[PATCH v1] emacs: Improved header display.

[David Edmondson]

Truncate the displayed headers to the window width. Show an ellipsis
if the displayed header is truncated. Add a binding 'T' to toggle the
truncation of headers. Add the not-displayed section of the header as
a tooltip to the displayed section.
---
 emacs/notmuch-show.el | 54 ++++++++++++++++++++++++++++++++++++++++++++++++---
 1 file changed, 51 insertions(+), 3 deletions(-)

diff --git a/emacs/notmuch-show.el b/emacs/notmuch-show.el
index a997482..523cef5 100644
--- a/emacs/notmuch-show.el
+++ b/emacs/notmuch-show.el
@@ -443,9 +443,56 @@ message at DEPTH in the current thread."
 	    ")\n")
     (overlay-put (make-overlay start (point)) 'face 'notmuch-message-summary-face)))
 
+(defun notmuch-truncate-nicely (addresses target-length)
+  ;; If it fits, everything is easy.
+  (if (< (length addresses) target-length)
+      (cons addresses nil)
+    (let* ((visible-length (- target-length (length "...")))
+	   (visible (substring addresses 0 visible-length))
+	   (invisible (substring addresses visible-length)))
+      ;; Try to terminate the visible string at a good break point.
+      (when (string-match "\\(.+\\),\\([^,]*\\)" visible)
+	;; Order is important (second clause is destructive on
+	;; `visible'.
+	(setq invisible (concat (match-string 2 visible) invisible)
+	      visible (match-string 1 visible)))
+      ;; `invisible' can end up with a leading space or
+      ;; comma-space, because the list of addresses is
+      ;; seperated with ", ", but we split on ",".
+      (setq invisible (replace-regexp-in-string "^[, ]*\\(.*\\)$" "\\1" invisible))
+      (cons visible invisible))))
+
+(defun notmuch-show-toggle-header-truncation ()
+  (interactive)
+  (let ((invisibility-spec-member (cons 'notmuch-show-mode t)))
+    (if (member invisibility-spec-member buffer-invisibility-spec)
+	(remove-from-invisibility-spec invisibility-spec-member)
+      (add-to-invisibility-spec invisibility-spec-member)))
+  ;; Required to have the change in visibility take effect.
+  (force-window-update))
+
 (defun notmuch-show-insert-header (header header-value)
   "Insert a single header."
-  (insert header ": " (notmuch-sanitize header-value) "\n"))
+  (let* ((header-value (notmuch-sanitize header-value))
+	 (header-colon (concat header ": "))
+	 (available-width (- (window-width) (length header-colon)))
+	 (v-i (notmuch-truncate-nicely header-value available-width)))
+
+    (insert header-colon)
+    (let ((visible (car v-i))
+	  (invisible (cdr v-i)))
+      (when invisible
+	(setq visible (propertize visible 'help-echo (concat "..." invisible))))
+      (insert visible)
+      (when invisible
+	(insert ", ")
+	(let ((start (point))
+	      overlay)
+	  (insert invisible)
+	  (setq overlay (make-overlay start (point)))
+	  (overlay-put overlay 'invisible 'notmuch-show-mode)
+	  (overlay-put overlay 'isearch-open-invisible #'delete-overlay))))
+    (insert "\n")))
 
 (defun notmuch-show-insert-headers (headers)
   "Insert the headers of the current message."
@@ -1328,6 +1375,7 @@ reset based on the original query."
     (define-key map "$" 'notmuch-show-toggle-process-crypto)
     (define-key map "<" 'notmuch-show-toggle-thread-indentation)
     (define-key map "t" 'toggle-truncate-lines)
+    (define-key map "T" 'notmuch-show-toggle-header-truncation)
     (define-key map "." 'notmuch-show-part-map)
     map)
   "Keymap for \"notmuch show\" buffers.")
@@ -1367,8 +1415,8 @@ All currently available key bindings:
   (use-local-map notmuch-show-mode-map)
   (setq major-mode 'notmuch-show-mode
 	mode-name "notmuch-show")
-  (setq buffer-read-only t
-	truncate-lines t))
+  (add-to-invisibility-spec (cons 'notmuch-show-mode t))
+  (setq buffer-read-only t))
 
 (defun notmuch-tree-from-show-current-query ()
   "Call notmuch tree with the current query"
-- 
2.1.1