feat(event) blink effect at event time (#123)

Similar to `Countdown` and `Pomodoro` DONE effects.

src/app.rs

@@ -213,7 +213,7 @@ impl App {
             event: EventState::new(EventStateArgs {
                 app_time,
                 event_time: time::PrimitiveDateTime::parse(
-                    "2025-10-09 19:54:29",
+                    "2025-10-09 21:32:30",
                     format_description!("[year]-[month]-[day] [hour]:[minute]:[second]"),
                 )
                 .unwrap(),

src/duration.rs

@@ -92,7 +92,7 @@ pub struct CalendarDuration {
     direction: CalendarDurationDirection,
 }
 
-#[derive(PartialEq, Debug, Clone)]
+#[derive(PartialEq, Debug, Clone, Copy)]
 pub enum CalendarDurationDirection {
     Since,
     Until,
@@ -124,8 +124,12 @@ impl CalendarDuration {
         }
     }
 
-    pub fn direction(&self) -> &CalendarDurationDirection {
-        &self.direction
+    pub fn direction(&self) -> CalendarDurationDirection {
+        self.direction
+    }
+
+    pub fn is_since(&self) -> bool {
+        self.direction == CalendarDurationDirection::Since
     }
 
     pub fn start_time(&self) -> &OffsetDateTime {

src/widgets/clock.rs

@@ -161,7 +161,7 @@ pub fn count_by_mode(times: u32, mode: &Mode) -> Duration {
 }
 
 const RANGE_OF_DONE_COUNT: u64 = 4;
-const MAX_DONE_COUNT: u64 = RANGE_OF_DONE_COUNT * 5;
+pub const MAX_DONE_COUNT: u64 = RANGE_OF_DONE_COUNT * 5;
 
 pub struct ClockState<T> {
     type_id: ClockTypeId,
@@ -447,18 +447,17 @@ impl<T> ClockState<T> {
     /// `tick` won't be called again after `Mode::Done` event (e.g. in `widget::Countdown`).
     /// That's why `update_done_count` is called from "outside".
     pub fn update_done_count(&mut self) {
-        if let Some(count) = self.done_count {
-            if count > 0 {
-                let value = count - 1;
-                self.done_count = Some(value)
-            } else {
-                // None means we are done and no counting anymore.
-                self.done_count = None
-            }
-        }
+        self.done_count = count_clock_done(self.done_count);
     }
 }
 
+/// Safe way to count a possible `done` value
+pub fn count_clock_done(value: Option<u64>) -> Option<u64> {
+    // Safe substraction for `Some(value > 1)`
+    // `None` means `done` == no counting anymore.
+    value.and_then(|count| count.checked_sub(1))
+}
+
 #[derive(Debug, Clone)]
 pub struct Countdown {}
 
@@ -649,17 +648,17 @@ where
     pub fn get_height(&self) -> u16 {
         DIGIT_HEIGHT
     }
+}
 
-    /// Checks whether to blink the clock while rendering.
-    /// Its logic is based on a given `count` value.
-    fn should_blink(&self, count_value: &Option<u64>) -> bool {
-        // Example:
-        // if `RANGE_OF_DONE_COUNT` is 4
-        // then for ranges `0..4`, `8..12` etc. it will return `true`
-        count_value
-            .map(|b| (b % (RANGE_OF_DONE_COUNT * 2)) < RANGE_OF_DONE_COUNT)
-            .unwrap_or(false)
-    }
+/// Helper to check whether to blink the clock while rendering.
+/// Its logic is based on a given `count` value.
+pub fn should_blink(count_value: Option<u64>) -> bool {
+    // Example:
+    // if `RANGE_OF_DONE_COUNT` is 4
+    // then for ranges `0..4`, `8..12` etc. it will return `true`
+    count_value
+        .map(|b| (b % (RANGE_OF_DONE_COUNT * 2)) < RANGE_OF_DONE_COUNT)
+        .unwrap_or(false)
 }
 
 // Helper to get horizontal lengths of a clock
@@ -1494,9 +1493,9 @@ where
         let format = state.format;
         let widths = clock_horizontal_lengths(&format, with_decis);
 
-        // to simulate a blink effect, just use an "empty" symbol (string)
-        // to "empty" all digits and to have an "empty" render area
-        let symbol = if self.blink && self.should_blink(&state.done_count) {
+        // To simulate a blink effect, just use an "empty" symbol (string)
+        // It's "empty" all digits and creates an "empty" render area
+        let symbol = if self.blink && should_blink(state.done_count) {
             " "
         } else {
             self.style.get_digit_symbol()

src/widgets/event.rs

@@ -8,7 +8,7 @@ use time::{OffsetDateTime, macros::format_description};
 
 use crate::{
     common::{AppTime, Style},
-    duration::{CalendarDuration, CalendarDurationDirection},
+    duration::CalendarDuration,
     events::{AppEventTx, TuiEvent, TuiEventHandler},
     utils::center,
     widgets::{clock, clock_elements::DIGIT_HEIGHT},
@@ -22,6 +22,9 @@ pub struct EventState {
     app_time: OffsetDateTime,
     start_time: OffsetDateTime,
     with_decis: bool,
+    /// counter to simulate `DONE` state
+    /// Default value: `None`
+    done_count: Option<u64>,
 }
 
 pub struct EventStateArgs {
@@ -54,12 +57,17 @@ impl EventState {
             app_time: app_datetime,
             start_time: app_datetime,
             with_decis,
+            done_count: None,
         }
     }
 
+    // Sets `app_time`
     pub fn set_app_time(&mut self, app_time: AppTime) {
         let app_datetime = OffsetDateTime::from(app_time);
         self.app_time = app_datetime;
+
+        // Since updating `app_time` is like a `Tick`, we check `done` state here
+        self.check_done();
     }
 
     pub fn set_with_decis(&mut self, with_decis: bool) {
@@ -69,6 +77,25 @@ impl EventState {
     pub fn get_percentage_done(&self) -> u16 {
         get_percentage(self.start_time, self.event_time, self.app_time)
     }
+
+    pub fn get_duration(&mut self) -> CalendarDuration {
+        CalendarDuration::from_start_end_times(self.event_time, self.app_time)
+    }
+
+    fn check_done(&mut self) {
+        let clock_duration = self.get_duration();
+        if clock_duration.is_since() {
+            let duration: Duration = clock_duration.into();
+            // give some offset to make sure we are around `Duration::ZERO`
+            // Without that we might miss it, because the app runs on its own FPS
+            if duration < Duration::from_millis(100) {
+                // reset `done_count`
+                self.done_count = Some(clock::MAX_DONE_COUNT);
+            }
+            // count (possible) `done`
+            self.done_count = clock::count_clock_done(self.done_count);
+        }
+    }
 }
 
 impl TuiEventHandler for EventState {
@@ -104,8 +131,7 @@ impl StatefulWidget for EventWidget {
     type State = EventState;
     fn render(self, area: Rect, buf: &mut Buffer, state: &mut Self::State) {
         let with_decis = state.with_decis;
-        let clock_duration =
-            CalendarDuration::from_start_end_times(state.event_time, state.app_time);
+        let clock_duration = state.get_duration();
         let clock_format = clock::format_by_duration(&clock_duration);
         let clock_widths = clock::clock_horizontal_lengths(&clock_format, with_decis);
         let clock_width = clock_widths.iter().sum();
@@ -117,8 +143,7 @@ impl StatefulWidget for EventWidget {
                 "[year]-[month]-[day] [hour]:[minute]:[second]"
             ))
             .unwrap_or_else(|e| format!("time format error: {}", e));
-
-        let time_prefix = if clock_duration.direction() == &CalendarDurationDirection::Since {
+        let time_prefix = if clock_duration.is_since() {
             let duration: Duration = clock_duration.clone().into();
             // Show `done` for a short of time (1 sec)
             if duration < Duration::from_secs(1) {
@@ -150,8 +175,9 @@ impl StatefulWidget for EventWidget {
         ]))
         .areas(area);
 
-        // TODO: Add logic to handle blink in `DONE` mode, similar to `ClockWidget<T>::should_blink`
-        let symbol = if self.blink {
+        // To simulate a blink effect, just use an "empty" symbol (string)
+        // It's "empty" all digits and creates an "empty" render area
+        let symbol = if self.blink && clock::should_blink(state.done_count) {
             " "
         } else {
             self.style.get_digit_symbol()