[PATCH 2/9] emacs: Refresh hello whenever the user switches to the buffer

[Austin Clements]

Previously, we refreshed hello when the user quit a search that was
started from hello.  This is fine assuming purely stack-oriented
buffer use, but is quite fragile and requires hacks to search.

This replaces that logic with a new approach that refreshes hello
whenever the user switches to the hello buffer, regardless of how this
happens.
---
 emacs/notmuch-hello.el |   52 ++++++++++++++++++++++++++++++++++++++----------
 1 file changed, 42 insertions(+), 10 deletions(-)

diff --git a/emacs/notmuch-hello.el b/emacs/notmuch-hello.el
index 9db8c99..c4f102f 100644
--- a/emacs/notmuch-hello.el
+++ b/emacs/notmuch-hello.el
@@ -263,8 +263,7 @@ afterwards.")
     (setq search (notmuch-hello-trim search))
     (let ((history-delete-duplicates t))
       (add-to-history 'notmuch-search-history search)))
-  (notmuch-search search notmuch-search-oldest-first nil nil
-		  #'notmuch-hello-search-continuation))
+  (notmuch-search search notmuch-search-oldest-first))
 
 (defun notmuch-hello-add-saved-search (widget)
   (interactive)
@@ -322,8 +321,7 @@ diagonal."
 (defun notmuch-hello-widget-search (widget &rest ignore)
   (notmuch-search (widget-get widget
 			      :notmuch-search-terms)
-		  notmuch-search-oldest-first
-		  nil nil #'notmuch-hello-search-continuation))
+		  notmuch-search-oldest-first))
 
 (defun notmuch-saved-search-count (search)
   (car (process-lines notmuch-command "count" search)))
@@ -476,9 +474,6 @@ Such a list can be computed with `notmuch-hello-query-counts'."
 
 (defimage notmuch-hello-logo ((:type png :file "notmuch-logo.png")))
 
-(defun notmuch-hello-search-continuation()
-  (notmuch-hello-update t))
-
 (defun notmuch-hello-update (&optional no-display)
   "Update the current notmuch view."
   ;; Lazy - rebuild everything.
@@ -491,6 +486,36 @@ Such a list can be computed with `notmuch-hello-query-counts'."
   (notmuch-poll)
   (notmuch-hello-update))
 
+(defvar notmuch-hello-inhibit-auto-refresh nil
+  "Don't refresh notmuch-hello on window configuration changes.")
+
+(defun notmuch-hello-window-configuration-change ()
+  "Hook function to update the hello buffer when it is switched to."
+  (let ((hello-buf (get-buffer "*notmuch-hello*"))
+	(do-refresh nil))
+    ;; Consider all windows in the currently selected frame, since
+    ;; that's where the configuration change happened.  This also
+    ;; refreshes our snapshot of all windows, so we have to do this
+    ;; even if we know we won't refresh (e.g., hello-buf is null).
+    (dolist (window (window-list))
+      (let ((last-buf (window-parameter window 'notmuch-hello-last-buffer))
+	    (cur-buf (window-buffer window)))
+	(when (not (eq last-buf cur-buf))
+	  ;; This window changed or is new.  Update recorded buffer
+	  ;; for next time.
+	  (set-window-parameter window 'notmuch-hello-last-buffer cur-buf)
+	  (when (and (eq cur-buf hello-buf) last-buf)
+	    ;; The user just switched to hello in this window (hello
+	    ;; is currently visible, was not visible on the last
+	    ;; configuration change, and this is not a new window)
+	    (setq do-refresh t)))))
+    (when (and do-refresh (not notmuch-hello-inhibit-auto-refresh))
+      (notmuch-hello t))
+    (when (null hello-buf)
+      ;; Clean up hook
+      (remove-hook 'window-configuration-change-hook
+		   #'notmuch-hello-window-configuration-change))))
+
 
 (defvar notmuch-hello-mode-map
   (let ((map (make-sparse-keymap)))
@@ -765,9 +790,16 @@ following:
   "Run notmuch and display saved searches, known tags, etc."
   (interactive)
 
-  (if no-display
-      (set-buffer "*notmuch-hello*")
-    (switch-to-buffer "*notmuch-hello*"))
+  ;; This may cause a window configuration change, so if the
+  ;; auto-refresh hook is already installed, avoid recursive refresh.
+  (let ((notmuch-hello-inhibit-auto-refresh t))
+    (if no-display
+	(set-buffer "*notmuch-hello*")
+      (switch-to-buffer "*notmuch-hello*")))
+
+  ;; Install auto-refresh hook
+  (add-hook 'window-configuration-change-hook
+	    #'notmuch-hello-window-configuration-change)
 
   (let ((target-line (line-number-at-pos))
 	(target-column (current-column))
-- 
1.7.10.4