💥 Color scheme specification now mandatory with git hook

When running as the git commit hook, we now require the color scheme to
be explicitly specified. If it's not specified, we ask the user to
re-install the hook (which is just one command). Otherwise, the
autodection will kick in and on some operating systems, we face the
garbage input issue (#69).

Author: zeenix

src/main.rs

@@ -16,7 +16,7 @@ use std::{
     error::Error,
     fs::File,
     io::{BufRead, BufReader, Write},
-    process,
+    process::{self, exit},
 };
 #[cfg(unix)]
 use std::{fs::Permissions, os::unix::prelude::PermissionsExt};
@@ -246,9 +246,17 @@ fn get_color_scheme(args: &Args) -> ColorScheme {
             _ => None,
         })
         .or(args.color_scheme)
-        .unwrap_or_else(|| match terminal_light::luma() {
-            Ok(luma) if luma > 0.6 => ColorScheme::Light,
-            _ => ColorScheme::Dark,
+        .unwrap_or_else(|| {
+            if args.hook.is_empty() {
+                match terminal_light::luma() {
+                    Ok(luma) if luma > 0.6 => ColorScheme::Light,
+                    _ => ColorScheme::Dark,
+                }
+            } else {
+                eprintln!("{}", NO_SCHEME_IN_HOOK_ERROR);
+
+                exit(-1);
+            }
         })
 }
 
@@ -259,3 +267,6 @@ const HOOK_CONTENT_TEMPL: &str = r#"
 exec < /dev/tty
 gimoji {color_scheme_arg} --hook $1 $2
 "#;
+
+const NO_SCHEME_IN_HOOK_ERROR: &str =
+    r#"No color scheme specified in the git hook. Please re-install it using `gimoji -i`."#;