[PATCH v4 1/1] Make buttons for attachments allow viewing as well as saving

[Austin Clements]

One indentation nit and then this LGTM.

Quoth Mark Walters on Jan 19 at  9:23 pm:
> Define a keymap for attachment buttons to allow multiple actions.
> Define 3 possible actions:
>     save attachment: exactly as currently,
>     view attachment: uses mailcap entry,
>     view attachment with user chosen program
> 
> Keymap on a button is: s for save, v for view and o for view with
> other program. Default (i.e. enter or mouse button) is save but this
> is configurable in notmuch customize.
> 
> One implementation detail: the view attachment function forces all
> attachments to be "displayed" using mailcap even if emacs could
> display them itself. Thus, for example, text/html appears in a browser
> and text/plain asks whether to save (on a standard debian setup)
> ---
>  emacs/notmuch-show.el |  116 ++++++++++++++++++++++++++++++++++++++----------
>  1 files changed, 92 insertions(+), 24 deletions(-)
> 
> diff --git a/emacs/notmuch-show.el b/emacs/notmuch-show.el
> index fc13462..1fcd72a 100644
> --- a/emacs/notmuch-show.el
> +++ b/emacs/notmuch-show.el
> @@ -112,6 +112,16 @@ indentation."
>    :type 'boolean
>    :group 'notmuch-show)
>  
> +(defcustom notmuch-show-part-button-default-action 'notmuch-show-save-part
> +  "Default part header button action (on ENTER or mouse click)."
> +  :group 'notmuch-show
> +  :type '(choice (const :tag "Save part"
> +			notmuch-show-save-part)
> +		 (const :tag "View part"
> +			notmuch-show-view-part)
> +		 (const :tag "View interactively"
> +			notmuch-show-interactively-view-part)))
> +
>  (defmacro with-current-notmuch-show-message (&rest body)
>    "Evaluate body with current buffer set to the text of current message"
>    `(save-excursion
> @@ -283,10 +293,21 @@ message at DEPTH in the current thread."
>  	(run-hooks 'notmuch-show-markup-headers-hook)))))
>  
>  (define-button-type 'notmuch-show-part-button-type
> -  'action 'notmuch-show-part-button-action
> +  'action 'notmuch-show-part-button-default
> +  'keymap 'notmuch-show-part-button-map
>    'follow-link t
>    'face 'message-mml)
>  
> +(defvar notmuch-show-part-button-map
> +  (let ((map (make-sparse-keymap)))
> +    (set-keymap-parent map button-map)
> +    (define-key map "s" 'notmuch-show-part-button-save)
> +    (define-key map "v" 'notmuch-show-part-button-view)
> +    (define-key map "o" 'notmuch-show-part-button-interactively-view)
> +    map)
> +  "Submap for button commands")
> +(fset 'notmuch-show-part-button-map notmuch-show-part-button-map)
> +
>  (defun notmuch-show-insert-part-header (nth content-type declared-type &optional name comment)
>    (let ((button))
>      (setq button
> @@ -301,29 +322,58 @@ message at DEPTH in the current thread."
>  		   " ]")
>  	   :type 'notmuch-show-part-button-type
>  	   :notmuch-part nth
> -	   :notmuch-filename name))
> +	   :notmuch-filename name
> +	   :notmuch-content-type content-type))
>      (insert "\n")
>      ;; return button
>      button))
>  
>  ;; Functions handling particular MIME parts.
>  
> -(defun notmuch-show-save-part (message-id nth &optional filename)
> -  (let ((process-crypto notmuch-show-process-crypto))
> -    (with-temp-buffer
> -      (setq notmuch-show-process-crypto process-crypto)
> -      ;; Always acquires the part via `notmuch part', even if it is
> -      ;; available in the JSON output.
> -      (insert (notmuch-show-get-bodypart-internal message-id nth))
> -      (let ((file (read-file-name
> -		   "Filename to save as: "
> -		   (or mailcap-download-directory "~/")
> -		   nil nil
> -		   filename)))
> -	;; Don't re-compress .gz & al.  Arguably we should make
> -	;; `file-name-handler-alist' nil, but that would chop
> -	;; ange-ftp, which is reasonable to use here.
> -	(mm-write-region (point-min) (point-max) file nil nil nil 'no-conversion t)))))
> +(defmacro notmuch-with-temp-part-buffer (message-id nth &rest body)
> +  (declare (indent 2))
> +  (let ((process-crypto (make-symbol "process-crypto")))
> +    `(let ((,process-crypto notmuch-show-process-crypto))
> +       (with-temp-buffer
> +	 (setq notmuch-show-process-crypto ,process-crypto)
> +	 ;; Always acquires the part via `notmuch part', even if it is
> +	 ;; available in the JSON output.
> +	 (insert (notmuch-show-get-bodypart-internal ,message-id ,nth))
> +	 , at body))))
> +
> +(defun notmuch-show-save-part (message-id nth &optional filename content-type)
> +  (notmuch-with-temp-part-buffer message-id nth
> +    (let ((file (read-file-name
> +		 "Filename to save as: "
> +		 (or mailcap-download-directory "~/")
> +		 nil nil
> +		 filename)))
> +      ;; Don't re-compress .gz & al.  Arguably we should make
> +      ;; `file-name-handler-alist' nil, but that would chop
> +      ;; ange-ftp, which is reasonable to use here.
> +      (mm-write-region (point-min) (point-max) file nil nil nil 'no-conversion t))))
> +
> +(defun notmuch-show-view-part (message-id nth &optional filename content-type )
> +  (notmuch-with-temp-part-buffer message-id nth
> +    ;; set mm-inlined-types to nil to force an external viewer
> +    (let ((handle (mm-make-handle (current-buffer) (list content-type)))
> +	  (mm-inlined-types nil))
> +      ;; We override mm-save-part as notmuch-show-save-part is better
> +      ;; since it offers the filename. We need to lexically bind
> +      ;; everything we need for notmuch-show-save-part to prevent
> +      ;; potential dynamic shadowing.
> +      (lexical-let ((message-id message-id)
> +		    (nth nth)
> +		    (filename filename)
> +		    (content-type content-type))
> +		   (flet ((mm-save-part (&rest args) (notmuch-show-save-part

This body of lexical-let should be indented like a normal let body.
You might have to load cl to get this indentation rule.

> +						      message-id nth filename content-type)))
> +		     (mm-display-part handle))))))
> +
> +(defun notmuch-show-interactively-view-part (message-id nth &optional filename content-type)
> +  (notmuch-with-temp-part-buffer message-id nth
> +    (let ((handle (mm-make-handle (current-buffer) (list content-type))))
> +      (mm-interactively-view-part handle))))
>  
>  (defun notmuch-show-mm-display-part-inline (msg part nth content-type)
>    "Use the mm-decode/mm-view functions to display a part in the
> @@ -1504,12 +1554,30 @@ buffer."
>  
>  ;; Commands typically bound to buttons.
>  
> -(defun notmuch-show-part-button-action (button)
> -  (let ((nth (button-get button :notmuch-part)))
> -    (if nth
> -	(notmuch-show-save-part (notmuch-show-get-message-id) nth
> -				(button-get button :notmuch-filename))
> -      (message "Not a valid part (is it a fake part?)."))))
> +(defun notmuch-show-part-button-default (&optional button)
> +  (interactive)
> +  (notmuch-show-part-button-internal button notmuch-show-part-button-default-action))
> +
> +(defun notmuch-show-part-button-save (&optional button)
> +  (interactive)
> +  (notmuch-show-part-button-internal button #'notmuch-show-save-part))
> +
> +(defun notmuch-show-part-button-view (&optional button)
> +  (interactive)
> +  (notmuch-show-part-button-internal button #'notmuch-show-view-part))
> +
> +(defun notmuch-show-part-button-interactively-view (&optional button)
> +  (interactive)
> +  (notmuch-show-part-button-internal button #'notmuch-show-interactively-view-part))
> +
> +(defun notmuch-show-part-button-internal (button handler)
> +  (let ((button (or button (button-at (point)))))
> +    (if button
> +	(let ((nth (button-get button :notmuch-part)))
> +	  (if nth
> +	      (funcall handler (notmuch-show-get-message-id) nth
> +		       (button-get button :notmuch-filename)
> +		       (button-get button :notmuch-content-type)))))))
>  
>  ;;
>