Make invalid timer states unrepresentable (#818)

This refactors the internals of the `Timer`, such that it's impossible
for different fields to contain conflicting information. This is done by
factoring out an `ActiveAttempt` struct that only exists when there is
an active attempt. Additionally inside it differentiates between the
attempt having ended or not. The not ended state has a split index and
an optional pause time, whereas the ended state has the date time of
when the attempt ended.

This does not yet touch the public API of the `Timer`. Factoring out the
notion of an active attempt and making sure invalid states are
unrepresentable is done so we can soon explore the possibility of
storing an active attempt in the splits file.

Author: CryZe

src/run/mod.rs

@@ -740,10 +740,10 @@ impl Run {
     /// # Panics
     ///
     /// This panics if there is no attempt in the Attempt History.
-    pub fn update_segment_history(&mut self, current_split_index: usize) {
+    pub fn update_segment_history(&mut self, segments_count: usize) {
         let mut previous_split_time = Time::zero();
 
-        let segments = self.segments.iter_mut().take(current_split_index);
+        let segments = &mut self.segments[..segments_count];
         let index = self
             .attempt_history
             .last()

src/timing/timer/active_attempt.rs

@@ -0,0 +1,229 @@
+use crate::{AtomicDateTime, Run, Time, TimeSpan, TimeStamp, TimingMethod};
+
+#[derive(Debug, Clone)]
+pub struct ActiveAttempt {
+    pub state: State,
+    pub attempt_started: AtomicDateTime,
+    pub start_time: TimeStamp,
+    pub start_time_with_offset: TimeStamp,
+    // This gets adjusted after resuming
+    pub adjusted_start_time: TimeStamp,
+    pub game_time_paused_at: Option<TimeSpan>,
+    pub loading_times: Option<TimeSpan>,
+}
+
+#[derive(Debug, Clone)]
+pub enum State {
+    NotEnded {
+        current_split_index: usize,
+        time_paused_at: Option<TimeSpan>,
+    },
+    Ended {
+        attempt_ended: AtomicDateTime,
+    },
+}
+
+pub struct TimerTime {
+    pub real_time: TimeSpan,
+    pub game_time: Option<TimeSpan>,
+}
+
+impl From<TimerTime> for Time {
+    fn from(time: TimerTime) -> Self {
+        Time {
+            real_time: Some(time.real_time),
+            game_time: time.game_time,
+        }
+    }
+}
+
+impl ActiveAttempt {
+    pub fn current_time(&self, run: &Run) -> TimerTime {
+        let real_time = match self.state {
+            State::Ended { .. } => {
+                let Time {
+                    real_time,
+                    game_time,
+                } = run.segments().last().unwrap().split_time();
+
+                return TimerTime {
+                    real_time: real_time.unwrap_or_default(),
+                    game_time,
+                };
+            }
+            State::NotEnded { time_paused_at, .. } => {
+                time_paused_at.unwrap_or_else(|| TimeStamp::now() - self.adjusted_start_time)
+            }
+        };
+
+        let game_time = self
+            .game_time_paused_at
+            .or_else(|| Some(real_time - self.loading_times?));
+
+        TimerTime {
+            real_time,
+            game_time,
+        }
+    }
+
+    pub fn get_pause_time(&self) -> Option<TimeSpan> {
+        if let State::NotEnded {
+            time_paused_at: Some(pause_time),
+            ..
+        } = self.state
+        {
+            return Some(TimeStamp::now() - self.start_time_with_offset - pause_time);
+        }
+
+        if self.start_time_with_offset != self.adjusted_start_time {
+            Some(self.start_time_with_offset - self.adjusted_start_time)
+        } else {
+            None
+        }
+    }
+
+    pub fn set_loading_times(&mut self, time: TimeSpan, run: &Run) {
+        self.loading_times = Some(time);
+        if self.game_time_paused_at.is_some() {
+            self.game_time_paused_at = Some(self.current_time(run).real_time - time);
+        }
+    }
+
+    pub fn prepare_split(&mut self, run: &Run) -> Option<(usize, Time)> {
+        let State::NotEnded {
+            current_split_index,
+            time_paused_at: None,
+        } = &mut self.state
+        else {
+            return None;
+        };
+
+        let real_time = TimeStamp::now() - self.adjusted_start_time;
+
+        if real_time < TimeSpan::zero() {
+            return None;
+        }
+
+        let game_time = self
+            .game_time_paused_at
+            .or_else(|| Some(real_time - self.loading_times?));
+
+        let previous_split_index = *current_split_index;
+        *current_split_index += 1;
+
+        if *current_split_index == run.len() {
+            self.state = State::Ended {
+                attempt_ended: AtomicDateTime::now(),
+            };
+        }
+
+        Some((
+            previous_split_index,
+            Time {
+                real_time: Some(real_time),
+                game_time,
+            },
+        ))
+    }
+
+    pub const fn current_split_index(&self) -> Option<usize> {
+        match self.state {
+            State::NotEnded {
+                current_split_index,
+                ..
+            } => Some(current_split_index),
+            State::Ended { .. } => None,
+        }
+    }
+
+    pub fn current_split_index_mut(&mut self) -> Option<&mut usize> {
+        match &mut self.state {
+            State::NotEnded {
+                current_split_index,
+                ..
+            } => Some(current_split_index),
+            State::Ended { .. } => None,
+        }
+    }
+
+    pub fn current_split_index_overflowing(&self, run: &Run) -> usize {
+        match self.state {
+            State::NotEnded {
+                current_split_index,
+                ..
+            } => current_split_index,
+            State::Ended { .. } => run.len(),
+        }
+    }
+
+    pub fn update_times(&self, run: &mut Run, timing_method: TimingMethod) {
+        self.update_attempt_history(run);
+        update_best_segments(run);
+        update_pb_splits(run, timing_method);
+        run.update_segment_history(self.current_split_index_overflowing(run));
+    }
+
+    pub fn update_attempt_history(&self, run: &mut Run) {
+        let (attempt_ended, time) = match self.state {
+            State::NotEnded { .. } => (AtomicDateTime::now(), Time::new()),
+            State::Ended { attempt_ended } => {
+                (attempt_ended, run.segments().last().unwrap().split_time())
+            }
+        };
+
+        let pause_time = self.get_pause_time();
+
+        run.add_attempt(
+            time,
+            Some(self.attempt_started),
+            Some(attempt_ended),
+            pause_time,
+        );
+    }
+}
+
+fn update_best_segments(run: &mut Run) {
+    let mut previous_split_time_rta = Some(TimeSpan::zero());
+    let mut previous_split_time_game_time = Some(TimeSpan::zero());
+
+    for split in run.segments_mut() {
+        let mut new_best_segment = split.best_segment_time();
+        if let Some(split_time) = split.split_time().real_time {
+            let current_segment = previous_split_time_rta.map(|previous| split_time - previous);
+            previous_split_time_rta = Some(split_time);
+            if split
+                .best_segment_time()
+                .real_time
+                .map_or(true, |b| current_segment.is_some_and(|c| c < b))
+            {
+                new_best_segment.real_time = current_segment;
+            }
+        }
+        if let Some(split_time) = split.split_time().game_time {
+            let current_segment =
+                previous_split_time_game_time.map(|previous| split_time - previous);
+            previous_split_time_game_time = Some(split_time);
+            if split
+                .best_segment_time()
+                .game_time
+                .map_or(true, |b| current_segment.is_some_and(|c| c < b))
+            {
+                new_best_segment.game_time = current_segment;
+            }
+        }
+        split.set_best_segment_time(new_best_segment);
+    }
+}
+
+fn update_pb_splits(run: &mut Run, method: TimingMethod) {
+    let (split_time, pb_split_time) = {
+        let last_segment = run.segments().last().unwrap();
+        (
+            last_segment.split_time()[method],
+            last_segment.personal_best_split_time()[method],
+        )
+    };
+    if split_time.is_some_and(|s| pb_split_time.map_or(true, |pb| s < pb)) {
+        super::set_run_as_pb(run);
+    }
+}