feat: preprocessor now has branch

- default main branch is selected
- can specifiy branch in the preprocessor
- branch can appear in the footer template too
- added workflow example in README.md

Author: CompEng0001

Cargo.lock

@@ -1,6 +1,6 @@
 [package]
 name = "mdbook-gitinfo"
-version = "0.1.1"
+version = "0.1.2"
 edition = "2024"
 authors = ["Seb Blair <s.blair@gre.ac.uk>"]
 description = "An mdBook preprocessor to inject Git commit metadata into generated books"

Cargo.toml

@@ -53,11 +53,25 @@ Add the following to your book.toml:
 ```toml
 [preprocessor.gitinfo]
 enable = true
-template = "Date: {{date}}{{sep}}commit: {{hash}}"
+template = "Date: {{date}}{{sep}}branch: {{branch}}{{sep}}commit: {{hash}}"
 separator = " • "
 font-size = "0.8em"
 date-format = "%Y-%m-%d"
 time-format = "%H:%M:%S"
+branch = "main" # default is main, therefore optional
+```
+
+
+### Example Output
+
+With the above configuration, this footer will be injected:
+
+```html
+<footer>
+  <span class="gitinfo-footer" style="font-size:0.8em;...">
+    Date: 2025-06-23 16:19:28 • branch: main • commit: 2160ec5
+  </span>
+</footer>
 ```
 
 > [!NOTE]
@@ -101,16 +115,22 @@ You can use the following placeholders in the template string:
 
 - `{{sep}}`: Separator (defaults to " • ")
 
-## Example Output
-
-With the above configuration, this footer will be injected:
-
-```html
-<footer>
-  <span class="gitinfo-footer" style="font-size:0.8em;...">
-    Date: 2025-06-23 16:19:28 • commit: 2160ec5
-  </span>
-</footer>
+## .github/workflow/...
+
+In order for mdbook-gitinfo to reference the correct commit whilst using `actions/checkout@v4`, set `fetch-depth` as `0`:
+
+```yml
+...
+jobs:
+  deploy:
+    runs-on: ubuntu-22.04
+    concurrency:
+      group: ${{ github.workflow }}-${{ github.ref }}
+    steps:
+      - uses: actions/checkout@v4
+        with:
+          fetch-depth: 0
+...
 ```
 
 ## Compatibility

README.md

@@ -39,6 +39,10 @@ pub struct GitInfoConfig {
     /// Default: `"%H:%M:%S"`.
     #[serde(rename = "time-format")]
     pub time_format: Option<String>,
+
+    /// Set the branch from where to get the commit history from
+    /// Default: "main"
+    pub branch: Option<String>,
 }
 
 /// Load and deserialize the `[preprocessor.gitinfo]` table from `book.toml`.

src/config.rs

@@ -62,6 +62,29 @@ where
     }
 }
 
+/// Verify the branch exists
+/// 
+/// # Arguments
+/// * `branch`: &str representing the branches name
+/// * `dir` - The path to the Git repository root or working directory to execute from.
+/// 
+/// # Returns
+/// * bool: true or false with respect to whether a branch exists locally or not.
+///
+/// # Example
+///
+/// ```no_run
+/// use std::path::Path;
+/// use mdbook_gitinfo::git::verify_branch;
+///
+/// if !git::verify_branch(&branch, &ctx.root) {
+///     eprintln!("Warning: Branch '{}' not found, falling back to 'main'", branch);
+///     branch = "main".to_string();
+/// }
+pub fn verify_branch(branch: &str, dir: &Path) -> bool {
+    get_git_output(["rev-parse", "--verify", branch], dir).is_ok()
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;

src/git.rs

@@ -18,7 +18,7 @@ use std::{io, process};
 /// The `GitInfo` struct implements the `Preprocessor` trait for injecting Git metadata.
 ///
 /// It reads settings from `[preprocessor.gitinfo]` in `book.toml`, including optional fields like
-/// `template`, `font-size`, `separator`, `date-format`, and `time-format`.
+/// `template`, `font-size`, `separator`, `date-format`, `time-format` and `branch`.
 pub struct GitInfo;
 
 impl GitInfo {
@@ -45,6 +45,13 @@ impl Preprocessor for GitInfo {
         let separator = cfg.separator.unwrap_or_else(|| " • ".to_string());
         let date_format = cfg.date_format.unwrap_or_else(|| "%Y-%m-%d".to_string());
         let time_format = cfg.time_format.unwrap_or_else(|| "%H:%M:%S".to_string());
+        let mut branch = cfg.branch.unwrap_or_else(|| "main".to_string());
+
+        // Verify the branch exists
+        if !git::verify_branch(&branch, &ctx.root) {
+            eprintln!("Warning: Branch '{}' not found, falling back to 'main'", branch);
+            branch = "main".to_string();
+        }
 
         let content_dir = ctx.config.book.src.clone();
 
@@ -57,12 +64,12 @@ impl Preprocessor for GitInfo {
 
                     // Configurable rendering options
                     let short_hash = git::get_git_output(
-                        ["log", "-1", "--format=%h", "--", &path_str],
+                        ["log", "-1", "--format=%h", &format!("{branch}"), "--", &path_str],
                         &ctx.root,
                     )
                     .unwrap_or_default();
                     let long_hash = git::get_git_output(
-                        ["log", "-1", "--format=%H", "--", &path_str],
+                        ["log", "-1", "--format=%H", &format!("{branch}"), "--", &path_str],
                         &ctx.root,
                     )
                     .unwrap_or_default();
@@ -103,6 +110,7 @@ impl Preprocessor for GitInfo {
                         &tag,
                         &formatted_date,
                         &separator,
+                        &branch,
                     );
 
                     // Inline style for visibility control
@@ -198,13 +206,15 @@ pub fn render_template(
     tag: &str,
     date: &str,
     sep: &str,
+    branch: &str,
 ) -> String {
     template
         .replace("{{hash}}", hash)
         .replace("{{long}}", long_hash)
         .replace("{{tag}}", tag)
         .replace("{{date}}", date)
         .replace("{{sep}}", sep)
+        .replace("{{branch}}", branch)
 }
 
 fn decorate_chapters<F>(item: &mut BookItem, decorate: &F)