Correctly apply hollidays and so on to the time validation

src/cache/cache_line.rs

@@ -1,8 +1,13 @@
+use std::rc::Rc;
+
 use chrono::serde::ts_seconds;
-use chrono::{DateTime, Local, Utc};
+use chrono::{DateTime, Datelike, FixedOffset, Local, NaiveDate, TimeDelta, Utc, Weekday};
 use serde::{Deserialize, Serialize};
 
 use crate::models::ExchangeRateResult;
+use crate::Hollidays;
+
+const CET: FixedOffset = unsafe { FixedOffset::east_opt(3600).unwrap_unchecked() };
 
 #[derive(Serialize, Deserialize, Debug)]
 pub struct CacheLine {
@@ -14,10 +19,63 @@ pub struct CacheLine {
 }
 
 impl CacheLine {
-    pub fn validate(&self) -> bool {
-        let today = Local::now().naive_local().date();
-        let saved = self.date.naive_local().date();
-        saved == today
+    pub fn is_valid(&self) -> bool {
+        self.is_valid_at(Local::now().with_timezone(&CET))
+    }
+
+    pub fn is_valid_at(&self, now_cet: DateTime<FixedOffset>) -> bool {
+        let saved_cet = self.date.with_timezone(&CET);
+
+        // Shortcut: if the saved time is somehow *in the future* vs. 'now', treat as invalid.
+        if saved_cet > now_cet {
+            return false;
+        }
+
+        // This can be optimized, but it won't make a difference for the application
+        let hollidays_opt = if now_cet.year() == saved_cet.year() {
+            Some(Rc::new(Hollidays::new(now_cet.year())))
+        } else {
+            None
+        };
+
+        let mut day_iter = saved_cet.date_naive();
+        let end_day = now_cet.date_naive();
+
+        // Helper: checks if a day is open (ECB publishes).
+        // weekend (Sat/Sun) or holiday is "closed".
+        let is_open_day = |date: NaiveDate| {
+            let wd = date.weekday();
+            let is_weekend = wd == Weekday::Sat || wd == Weekday::Sun;
+
+            let hollidays = hollidays_opt
+                .clone()
+                .unwrap_or_else(|| Rc::new(Hollidays::new(date.year())));
+
+            let is_holiday = hollidays.is_holliday(&date);
+
+            !(is_weekend || is_holiday)
+        };
+
+        while day_iter <= end_day {
+            if is_open_day(day_iter) {
+                // Potential publish time is day_iter at 16:00 CET
+                let publish_time_cet = unsafe {
+                    day_iter
+                        .and_hms_opt(16, 0, 0)
+                        .unwrap_unchecked()
+                        .and_local_timezone(CET)
+                        .unwrap()
+                };
+
+                if publish_time_cet > saved_cet && publish_time_cet <= now_cet {
+                    return false;
+                }
+            }
+            day_iter += TimeDelta::days(1);
+        }
+
+        // If we never found an open day’s 16:00 that invalidates the cache, we're good.
+        true
     }
 
     pub fn new(exchange_rate_results: Vec<ExchangeRateResult>) -> Self {
@@ -28,3 +86,75 @@ impl CacheLine {
         }
     }
 }
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use chrono::TimeZone;
+
+    fn cl(date_utc: DateTime<Utc>) -> CacheLine {
+        CacheLine {
+            date: date_utc,
+            exchange_rate_results: vec![],
+        }
+    }
+
+    #[test]
+    fn test_cache_in_future() {
+        let now_cet = Utc
+            .with_ymd_and_hms(2025, 1, 1, 9, 0, 0)
+            .unwrap()
+            .with_timezone(&CET);
+        let future_utc = Utc.with_ymd_and_hms(2025, 1, 2, 9, 0, 0).unwrap();
+        assert!(!cl(future_utc).is_valid_at(now_cet));
+    }
+
+    #[test]
+    fn test_same_open_day_before_16() {
+        let now_cet = Utc
+            .with_ymd_and_hms(2025, 1, 8, 12, 0, 0)
+            .unwrap()
+            .with_timezone(&CET);
+        let cache_utc = Utc.with_ymd_and_hms(2025, 1, 8, 10, 0, 0).unwrap();
+        assert!(cl(cache_utc).is_valid_at(now_cet));
+    }
+
+    #[test]
+    fn test_same_day_after_16() {
+        let now_cet = Utc
+            .with_ymd_and_hms(2025, 1, 8, 17, 0, 0)
+            .unwrap()
+            .with_timezone(&CET);
+        let cache_utc = Utc.with_ymd_and_hms(2025, 1, 8, 14, 0, 0).unwrap();
+        assert!(!cl(cache_utc).is_valid_at(now_cet));
+    }
+
+    #[test]
+    fn test_saved_after_16_same_day() {
+        let now_cet = Utc
+            .with_ymd_and_hms(2025, 1, 8, 18, 0, 0)
+            .unwrap()
+            .with_timezone(&CET);
+        let cache_utc = Utc.with_ymd_and_hms(2025, 1, 8, 17, 0, 0).unwrap();
+        assert!(cl(cache_utc).is_valid_at(now_cet));
+    }
+
+    #[test]
+    fn test_multi_day_old_cache_should_invalidate_if_open_day_passed() {
+        let now_cet = Utc
+            .with_ymd_and_hms(2025, 1, 10, 18, 0, 0)
+            .unwrap()
+            .with_timezone(&CET);
+        let cache_utc = Utc.with_ymd_and_hms(2025, 1, 5, 10, 0, 0).unwrap();
+        assert!(!cl(cache_utc).is_valid_at(now_cet));
+    }
+
+    #[test]
+    fn test_multi_day_holiday_scenario() {
+        let now_cet = Utc
+            .with_ymd_and_hms(2025, 12, 26, 19, 0, 0)
+            .unwrap()
+            .with_timezone(&CET);
+        let cache_utc = Utc.with_ymd_and_hms(2025, 12, 24, 10, 0, 0).unwrap();
+        assert!(cl(cache_utc).is_valid_at(now_cet));
+    }
+}

src/main.rs

@@ -45,7 +45,7 @@ async fn main() -> ExitCode {
         || false,
         |c| {
             c.get_cache_line(cli.resolution)
-                .map_or_else(|| false, |cl| cl.validate())
+                .map_or_else(|| false, |cl| cl.is_valid())
         },
     );
     let mut parsed = if cache_ok {