From: Michal Sojka <sojkam1@fel.cvut.cz>
To: notmuch@notmuchmail.org
Subject: [PATCH v2] Emacs: Add address completion mechanism implemented in
	elisp
Date: Mon, 11 Aug 2014 16:32:29 +0200
Message-Id: <1407767549-30861-1-git-send-email-sojkam1@fel.cvut.cz>
Precedence: list

Currently, notmuch has an address completion mechanism that requires
external command to provide completion candidates. This patch adds a
completion mechanism inspired by https://github.com/tjim/nevermore,
which is implemented in Emacs lisp only.

The core of the new mechanism is the function notmuch-address-harvest
that collects the completion candidates from the notmuch database and
stores them in notmuch-address-completions variable.
notmuch-address-harvest is called on the first entry to message-mode
and runs asychnornously so that the user doesn't have to wait for it
to complete while composing the message. The
notmuch-address-completions variable is used in message-mode as a
source of completion candidates. Currently, there are two ways how the
notmuch-address-completions variable is used.

First, preexisting address completion mechanism is extended to use
notmuch-address-completions in addition to the external command. This
new behavior is configured by setting notmuch-address-command to nil,
which is the new default. Note that this may *BREAK EXISTING SETUPS*
when the user used external command named "notmuch-addresses", i.e.
the previous default. The result will be that the user will use the
new mechanism instead of the his command. I believe that many users
may not even recognize this because the new mechanism works the same
as http://commonmeasure.org/~jkr/git/notmuch_addresses.git and perhaps
also as other commands suggested at
http://notmuchmail.org/emacstips/#address_completion.

Second way of using notmuch-address-completions is notmuch-company.el.
This presents the possible completions in a nice popup box after a
short typing delay but requires company-mode to be installed.

Changes from v1:
- Use of notmuch-parser.el instead of the custom parser in the
  original code. The notmuch parser is slightly faster.
- Use of functions in notmuch-query.el instead of functions in the
  original code with almost the same functionality.
- Integrated with existing completion mechanism in notmuch.
- notmuch-company.el was moved from emacs/contrib to emacs and
  no-byte-compile directive was added to it.
- Aligned with notmuch naming conventions.
- Documented bugs found in notmuch-company.el
---
 emacs/Makefile.local     |  6 ++-
 emacs/notmuch-address.el | 95 +++++++++++++++++++++++++++++++++++++++++++-----
 emacs/notmuch-company.el | 69 +++++++++++++++++++++++++++++++++++
 emacs/notmuch-lib.el     |  3 ++
 4 files changed, 163 insertions(+), 10 deletions(-)
 create mode 100644 emacs/notmuch-company.el

diff --git a/emacs/Makefile.local b/emacs/Makefile.local
index c0d6b19..9214d6e 100644
--- a/emacs/Makefile.local
+++ b/emacs/Makefile.local
@@ -18,6 +18,7 @@ emacs_sources := \
 	$(dir)/notmuch-tag.el \
 	$(dir)/coolj.el \
 	$(dir)/notmuch-print.el \
+	$(dir)/notmuch-company.el \
 	$(dir)/notmuch-version.el
 
 $(dir)/notmuch-version.el: $(dir)/Makefile.local version.stamp
@@ -29,7 +30,10 @@ $(dir)/notmuch-version.el: $(srcdir)/$(dir)/notmuch-version.el.tmpl
 emacs_images := \
 	$(srcdir)/$(dir)/notmuch-logo.png
 
-emacs_bytecode = $(emacs_sources:.el=.elc)
+# Do not try to install files that are not byte-compiled.
+emacs_no_byte_compile := $(dir)/notmuch-company.el
+
+emacs_bytecode = $(patsubst %.el,%.elc,$(filter-out $(emacs_no_byte_compile),$(emacs_sources)))
 
 # Because of defmacro's and defsubst's, we have to account for load
 # dependencies between Elisp files when byte compiling.  Otherwise,
diff --git a/emacs/notmuch-address.el b/emacs/notmuch-address.el
index fa65cd5..a50f4f4 100644
--- a/emacs/notmuch-address.el
+++ b/emacs/notmuch-address.el
@@ -20,14 +20,18 @@
 ;; Authors: David Edmondson <dme@dme.org>
 
 (require 'message)
+(require 'notmuch-query)
+(require 'notmuch-parser)
 
 ;;
 
-(defcustom notmuch-address-command "notmuch-addresses"
-  "The command which generates possible addresses. It must take a
-single argument and output a list of possible matches, one per
-line."
-  :type 'string
+(defcustom notmuch-address-command nil
+  "The command which generates possible addresses for completion.
+It must take a single argument and output a list of possible
+matches, one per line. If set to nil, addresses are generated by
+a built-in completion mechanism."
+  :type '(radio (const :tag "No command: Use built-in completion" nil)
+		 (string :tag "Custom command" :value "notmuch-addresses"))
   :group 'notmuch-send
   :group 'notmuch-external)
 
@@ -42,6 +46,10 @@ to know how address selection is made by default."
   :group 'notmuch-send
   :group 'notmuch-external)
 
+(defvar notmuch-address-completions nil
+  "Hash of email addresses for completion during email composition.
+  This variable is set by calling `notmuch-address-harvest'.")
+
 (defun notmuch-address-selection-function (prompt collection initial-input)
   "Call (`completing-read'
       PROMPT COLLECTION nil nil INITIAL-INPUT 'notmuch-address-history)"
@@ -60,7 +68,16 @@ to know how address selection is made by default."
 	  (push notmuch-address-message-alist-member message-completion-alist))))
 
 (defun notmuch-address-options (original)
-  (process-lines notmuch-address-command original))
+  (cond
+   ((eq notmuch-address-command nil)
+    (let ((candidates))
+      (maphash (lambda (key val)
+		 (let ((re (concat "\\<" (regexp-quote original))))
+		   (when (string-match re key)
+		     (push key candidates))))
+	       notmuch-address-completions)
+      candidates))
+   (t (process-lines notmuch-address-command original))))
 
 (defun notmuch-address-expand-name ()
   (let* ((end (point))
@@ -108,11 +125,71 @@ to know how address selection is made by default."
 			   (not (file-directory-p bin))))
 	      (throw 'found-command bin))))))))
 
-;; If we can find the program specified by `notmuch-address-command',
-;; insinuate ourselves into `message-mode'.
-(when (notmuch-address-locate-command notmuch-address-command)
+(defun notmuch-address-harvest-msg (msg)
+  (let* ((headers (plist-get msg :headers))
+	 (to (ignore-errors (mail-extract-address-components (plist-get headers :To) t)))
+	 (cc (ignore-errors (mail-extract-address-components (plist-get headers :Cc) t)))
+	 (bcc (ignore-errors (mail-extract-address-components (plist-get headers :Bcc) t))))
+    (mapc (lambda (parts)
+	    (let* ((name (car parts))
+		   (email (cadr parts))
+		   (entry (if name (format "%s <%s>" name email) email)))
+	      (puthash entry t notmuch-address-completions)))
+	  (append to cc bcc))
+    nil))
+
+(defun notmuch-address-harvest-handle-result (obj)
+  (notmuch-query-map-threads 'notmuch-address-harvest-msg (list obj)))
+
+(defun notmuch-address-harvest-filter (proc string)
+  (when (buffer-live-p (process-buffer proc))
+    (with-current-buffer (process-buffer proc)
+      (save-excursion
+	(goto-char (point-max))
+	(insert string))
+      (notmuch-sexp-parse-partial-list
+       'notmuch-address-harvest-handle-result (process-buffer proc)))))
+
+(defvar notmuch-address-harvest-proc nil)   ; the process of a harvest underway
+
+(defun notmuch-address-harvest ()
+  "Collect possible addresses for completion. It queries the
+notmuch database for all emails sent by the user and collects the
+destination addresses from them in
+`notmuch-address-completions'. This takes some time so the
+address collection runs asynchronously."
+  (when notmuch-address-harvest-proc
+    (kill-buffer (process-buffer notmuch-address-harvest-proc)) ; this also kills the process
+    (setq notmuch-address-harvest-proc nil))
+  (setq notmuch-address-completions (make-hash-table :test 'equal))
+  (setq notmuch-address-harvest-proc
+        (notmuch-start-notmuch
+         "notmuch-address-harvest"	; process name
+         " *notmuch-address-harvest*"	; process buffer
+         nil				; process sentinel
+         "show"				; notmuch command
+         "--format=sexp"
+         "--format-version=2"
+         "--body=false"
+         "--entire-thread=false"
+	 (mapconcat (lambda (x) (concat "from:" x)) (notmuch-user-emails) " or ")))
+  (set-process-filter notmuch-address-harvest-proc 'notmuch-address-harvest-filter)
+  (set-process-query-on-exit-flag notmuch-address-harvest-proc nil)
+  ;; return value
+  nil)
+
+;; If we can find the program specified by `notmuch-address-command'
+;; or if it is nil, insinuate ourselves into `message-mode'.
+(when (or (eq notmuch-address-command nil)
+	  (notmuch-address-locate-command notmuch-address-command))
   (notmuch-address-message-insinuate))
 
+(defun notmuch-address-harvest-start ()
+  (when (not notmuch-address-completions) (notmuch-address-harvest)))
+
+(when (eq notmuch-address-command nil)
+  (add-hook 'message-mode-hook 'notmuch-address-harvest-start))
+
 ;;
 
 (provide 'notmuch-address)
diff --git a/emacs/notmuch-company.el b/emacs/notmuch-company.el
new file mode 100644
index 0000000..748fcee
--- /dev/null
+++ b/emacs/notmuch-company.el
@@ -0,0 +1,69 @@
+;; -*-no-byte-compile: t; -*-
+
+;; notmuch-company.el --- Mail address completion for notmuch via company-mode
+
+;; Author: Trevor Jim <tjim@mac.com>
+;; Keywords: mail, completion
+
+;; This program is free software; you can redistribute it and/or modify
+;; it under the terms of the GNU General Public License as published by
+;; the Free Software Foundation, either version 3 of the License, or
+;; (at your option) any later version.
+
+;; This program is distributed in the hope that it will be useful,
+;; but WITHOUT ANY WARRANTY; without even the implied warranty of
+;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+;; GNU General Public License for more details.
+
+;; You should have received a copy of the GNU General Public License
+;; along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+;;; Commentary:
+
+;; To enable this, install company mode (https://company-mode.github.io/)
+;; and add
+;;
+;;     (require 'notmuch-company)
+;;
+;; to your .emacs.
+;;
+;; NB company-minimum-prefix-length defaults to 3 so you don't get
+;; completion unless you type 3 characters
+
+;;; Bugs:
+;;
+;; - matching is case sensitive
+;; - matching of non-ascii characters doesn't work well
+
+;;; Code:
+
+(require 'company)
+(require 'message)
+(require 'notmuch-address)
+
+(defvar-local notmuch-company-last-prefix nil)
+;;;###autoload
+(defun notmuch-company (command &optional arg &rest ignore)
+  "`company-mode' completion back-end for `notmuch'."
+  (interactive (list 'interactive))
+  (let ((case-fold-search t))
+    (pcase command
+      (`interactive (company-begin-backend 'notmuch-company))
+      (`prefix (and (eq major-mode 'message-mode)
+                    (looking-back "^\\(To\\|Cc\\|Bcc\\):.*"
+                                  (line-beginning-position))
+                    (setq notmuch-company-last-prefix (company-grab-symbol))))
+      (`candidates (let ((results (completion-substring--all-completions arg notmuch-address-completions nil 0)))
+                     (when results (car results))))
+      (`match (if (string-match notmuch-company-last-prefix arg)
+                  (match-end 0)
+                0))
+      (`no-cache t))))
+
+(add-hook 'message-mode-hook '(lambda ()
+                                (company-mode)
+                                (make-local-variable 'company-backends)
+                                (setq company-backends '(notmuch-company))
+				(notmuch-address-harvest-start)))
+
+(provide 'notmuch-company)
diff --git a/emacs/notmuch-lib.el b/emacs/notmuch-lib.el
index c06baac..e36c4cf 100644
--- a/emacs/notmuch-lib.el
+++ b/emacs/notmuch-lib.el
@@ -224,6 +224,9 @@ on the command line, and then retry your notmuch command")))
   "Return the user.other_email value (as a list) from the notmuch configuration."
   (split-string (notmuch-config-get "user.other_email") "\n" t))
 
+(defun notmuch-user-emails ()
+  (cons (notmuch-user-primary-email) (notmuch-user-other-email)))
+
 (defun notmuch-poll ()
   "Run \"notmuch new\" or an external script to import mail.
 
-- 
2.0.1