edraw-import.el

;;; edraw-import.el --- Convert to Edraw SVG  -*- lexical-binding: t; -*-

;; Copyright (C) 2024  AKIYAMA Kouhei

;; Author: AKIYAMA Kouhei <misohena@gmail.com>
;; Keywords: 

;; 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 <https://www.gnu.org/licenses/>.

;;; Commentary:

;; 

;;; Code:

(require 'edraw-dom-svg)

(defgroup edraw-import nil
  "Edraw import feature."
  :tag "Edraw Import"
  :prefix "edraw-import-"
  :group 'edraw)

;;@todo Unify `edraw-editor-svg-body-id'
(defconst edraw-import-svg-body-id "edraw-body")
(defconst edraw-import-svg-imported-definitions-id "edraw-imported-definitions")

;;;; Common

;;;###autoload
(defun edraw-convert-file-to-edraw-svg (file)
  ;; @todo Select importer that matches file extension.
  (edraw-import-svg-file file t))

;;;###autoload
(defun edraw-convert-buffer-to-edraw-svg-xml (buffer output)
  (interactive
   (list (current-buffer) (current-buffer)))

  ;; @todo Select the importer that matches the buffer mode or file extension.

  (when (and
         (called-interactively-p 'interactive)
         (not (edraw-import-svg-comfirm)))
    (keyboard-quit))

  (when-let ((svg (edraw-import-svg-buffer buffer)))
    (with-current-buffer output
      (erase-buffer)
      (edraw-svg-print svg nil nil))))

(defun edraw-import-svg-comfirm ()
  (y-or-n-p
   (edraw-msg "If you import diagrams generated with other software into Edraw, they may not be displayed correctly or the editing operation may become unstable. The original information is lost in the converted data. Do you want to convert to a format for Edraw?")))

(defun edraw-import-error (string &rest args)
  (apply #'error string args))

(defvar edraw-import-warning-messages nil)
(defvar edraw-import-warning-count 0)
(defvar edraw-import-warning-blocks 0)
(defvar edraw-import-warning-buffer nil)
(defvar edraw-import-warning-suppress-types nil)

(defun edraw-import-warning-suppress-types (&rest types)
  (nconc
   types
   edraw-import-warning-suppress-types))

(defun edraw-import-display-warning (message &rest args)
  (display-warning 'edraw-import
                   (apply #'format-message message args)
                   :warning
                   edraw-import-warning-buffer))

(defun edraw-import-warn (type string &rest args)
  (unless (memq type edraw-import-warning-suppress-types)
    (let ((msg (apply #'format string args)))
      (cl-incf edraw-import-warning-count)
      (unless (member msg edraw-import-warning-messages)
        (push msg edraw-import-warning-messages)
        (apply #'edraw-import-display-warning
               string args)))))

(defmacro edraw-import-warning-block (&rest body)
  `(progn
     (when (= edraw-import-warning-blocks 0)
       (setq edraw-import-warning-count 0
             edraw-import-warning-messages nil))
     (unwind-protect
         (let ((edraw-import-warning-blocks (1+ edraw-import-warning-blocks)))
           ,@body)
       (when (= edraw-import-warning-blocks 0)
         (when (> edraw-import-warning-count 0)
           (edraw-import-display-warning
            (edraw-msg "edraw-import: %s warnings raised")
            edraw-import-warning-count))
         (setq edraw-import-warning-count 0
               edraw-import-warning-messages nil)))))

;;;; Import From General SVG

(defcustom edraw-import-svg-level 'strict
  "Level to verify and keep unsupported SVG features."
  :group 'edraw-import
  :type '(choice (const strict)
                 (const loose)))

(defcustom edraw-import-svg-keep-unsupported-defs t
  "Non-nil means that unsupported definition elements are not discarded."
  :group 'edraw-import
  :type 'boolean)

(defcustom edraw-import-svg-remove-referenced-from-use-in-defs t
  "Non-nil means that elements used from `use' elements are
removed from within defs elements.

The importer replaces each `use' element with a clone of the
element it references, so it is usually safe to remove referenced
elements. However, problems can arise if the elements referenced
by the `use' elements are also referenced elsewhere."
  :group 'edraw-import
  :type 'boolean)

(defcustom edraw-import-svg-expand-use-element t
  "Non-nil means that use elements are replaced with the referenced element."
  :group 'edraw-import
  :type 'boolean)

(defcustom edraw-import-svg-style-to-attrs t
  "Non-nil means converting style attributes into individual
presentation attributes."
  :group 'edraw-import
  :type 'boolean)

(defvar edraw-import-svg-in-defs nil)

(defun edraw-import-svg-file (file interactively)
  (or
   ;; SVG for edraw
   (let ((svg (edraw-svg-read-from-file file nil)))
     (unless svg
       (error (edraw-msg "Not SVG data")))
     (when (edraw-dom-get-by-id svg edraw-import-svg-body-id)
       svg))
   ;; Convert
   ;; Do not use `edraw-svg-read-from-file' as it cannot handle
   ;; namespaces correctly.
   (progn
     (when (and interactively
                (not (edraw-import-svg-comfirm)))
       (keyboard-quit))
     (edraw-import-svg-dom
      (with-temp-buffer
        (insert-file-contents file)
        (edraw-import-svg-decode-buffer))))))

(defun edraw-import-svg-decode-buffer ()
  (edraw-xml-escape-ns-buffer)
  (edraw-import-svg-unescape-ns-element
   (car (edraw-dom-split-top-nodes (libxml-parse-xml-region
                                    (point-min) (point-max))))
   nil))

;;;###autoload
(defun edraw-import-svg-buffer (buffer)
  (edraw-import-warning-block
   (edraw-import-svg-dom
    (with-temp-buffer
      (insert-buffer-substring-no-properties buffer)
      (edraw-import-svg-decode-buffer)))))

;;;###autoload
(defun edraw-import-svg-string (string)
  (edraw-import-warning-block
   (edraw-import-svg-dom
    (with-temp-buffer
      (insert string)
      (edraw-import-svg-decode-buffer)))))

(defun edraw-import-svg-dom (dom)
  ;; Note: The DOM must be preprocessed using
  ;; `edraw-xml-escape-ns-buffer' and
  ;; `edraw-import-svg-unescape-ns-element'.
  (edraw-import-warning-block
   (let* ((svg-comments (edraw-dom-split-top-nodes dom))
          (svg (car svg-comments)))

     (unless (eq (edraw-dom-tag svg) 'svg)
       (edraw-import-error (edraw-msg "Not SVG data")))

     (if (edraw-dom-get-by-id svg edraw-import-svg-body-id)
         (progn
           (edraw-import-warn 'noconv (edraw-msg "Already an SVG for Edraw"))
           dom)

       ;; `edraw-svg-attr-length' requires ability to get parent from
       ;; child element only.
       (edraw-dom-update-parent-links svg)

       (let* ((edraw-dom-inhibit-parent-links t) ;; Do not create parent links(?)
              (context
               (list
                ;; plist
                (list
                 :dom-original svg
                 :ids-ref-from-use nil)))
              (converted (edraw-import-svg-convert-children svg context))
              (definitions (plist-get (car context) :definitions)))
         (edraw-dom-element
          'svg
          :attributes
          (edraw-import-svg-convert-element-attributes svg context)
          :xmlns "http://www.w3.org/2000/svg"
          :xmlns:xlink "http://www.w3.org/1999/xlink"
          ;; Children
          (when definitions
            (edraw-import-svg-remove-empty-defs-and-group
             (edraw-import-svg-remove-referenced-from-use-in-defs
              (edraw-dom-element 'g
                                 :id edraw-import-svg-imported-definitions-id
                                 :children definitions)
              context)))
          (edraw-dom-element 'g
                             :id edraw-import-svg-body-id
                             :children converted)))))))

(defun edraw-import-svg-remove-empty-defs-and-group (dom)
  (if (and (edraw-dom-element-p dom)
           (memq (edraw-dom-tag dom) '(defs g)))
      (progn
        (dolist (child (copy-sequence (edraw-dom-children dom)))
          (unless (edraw-import-svg-remove-empty-defs-and-group child)
            (edraw-dom-remove-node dom child)))
        (if (dom-children dom)
            dom
          nil))
    dom))

;;;;; Convert Children

(defun edraw-import-svg-convert-children (parent context)
  (let (new-children)
    (dolist (node (dom-children parent))
      (if (edraw-dom-element-p node)
          (if-let ((new-node (edraw-import-svg-convert-element node context)))
              (if (and (consp new-node)
                       (consp (car new-node)))
                  ;; List of node
                  (dolist (node new-node)
                    (push node new-children))
                ;; Single node (element or text)
                (push new-node new-children))
            ;; Discard element
            nil)
        (push node new-children)))
    (nreverse new-children)))

;;;;; Resolve XML Namespace

(defun edraw-import-svg-unescape-ns-element (elem namespaces)
  (let* ((namespaces (nconc
                      (edraw-xml-collect-ns-decls elem)
                      namespaces))
         (tag (edraw-import-svg-normalize-name (edraw-dom-tag elem)
                                               namespaces)))
    (unless tag
      (error "Unexpected xmlns decl in tag name"))

    (edraw-dom-element
     tag
     :attributes
     (cl-loop for (key . value) in (edraw-dom-attributes elem)
              for attr-name = (edraw-import-svg-normalize-name key namespaces)
              when attr-name ;; Ignore xmlns:<ns>= and xmlns=
              collect (cons attr-name value))
     :children
     (cl-loop for child in (edraw-dom-children elem)
              if (edraw-dom-element-p child)
              collect (edraw-import-svg-unescape-ns-element child namespaces)
              else
              collect child))))

(defun edraw-import-svg-normalize-name (name-symbol namespaces)
  "Normalize the NAME-SYMBOL of tags and attributes.

SVG names strip the namespace prefix. XLink names begin with
xlink:. In other cases, the namespace URL is appended to the name
in parentheses.

The result value might look like this:
 xmlns    : nil
 xmlns:?  : nil
 SVG      : rect
 XLink    : xlink:href
 XML      : xml:space
 Otherwise: <unknown>:version\\(http://www.inkscape.org/namespaces/inkscape\\)
            <unknown>:hogehoge\\(unknownns\\)"
  (let* ((ns-name (edraw-xml-unescape-ns-name name-symbol))
         (ns-prefix (car ns-name))
         (name (cdr ns-name))
         (ns-url (alist-get ns-prefix namespaces
                            nil nil #'equal)))
    (unless (eq ns-prefix 'xmlns)
      (pcase ns-url
        ('nil (cond
               ;; No xmlns declaration for default. SVG?
               ((null ns-prefix)
                (edraw-import-warn 'no-xmlns-default
                                   "No xmlns declaration for default")
                name)
               ;; For eample, xml:space, xml:lang
               ((equal ns-prefix "xml")
                (intern (format "%s:%s" ns-prefix name)))
               ;; No xmlns declaration for NS-PREFIX
               (t
                (edraw-import-warn 'no-xmlns
                                   "No xmlns declaration for `%s'" ns-prefix)
                (intern (format "<unknown>:%s(%s)" name ns-prefix)))))
        ("http://www.w3.org/2000/svg"
         name)
        ("http://www.w3.org/1999/xlink"
         (intern (format "xlink:%s" name)))
        (_
         ;; Unknown namespace URL
         (intern (format "<unknown>:%s(%s)" name ns-url)))))))

(defun edraw-import-svg-unknown-ns-name-p (name-symbol)
  (string-prefix-p "<unknown>:" (symbol-name name-symbol)))


;;;;; Convert Element

(defvar edraw-import-svg-convert-element-alist
  '((defs . edraw-import-svg-convert-definition)
    (g . edraw-import-svg-convert-group)
    (rect . edraw-import-svg-convert-shape)
    (ellipse . edraw-import-svg-convert-shape)
    (path . edraw-import-svg-convert-shape)
    (image . edraw-import-svg-convert-shape)
    (circle . edraw-import-svg-convert-circle)
    (line . edraw-import-svg-convert-line)
    (polyline . edraw-import-svg-convert-poly-shape)
    (polygon . edraw-import-svg-convert-poly-shape)
    (text . edraw-import-svg-convert-text)
    (tspan . edraw-import-svg-convert-tspan)
    (comment . edraw-import-svg-convert-comment)
    (a . edraw-import-svg-convert-a)
    (use . edraw-import-svg-convert-use)
    ;; Not supported:
    ;; animate
    ;; animateMotion
    ;; animateTransform
    ;; clipPath
    ;; desc
    ;; fe*
    ;; filter
    ;; foreignObject
    ;; linearGradient
    ;; marker
    ;; mask
    ;; metadata
    ;; mpath
    ;; pattern
    ;; radialGradient
    ;; script
    ;; set
    ;; stop
    ;; style
    ;; svg
    ;; switch
    ;; symbol
    ;; textPath
    ;; view
    ))

(defun edraw-import-svg-convert-element (elem context)
  (let ((tag (edraw-dom-tag elem)))
    (if-let ((fun (alist-get tag edraw-import-svg-convert-element-alist)))
        (funcall fun elem context)
      (if (or (and edraw-import-svg-in-defs
                   (not (edraw-import-svg-unknown-ns-name-p tag)))
              (eq edraw-import-svg-level 'loose))
          (progn
            (edraw-import-warn 'keep-unsupported-element
                               (edraw-msg "Keep unsupported element: %s") tag)
            (edraw-import-svg-convert-unsupported-element elem context))
        (edraw-import-warn 'discard-unsupported-element
                           (edraw-msg "Discard unsupported element: %s") tag)
        nil))))

(defun edraw-import-svg-convert-comment (_elem _context)
  ;; Discard comment
  nil)

(defun edraw-import-svg-convert-a (elem context)
  ;; Expose contents
  ;; @todo check style?
  (edraw-import-svg-convert-children elem context))

(defun edraw-import-svg-convert-use (elem context)
  ;; https://www.w3.org/TR/SVG11/struct.html#UseElement
  (if (not edraw-import-svg-expand-use-element)
      (progn
        (edraw-import-warn 'discard-unsupported-element
                           (edraw-msg "Discard unsupported element: %s")
                           (edraw-dom-tag elem))
        nil)
    (let* ((href (or (dom-attr elem 'xlink:href)
                     (dom-attr elem 'href)))
           (x (dom-attr elem 'x))
           (y (dom-attr elem 'y))
           ;;(width (dom-attr elem 'width))
           ;;(height (dom-attr elem 'height))
           (ref-id (and (stringp href)
                        (not (string-empty-p href))
                        (= (aref href 0) ?#)
                        (substring href 1)))
           (ref-elem (and ref-id
                          (edraw-dom-get-by-id
                           (plist-get (car context) :dom-original) ref-id)))
           (supported-tag (and ref-elem
                               (memq (edraw-dom-tag ref-elem)
                                     '(id
                                       rect ellipse path text image g
                                       circle line polyline polygon
                                       ;;@todo tspan?
                                       ;;@todo a?
                                       ;; Reject symbol and svg
                                       ))))
           (recursive (and ref-elem
                           (memq ref-elem
                                 (plist-get (car context) :use-converting-elements))))
           (converted-ref-elem
            (and supported-tag
                 (not recursive)
                 (edraw-import-svg-convert-element
                  ref-elem
                  (list
                   (edraw-plist-put
                    (car context) :use-converting-elements
                    (cons ref-elem
                          (plist-get (car context) :use-converting-elements))))))))
      ;;(message "href=%s ref-id=%s ref=elem=%s supported-tag=%s recursive=%s" href ref-id ref-elem supported-tag recursive)
      (unless converted-ref-elem
        (edraw-import-warn
         'discard-unsupported-element ;;@todo unsupported-element-format?
         (edraw-msg "Discard `use' element with unsupported format")))

      (when converted-ref-elem
        (let* ((new-attributes (seq-filter
                                (lambda (attr)
                                  (and (not (edraw-dom-attr-internal-p (car
                                                                        attr)))
                                       (not (memq (car attr)
                                                  '(id x y width height
                                                       href xlink:href
                                                       transform)))))
                                (dom-attributes elem)))
               (old-transform (dom-attr elem 'transform)) ;;@todo Consider style's transform
               (new-transform (if (or x y)
                                  (concat old-transform ;; or nil
                                          (when old-transform " ")
                                          "translate("
                                          (edraw-to-string (or x 0)) ;; edraw-svg-numstr? for matrix
                                          ","
                                          (edraw-to-string (or y 0)) ;; edraw-svg-numstr? for matrix
                                          ")")
                                old-transform)))
          (when new-transform
            (push (cons 'transform new-transform) new-attributes))
          (push ref-id (plist-get (car context) :ids-ref-from-use))
          (edraw-dom-element 'g
                             :attributes new-attributes
                             converted-ref-elem))))))

(defun edraw-import-svg-remove-referenced-from-use-in-defs (dom context)
  (when edraw-import-svg-remove-referenced-from-use-in-defs
    (dolist (id (plist-get (car context) :ids-ref-from-use))
      (let* ((referenced (edraw-dom-get-by-id dom id))
             (p referenced))
        (when referenced
          (while (and (setq p (edraw-dom-parent dom p))
                      (not (eq (edraw-dom-tag p) 'defs))))
          (when p
            (edraw-dom-remove-node dom referenced))))))
  dom)

(defun edraw-import-svg-convert-definition (elem context)
  (push
   (let ((edraw-import-svg-in-defs edraw-import-svg-keep-unsupported-defs))
     (edraw-dom-element
      (edraw-dom-tag elem)
      :attributes (edraw-import-svg-convert-element-attributes elem context)
      :children (edraw-import-svg-convert-children elem context)))
   (plist-get (car context) :definitions))
  nil)

(defun edraw-import-svg-convert-unsupported-element (elem context)
  (edraw-dom-element
   (edraw-dom-tag elem)
   :attributes (edraw-import-svg-convert-element-attributes elem context)
   :children (edraw-import-svg-convert-children elem context)))

(defun edraw-import-svg-convert-group (elem context)
  (edraw-dom-element
   (edraw-dom-tag elem)
   :attributes (edraw-import-svg-convert-element-attributes elem context)
   :children (edraw-import-svg-convert-children elem context)))

(defun edraw-import-svg-convert-shape (elem context)
  (edraw-dom-element
   (edraw-dom-tag elem)
   :attributes (edraw-import-svg-convert-element-attributes elem context)))

(defun edraw-import-svg-convert-circle (elem context)
  (let ((r (dom-attr elem 'r)))
    (when r
      (edraw-dom-element
       'ellipse
       :rx r
       :ry r
       :attributes (edraw-import-svg-convert-element-attributes
                    elem context '(r))))))

(defun edraw-import-svg-convert-line (elem context)
  (let ((x1 (edraw-svg-attr-length elem 'x1))
        (y1 (edraw-svg-attr-length elem 'y1))
        (x2 (edraw-svg-attr-length elem 'x2))
        (y2 (edraw-svg-attr-length elem 'y2)))
    (when (and x1 y1 x2 y2)
      (edraw-dom-element
       'path
       :d (edraw-path-d-from-command-list `((M ,x1 ,y1 ,x2 ,y2)))
       :attributes (edraw-import-svg-convert-element-attributes
                    elem context '(x1 y1 x2 y2))))))

(defun edraw-import-svg-convert-poly-shape (elem context) ;; polyline or polygon
  (let* ((closepath (eq (edraw-dom-tag elem) 'polygon))
         (points-attr (dom-attr elem 'points))
         (points (edraw-svg-parse-points (or points-attr ""))))
    (cond
     ((null points-attr)
      (edraw-import-warn 'no-points-attr
                         (edraw-msg "No `points' attribute: %s")
                         (edraw-dom-tag elem))
      nil)
     ((null points)
      (edraw-import-warn 'no-points-attr ;; empty-points-attr?
                         (edraw-msg "Empty `points' attribute: %s")
                         (edraw-dom-tag elem))
      nil)
     (t
      (edraw-dom-element
       'path
       :d (edraw-path-d-from-command-list
           (nconc
            (list (cons 'M (cl-loop for (x . y) in points
                                    collect x collect y)))
            (when closepath (list (list 'Z)))))
       :attributes (edraw-import-svg-convert-element-attributes
                    elem context '(points)))))))

(defun edraw-import-svg-convert-text (elem context)
  ;;@todo Extract text attributes from style properties? Should edraw-dom-svg.el parse style?
  (edraw-dom-element
   (edraw-dom-tag elem)
   :attributes (edraw-import-svg-convert-element-attributes elem context)
   :children (edraw-import-svg-convert-children elem context)))

(defun edraw-import-svg-convert-tspan (elem context)
  (edraw-dom-element
   (edraw-dom-tag elem)
   :attributes (edraw-import-svg-convert-element-attributes elem context)
   :children (edraw-import-svg-convert-children elem context)))


;;;;; Convert Attribute

(defun edraw-import-svg-convert-element-attributes (elem context &optional
                                                         exclude-attrs)
  (cl-letf (((plist-get (car context) :override-attrs) nil))
    (let ((new-attrs
           (edraw-import-svg-convert-attributes
            (if exclude-attrs
                (cl-loop for kv in (edraw-dom-attributes elem)
                         unless (memq (car kv) exclude-attrs)
                         collect kv)
              (edraw-dom-attributes elem))
            elem
            context)))
      ;; Override attributes
      (cl-loop for (pname . pvalue) in (plist-get (car context) :override-attrs)
               do (setf (alist-get pname new-attrs) pvalue))
      new-attrs)))

(defun edraw-import-svg-convert-attributes (attributes elem context)
  (cl-loop for (k . v) in attributes
           for new-attr = (edraw-import-svg-convert-attribute k v elem context)
           when new-attr
           collect new-attr))

(defvar edraw-import-svg-convert-attributes-alist
  ;; https://developer.mozilla.org/ja/docs/Web/SVG/Attribute
  '((class . edraw-import-svg-convert-attr-keep)
    (id . edraw-import-svg-convert-attr-keep)
    (opacity . edraw-import-svg-convert-attr-keep)
    (fill . edraw-import-svg-convert-attr-keep)
    (fill-opacity . edraw-import-svg-convert-attr-keep)
    (fill-rule . edraw-import-svg-convert-attr-keep)
    (stroke . edraw-import-svg-convert-attr-keep)
    (stroke-opacity . edraw-import-svg-convert-attr-keep)
    (stroke-width . edraw-import-svg-convert-attr-keep)
    (stroke-dasharray . edraw-import-svg-convert-attr-keep)
    (stroke-dashoffset . edraw-import-svg-convert-attr-keep)
    (stroke-linecap . edraw-import-svg-convert-attr-keep)
    (stroke-linejoin . edraw-import-svg-convert-attr-keep)
    (stroke-miterlimit . edraw-import-svg-convert-attr-keep)

    (style . edraw-import-svg-convert-attr-style)
    (transform . edraw-import-svg-convert-attr-keep)
    ;; geometry
    (x . edraw-import-svg-convert-attr-keep) ;;@todo check text's x
    (y . edraw-import-svg-convert-attr-keep) ;;@todo check text's y
    (cx . edraw-import-svg-convert-attr-keep)
    (cy . edraw-import-svg-convert-attr-keep)
    (width . edraw-import-svg-convert-attr-keep)
    (height . edraw-import-svg-convert-attr-keep)
    (r . edraw-import-svg-convert-attr-keep)
    (rx . edraw-import-svg-convert-attr-keep)
    (ry . edraw-import-svg-convert-attr-keep)
    ;; path
    (d . edraw-import-svg-convert-attr-d)
    (marker-start . edraw-import-svg-convert-attr-keep) ;;@todo check
    (marker-mid . edraw-import-svg-convert-attr-keep) ;;@todo check
    (marker-end . edraw-import-svg-convert-attr-keep) ;;@todo check
    ;; text
    (dx . edraw-import-svg-convert-attr-keep)
    (dy . edraw-import-svg-convert-attr-keep)
    (font-family . edraw-import-svg-convert-attr-keep)
    (font-size . edraw-import-svg-convert-attr-keep)
    (font-weight . edraw-import-svg-convert-attr-keep)
    (font-style . edraw-import-svg-convert-attr-keep)
    (text-decoration . edraw-import-svg-convert-attr-keep)
    (text-anchor . edraw-import-svg-convert-attr-keep)
    (writing-mode . edraw-import-svg-convert-attr-keep)
    ;; image
    (xlink:href . edraw-import-svg-convert-attr-keep)
    (href . edraw-import-svg-convert-attr-keep)
    (preserveAspectRatio . edraw-import-svg-convert-attr-keep) ;; svg or image
    ;; svg
    (viewBox . edraw-import-svg-convert-attr-keep)
    (version . edraw-import-svg-convert-attr-keep)
    (xmlns . edraw-import-svg-convert-attr-keep)
    (xmlns:xlink . edraw-import-svg-convert-attr-keep)
    ;; Inkscape
    (<unknown>:role\(http://sodipodi.sourceforge.net/DTD/sodipodi-0.dtd\)
     . edraw-import-svg-convert-attr-inkscape-role)
    ))

(defun edraw-import-svg-convert-attribute (attr-name value elem context)
  (let ((fun (alist-get attr-name
                        edraw-import-svg-convert-attributes-alist)))
    (cond
     (fun
      (funcall fun attr-name value elem context))
     ;; Ignore internal attribute
     ((edraw-dom-attr-internal-p attr-name)
      nil)
     ;; Keep data attribute
     ((string-prefix-p "data-" (symbol-name attr-name))
      (cons attr-name value))
     ;; Unsupported attribute
     (t
      (if (or (and edraw-import-svg-in-defs
                   (not (edraw-import-svg-unknown-ns-name-p attr-name)))
              (eq edraw-import-svg-level 'loose))
          (progn
            (edraw-import-warn 'keep-unsupported-attribute
                               (edraw-msg "Keep unsupported attribute: %s")
                               attr-name)
            (cons attr-name value))
        (edraw-import-warn 'discard-unsupported-attribute
                           (edraw-msg "Discard unsupported attribute: %s")
                           attr-name)
        nil)))))

(defun edraw-import-svg-convert-attr-keep (attr-name value _elem _context)
  (cons attr-name value))

(defconst edraw-import-svg-style-props
  '((opacity (rect circle ellipse path text image g line polyline polygon))
    (fill (rect circle ellipse path text g line polyline polygon))
    (fill-opacity (rect circle ellipse path text g line polyline polygon))
    (stroke (rect circle ellipse path text g line polyline polygon))
    (stroke-opacity (rect circle ellipse path text g line polyline polygon))
    (stroke-width (rect circle ellipse path text g line polyline polygon))
    (stroke-dasharray (rect circle ellipse path text g line polyline polygon))
    (stroke-dashoffset (rect circle ellipse path text g line polyline polygon))
    ;;(transform (rect circle ellipse path text image g line polyline polygon))
    ;; path
    (fill-rule (path g line polyline polygon))
    (stroke-linecap (path g line polyline polygon))
    (stroke-linejoin (path g line polyline polygon))
    (stroke-miterlimit (path g line polyline polygon))
    ;; text
    (font-family (text))
    (font-size (text))
    (font-weight (text))
    (font-style (text))
    (text-decoration (text))
    (text-anchor (text))
    ;;(writing-mode (text))
    ))

(defun edraw-import-svg-convert-attr-style (attr-name value elem context)
  (edraw-import-warn 'poorly-supported-attribute
                     (edraw-msg "Support for `style' attributes is insufficient and may cause display and operation problems"))

  ;; Convert style attribute to presentation attributes
  (if edraw-import-svg-style-to-attrs
      ;; https://www.w3.org/TR/SVG11/styling.html
      ;; https://www.w3.org/TR/SVG2/styling.html#PresentationAttributes
      (condition-case err
          (let ((tag (edraw-dom-tag elem))
                new-value
                override-attrs)

            (cl-loop for (pname-token . pvalue-range)
                     in (edraw-css-split-decl-list value (list 0))
                     ;; https://www.w3.org/TR/SVG11/styling.html#CaseSensitivity
                     ;; @todo Convert property name case ( Fill: => fill= )
                     ;; @todo Convert property value case ( Italic => italic )
                     for pname = (intern (edraw-css-token-value value pname-token))
                     for pinfo = (alist-get pname edraw-import-svg-style-props)
                     if (memq tag (car pinfo)) ;; Use presentation attr
                     do (push (cons pname
                                    ;; @todo Check value format
                                    (substring value
                                               (car pvalue-range)
                                               (cdr pvalue-range)))
                              override-attrs)
                     else ;; Use style attr
                     do (setq new-value
                              (concat new-value (and new-value ";")
                                      (substring value
                                                 (cadr pname-token)
                                                 (cdr pvalue-range)))))
            (setf (plist-get (car context) :override-attrs)
                  (append
                   (plist-get (car context) :override-attrs)
                   override-attrs))
            (cons attr-name new-value))
        (error
         (edraw-import-warn 'css-error
                            (edraw-msg "CSS Style parsing error: %s") err)
         (cons attr-name value)))
    (cons attr-name value)))

(defun edraw-import-svg-convert-attr-d (attr-name value _elem _context)
  ;; Check unsupported path data (A command)
  (let ((cmds (condition-case err
                  (edraw-path-d-parse value)
                (error
                 (edraw-import-warn 'path-syntax
                                    (edraw-msg "Parsing error: %s") err)
                 (setq value nil) ;;Discard
                 nil))))
    ;; Check empty path data
    (unless cmds
      (setq value nil cmds nil) ;;Discard
      (edraw-import-warn 'path-empty (edraw-msg "Empty path data")))

    ;; Check unsupported path command
    ;;@todo Call `edraw-path-cmdlist-from-d'?
    (when-let ((c (seq-find (lambda (cmd)
                              (not (memq
                                    (car cmd)
                                    '(M m Z z L l H h V v C c S s Q q T t))))
                            cmds)))
      ;; As of 2024-03-11, if there is an unsupported command, an
      ;; error will occur during editing, so discard it.
      (unless (eq edraw-import-svg-level 'loose)
        (setq value nil cmds nil)) ;;Discard
      (edraw-import-warn 'path-unsupported-command
                         (edraw-msg "Unsupported path command: `%s'") (car c)))

    ;; Check not start with M
    (when (and cmds (not (memq (caar cmds) '(M m))))
      (setq value nil cmds nil) ;;Discard
      (edraw-import-warn 'path-not-start-m
                         (edraw-msg "Path data does not start with M"))))

  (when value
    (cons attr-name value)))

(defun edraw-import-svg-convert-attr-inkscape-role (attr-name
                                                    value elem _context)
  (if (and (eq (edraw-dom-tag elem) 'tspan)
           (string= value "line"))
      (cons 'class "edraw-text-line") ;;@todo If elem already has a class?
    ;; Otherwise discard
    (edraw-import-warn 'discard-unsupported-attribute
                       (edraw-msg "Discard unsupported attribute: %s")
                       attr-name)
    nil))

;;;; XML

;;@todo Use xmltok.el?

;; https://www.w3.org/TR/xml/#NT-S
(defconst edraw-xml-re-wsp "[ \t\r\n]+")
(defconst edraw-xml-re-wsp-opt "[ \t\r\n]*")
;; https://www.w3.org/TR/xml/#NT-Name
(defconst edraw-xml-re-name "\\(?:[_[:alpha:]][-._[:alnum:]]*\\)")
(defconst edraw-xml-re-name-with-colon
  (concat
   ;; (1)<name>(:(2)<name>)?
   "\\(?:\\(" edraw-xml-re-name "\\)\\(?::\\(" edraw-xml-re-name "\\)\\)?\\)"))
(defconst edraw-xml-re-start
  (concat
   "<\\(?:"
   ;; (1)
   "\\(!--\\)" "\\|"
   ;; (2)
   "\\(!\\[CDATA\\[\\)" "\\|"
   ;; (3)
   "\\(\\?\\)" "\\|"
   ;; (4):(5)
   edraw-xml-re-name-with-colon
   "\\|"
   ;; (6):(7)
   "\\(?:/" edraw-xml-re-name-with-colon "\\)"
   "\\)"))
;; https://www.w3.org/TR/xml/#NT-Attribute
(defconst edraw-xml-re-attr
  (concat
   edraw-xml-re-wsp
   ;; (1):(2)
   edraw-xml-re-name-with-colon
   edraw-xml-re-wsp-opt
   "="
   edraw-xml-re-wsp-opt
   ;; (3)"..." or '...'
   "\\(\\(?:\"[^<&\"]*\"\\)\\|\\(?:'[^<&']*'\\)\\)"))
(defconst edraw-xml-re-tag-close
  (concat "\\(?:" edraw-xml-re-wsp-opt "/>\\|>\\)"))

(defun edraw-xml-escape-ns-buffer ()
  "Replace tag names and attribute names related to namespace.

`libxml-parse-xml-region' removes all elements related to the
namespace, so replace tag and attribute names to avoid this.

Make the following substitutions:

<(ns):(tag)   => <_ns-(ns)--(tag)
</(ns):(tag)  => </_ns-(ns)--(tag)
(ns):(attr)=  => _ns-(ns)--(attr)
xmlns:(ns)=   => _ns-xmlns--(ns)
xmlns=        => _ns-xmlns--

To split an escaped name string on a colon, use `edraw-xml-unescape-ns-name'."
  (save-excursion
    (goto-char (point-min))
    (while (re-search-forward edraw-xml-re-start nil t) ;; Skip CharData
      (cond
       ((match-beginning 1)
        (search-forward "-->")) ;; error if not found
       ((match-beginning 2)
        (search-forward "]]>")) ;; error if not found
       ((match-beginning 3)
        (search-forward "?>")) ;; error if not found
       ((match-beginning 6)
        ;; Replace </(6):(7) with </_ns-(6)--(7)
        (when (match-beginning 7)
          (replace-match
           (concat "</" "_ns-" (match-string 6) "--" (match-string 7)) t))
        (search-forward ">")) ;; error if not found
       ((match-beginning 4)
        ;; Replace <(4):(5) with <_ns-(4)--(5)
        (when (match-beginning 5)
          (replace-match
           (concat "<" "_ns-" (match-string 4) "--" (match-string 5)) t))

        ;; Replace attribute names
        (save-match-data
          (while (looking-at edraw-xml-re-attr)
            (goto-char (match-end 0))
            ;; Replace (1):(2)= with _ns-(1)--(2)=
            ;; Replace (1:xmlns)= with _ns-(1:xmlns)--=
            (when (or (match-beginning 2)
                      (equal (match-string 1) "xmlns"))
              (let (;;(ns-url (substring (match-string 3) 1 -1))
                    (name1 (match-string 1))
                    (name2 (match-string 2)))
                (save-excursion
                  (delete-region (match-beginning 1) (or (match-end 2)
                                                         (match-end 1)))
                  (goto-char (match-beginning 1))
                  (insert (concat "_ns-" name1 "--" name2)))))))

        (unless (looking-at edraw-xml-re-tag-close)
          (error "XML syntax error: tag not closed"))
        (goto-char (match-end 0)))))))

(defun edraw-xml-unescape-ns-name (name)
  (let ((name-str (symbol-name name)))
    (if (string-match "\\`_ns-\\(.+\\)--\\(.*\\)\\'" name-str)
        (let ((name1 (match-string 1 name-str))
              (name2 (match-string 2 name-str)))
          (if (string= name1 "xmlns")
              ;; ('xmlns . "name"-or-nil)
              (cons (intern name1)
                    (and (not (string-empty-p name2)) name2))
            ;; ("name" . attr-or-tag)
            (cons name1 (intern name2))))
      ;; (nil . attr-or-tag)
      (cons nil name))))

(defun edraw-xml-collect-ns-decls (elem)
  "Collect namespace declarations from DOM element ELEM.

Return ((prefix-symbol-or-nil . url-string) ...)"
  (when (edraw-dom-element-p elem)
    (cl-loop for (key . value) in (edraw-dom-attributes elem)
             for (name1 . name2) = (edraw-xml-unescape-ns-name key)
             when (eq name1 'xmlns) collect (cons name2 value))))

(provide 'edraw-import)
;;; edraw-import.el ends here