Create fsrs upadte method

src/data/entities.rs

@@ -1,8 +1,10 @@
 use crate::app::AppState;
 use crate::core::srs::{FADE_PER_DAY, MAX_SCORE, OrderMode, WordOpenMode};
 use crate::data::{INVALID_ID, Id};
-use chrono::{DateTime, Utc};
+use chrono::{DateTime, Local, NaiveDate, Utc};
+use fsrs::{FSRS, MemoryState};
 use log::info;
+use rand::{RngExt, random, rng};
 use rayon::prelude::*;
 use rhai::{Engine, Scope};
 use std::collections::HashMap;
@@ -137,6 +139,9 @@ pub struct CardStatistics {
     pub set_id: Id,
     pub last_open: DateTime<Utc>,
     pub score: u8,
+    pub fsrs_opened: NaiveDate,
+    pub fsrs_memory: Option<MemoryState>,
+    pub fsrs_open_day: NaiveDate,
 }
 impl CardStatistics {
     pub fn update(&mut self, status: WordOpenMode) {
@@ -157,6 +162,29 @@ impl CardStatistics {
         self.last_open = Utc::now();
     }
 
+    pub fn update_fsrs(&mut self, status: WordOpenMode, by_fsrs: bool, fsrs: FSRS)
+    {
+        let today = Local::now().to_utc().date_naive().to_epoch_days();
+        let written = self.fsrs_opened.to_epoch_days();
+        let memory = fsrs
+            .next_states(self.fsrs_memory, 0.9, (today - written) as u32)
+            .expect("Wrong next stage calculation");
+        let next = match status {
+            WordOpenMode::Easy => memory.easy,
+            WordOpenMode::Ok => memory.good,
+            WordOpenMode::Hard => memory.hard,
+            WordOpenMode::None => memory.again,
+        };
+
+        let mut next_day = today + next.interval.round() as i32;
+        if next_day - today >= 5 {
+            let offset = ((rng().random::<f32>() - 0.5) * 3.0).round() as i32;
+            next_day += offset;
+        }
+        self.fsrs_memory = Some(next.memory);
+        self.fsrs_open_day = NaiveDate::from_epoch_days(next_day).unwrap();
+        self.fsrs_opened = self.last_open.date_naive();
+    }
     pub fn calculated_score(&self) -> f32 {
         let time = Utc::now() - self.last_open;
         let days = time.num_days();