feat(cli): add "--force" flag to install command

This will the user to overwrite the existing
'index.hbs' file in the theme directory. It should
ideally be used when there are updates to the major
version.

src/bin/mdbook-catppuccin.rs

@@ -1,6 +1,6 @@
 use std::{io, process};
 
-use clap::{command, crate_version, Arg, ArgMatches, Command};
+use clap::{command, crate_version, Arg, ArgAction, ArgMatches, Command};
 use mdbook::errors::Error;
 use mdbook::preprocess::{CmdPreprocessor, Preprocessor};
 use semver::{Version, VersionReq};
@@ -40,6 +40,13 @@ pub fn make_app() -> Command {
                         .default_value(".")
                         .help("Root directory for the book, this should contain the configuration file `book.toml`")
                 )
+                .arg(
+                    Arg::new("force")
+                    .long("force")
+                    .short('f')
+                    .action(ArgAction::SetTrue)
+                    .help("Overwrite the existing 'index.hbs' file, should only be used when upgrading major versions")
+                )
                 .about("Install the necessary files needed and update the config to include them"),
         )
 }
@@ -116,6 +123,7 @@ mod install {
         let dir = sub_args.get_one::<String>("dir").unwrap();
         let project_dir = PathBuf::from(dir);
         let toml_config = project_dir.join("book.toml");
+        let is_force = sub_args.get_flag("force");
 
         if !toml_config.exists() {
             error!(
@@ -127,7 +135,7 @@ mod install {
 
         let (toml, mut document) = read_configuration_file(&toml_config);
         let theme_dir = populate_theme_directory(&document, &project_dir);
-        copy_assets(&mut document, &theme_dir);
+        copy_assets(&mut document, &theme_dir, is_force);
         update_configuration_file(document, toml, toml_config);
 
         info!("mdbook-catppuccin is now installed. Build your book with `mdbook build` to try out your new catppuccin colour palettes!");
@@ -162,7 +170,7 @@ mod install {
         theme_dir
     }
 
-    fn copy_assets(document: &mut Document, theme_dir: &Path) {
+    fn copy_assets(document: &mut Document, theme_dir: &Path, is_force: bool) {
         if let Ok(preprocessor) = document.insert_into_preprocessor("catppuccin") {
             let value = toml_edit::value(Value::from(VERSION.trim()).decorated(
                 " ",
@@ -192,11 +200,18 @@ mod install {
                 let file_exists = Path::new(path_str).try_exists();
                 if let Ok(val) = file_exists {
                     if val {
-                        info!(
-                            "'{}' already exists and therefore will not be overwritten",
-                            path.display()
-                        );
-                        break;
+                        if is_force {
+                            info!(
+                                "Force flag detected. Overwriting existing '{}'",
+                                path.display()
+                            );
+                        } else {
+                            info!(
+                                "'{}' already exists and therefore will not be overwritten",
+                                path.display()
+                            );
+                            break;
+                        }
                     }
                 } else {
                     error!("Unexpected error, cannot determine if 'index.hbs' exists");