Only overwrite old cache if an update was made

src/cache/cache_line.rs

@@ -9,7 +9,7 @@ use crate::Hollidays;
 
 const CET: FixedOffset = unsafe { FixedOffset::east_opt(3600).unwrap_unchecked() };
 
-#[derive(Serialize, Deserialize, Debug)]
+#[derive(Serialize, Deserialize, Debug, PartialEq)]
 pub struct CacheLine {
     #[serde(with = "ts_seconds")]
     date: DateTime<Utc>,
@@ -86,6 +86,13 @@ impl CacheLine {
         }
     }
 }
+
+impl PartialEq<Vec<ExchangeRateResult>> for CacheLine {
+    fn eq(&self, other: &Vec<ExchangeRateResult>) -> bool {
+        &self.exchange_rate_results == other
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;

src/main.rs

@@ -65,12 +65,24 @@ async fn main() -> ExitCode {
                 return ExitCode::FAILURE;
             }
         };
+
         if !cache_ok {
-            if let Some(cache_safe) = cache.as_mut() {
-                let cache_line = CacheLine::new(parsed.clone());
-                cache_safe.set_cache_line(cli.resolution, cache_line);
-                if let Err(e) = cache_safe.save() {
-                    eprintln!("Failed to save to cache with: {:?}", e);
+            let not_equal_cache = cache.as_ref().map_or_else(
+                || true,
+                |cache_local| {
+                    cache_local
+                        .get_cache_line(cli.resolution)
+                        .map_or_else(|| true, |cache_line| cache_line == &parsed)
+                },
+            );
+
+            if not_equal_cache {
+                if let Some(cache_safe) = cache.as_mut() {
+                    let cache_line = CacheLine::new(parsed.clone());
+                    cache_safe.set_cache_line(cli.resolution, cache_line);
+                    if let Err(e) = cache_safe.save() {
+                        eprintln!("Failed to save to cache with: {:?}", e);
+                    }
                 }
             }
         }

src/models.rs

@@ -1,7 +1,7 @@
 use serde::{Deserialize, Serialize};
 use std::collections::HashMap;
 
-#[derive(Debug, Serialize, Deserialize, Clone)]
+#[derive(Debug, Serialize, Deserialize, Clone, PartialEq)]
 pub struct ExchangeRateResult {
     pub time: String,
     pub rates: HashMap<String, f64>,