Add commit-msg hook to git templates

modules/home-manager/git.nix → modules/home-manager/git/default.nix

@@ -1,4 +1,6 @@
 { pkgs, config, lib, colors, ... }: {
+  imports = [ ./template.nix ];
+
   home = {
     packages = [ pkgs.nano ];
 

modules/home-manager/git/template.nix

@@ -0,0 +1,23 @@
+{ pkgs, lib, config, ... }: {
+  programs.git.extraConfig.init.templatedir = "${config.home.homeDirectory}/.git_template";
+
+  home.file.".git_template/hooks/commit-msg".source = pkgs.writeShellScript "commit-msg" ''
+    PATH=${lib.makeBinPath [ pkgs.coreutils ]}
+
+    readonly COMMIT_MSG_FILE="$1"
+
+    function check_commit_msg_length {
+        readonly MAX_MSG_LENGTH=72
+
+        local title=$(head -n 1 "$COMMIT_MSG_FILE")
+
+        if [ ''${#title} -gt $MAX_MSG_LENGTH ]; then
+            # TODO figure out how to use hex colors variable
+            echo -e "\x1b[1;38;5;203mCommit title is ''${#title} characters long, must be equal or shorter than $MAX_MSG_LENGTH characters!\e[0m";
+            exit 1
+        fi
+    }
+
+    check_commit_msg_length
+  '';
+}