;;; ob-processing.el --- org-babel functions for evaluation of processing

;; Copyright (C) 2009-2015 Free Software Foundation, Inc.

;; Author: Jarmo Hurri (adapted from ob-asymptote.el written by Eric Schulte)
;; Keywords: literate programming, reproducible research
;; Homepage: http://orgmode.org

;; This file is part of GNU Emacs.

;; GNU Emacs 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.

;; GNU Emacs 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 GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.

;;; Commentary:

;; Org-Babel support for evaluating processing source code.
;;
;; This differs from most standard languages in that
;;
;; 1) there is no such thing as a "session" in processing
;;
;; 2) results can only be exported as html; in this case, the
;;    processing code is embedded via a file into a javascript block
;;    using the processing.js module; the script then draws the
;;    resulting output when the web page is viewed in a browser
;;
;; 3) when not exporting html, evaluation of processing code results
;;    in interactive viewing of the results via Processing 2.0 Emacs
;;    mode; note that the user is responsible for making sure that
;;    processing.js is available on the website

;;; Requirements:

;; - processing2-emacs mode :: https://github.com/ptrv/processing2-emacs
;; - Processing.js module :: http://processingjs.org/

;;; Code:
(require 'ob)
(require 'ox)

(eval-when-compile (require 'cl))

;; declaration needed because requiring ob does not define the variable
(eval-when-compile (defvar org-babel-temporary-directory))

(defvar org-babel-tangle-lang-exts)
(add-to-list 'org-babel-tangle-lang-exts '("processing" . "pde"))

;; default header tags depend on whether exporting html or not; if not
;; exporting html, then no results are produced; otherwise results are
;; html
(defvar org-babel-default-header-args:processing
  '((:results . (or (and org-export-current-backend "html")  "none"))
    (:exports . "results"))
  "Default arguments when evaluating a Processing source block.")

(defvar org-babel-processing-processing-js-filename
  "processing.js"
  "Filename of the processing.js file.")

;; a running index for producing unique ids for processing sketches
(defvar org-babel-processing-sketch-number 0)
(add-hook 'org-export-before-processing-hook
	  (lambda (backend) (setq org-babel-processing-sketch-number 0)))

;; declaration of needed function from processing mode in case
;; processing-mode is not available
(if (null (require 'processing-mode nil :noerror))
  (declare-function processing-sketch-run "processing-mode.el" nil))

(defun org-babel-execute:processing (body params)
  "Execute a block of Processing code.
This function is called by `org-babel-execute-src-block'."
  (let ((sketch-code
	 (org-babel-expand-body:generic
	  body
	  params
	  (org-babel-variable-assignments:processing params))))
    (if (and (not (null org-babel-exp-reference-buffer))
	     (string= org-export-current-backend "html"))
	;; results are html if exporting html
	(let ((sketch-canvas-id
	       (concat "org-processing-canvas-"
		       (number-to-string org-babel-processing-sketch-number))))
	  (setq org-babel-processing-sketch-number
		(1+ org-babel-processing-sketch-number))
	  (concat "<script src=\""
		  org-babel-processing-processing-js-filename
		  "\"></script>\n <script type=\"text/processing\""
		  " data-processing-target=\""
		  sketch-canvas-id
		  "\">\n"
		  sketch-code
		  "\n</script> <canvas id=\""
		  sketch-canvas-id
		  "\"></canvas>"))
      ;; if not exporting html, show sketch in external viewer
      ;; note: sketch filename can not contain a hyphen, since it has to be
      ;; a valid java class name - for this reason make-temp-file is repeated
      ;; until no hyphen is in the name; also sketch dir name must be the same
      ;; as the basename of the sketch file
      (let* ((temporary-file-directory org-babel-temporary-directory)
	     (sketch-dir
	      (let (sketch-dir-candidate)
		(while
		    (progn
		      (setq sketch-dir-candidate
			    (make-temp-file "processing" t))
		      (if (string-match
			   "-"
			   (file-name-nondirectory sketch-dir-candidate))
			  (progn
			    (delete-directory sketch-dir-candidate)
			    t)
			nil)))
		sketch-dir-candidate))
	     (sketch-filename
	      (concat sketch-dir
		      "/"
		      (file-name-nondirectory sketch-dir)
		      ".pde")))
	(with-temp-file sketch-filename (insert sketch-code))
	(find-file sketch-filename)
	(processing-sketch-run)
	(kill-buffer)
	nil)))) ;; signal no output in this case

(defun org-babel-prep-session:processing (session params)
  "Return an error if the :session header argument is set.
Processing does not support sessions"
  (error "Processing does not support sessions"))

(defun org-babel-variable-assignments:processing (params)
  "Return list of processing statements assigning the block's variables."
  (mapcar #'org-babel-processing-var-to-processing
	  (mapcar #'cdr (org-babel-get-header params :var))))

(defun org-babel-processing-var-to-processing (pair)
  "Convert an elisp value into a Processing variable.
The elisp value PAIR is converted into Processing code specifying
a variable of the same value."
  (let ((var (car pair))
        (val (let ((v (cdr pair)))
	       (if (symbolp v) (symbol-name v) v))))
    (cond
     ((integerp val)
      (format "int %S=%S;" var val))
     ((floatp val)
      (format "float %S=%S;" var val))
     ((stringp val)
      (format "String %S=\"%s\";" var val))
     ((and (listp val) (not (listp (car val))))
      (let* ((type (org-babel-processing-define-type val))
	     (fmt (if (eq 'String type) "\"%s\"" "%s"))
	     (vect (mapconcat (lambda (e) (format fmt e)) val ", ")))
	(format "%s[] %S={%s};" type var vect)))
     ((listp val)
      (let* ((type (org-babel-processing-define-type val))
	     (fmt (if (eq 'String type) "\"%s\"" "%s"))
             (array (mapconcat (lambda (row)
				 (concat "{"
					 (mapconcat (lambda (e) (format fmt e))
						    row ", ")
					 "}"))
			       val ",")))
        (format "%S[][] %S={%s};" type var array))))))

(defun org-babel-processing-define-type (data)
  "Determine type of DATA.

DATA is a list.  Return type as a symbol.

The type is `String' if any element in DATA is
a string.  Otherwise, it is either `float', if some elements are
floats, or `int'."
  (let* ((type 'int)
	 find-type			; for byte-compiler
	 (find-type
	  (function
	   (lambda (row)
	     (catch 'exit
	       (mapc (lambda (el)
		       (cond ((listp el) (funcall find-type el))
			     ((stringp el) (throw 'exit (setq type 'String)))
			     ((floatp el) (setq type 'float))))
		     row))))))
    (funcall find-type data) type))

(provide 'ob-processing)

;;; ob-processing.el ends here