Check user login status before fetching problems (#93)

cache/src/kvstore.rs

@@ -118,6 +118,11 @@ impl KvStore {
         Ok(None)
     }
 
+    /// Check if key exists in the cache
+    pub fn has_key(&self, key: String) -> bool {
+        self.index.contains_key(&key)
+    }
+
     /// Removes the given key.
     pub fn remove(&mut self, key: String) -> Result<()> {
         // check if key exist in index and delete if from the log file

src/service/leetcode.rs

@@ -85,6 +85,14 @@ impl<'a> ServiceProvider<'a> for Leetcode<'a> {
     }
 
     async fn list_problems(&mut self, list: List) -> Result<()> {
+        if !self.is_user_logged_in() {
+            print!(
+                "{}",
+                Color::Red("You need to login to list problems").make()
+            );
+            return Ok(());
+        }
+
         let problems_res = self.fetch_all_problems().await?;
         let mut probs: ProblemInfoSeq = vec![];
 
@@ -306,6 +314,10 @@ impl<'a> Leetcode<'a> {
         })
     }
 
+    fn is_user_logged_in(&self) -> bool {
+        self.cache.has_key(CacheKey::Session.into())
+    }
+
     fn cache_session(&mut self, session: Session) -> Result<()> {
         let session_str = serde_json::to_string(&session)?;
         self.cache.set(CacheKey::Session.into(), session_str)?;