Re-work header extraction

Let the user be able to customize which headers to insert.

* git-email.el (git-email--extract-header):
(git-email-headers):
(git-email--extract-headers):
(git-email-send-email):

1 files changed, 29 insertions, 16 deletions

diff --git a/git-email.el b/git-email.el
index 0eb9a66..aed11a0 100644
--- a/git-email.el
+++ b/git-email.el
@@ -51,17 +51,31 @@
   :group 'git-email
   :type 'symbol)
 
-(defun git-email--extract-header (header patch-file)
-  "Extract HEADER from PATCH-FILE.
+(defcustom git-email-headers
+  '("subject" "from" "in-reply-to" "message-id" "references")
+  "List of headers that should get inserted into the message buffer.
+The 'to' address will always be inserted based on the 'sendemail.to' variable
+in you git config.  If the variable is not set, the 'to' address will be empty."
+  :group 'git-email
+  :type '(string))
+
+(defun git-email--extract-header (header)
+  "Extract HEADER from current buffer."
+  (goto-char (point-min))
+  (buffer-substring-no-properties
+   (if (re-search-forward (format " *%s: +" header) nil t)
+       (point)
+     (point-at-eol))
+   (point-at-eol)))
+
+(defun git-email--extract-headers (patch-file)
+  "Extract headers from PATCH-FILE.
 If the header is not found, return an empty string."
   (with-temp-buffer
     (insert-file-contents patch-file)
-    (goto-char (point-min))
-    (buffer-substring-no-properties
-     (if (re-search-forward (format " *%s: +" header) nil t)
-	 (point)
-       (point-at-eol))
-     (point-at-eol))))
+    (mapcar (lambda (header)
+	      `(,header ,(git-email--extract-header header)))
+	    git-email-headers)))
 
 (defun git-email--extract-diff (patch-file)
   "Extract the diff from PATCH-FILE."
@@ -78,20 +92,19 @@ Extracts the relevant headers and the diff from the PATCH-FILE and inserts
 them into the message buffer."
   (interactive)
   (let* ((default-directory (cdr (project-current)))
-	 (subject (git-email--extract-header "subject" patch-file))
-	 (from (git-email--extract-header "from" patch-file))
+	 (headers (git-email--extract-headers patch-file))
+	 (used-headers (seq-filter
+			(lambda (header)
+			  (not (string-equal (car (cdr header)) "")))
+			headers))
 	 (sendemail-to
 	  (shell-command-to-string "git config --list | grep sendemail.to"))
 	 (to (if (string-equal sendemail-to "")
 		 "to"
 	       (substring sendemail-to 13 -1))) ; Remove newline
-	 (in-reply-to (git-email--extract-header "in-reply-to" patch-file))
-	 (msg-id (git-email--extract-header "message-id" patch-file))
 	 (diff (git-email--extract-diff patch-file)))
-    (funcall git-email--compose-message-function to subject
-	     `(("in-reply-to" ,in-reply-to)
-	       ("message-id" ,msg-id)
-	       ("from" ,from)))
+    (funcall git-email--compose-message-function to (cadr (assoc "subject" used-headers))
+	     used-headers)
     ;; (let ((body (or (re-search-forward "<#part .*>")
     ;; 		   (re-search-forward "--text follows this line--"))))
     (goto-char (point-max))