#+TITLE: Language - JavaScript - LSP
#+AUTHOR: Juan Placencia

* Package

Define JavaScript language LSP Integration package.

#+BEGIN_SRC emacs-lisp
  (use-package emacs
    :after (uno-lang-js uno-dev-lsp projectile)
    :if (executable-find "node")
    :config
    (provide 'uno-lang-js-lsp))
#+END_SRC

* LSP Integration

#+BEGIN_SRC emacs-lisp
  (use-package emacs
    :after uno-lang-js-lsp
    :custom
    (lsp-eslint-auto-fix-on-save t)
    :init
    (require 'seq)
    (defun uno/lang/js/lsp ()
      "Set up LSP for JavaScript."
      (require 'lsp-javascript)
      (make-local-variable 'lsp-disabled-clients)
      (when (uno/lang/js/lsp/local-provider)
        (plist-put lsp-deps-providers
                   :local '(:path uno/lang/js/lsp/local-provider))
        (setq-local lsp-auto-guess-root t))
      (uno/lang/js/lsp/add-to-local
       'typescript-language-server
       "typescript-language-server/lib/cli.js")
      (uno/lang/js/lsp/add-to-local
       'typescript
       "typescript/bin/tsserver")
       (when (uno/lang/js/lsp/local-provider "eslint/bin/eslint.js")
         (let ((-eslint
                (uno/lang/js/lsp/local-provider "eslint/bin/eslint.js"))
               (-node-path (uno/lang/js/lsp/local-provider))
               (-package-manager (uno/lang/js/lsp/local-provider-type)))
           (setq-local
            flycheck-javascript-eslint-executable -eslint
            lsp-eslint-node-path -node-path
            lsp-eslint-package-manager -package-manager))))
    (defun uno/lang/js/lsp/add-to-local (name file)
      "Add NAME dependency from FILE to local instance."
      (when (uno/lang/js/lsp/local-provider file)
        (lsp-dependency name `(:local ,file))
        t))
    (defun uno/lang/js/lsp/local-provider (&optional path)
      "Provide path for local SDK instance relative to PATH."
      (seq-reduce
       (lambda (current sdk)
         (if current
             current
           (let ((-path (concat (projectile-project-root) sdk path)))
             (if (file-exists-p -path) -path nil))))
       '(".yarn/sdks/" "node_modules/")
       nil))
    (defun uno/lang/js/lsp/local-provider-type ()
      "Check SDK instance type."
      (let ((-root (projectile-project-root)))
        (cond
         ((file-exists-p (concat -root ".yarn/")) "yarn")
         ((file-exists-p (concat -root "node_modules/")) "npm"))))
    ;; https://github.com/emacs-lsp/lsp-mode/issues/1842#issuecomment-942861229
    (defun uno/lang/js/lsp/eslint-autofix ()
      "Run lsp-eslint-apply-all-fixes before lsp--before-save."
      (when lsp-eslint-auto-fix-on-save
        (lsp-eslint-fix-all)))
    (advice-add 'lsp--before-save :before #'uno/lang/js/lsp/eslint-autofix)
    (uno/add-useless-buffer "\\*eslint\\*")
    (uno/add-useless-buffer "\\*eslint::.*\\*"))
#+END_SRC