Wait for user to stop typing to trigger search from khoj.el in Emacs

- Improves user experience by aligning idle time with search latency
  to avoid display jitter (to render results) while user is typing

- Makes the idle time configurable

Closes #480

src/interface/emacs/khoj.el

@@ -87,6 +87,12 @@
   :group 'khoj
   :type 'integer)
 
+(defcustom khoj-search-on-idle-time 0.3
+  "Idle time (in seconds) to wait before triggering search."
+  :group 'khoj
+  :type 'number)
+
+
 (defcustom khoj-default-content-type "org"
   "The default content type to perform search on."
   :group 'khoj
@@ -115,6 +121,9 @@
 (defvar khoj--content-type "org"
   "The type of content to perform search on.")
 
+(defvar khoj--search-on-idle-timer nil
+  "Idle timer to trigger incremental search.")
+
 (declare-function org-element-property "org-mode" (PROPERTY ELEMENT))
 (declare-function org-element-type "org-mode" (ELEMENT))
 (declare-function markdown-mode "markdown-mode" ())
@@ -920,6 +929,9 @@ RECEIVE-DATE is the message receive date."
   (message "khoj.el: Teardown Incremental Search")
   ;; unset khoj minibuffer window
   (setq khoj--minibuffer-window nil)
+  (when (and khoj--search-on-idle-timer
+             (timerp khoj--search-on-idle-timer))
+    (cancel-timer khoj--search-on-idle-timer))
   ;; delete open connections to khoj server
   (khoj--delete-open-network-connections-to-server)
   ;; remove hooks for khoj incremental query and self
@@ -942,8 +954,10 @@ RECEIVE-DATE is the message receive date."
           ;; set current (mini-)buffer entered as khoj minibuffer
           ;; used to query khoj API only when user in khoj minibuffer
           (setq khoj--minibuffer-window (current-buffer))
-          (add-hook 'post-command-hook #'khoj--incremental-search) ; do khoj incremental search after every user action
-          (add-hook 'minibuffer-exit-hook #'khoj--teardown-incremental-search)) ; teardown khoj incremental search on minibuffer exit
+          ; do khoj incremental search after idle time
+          (setq khoj--search-on-idle-timer (run-with-idle-timer khoj-search-on-idle-time t #'khoj--incremental-search))
+          ; teardown khoj incremental search on minibuffer exit
+          (add-hook 'minibuffer-exit-hook #'khoj--teardown-incremental-search))
       (read-string khoj--query-prompt))))