feat(template): start work on template runner

Author: devnote-dev

src/template/runner.cr

@@ -0,0 +1,40 @@
+module Lua
+  class Runner
+    @script : String
+    @output : IO
+    @state : Lua::State
+
+    def initialize(@script, @output)
+      @state = Lua::State.new
+      @state.open :all
+    end
+
+    def load_normal_env : Nil
+      Lua.create_function @state, "current_dir" do |_|
+        Dir.current
+      end
+
+      Lua.create_function @state, "run_command" do |args|
+        command, *rest = args.map(&.as_s) rescue raise "expected all string arguments to 'run_command'"
+        Process.run(command, rest).exit_code
+      end
+    end
+
+    def load_test_env : Nil
+      Lua.create_function @state, "current_dir" do |_|
+        Dir.current
+      end
+
+      Lua.create_function @state, "run_command" do |_|
+        0
+      end
+    end
+
+    def load_checks_env : Nil
+      # TODO
+    end
+
+    def run : Nil
+    end
+  end
+end