ob-mermaid.el

;;; ob-mermaid.el --- org-babel support for mermaid evaluation

;; Copyright (C) 2018 Alexei Nunez

;; Author: Alexei Nunez <alexeirnunez@gmail.com>
;; URL: https://github.com/arnm/ob-mermaid
;; Keywords: lisp
;; Version: 0

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

;;; Commentary:

;; Org-Babel support for evaluating mermaid diagrams.

;;; Requirements:

;; mermaid.cli | https://github.com/mermaidjs/mermaid.cli

;;; Code:
(require 'ob)
(require 'ob-eval)

(defvar org-babel-default-header-args:mermaid
  '((:results . "file") (:exports . "results"))
  "Default arguments for evaluatiing a mermaid source block.")

(defcustom ob-mermaid-cli-path nil
  "Path to mermaid.cli executable."
  :group 'org-babel
  :type 'string)

(defun org-babel-execute:mermaid (body params)
  (let* ((out-file (or (cdr (assoc :file params))
                       (error "mermaid requires a \":file\" header argument")))
	 (theme (cdr (assoc :theme params)))
	 (width (cdr (assoc :width params)))
	 (height (cdr (assoc :height params)))
	 (scale (cdr (assoc :scale params)))
	 (background-color (cdr (assoc :background-color params)))
	 (mermaid-config-file (cdr (assoc :mermaid-config-file params)))
	 (css-file (cdr (assoc :css-file params)))
	 (puppeteer-config-file (cdr (assoc :puppeteer-config-file params)))
	 (pdf-fit (assoc :pdf-fit params))
         (temp-file (org-babel-temp-file "mermaid-"))
         (mmdc (or ob-mermaid-cli-path
									 (if (executable-find "mmdc")
											 (unless (file-executable-p mmdc)
												 ;; cannot happen with `executable-find', so we complain about
												 ;; `ob-mermaid-cli-path'
												 (error "Cannot find or execute %s, please check `ob-mermaid-cli-path'" mmdc))
										 (executable-find "mmdc"))
                   (error "`ob-mermaid-cli-path' is not set and mmdc is not in `exec-path'")))
         (cmd (concat mmdc
                      " -i " (org-babel-process-file-name temp-file)
                      " -o " (org-babel-process-file-name out-file)
		      (when theme
			(concat " -t " theme))
		      (when background-color
			(concat " -b " background-color))
		      (when width
			(concat " -w " width))
		      (when height
			(concat " -H " height))
		      (when scale
			(concat " -s " (number-to-string scale)))
		      (when pdf-fit
			(concat " -f "))
		      (when mermaid-config-file
			(concat " -c " (org-babel-process-file-name mermaid-config-file)))
		      (when css-file
			(concat " -C " (org-babel-process-file-name css-file)))
                      (when puppeteer-config-file
                        (concat " -p " (org-babel-process-file-name puppeteer-config-file))))))
    (with-temp-file temp-file (insert body))
    (message "%s" cmd)
    (org-babel-eval cmd "")
    nil))

(provide 'ob-mermaid)


;;; ob-mermaid.el ends here