refactor(rules): replace unwrap() with explicit error handling and propagate errors safely

- Replace Option::unwrap() with pattern matching in add_rule label check
- Handle home directory resolution failures with proper Error types
- Add directory creation in save() to ensure parent directories exist
- Replace chrono unwraps with ? operator for date calculations
- Use unwrap_or with sensible defaults for parsing edge cases
- Keep unwrap in test code where immediate failure is desired
- All existing functionality preserved; no API changes

src/rules.rs

@@ -202,9 +202,11 @@ impl Rules {
             current_labels.append(&mut ls);
         }
 
-        if label.is_some() && current_labels.contains(label.unwrap()) {
+        if let Some(label_ref) = label {
-            log::warn!("a rule already applies to label {}", label.unwrap());
+            if current_labels.contains(label_ref) {
-            return self;
+                log::warn!("a rule already applies to label {}", label_ref);
+                return self;
+            }
         }
 
         let id = if let Some((_, max)) = self.rules.iter().max_by_key(|(_, r)| r.id()) {
@@ -497,9 +499,16 @@ impl Rules {
     /// * IO errors when writing to the file system
     /// * File system permission errors
     pub fn save(&self) -> Result<()> {
-        let home_dir = env::home_dir().unwrap();
+        let home_dir = env::home_dir().ok_or_else(|| {
+            Error::HomeExpansionFailed("~/.cull-gmail/rules.toml".to_string())
+        })?;
         let path = PathBuf::new().join(home_dir).join(".cull-gmail/rules.toml");
         
+        // Ensure directory exists
+        if let Some(parent) = path.parent() {
+            fs::create_dir_all(parent)?;
+        }
+
         let res = toml::to_string(self);
         log::trace!("toml conversion result: {res:#?}");
 
@@ -536,7 +545,9 @@ impl Rules {
     /// * TOML parsing errors if the file is malformed
     /// * File not found errors if the configuration doesn't exist
     pub fn load() -> Result<Rules> {
-        let home_dir = env::home_dir().unwrap();
+        let home_dir = env::home_dir().ok_or_else(|| {
+            Error::HomeExpansionFailed("~/.cull-gmail/rules.toml".to_string())
+        })?;
         let path = PathBuf::new().join(home_dir).join(".cull-gmail/rules.toml");
         log::trace!("Loading config from {}", path.display());
 
@@ -584,7 +595,10 @@ mod tests {
     fn setup_test_environment() {
         get_test_logger();
         // Clean up any existing test files
-        let home_dir = env::home_dir().unwrap();
+        let Some(home_dir) = env::home_dir() else {
+            // Skip cleanup if home directory cannot be determined
+            return;
+        };
         let test_config_dir = home_dir.join(".cull-gmail");
         let test_rules_file = test_config_dir.join("rules.toml");
         if test_rules_file.exists() {

src/rules/eol_rule.rs

@@ -320,7 +320,7 @@ impl EolRule {
     /// Describe the action that will be performed by the rule and its conditions
     fn get_action_period_count_strings(&self) -> (String, usize, String) {
         let count = &self.retention[2..];
-        let count = count.parse::<usize>().unwrap();
+        let count = count.parse::<usize>().unwrap_or(0); // Default to 0 if parsing fails
         let mut period = match self.retention.chars().nth(0) {
             Some('d') => "day",
             Some('w') => "week",
@@ -375,11 +375,11 @@ impl EolRule {
         let deadline = match message_age {
             MessageAge::Days(c) => {
                 let delta = TimeDelta::days(c);
-                today.checked_sub_signed(delta).unwrap()
+                today.checked_sub_signed(delta)?
             }
             MessageAge::Weeks(c) => {
                 let delta = TimeDelta::weeks(c);
-                today.checked_sub_signed(delta).unwrap()
+                today.checked_sub_signed(delta)?
             }
             MessageAge::Months(c) => {
                 let day = today.day();
@@ -398,7 +398,7 @@ impl EolRule {
 
                 Local
                     .with_ymd_and_hms(new_year, new_month, day, 0, 0, 0)
-                    .unwrap()
+                    .single()?
             }
             MessageAge::Years(c) => {
                 let day = today.day();
@@ -408,7 +408,7 @@ impl EolRule {
 
                 Local
                     .with_ymd_and_hms(new_year, month, day, 0, 0, 0)
-                    .unwrap()
+                    .single()?
             }
         };
 
@@ -477,8 +477,8 @@ mod test {
     fn test_eol_query_for_eol_rule_5_years() {
         let rule = build_test_rule(crate::MessageAge::Years(5));
 
-        let test_today = Local.with_ymd_and_hms(2025, 9, 15, 0, 0, 0).unwrap();
+        let test_today = Local.with_ymd_and_hms(2025, 9, 15, 0, 0, 0).single().unwrap();
-        let query = rule.calculate_for_date(test_today).unwrap();
+        let query = rule.calculate_for_date(test_today).expect("Failed to calculate query");
 
         assert_eq!("before: 2020-09-15", query);
     }
@@ -487,8 +487,8 @@ mod test {
     fn test_eol_query_for_eol_rule_1_month() {
         let rule = build_test_rule(crate::MessageAge::Months(1));
 
-        let test_today = Local.with_ymd_and_hms(2025, 9, 15, 0, 0, 0).unwrap();
+        let test_today = Local.with_ymd_and_hms(2025, 9, 15, 0, 0, 0).single().unwrap();
-        let query = rule.calculate_for_date(test_today).unwrap();
+        let query = rule.calculate_for_date(test_today).expect("Failed to calculate query");
 
         assert_eq!("before: 2025-08-15", query);
     }
@@ -497,8 +497,8 @@ mod test {
     fn test_eol_query_for_eol_rule_13_weeks() {
         let rule = build_test_rule(crate::MessageAge::Weeks(13));
 
-        let test_today = Local.with_ymd_and_hms(2025, 9, 15, 0, 0, 0).unwrap();
+        let test_today = Local.with_ymd_and_hms(2025, 9, 15, 0, 0, 0).single().unwrap();
-        let query = rule.calculate_for_date(test_today).unwrap();
+        let query = rule.calculate_for_date(test_today).expect("Failed to calculate query");
 
         assert_eq!("before: 2025-06-16", query);
     }
@@ -507,8 +507,8 @@ mod test {
     fn test_eol_query_for_eol_rule_365_days() {
         let rule = build_test_rule(crate::MessageAge::Days(365));
 
-        let test_today = Local.with_ymd_and_hms(2025, 9, 15, 0, 0, 0).unwrap();
+        let test_today = Local.with_ymd_and_hms(2025, 9, 15, 0, 0, 0).single().unwrap();
-        let query = rule.calculate_for_date(test_today).unwrap();
+        let query = rule.calculate_for_date(test_today).expect("Failed to calculate query");
 
         assert_eq!("before: 2024-09-15", query);
     }