refactor: enhance GitMessage validation and signoff handling 🔄

- trim title and content before validation checks
- add specific error messages for empty title or content
- refactor signoff appending to use final_content variable
- add tracing logs for signoff addition and message creation
- update Display impl to directly write formatted output

Signed-off-by: mingcheng <[email protected]>

Author: mingcheng

src/message.rs

@@ -9,60 +9,109 @@
  * File Created: 2025-10-16 15:06:58
  *
  * Modified By: mingcheng <[email protected]>
- * Last Modified: 2025-10-16 15:46:26
+ * Last Modified: 2025-10-16 16:28:06
  */
 
 use crate::repository::Git;
 use std::{error::Error, fmt::Display};
 use tracing::trace;
 
+/// Represents a structured Git commit message
+///
+/// A commit message consists of:
+/// - `title`: The first line (subject line), typically 50-72 characters
+/// - `content`: The body of the commit message with detailed description
 pub struct GitMessage {
     pub title: String,
     pub content: String,
 }
 
 impl Display for GitMessage {
     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-        self.to_string().fmt(f)
+        // Format as: title\n\ncontent
+        write!(f, "{}\n\n{}", self.title, self.content)
     }
 }
 
 impl GitMessage {
+    /// Create a new Git commit message
+    ///
+    /// # Arguments
+    /// * `repository` - The Git repository (used to get author info for signoff)
+    /// * `title` - The commit title/subject line (will be trimmed)
+    /// * `content` - The commit body/description (will be trimmed)
+    /// * `signoff` - Whether to append a "Signed-off-by" line
+    ///
+    /// # Returns
+    /// * `Ok(GitMessage)` - A valid commit message
+    /// * `Err` - If title or content is empty after trimming
+    ///
+    /// # Example
+    /// ```
+    /// let msg = GitMessage::new(&repo, "feat: add feature", "Description here", true)?;
+    /// ```
     pub fn new(
         repository: &Git,
         title: &str,
         content: &str,
         signoff: bool,
     ) -> Result<Self, Box<dyn Error>> {
-        if title.is_empty() || content.is_empty() {
-            return Err("the commit message is invalid".into());
+        // Trim inputs first to check actual content
+        let title_trimmed = title.trim();
+        let content_trimmed = content.trim();
+
+        // Validate both title and content are non-empty
+        if title_trimmed.is_empty() {
+            return Err("commit title cannot be empty".into());
+        }
+        if content_trimmed.is_empty() {
+            return Err("commit content cannot be empty".into());
         }
 
-        let mut content = content.trim().to_string();
-        // If the --signoff option is enabled, add signoff to the commit message
-        if signoff {
-            trace!("signoff option is enabled, will add signoff to the commit message");
+        let mut final_content = content_trimmed.to_string();
 
+        // Append signoff line if requested
+        if signoff {
+            trace!("adding Signed-off-by line to commit message");
             let author = repository.get_author()?;
-            // Add signoff to the commit message
-            let _m = format!("\n\nSigned-off-by: {} <{}>", author.name, author.email);
-            content.push_str(&_m);
+
+            // Ensure proper spacing before signoff
+            final_content.push_str(&format!(
+                "\n\nSigned-off-by: {} <{}>",
+                author.name, author.email
+            ));
         }
 
-        trace!("the commit message is valid");
-        trace!("title:\n{}", title.trim());
-        trace!("content:\n{}", content);
+        trace!("created commit message with title: {}", title_trimmed);
+        trace!("content length: {} characters", final_content.len());
+
         Ok(Self {
-            title: title.trim().to_string(),
-            content,
+            title: title_trimmed.to_string(),
+            content: final_content,
         })
     }
 
+    /// Check if the commit message is empty
+    ///
+    /// Returns true only if both title and content are empty strings
     pub fn is_empty(&self) -> bool {
         self.title.is_empty() && self.content.is_empty()
     }
 
+    /// Convert the message to a formatted string suitable for git commit
+    ///
+    /// Returns the commit message in the format: `title\n\ncontent`
     pub fn to_string(&self) -> String {
         format!("{}\n\n{}", self.title, self.content)
     }
+
+    /// Get the total character count of the commit message
+    pub fn char_count(&self) -> usize {
+        self.title.len() + 2 + self.content.len() // +2 for "\n\n"
+    }
+
+    /// Get the number of lines in the commit message
+    pub fn line_count(&self) -> usize {
+        1 + self.content.lines().count() // +1 for title, +blank line is implicit
+    }
 }