std::sync::Mutex::new(HashMap::new()))
+    }
+
+    /// Open a calendar by name
+    pub async fn open(&self, user: &Arc<User>, name: &str) -> Result<Option<Arc<Calendar>>> {
+        let (list, _ct) = CalendarList::load(user).await?;
+
+        match list.get(name) {
+            None => Ok(None),
+            Some(ident) => Ok(Some(self.open_by_id(user, ident).await?)),
+        }
+    }
+
+    /// Open a calendar by unique id
+    /// Check user.rs::open_mailbox_by_id to understand this function
+    pub async fn open_by_id(&self, user: &Arc<User>, id: UniqueIdent) -> Result<Arc<Calendar>> {
+        {
+            let cache = self.0.lock().unwrap();
+            if let Some(cal) = cache.get(&id).and_then(Weak::upgrade) {
+                return Ok(cal);
+            }
+        }
+
+        let cal = Arc::new(Calendar::open(&user.creds, id).await?);
+
+        let mut cache = self.0.lock().unwrap();
+        if let Some(concurrent_cal) = cache.get(&id).and_then(Weak::upgrade) {
+            drop(cal); // we worked for nothing but at least we didn't starve someone else
+            Ok(concurrent_cal)
+        } else {
+            cache.insert(id, Arc::downgrade(&cal));
+            Ok(cal)
+        }
+    }
+
+    /// List calendars
+    pub async fn list(&self, user: &Arc<User>) -> Result<Vec<String>> {
+        CalendarList::load(user).await.map(|(list, _)| list.names())
+    }
+
+    /// Delete a calendar from the index
+    pub async fn delete(&self, user: &Arc<User>, name: &str) -> Result<()> {
+        // We currently assume that main cal is a bit specific
+        if name == MAIN_CAL {
+            bail!("Cannot delete main calendar");
+        }
+
+        let (mut list, ct) = CalendarList::load(user).await?;
+        if list.has(name) {
+            //@TODO: actually delete calendar content
+            list.bind(name, None);
+            list.save(user, ct).await?;
+            Ok(())
+        } else {
+            bail!("Calendar {} does not exist", name);
+        }
+    }
+
+    /// Rename a calendar in the index
+    pub async fn rename(&self, user: &Arc<User>, old: &str, new: &str) -> Result<()> {
+        if old == MAIN_CAL {
+            bail!("Renaming main calendar is not supported currently");
+        }
+        if !new.chars().all(char::is_alphanumeric) {
+            bail!("Unsupported characters in new calendar name, only alphanumeric characters are allowed currently");
+        }
+        if new.len() > MAX_CALNAME_CHARS {
+            bail!("Calendar name can't contain more than 32 characters");
+        }
+
+        let (mut list, ct) = CalendarList::load(user).await?;
+        list.rename(old, new)?;
+        list.save(user, ct).await?;
+
+        Ok(())
+    }
+
+    /// Create calendar
+    pub async fn create(&self, user: &Arc<User>, name: &str) -> Result<()> {
+        if name == MAIN_CAL {
+            bail!("Main calendar is automatically created, can't create it manually");
+        }
+        if !name.chars().all(char::is_alphanumeric) {
+            bail!("Unsupported characters in new calendar name, only alphanumeric characters are allowed");
+        }
+        if name.len() > MAX_CALNAME_CHARS {
+            bail!("Calendar name can't contain more than 32 characters");
+        }
+
+        let (mut list, ct) = CalendarList::load(user).await?;
+        match list.create(name) {
+            CalendarExists::Existed(_) => bail!("Calendar {} already exists", name),
+            CalendarExists::Created(_) => (),
+        }
+        list.save(user, ct).await?;
+
+        Ok(())
+    }
+
+    /// Has calendar
+    pub async fn has(&self, user: &Arc<User>, name: &str) -> Result<bool> {
+        CalendarList::load(user)
+            .await
+            .map(|(list, _)| list.has(name))
+    }
+}
+
+// ------
+// ------ From this point, implementation is hidden from the rest of the crate
+// ------
+
+#[derive(Serialize, Deserialize)]
+struct CalendarList(BTreeMap<String, CalendarListEntry>);
+
+#[derive(Serialize, Deserialize, Clone, Copy, Debug)]
+struct CalendarListEntry {
+    id_lww: (u64, Option<UniqueIdent>),
+}
+
+impl CalendarList {
+    // ---- Index persistence related functions
+
+    /// Load from storage
+    async fn load(user: &Arc<User>) -> Result<(Self, Option<storage::RowRef>)> {
+        let row_ref = storage::RowRef::new(CAL_LIST_PK, CAL_LIST_SK);
+        let (mut list, row) = match user
+            .storage
+            .row_fetch(&storage::Selector::Single(&row_ref))
+            .await
+        {
+            Err(storage::StorageError::NotFound) => (Self::new(), None),
+            Err(e) => return Err(e.into()),
+            Ok(rv) => {
+                let mut list = Self::new();
+                let (row_ref, row_vals) = match rv.into_iter().next() {
+                    Some(row_val) => (row_val.row_ref, row_val.value),
+                    None => (row_ref, vec![]),
+                };
+
+                for v in row_vals {
+                    if let storage::Alternative::Value(vbytes) = v {
+                        let list2 =
+                            open_deserialize::<CalendarList>(&vbytes, &user.creds.keys.master)?;
+                        list.merge(list2);
+                    }
+                }
+                (list, Some(row_ref))
+            }
+        };
+
+        // Create default calendars (currently only one calendar is created)
+        let is_default_cal_missing = [MAIN_CAL]
+            .iter()
+            .map(|calname| list.create(calname))
+            .fold(false, |acc, r| {
+                acc || matches!(r, CalendarExists::Created(..))
+            });
+
+        // Save the index if we created a new calendar
+        if is_default_cal_missing {
+            list.save(user, row.clone()).await?;
+        }
+
+        Ok((list, row))
+    }
+
+    /// Save an updated index
+    async fn save(&self, user: &Arc<User>, ct: Option<storage::RowRef>) -> Result<()> {
+        let list_blob = seal_serialize(self, &user.creds.keys.master)?;
+        let rref = ct.unwrap_or(storage::RowRef::new(CAL_LIST_PK, CAL_LIST_SK));
+        let row_val = storage::RowVal::new(rref, list_blob);
+        user.storage.row_insert(vec![row_val]).await?;
+        Ok(())
+    }
+
+    // ----- Index manipulation functions
+
+    /// Ensure that a given calendar exists
+    /// (Don't forget to save if it returns CalendarExists::Created)
+    fn create(&mut self, name: &str) -> CalendarExists {
+        if let Some(CalendarListEntry {
+            id_lww: (_, Some(id)),
+        }) = self.0.get(name)
+        {
+            return CalendarExists::Existed(*id);
+        }
+
+        let id = gen_ident();
+        self.bind(name, Some(id)).unwrap();
+        CalendarExists::Created(id)
+    }
+
+    /// Get a list of all calendar names
+    fn names(&self) -> Vec<String> {
+        self.0
+            .iter()
+            .filter(|(_, v)| v.id_lww.1.is_some())
+            .map(|(k, _)| k.to_string())
+            .collect()
+    }
+
+    /// For a given calendar name, get its Unique Identifier
+    fn get(&self, name: &str) -> Option<UniqueIdent> {
+        self.0
+            .get(name)
+            .map(|CalendarListEntry { id_lww: (_, ident) }| *ident)
+            .flatten()
+    }
+
+    /// Check if a given calendar name exists
+    fn has(&self, name: &str) -> bool {
+        self.get(name).is_some()
+    }
+
+    /// Rename a calendar
+    fn rename(&mut self, old: &str, new: &str) -> Result<()> {
+        if self.has(new) {
+            bail!("Calendar {} already exists", new);
+        }
+        let ident = match self.get(old) {
+            None => bail!("Calendar {} does not exist", old),
+            Some(ident) => ident,
+        };
+
+        self.bind(old, None);
+        self.bind(new, Some(ident));
+
+        Ok(())
+    }
+
+    // ----- Internal logic
+
+    /// New is not publicly exposed, use `load` instead
+    fn new() -> Self {
+        Self(BTreeMap::new())
+    }
+
+    /// Low level index updating logic (used to add/rename/delete) an entry
+    fn bind(&mut self, name: &str, id: Option<UniqueIdent>) -> Option<()> {
+        let (ts, id) = match self.0.get_mut(name) {
+            None => {
+                if id.is_none() {
+                    // User wants to delete entry with given name (passed id is None)
+                    // Entry does not exist (get_mut is None)
+                    // Nothing to do
+                    return None;
+                } else {
+                    // User wants entry with given name to be present (id is Some)
+                    // Entry does not exist
+                    // Initialize entry
+                    (now_msec(), id)
+                }
+            }
+            Some(CalendarListEntry { id_lww }) => {
+                if id_lww.1 == id {
+                    // Entry is already equals to the requested id (Option<UniqueIdent)
+                    // Nothing to do
+                    return None;
+                } else {
+                    // Entry does not equal to what we know internally
+                    // We update the Last Write Win CRDT here with the new id value
+                    (std::cmp::max(id_lww.0 + 1, now_msec()), id)
+                }
+            }
+        };
+
+        // If we did not return here, that's because we have to update
+        // something in our internal index.
+        self.0
+            .insert(name.into(), CalendarListEntry { id_lww: (ts, id) });
+        Some(())
+    }
+
+    // Merge 2 calendar lists by applying a LWW logic on each element
+    fn merge(&mut self, list2: Self) {
+        for (k, v) in list2.0.into_iter() {
+            if let Some(e) = self.0.get_mut(&k) {
+                e.merge(&v);
+            } else {
+                self.0.insert(k, v);
+            }
+        }
+    }
+}
+
+impl CalendarListEntry {
+    fn merge(&mut self, other: &Self) {
+        // Simple CRDT merge rule
+        if other.id_lww.0 > self.id_lww.0
+            || (other.id_lww.0 == self.id_lww.0 && other.id_lww.1 > self.id_lww.1)
+        {
+            self.id_lww = other.id_lww;
+        }
+    }
+}
+
+pub(crate) enum CalendarExists {
+    Created(UniqueIdent),
+    Existed(UniqueIdent),
+}