tvl-depot/users/sterni/mblog/note.lisp
sterni 56ec3b1803 refactor(sterni/mblog): add (sub)class for apple note messages
* Upon creation of an apple-note object we can check if certain fields
  we are interested in are present and of the right type etc.

  These currently are:

  - UUID (for links later)
  - Subject (title)
  - Time
  - Text part with supported MIME type

  These are then put into their own shortcut fields in the apple-note
  subclass which allows for easier access and forces us to make sure
  they are present.

* Split out everything note related into its own package. Using the new
  type, we can expose an interface which sort of makes sense.

Change-Id: Ic9d67518354e61a3cc8388bb0e566fce661e90d0
Reviewed-on: https://cl.tvl.fyi/c/depot/+/5072
Tested-by: BuildkiteCI
Reviewed-by: sterni <sternenseemann@systemli.org>
2022-02-02 20:47:45 +00:00

121 lines
4.4 KiB
Common Lisp

(in-package :note)
(declaim (optimize (safety 3)))
;;; util
(defun html-escape-stream (in out)
"Escape characters read from stream IN and write them to
stream OUT escaped using WHO:ESCAPE-CHAR-MINIMAL."
(loop for char = (read-char in nil nil)
while char
do (write-string (who:escape-char-minimal char) out)))
(defun cid-header-value (cid)
"Takes a Content-ID as present in Apple Notes' <object> tags and properly
surrounds them with angle brackets for a MIME header"
(concatenate 'string "<" cid ">"))
;; TODO(sterni): move into mime4cl
(defun find-mime-message-header (header-name message)
(when-let ((header (assoc header-name
(mime:mime-message-headers message)
:test #'string-equal)))
(cdr header)))
(defun find-mime-message-date (message)
(when-let ((date-string (find-mime-message-header "Date" message)))
(date-time-parser:parse-date-time date-string)))
;;; main implementation
(defun apple-note-mime-subtype-p (x)
(member x '("plain" "html") :test #'string-equal))
(deftype apple-note-mime-subtype ()
'(satisfies apple-note-mime-subtype-p))
(defclass apple-note (mime:mime-message)
((text-part
:type mime:mime-text
:initarg :text-part
:reader apple-note-text-part)
(subject
:type string
:initarg :subject
:reader apple-note-subject)
(uuid
:type string
:initarg :uuid
:reader apple-note-uuid)
(time
:type integer
:initarg :time
:reader apple-note-time)
(mime-subtype
:type apple-note-mime-subtype
:initarg :mime-subtype
:reader apple-note-mime-subtype))
(:documentation
"Representation of a Note created using Apple's Notes using the IMAP backend"))
(defun apple-note-p (msg)
"Checks X-Uniform-Type-Identifier of a MIME:MIME-MESSAGE
to determine if a given mime message claims to be an Apple Note."
(when-let (uniform-id (assoc "X-Uniform-Type-Identifier"
(mime:mime-message-headers msg)
:test #'string-equal))
(string-equal (cdr uniform-id) "com.apple.mail-note")))
(defun make-apple-note (msg)
(check-type msg mime-message)
(unless (apple-note-p msg)
(error "Passed message is not an Apple Note according to headers"))
(let ((text-part (mime:find-mime-text-part msg))
(subject (find-mime-message-header "Subject" msg))
(uuid (when-let ((val (find-mime-message-header
"X-Universally-Unique-Identifier"
msg)))
(string-downcase val)))
(time (find-mime-message-date msg)))
;; The idea here is that we don't need to check a lot manually, instead
;; the type annotation are going to do this for us (with sufficient safety?)
(change-class msg 'apple-note
:text-part text-part
:subject subject
:uuid uuid
:time time
:mime-subtype (mime:mime-subtype text-part))))
(defgeneric apple-note-html-fragment (note out)
(:documentation
"Takes an APPLE-NOTE and writes its text content as HTML to
the OUT stream. The <object> tags are resolved to <img> which
refer to the respective attachment's filename as a relative path,
but extraction of the attachments must be done separately. The
surrounding <html> and <body> tags are stripped and <head>
discarded completely, so only a fragment which can be included
in custom templates remains."))
(defmethod apple-note-html-fragment ((note apple-note) (out stream))
(let ((text (apple-note-text-part note)))
(cond
;; notemap creates text/plain notes we need to handle properly.
;; Additionally we *could* check X-Mailer which notemap sets
((string-equal (apple-note-mime-subtype note) "plain")
(html-escape-stream (mime:mime-body-stream text :binary nil) out))
;; Notes.app creates text/html parts
((string-equal (apple-note-mime-subtype note) "html")
(closure-html:parse
(mime:mime-body-stream text)
(make-instance
'apple-note-transformer
:cid-lookup
(lambda (cid)
(when-let* ((part (mime:find-mime-part-by-id note (cid-header-value cid)))
(file (mime:mime-part-file-name part)))
file))
:next-handler
(closure-html:make-character-stream-sink out))))
(t (error "Internal error: unexpected MIME subtype")))))