add device message if quota is exceeding (#2621)

* resultify update_recent_quota()

* add a device-message if quota exceeds QUOTA_WARN_THRESHOLD_PERCENTAGE

* check if a quota warning should be added during housekeeping, this is at least once a day

* dc_get_config("quota_exceeding") is useful for bots

* make clippy happy

* reword QuotaExceedingMsgBody message

* avoid lots of warnings if quota jitters around the warning threshold

* allow clippy::assertions_on_constants

these constants depend on each other, it makes sense to check that they are not changed in an incompatible way

src/quota.rs

@@ -4,13 +4,17 @@ use anyhow::{anyhow, Result};
 use async_imap::types::{Quota, QuotaResource};
 use indexmap::IndexMap;
 
+use crate::chat::add_device_msg_with_importance;
+use crate::config::Config;
+use crate::constants::Viewtype;
 use crate::context::Context;
 use crate::dc_tools::time;
 use crate::imap::scan_folders::get_watched_folders;
 use crate::imap::Imap;
 use crate::job::{Action, Status};
+use crate::message::Message;
 use crate::param::Params;
-use crate::{job, EventType};
+use crate::{job, stock_str, EventType};
 
 /// warn about a nearly full mailbox after this usage percentage is reached.
 /// quota icon is "yellow".
@@ -20,6 +24,12 @@ pub const QUOTA_WARN_THRESHOLD_PERCENTAGE: u64 = 80;
 // this threshold only makes the quota icon "red".
 pub const QUOTA_ERROR_THRESHOLD_PERCENTAGE: u64 = 99;
 
+/// if quota is below this value (again),
+/// QuotaExceeding is cleared.
+/// This value should be a bit below QUOTA_WARN_THRESHOLD_PERCENTAGE to
+/// avoid jittering and lots of warnings when quota is exactly at the warning threshold.
+pub const QUOTA_ALLCLEAR_PERCENTAGE: u64 = 75;
+
 // if recent quota is older,
 // it is re-fetched on dc_get_connectivity_html()
 pub const QUOTA_MAX_AGE_SECONDS: i64 = 60;
@@ -63,6 +73,29 @@ async fn get_unique_quota_roots_and_usage(
     Ok(unique_quota_roots)
 }
 
+fn get_highest_usage<'t>(
+    unique_quota_roots: &'t IndexMap<String, Vec<QuotaResource>>,
+) -> Result<(u64, &'t String, &QuotaResource)> {
+    let mut highest: Option<(u64, &'t String, &QuotaResource)> = None;
+    for (name, resources) in unique_quota_roots {
+        for r in resources {
+            let usage_percent = r.get_usage_percentage();
+            match highest {
+                None => {
+                    highest = Some((usage_percent, name, r));
+                }
+                Some((up, ..)) => {
+                    if up <= usage_percent {
+                        highest = Some((usage_percent, name, r));
+                    }
+                }
+            };
+        }
+    }
+
+    highest.ok_or_else(|| anyhow!("no quota_resource found, this is unexpected"))
+}
+
 impl Context {
     // Adds a job to update `quota.recent`
     pub(crate) async fn schedule_quota_update(&self) {
@@ -77,11 +110,17 @@ impl Context {
     /// Updates `quota.recent`, sets `quota.modified` to the current time
     /// and emits an event to let the UIs update connectivity view.
     ///
+    /// Moreover, once each time quota gets larger than `QUOTA_WARN_THRESHOLD_PERCENTAGE`,
+    /// a device message is added.
+    /// As the message is added only once, the user is not spammed
+    /// in case for some providers the quota is always at ~100%
+    /// and new space is allocated as needed.
+    ///
     /// Called in response to `Action::UpdateRecentQuota`.
-    pub(crate) async fn update_recent_quota(&self, imap: &mut Imap) -> Status {
+    pub(crate) async fn update_recent_quota(&self, imap: &mut Imap) -> Result<Status> {
         if let Err(err) = imap.prepare(self).await {
             warn!(self, "could not connect: {:?}", err);
-            return Status::RetryNow;
+            return Ok(Status::RetryNow);
         }
 
         let quota = if imap.can_check_quota() {
@@ -91,12 +130,51 @@ impl Context {
             Err(anyhow!("Quota not supported by your provider."))
         };
 
+        if let Ok(quota) = &quota {
+            match get_highest_usage(quota) {
+                Ok((highest, _, _)) => {
+                    if highest >= QUOTA_WARN_THRESHOLD_PERCENTAGE {
+                        if self.get_config_int(Config::QuotaExceeding).await? == 0 {
+                            self.set_config(Config::QuotaExceeding, Some(&highest.to_string()))
+                                .await?;
+
+                            let mut msg = Message::new(Viewtype::Text);
+                            msg.text = Some(stock_str::quota_exceeding(self, highest).await);
+                            add_device_msg_with_importance(self, None, Some(&mut msg), true)
+                                .await?;
+                        }
+                    } else if highest <= QUOTA_ALLCLEAR_PERCENTAGE {
+                        self.set_config(Config::QuotaExceeding, None).await?;
+                    }
+                }
+                Err(err) => warn!(self, "cannot get highest quota usage: {:?}", err),
+            }
+        }
+
         *self.quota.write().await = Some(QuotaInfo {
             recent: quota,
             modified: time(),
         });
 
         self.emit_event(EventType::ConnectivityChanged);
-        Status::Finished(Ok(()))
+        Ok(Status::Finished(Ok(())))
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::quota::{
+        QUOTA_ALLCLEAR_PERCENTAGE, QUOTA_ERROR_THRESHOLD_PERCENTAGE,
+        QUOTA_WARN_THRESHOLD_PERCENTAGE,
+    };
+
+    #[allow(clippy::assertions_on_constants)]
+    #[async_std::test]
+    async fn test_quota_thresholds() -> anyhow::Result<()> {
+        assert!(QUOTA_ALLCLEAR_PERCENTAGE > 50);
+        assert!(QUOTA_ALLCLEAR_PERCENTAGE < QUOTA_WARN_THRESHOLD_PERCENTAGE);
+        assert!(QUOTA_WARN_THRESHOLD_PERCENTAGE < QUOTA_ERROR_THRESHOLD_PERCENTAGE);
+        assert!(QUOTA_ERROR_THRESHOLD_PERCENTAGE < 100);
+        Ok(())
     }
 }