From f3ee2edf1b8f4829d7b6c7e1804e1341d538e11a Mon Sep 17 00:00:00 2001
From: Ting Zhou <zhouting@umich.edu>
Date: Thu, 26 Apr 2018 16:33:41 -0700
Subject: [PATCH] Add: add lsp-javascript backend for javascript layer

---
 layers/+lang/javascript/README.org  | 46 +++++++++++++++---
 layers/+lang/javascript/config.el   |  4 ++
 layers/+lang/javascript/funcs.el    | 75 ++++++++++++++++++++++++++++-
 layers/+lang/javascript/packages.el | 25 +++++-----
 4 files changed, 128 insertions(+), 22 deletions(-)

diff --git a/layers/+lang/javascript/README.org b/layers/+lang/javascript/README.org
index f70606961..05cfa5b0b 100644
--- a/layers/+lang/javascript/README.org
+++ b/layers/+lang/javascript/README.org
@@ -6,8 +6,11 @@
 - [[#description][Description]]
   - [[#features][Features:]]
 - [[#install][Install]]
-- [[#configuration][Configuration]]
+  - [[#choosing-a-backend][Choosing a backend]]
+- [[#backends][Backends]]
   - [[#tern][Tern]]
+  - [[#language-server-protocol][Language Server Protocol]]
+- [[#configuration][Configuration]]
   - [[#indentation][Indentation]]
   - [[#repl][REPL]]
   - [[#node-modules][Node Modules]]
@@ -39,12 +42,6 @@ To use this configuration layer, add it to your =~/.spacemacs=. You will need to
 add =javascript= to the existing =dotspacemacs-configuration-layers= list in
 this file.
 
-You will also need to install =tern= to use the auto-completion and
-documentation features:
-#+BEGIN_SRC sh
-  $ npm install -g tern
-#+END_SRC
-
 To use the formatting features, install =js-beautify=:
 #+BEGIN_SRC sh
   $ npm install -g js-beautify
@@ -63,8 +60,33 @@ If you install these in non-standard locations, then add the following to your =
   (add-to-list 'exec-path "/path/to/node/bins" t)
 #+END_SRC
 
-* Configuration
+** Choosing a backend
+To choose a default backend set the layer variable =javascript-backend=:
+
+#+BEGIN_SRC elisp
+(javascript :variables javascript-backend 'tern)
+#+END_SRC
+
+Backend can be chosen on a per project basis using directory local variables
+(files named =.dir-locals.el= at the root of a project), an example to use the
+=lsp= backend:
+
+#+BEGIN_SRC elisp
+;;; Directory Local Variables
+;;; For more information see (info "(emacs) Directory Variables")
+
+((js2-mode (javascript-backend . lsp)))
+#+END_SRC
+
+*Note:* you can easily add a directory local variable with ~SPC f v d~.
+
+* Backends
 ** Tern
+Install =tern= to use the auto-completion and documentation features:
+#+BEGIN_SRC sh
+  $ npm install -g tern
+#+END_SRC
+
 To make tern re-use the server across multiple different editing sessions (thus
 creating multiple =.tern-port= files for each document you have open [[http://ternjs.net/doc/manual.html][see here
 for more details]]):
@@ -85,6 +107,14 @@ layer:
   (javascript :variables tern-command '("node" "/path/to/tern/bin/tern"))
 #+END_SRC
 
+** Language Server Protocol
+You just have to install python language server package:
+
+#+begin_src sh
+npm i -g typescript javascript-typescript-langserver flow-language-server typescript-language-server
+#+end_src
+
+* Configuration
 ** Indentation
 To change how js2-mode indents code, set the variable =js2-basic-offset=, as
 such:
diff --git a/layers/+lang/javascript/config.el b/layers/+lang/javascript/config.el
index d1e74ae02..cdae234d3 100644
--- a/layers/+lang/javascript/config.el
+++ b/layers/+lang/javascript/config.el
@@ -15,3 +15,7 @@
 
 (defvar javascript-disable-tern-port-files t
   "Stops tern from creating tern port files.")
+
+(defvar javascript-backend 'tern
+  "The backend to use for IDE features. Possible values are `tern'
+and `lsp'.")
diff --git a/layers/+lang/javascript/funcs.el b/layers/+lang/javascript/funcs.el
index a93d6cdd7..f41ad10f7 100644
--- a/layers/+lang/javascript/funcs.el
+++ b/layers/+lang/javascript/funcs.el
@@ -80,13 +80,44 @@
   (skewer-repl)
   (evil-insert-state))
 
+
+;; backend
+
+(defun spacemacs//javascript-setup-backend ()
+  "Conditionally setup javascript backend."
+  (pcase javascript-backend
+    (`tern(spacemacs//javascript-setup-tern))
+    (`lsp (spacemacs//javascript-setup-lsp))))
+
+(defun spacemacs//javascript-setup-company ()
+  "Conditionally setup company based on backend."
+  (pcase javascript-backend
+    (`tern (spacemacs//javascript-setup-tern-company))
+    (`lsp (spacemacs//javascript-setup-lsp-company))))
+
 
 ;; tern
 
+(defun spacemacs//javascript-setup-tern ()
+  "Setup tern backend."
+  (add-hook 'js2-mode-hook 'tern-mode)
+  (progn
+    (spacemacs|hide-lighter tern-mode)
+    (when javascript-disable-tern-port-files
+      (add-to-list 'tern-command "--no-port-file" 'append))
+    (spacemacs//set-tern-key-bindings 'js2-mode)))
+
+(defun spacemacs//javascript-setup-tern-company ()
+  "Setup tern auto-completion."
+  (spacemacs|add-company-backends
+    :backends company-tern
+    :modes js2-mode)
+  (company-mode))
+
 (defun spacemacs//set-tern-key-bindings (mode)
   "Set the key bindings for tern and the given MODE."
   (add-to-list (intern (format "spacemacs-jump-handlers-%S" mode))
-            '(tern-find-definition :async t))
+               '(tern-find-definition :async t))
   (spacemacs/set-leader-keys-for-major-mode mode
     "rrV" 'tern-rename-variable
     "hd" 'tern-get-docs
@@ -100,3 +131,45 @@
     (unless found
       (spacemacs-buffer/warning "tern binary not found!"))
     found))
+
+
+;; lsp
+
+(defun spacemacs//javascript-setup-lsp ()
+  "Setup lsp backend."
+  (if (configuration-layer/layer-used-p 'lsp)
+      (progn
+        (add-hook 'js-mode-hook #'lsp-javascript-typescript-enable)
+        (require 'lsp-javascript-flow)
+        (add-hook 'js-mode-hook #'lsp-javascript-flow-enable)
+        (add-hook 'js2-mode-hook #'lsp-javascript-flow-enable) ;; for js2-mode support
+        (require 'lsp-typescript)
+        (add-hook 'js-mode-hook #'lsp-typescript-enable)
+        (add-hook 'js2-mode-hook #'lsp-typescript-enable) ;; for js2-mode support
+        (spacemacs//set-lsp-key-bindings 'js2-mode))
+    (message "`lsp' layer is not installed, please add `lsp' layer to your dofile.")))
+
+(defun spacemacs//javascript-setup-lsp-company ()
+  "Setup lsp auto-completion."
+  (if (configuration-layer/layer-used-p 'lsp)
+      (progn
+        ;; fix lsp-javascript company prefix
+        ;; https://github.com/emacs-lsp/lsp-javascript/issues/9#issuecomment-379515379
+        (defun my-company-transformer (candidates)
+          (let ((completion-ignore-case t))
+            (all-completions (company-grab-symbol) candidates)))
+        (defun my-js-hook nil
+          (make-local-variable 'company-transformers)
+          (push 'my-company-transformer company-transformers))
+        (add-hook 'js-mode-hook 'my-js-hook)
+
+        (spacemacs|add-company-backends
+          :backends company-lsp
+          :modes js2-mode)
+        (company-mode))
+    (message "`lsp' layer is not installed, please add `lsp' layer to your dofile.")))
+
+(defun spacemacs//set-lsp-key-bindings (mode)
+  "Set the key bindings for tern and the given MODE."
+  (add-to-list (intern (format "spacemacs-jump-handlers-%S" mode))
+               '(lsp-ui-peek-find-definitions)))
diff --git a/layers/+lang/javascript/packages.el b/layers/+lang/javascript/packages.el
index 2536df594..8395feba0 100644
--- a/layers/+lang/javascript/packages.el
+++ b/layers/+lang/javascript/packages.el
@@ -30,6 +30,7 @@
         web-beautify
         skewer-mode
         livid-mode
+        (lsp-javascript-typescript :requires lsp-mode)
         ))
 
 (defun javascript/post-init-add-node-modules-path ()
@@ -66,12 +67,10 @@
   (use-package company-tern
     :if (and (configuration-layer/package-used-p 'company)
              (configuration-layer/package-used-p 'tern))
-    :defer t
-    :init (spacemacs|add-company-backends
-            :backends company-tern
-            :modes js2-mode)))
+    :defer t))
 
 (defun javascript/post-init-company ()
+  (add-hook 'js2-mode-hook #'spacemacs//javascript-setup-company)
   (spacemacs|add-company-backends
     :backends company-capf
     :modes coffee-mode))
@@ -104,7 +103,9 @@
     (progn
       (add-to-list 'auto-mode-alist '("\\.js\\'" . js2-mode))
       ;; Required to make imenu functions work correctly
-      (add-hook 'js2-mode-hook 'js2-imenu-extras-mode))
+      (add-hook 'js2-mode-hook 'js2-imenu-extras-mode)
+      ;; setup javascript backend
+      (add-hook 'js2-mode-hook 'spacemacs//javascript-setup-backend))
     :config
     (progn
       ;; prefixes
@@ -193,14 +194,7 @@
 
 (defun javascript/init-tern ()
   (use-package tern
-    :defer t
-    :init (add-hook 'js2-mode-hook 'tern-mode)
-    :config
-    (progn
-      (spacemacs|hide-lighter tern-mode)
-      (when javascript-disable-tern-port-files
-        (add-to-list 'tern-command "--no-port-file" 'append))
-      (spacemacs//set-tern-key-bindings 'js2-mode))))
+    :defer t))
 
 (defun javascript/init-web-beautify ()
   (use-package web-beautify
@@ -253,3 +247,8 @@
         :documentation "Live evaluation of JS buffer change."
         :evil-leader-for-mode (js2-mode . "Tl"))
       (spacemacs|diminish livid-mode " 🅻" " [l]"))))
+
+(defun javascript/init-lsp-javascript-typescript ()
+  (use-package lsp-javascript-typescript
+    :commands lsp-javascript-typescript-enable
+    :defer t))