(eval-when-compile (require 'cl))
(require 'mail-parse)
(require 'mailcap)
(eval-and-compile
(autoload 'mm-body-7-or-8 "mm-bodies")
(autoload 'mm-long-lines-p "mm-bodies"))
(defcustom mm-content-transfer-encoding-defaults
'(("text/x-patch" 8bit)
("text/.*" qp-or-base64)
("message/rfc822" 8bit)
("application/emacs-lisp" qp-or-base64)
("application/x-emacs-lisp" qp-or-base64)
("application/x-patch" qp-or-base64)
(".*" base64))
"Alist of regexps that match MIME types and their encodings.
If the encoding is `qp-or-base64', then either quoted-printable
or base64 will be used, depending on what is more efficient.
`qp-or-base64' has another effect. It will fold long lines so that
MIME parts may not be broken by MTA. So do `quoted-printable' and
`base64'.
Note: It affects body encoding only when a part is a raw forwarded
message (which will be made by `gnus-summary-mail-forward' with the
arg 2 for example) or is neither the text/* type nor the message/*
type. Even though in those cases, you can use the `encoding' MML tag
to specify encoding of non-ASCII MIME parts."
:type '(repeat (list (regexp :tag "MIME type")
(choice :tag "encoding"
(const 7bit)
(const 8bit)
(const qp-or-base64)
(const quoted-printable)
(const base64))))
:group 'mime)
(defvar mm-use-ultra-safe-encoding nil
"If non-nil, use encodings aimed at Procrustean bed survival.
This means that textual parts are encoded as quoted-printable if they
contain lines longer than 76 characters or starting with \"From \" in
the body. Non-7bit encodings (8bit, binary) are generally disallowed.
This is to reduce the probability that a broken MTA or MDA changes the
message.
This variable should never be set directly, but bound before a call to
`mml-generate-mime' or similar functions.")
(defun mm-insert-rfc822-headers (charset encoding)
"Insert text/plain headers with CHARSET and ENCODING."
(insert "MIME-Version: 1.0\n")
(insert "Content-Type: text/plain; charset="
(mail-quote-string (downcase (symbol-name charset))) "\n")
(insert "Content-Transfer-Encoding: "
(downcase (symbol-name encoding)) "\n"))
(defun mm-insert-multipart-headers ()
"Insert multipart/mixed headers."
(let ((boundary "=-=-="))
(insert "MIME-Version: 1.0\n")
(insert "Content-Type: multipart/mixed; boundary=\"" boundary "\"\n")
boundary))
(defun mm-default-file-encoding (file)
"Return a default encoding for FILE."
(if (not (string-match "\\.[^.]+$" file))
"application/octet-stream"
(mailcap-extension-to-mime (match-string 0 file))))
(defun mm-safer-encoding (encoding)
"Return an encoding similar to ENCODING but safer than it."
(cond
((eq encoding '7bit) '7bit) ((memq encoding '(8bit quoted-printable)) 'quoted-printable)
(t 'base64)))
(defun mm-encode-content-transfer-encoding (encoding &optional type)
"Encode the current buffer with ENCODING for MIME type TYPE.
ENCODING can be: nil (do nothing); one of `quoted-printable', `base64';
`7bit', `8bit' or `binary' (all do nothing); a function to do the encoding."
(cond
((eq encoding 'quoted-printable)
(quoted-printable-encode-region (point-min) (point-max) t))
((eq encoding 'base64)
(when (string-match "\\`text/" type)
(goto-char (point-min))
(while (search-forward "\n" nil t)
(replace-match "\r\n" t t)))
(base64-encode-region (point-min) (point-max)))
((memq encoding '(7bit 8bit binary))
)
((null encoding)
)
((functionp encoding)
(ignore-errors (funcall encoding (point-min) (point-max))))
(t
(error "Unknown encoding %s" encoding))))
(defun mm-encode-buffer (type)
"Encode the buffer which contains data of MIME type TYPE.
TYPE is a string or a list of the components.
The encoding used is returned."
(let* ((mime-type (if (stringp type) type (car type)))
(encoding
(or (and (listp type)
(cadr (assq 'encoding type)))
(mm-content-transfer-encoding mime-type)))
(bits (mm-body-7-or-8)))
(when (and (eq bits '7bit) (not (mm-long-lines-p 76)))
(setq encoding bits))
(mm-encode-content-transfer-encoding encoding mime-type)
encoding))
(defun mm-insert-headers (type encoding &optional file)
"Insert headers for TYPE."
(insert "Content-Type: " type)
(when file
(insert ";\n\tname=\"" (file-name-nondirectory file) "\""))
(insert "\n")
(insert (format "Content-Transfer-Encoding: %s\n" encoding))
(insert "Content-Disposition: inline")
(when file
(insert ";\n\tfilename=\"" (file-name-nondirectory file) "\""))
(insert "\n")
(insert "\n"))
(defun mm-content-transfer-encoding (type)
"Return a CTE suitable for TYPE to encode the current buffer."
(let ((rules mm-content-transfer-encoding-defaults))
(catch 'found
(while rules
(when (string-match (caar rules) type)
(throw 'found
(let ((encoding
(if (eq (cadr (car rules)) 'qp-or-base64)
(mm-qp-or-base64)
(cadr (car rules)))))
(if mm-use-ultra-safe-encoding
(mm-safer-encoding encoding)
encoding))))
(pop rules)))))
(defun mm-qp-or-base64 ()
"Return the type with which to encode the buffer.
This is either `base64' or `quoted-printable'."
(if (equal mm-use-ultra-safe-encoding '(sign . "pgp"))
'quoted-printable
(save-excursion
(let ((limit (min (point-max) (+ 2000 (point-min))))
(n8bit 0))
(goto-char (point-min))
(skip-chars-forward "\x20-\x7f\r\n\t" limit)
(while (< (point) limit)
(incf n8bit)
(forward-char 1)
(skip-chars-forward "\x20-\x7f\r\n\t" limit))
(if (or (< (* 6 n8bit) (- limit (point-min)))
(= n8bit 1))
'quoted-printable
'base64)))))
(provide 'mm-encode)