Add support for darwin

rebuild.sh

@@ -1,3 +1,20 @@
 #!/usr/bin/env bash
+
 cd "$(dirname "$0")" || exit
-exec nixos-rebuild -I nixos-config="machines/$(hostname)/configuration.nix" "$@" --flake '.#'
+
+uname="$(uname -s)"
+case "${uname}" in
+    Linux*)     machine=linux;;
+    Darwin*)    machine=mac;;
+    *)          machine="unknown"
+esac
+
+if [[ "$machine" ==  "linux" ]]; then
+    exec nixos-rebuild -I nixos-config="machines/$(hostname)/configuration.nix" "$@" --flake '.#'
+elif [[ "$machine" ==  "mac" ]]; then
+    exec darwin-rebuild "$@" --flake . --impure # TODO: What is causing this impurity?
+else 
+    echo 'Unsupported OS.'
+    echo 'Exiting...'
+    exit 1
+fi