[lang/lua] Add LSP flag and support for Lua

modules/lang/lua/config.el

@@ -31,6 +31,32 @@
   (when (featurep! :checkers syntax)
     (require 'flycheck-moonscript nil t)))
 
+;;
+;;; LSP
+(defvar lua-lsp-dir (concat doom-etc-dir "lsp/lua-language-server/")
+  "Absolute path to the directory of sumneko's lua-language-server.
+This directory MUST contain the 'main.lua' file and be the in-source
+build of lua-language-server.")
+
+;; We need the absolute path to lua-language-server binary
+;; because the bundled dependencies aren't found otherwise
+;; The only reason this is a function is to dynamically change
+;; when/if lua-lsp-dir variable changed
+(defun doom--abs-path-to-lua-lsp ()
+  "Return the absolute path to lua-language-server."
+  (let ((binary-subdir
+         (cond (IS-MAC "bin/macOS/")
+               (IS-LINUX "bin/Linux/")
+               ;; TODO : Forwards or backwards slash for WIN ?
+               (IS-WINDOWS "bin/Windows/")
+               ;; TODO : Error or empty string here ?
+               (t ""))))
+    (concat lua-lsp-dir binary-subdir "lua-language-server")))
+
+(after! lua-mode
+  (set-eglot-client! 'lua-mode `(,(doom--abs-path-to-lua-lsp) "-E" "-e" "LANG=\"en\"" ,(concat lua-lsp-dir "main.lua"))))
+(when (featurep! +lsp)
+  (add-hook 'lua-mode-local-vars-hook #'lsp!))
 
 ;;
 ;;; Frameworks