🐛 fix(message_age): correct data type for message age count

- change the data type of count from usize to i64 to allow negative values
- add parse method to parse message age from string

src/retention/message_age.rs

@@ -4,13 +4,13 @@ use std::fmt::Display;
 #[derive(Debug)]
 pub enum MessageAge {
     /// Number of days to retain the message
-    Days(usize),
+    Days(i64),
     /// Number of weeks to retain the message
-    Weeks(usize),
+    Weeks(i64),
     /// Number of months to retain the message
-    Months(usize),
+    Months(i64),
     /// Number of years to retain the message
-    Years(usize),
+    Years(i64),
 }
 
 impl Display for MessageAge {
@@ -26,7 +26,7 @@ impl Display for MessageAge {
 
 impl MessageAge {
     /// Create a new MessageAge enum
-    pub fn new(period: &str, count: usize) -> Self {
+    pub fn new(period: &str, count: i64) -> Self {
         match period.to_lowercase().as_str() {
             "days" => MessageAge::Days(count),
             "weeks" => MessageAge::Weeks(count),
@@ -36,6 +36,19 @@ impl MessageAge {
         }
     }
 
+    pub(crate) fn parse(str: &str) -> Option<MessageAge> {
+        let period = str.chars().nth(0).unwrap_or('x');
+        let count = str[2..].to_string().parse::<i64>().unwrap_or(0);
+
+        match period {
+            'd' => Some(MessageAge::Days(count)),
+            'w' => Some(MessageAge::Weeks(count)),
+            'm' => Some(MessageAge::Months(count)),
+            'y' => Some(MessageAge::Years(count)),
+            _ => None,
+        }
+    }
+
     pub(crate) fn label(&self) -> String {
         match self {
             MessageAge::Days(v) => format!("retention/{v}-days"),