From 95a7ca04d1c3b573cbc1cba3378f50450f090ab4 Mon Sep 17 00:00:00 2001
From: dannyfreeman <danny@dfreeman.email>
Date: Wed, 9 Nov 2022 08:46:45 -0500
Subject: [PATCH] Eglot: Display progress notifications in minibuffer as they
 arrive

* lisp/progmodes/eglot.el (eglot-report-progress): New custom variable.
(eglot-lsp-server): New slot for tracking active progress reporters.
(eglot-handle-notification): New impl for $/progress server responses.
(eglot--format-markup): replace tab with spaces.
(eglot--TextDocumentItem): replace tab with spaces.

The LSP spec describes methods for reporting progress on long running
jobs to the client:

https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification/#progress
https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification/#workDoneProgress

This change reports those notifications in the minibuffer as they come
in. It shows a percent indicator (if the server provides theme), or a
spinner. This change should open the door for writing a "cancel long
running request" command, which are identified by these progress
notifications. See
https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification/#window_workDoneProgress_cancel
---
 lisp/progmodes/eglot.el | 49 +++++++++++++++++++++++++++++++++++++++--
 1 file changed, 47 insertions(+), 2 deletions(-)

diff --git a/lisp/progmodes/eglot.el b/lisp/progmodes/eglot.el
index a0fb253e10..1c991e5c35 100644
--- a/lisp/progmodes/eglot.el
+++ b/lisp/progmodes/eglot.el
@@ -386,6 +386,11 @@ eglot-menu-string
   "String displayed in mode line when Eglot is active."
   :type 'string)
 
+(defcustom eglot-report-progress t
+  "If non-nil, show progress of long running server work in the minibuffer."
+  :type 'boolean
+  :version "29.1")
+
 (defvar eglot-withhold-process-id nil
   "If non-nil, Eglot will not send the Emacs process id to the language server.
 This can be useful when using docker to run a language server.")
@@ -831,6 +836,9 @@ eglot-lsp-server
    (project
     :documentation "Project associated with server."
     :accessor eglot--project)
+   (progress-reporter-alist
+    :documentation "Alist of (PROGRESS-TOKEN . PROGRESS-REPORTER)."
+    :accessor eglot--progress-reporter-alist)
    (inhibit-autoreconnect
     :initform t
     :documentation "Generalized boolean inhibiting auto-reconnection if true."
@@ -1569,7 +1577,7 @@ eglot--format-markup
       (setq-local markdown-fontify-code-blocks-natively t)
       (insert string)
       (let ((inhibit-message t)
-	    (message-log-max nil))
+            (message-log-max nil))
         (ignore-errors (delay-mode-hooks (funcall mode))))
       (font-lock-ensure)
       (string-trim (buffer-string)))))
@@ -2049,6 +2057,43 @@ eglot-handle-notification
   (_server (_method (eql telemetry/event)) &rest _any)
   "Handle notification telemetry/event.") ;; noop, use events buffer
 
+(defun eglot--progress-report-message (title message)
+  "Format a $/progress report message, given a TITLE and/or MESSAGE string."
+  (cond
+   ((and title message) (format "%s %s" title message))
+   (title title)
+   (message message)))
+
+(defun eglot--progress-reporter (server token)
+  "Get a prgress-reporter identified by the progress TOKEN from the SERVER ."
+  (cdr (assoc token (eglot--progress-reporter-alist server))))
+
+(defun eglot--progress-reporter-delete (server token)
+  "Delete progress-reporters identified by the progress TOKEN from the SERVER."
+  (setf (eglot--progress-reporter-alist server)
+        (assoc-delete-all token (eglot--progress-reporter-alist server))))
+
+(cl-defmethod eglot-handle-notification
+  (server (_method (eql $/progress)) &key token value)
+  "Handle a $/progress notification identified by TOKEN from the SERVER."
+  (when eglot-report-progress
+    (cl-destructuring-bind (&key kind title percentage message) value
+      (pcase kind
+        ("begin" (let* ((prefix (format (concat "[eglot] %s %s:" (when percentage " "))
+                                        (eglot-project-nickname server) token))
+                        (pr (if percentage
+                                (make-progress-reporter prefix 0 100 percentage 1 0)
+                              (make-progress-reporter prefix nil nil nil 1 0))))
+                   (eglot--progress-reporter-delete server token)
+                   (setf (eglot--progress-reporter-alist server)
+                         (cons (cons token pr) (eglot--progress-reporter-alist server)))
+                   (progress-reporter-update pr percentage (eglot--progress-report-message title message))))
+        ("report" (when-let ((pr (eglot--progress-reporter server token)))
+                    (progress-reporter-update pr percentage (eglot--progress-report-message title message))))
+        ("end" (when-let ((pr (eglot--progress-reporter server token)))
+                 (progress-reporter-done pr)
+                 (eglot--progress-reporter-delete server token)))))))
+
 (cl-defmethod eglot-handle-notification
   (_server (_method (eql textDocument/publishDiagnostics)) &key uri diagnostics
            &allow-other-keys) ; FIXME: doesn't respect `eglot-strict-mode'
@@ -2172,7 +2217,7 @@ eglot--TextDocumentItem
   (append
    (eglot--VersionedTextDocumentIdentifier)
    (list :languageId
-	 (eglot--language-id (eglot--current-server-or-lose))
+         (eglot--language-id (eglot--current-server-or-lose))
          :text
          (eglot--widening
           (buffer-substring-no-properties (point-min) (point-max))))))
-- 
2.38.1