emacs/show: display count of duplicates in headerline

There is no real cost here, except screen real estate. Some people
might prefer hiding the duplicate count, but we leave that for a
future commit.

emacs/notmuch-show.el

@@ -530,7 +530,7 @@ Return unchanged ADDRESS if parsing fails."
 	  (plist-put msg :height height)
 	  height))))
 
-(defun notmuch-show-insert-headerline (headers date tags depth)
+(defun notmuch-show-insert-headerline (headers date tags depth duplicate file-count)
   "Insert a notmuch style headerline based on HEADERS for a
 message at DEPTH in the current thread."
   (let ((start (point))
@@ -550,7 +550,14 @@ message at DEPTH in the current thread."
 	    date
 	    ") ("
 	    (notmuch-tag-format-tags tags tags)
-	    ")\n")
+	    ")")
+    (insert
+     (if (> file-count 1)
+	 (let ((txt (format "%d/%d\n" duplicate file-count)))
+	   (concat
+	    (notmuch-show-spaces-n (- (window-width) (+ (current-column) (length txt))))
+	    txt))
+       "\n"))
     (overlay-put (make-overlay start (point))
 		 'face 'notmuch-message-summary-face)))
 
@@ -1154,6 +1161,8 @@ is t, hide the part initially and show the button."
 (defun notmuch-show-insert-msg (msg depth)
   "Insert the message MSG at depth DEPTH in the current thread."
   (let* ((headers (plist-get msg :headers))
+	 (duplicate (or (plist-get msg :duplicate) 0))
+	 (files (length (plist-get msg :filename)))
 	 ;; Indentation causes the buffer offset of the start/end
 	 ;; points to move, so we must use markers.
 	 message-start message-end
@@ -1165,7 +1174,7 @@ is t, hide the part initially and show the button."
 				    (or (and notmuch-show-relative-dates
 					     (plist-get msg :date_relative))
 					(plist-get headers :Date))
-				    (plist-get msg :tags) depth)
+				    (plist-get msg :tags) depth duplicate files)
     (setq content-start (point-marker))
     ;; Set `headers-start' to point after the 'Subject:' header to be
     ;; compatible with the existing implementation. This just sets it

test/T450-emacs-show.sh

@@ -341,7 +341,7 @@ test_expect_equal_file EXPECTED OUTPUT
 add_email_corpus duplicate
 
 ID3=87r2ecrr6x.fsf@zephyr.silentflame.com
-test_begin_subtest "duplicate=3"
+test_begin_subtest "duplicate=3, subject"
 test_emacs "(notmuch-show \"id:${ID3}\")
 	   (notmuch-show-choose-duplicate 3)
 	   (test-visible-output \"OUTPUT\")"
@@ -367,4 +367,10 @@ cat <<EOF > EXPECTED
 (error Duplicate 1000 out of range [1,5])
 EOF
 test_expect_equal_file EXPECTED MESSAGES
+test_begin_subtest "duplicate=4"
+test_emacs "(notmuch-show \"id:${ID3}\")
+	   (notmuch-show-choose-duplicate 4)
+	   (test-visible-output \"OUTPUT\")"
+test_expect_equal_file_nonempty $EXPECTED/notmuch-show-duplicate-4 OUTPUT
+
 test_done

test/T460-emacs-tree.sh

@@ -203,7 +203,7 @@ test_expect_equal "$(cat MESSAGES)" "COMPLETE"
 add_email_corpus duplicate
 
 ID3=87r2ecrr6x.fsf@zephyr.silentflame.com
-test_begin_subtest "duplicate=3"
+test_begin_subtest "duplicate=3, subject"
 test_emacs "(notmuch-tree \"id:${ID3}\")
 	   (notmuch-test-wait)
 	   (notmuch-tree-show-message t)
@@ -214,4 +214,12 @@ file=$(notmuch search --output=files id:${ID3} | head -n 3 | tail -n 1)
 subject=$(grep '^Subject:' $file)
 test_expect_equal "$output" "$subject"
 
+test_begin_subtest "duplicate=4"
+test_emacs "(notmuch-show \"id:${ID3}\")
+	   (notmuch-test-wait)
+	   (notmuch-tree-show-message t)
+	   (notmuch-show-choose-duplicate 4)
+	   (test-visible-output \"OUTPUT\")"
+test_expect_equal_file_nonempty $NOTMUCH_SRCDIR/test/emacs-show.expected-output/notmuch-show-duplicate-4 OUTPUT
+
 test_done

test/T465-emacs-unthreaded.sh

@@ -60,7 +60,7 @@ test_expect_equal "$(cat MESSAGES)" "COMPLETE"
 add_email_corpus duplicate
 
 ID3=87r2ecrr6x.fsf@zephyr.silentflame.com
-test_begin_subtest "duplicate=3"
+test_begin_subtest "duplicate=3, subject"
 test_emacs "(let ((notmuch-tree-show-out t))
 	      (notmuch-unthreaded \"id:${ID3}\")
 	      (notmuch-test-wait)
@@ -72,4 +72,14 @@ file=$(notmuch search --output=files id:${ID3} | head -n 3 | tail -n 1)
 subject=$(grep '^Subject:' $file)
 test_expect_equal "$output" "$subject"
 
+test_begin_subtest "duplicate=4"
+test_emacs "(let ((notmuch-tree-show-out t))
+	      (notmuch-unthreaded \"id:${ID3}\")
+	      (notmuch-test-wait)
+	      (notmuch-tree-show-message nil)
+	      (notmuch-show-choose-duplicate 4)
+	      (test-visible-output \"OUTPUT\"))"
+test_expect_equal_file_nonempty $NOTMUCH_SRCDIR/test/emacs-show.expected-output/notmuch-show-duplicate-4 OUTPUT
+
+
 test_done

test/emacs-show.expected-output/notmuch-show-duplicate-4

@@ -0,0 +1,20 @@
+Sean Whitton <spwhitton@spwhitton.name> (2018-12-20) (inbox signed)         4/5
+Subject: [Pkg-emacsen-addons] Bug#916811: Increase severity to 'serious'
+To: 916805@bugs.debian.org, 916807@bugs.debian.org, 916808@bugs.debian.org, 916809@bugs.debian.org, 916811@bugs.debian.org, 916867@bugs.debian.org, 916869@bugs.debian.org, 916872@bugs.debian.org, 916875@bugs.debian.org, 916876@bugs.debian.org
+Date: Thu, 20 Dec 2018 18:25:26 +0000
+
+[ multipart/mixed ]
+[ multipart/signed ]
+[ Unknown key ID 0x695B7AE4BF066240 or unsupported algorithm ]
+[ text/plain ]
+control: severity -1 serious
+
+Hello,
+
+Emacs 26.1 has reached Debian unstable (sooner than expected; sorry for
+all the e-mails).
+
+[ 2-line signature. Click/Enter to show. ]
+[ signature.asc: application/pgp-signature ]
+[ text/plain ]
+[ 4-line signature. Click/Enter to show. ]