;;; ob-fortran.el --- Babel Functions for Fortran    -*- lexical-binding: t; -*-

;; Copyright (C) 2011-2022 Free Software Foundation, Inc.

;; Authors: Sergey Litvinov
;;       Eric Schulte
;; Keywords: literate programming, reproducible research, fortran
;; Homepage: https://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 <https://www.gnu.org/licenses/>.

;;; Commentary:

;; Org-Babel support for evaluating fortran code.

;;; Code:
(require 'ob)
(require 'org-macs)
(require 'cc-mode)
(require 'cl-lib)

(declare-function org-entry-get "org"
		  (pom property &optional inherit literal-nil))

(defvar org-babel-tangle-lang-exts)
(add-to-list 'org-babel-tangle-lang-exts '("fortran" . "F90"))

(defvar org-babel-default-header-args:fortran '())

(defcustom org-babel-fortran-compiler "gfortran"
  "Fortran command used to compile Fortran source code file."
  :group 'org-babel
  :package-version '(Org . "9.5")
  :type  'string)

(defun org-babel-execute:fortran (body params)
  "This function should only be called by `org-babel-execute:fortran'."
  (let* ((tmp-src-file (org-babel-temp-file "fortran-src-" ".F90"))
         (tmp-bin-file (org-babel-temp-file "fortran-bin-" org-babel-exeext))
         (cmdline (cdr (assq :cmdline params)))
         (flags (cdr (assq :flags params)))
         (full-body (org-babel-expand-body:fortran body params)))
    (with-temp-file tmp-src-file (insert full-body))
    (org-babel-eval
     (format "%s -o %s %s %s"
	     org-babel-fortran-compiler
	     (org-babel-process-file-name tmp-bin-file)
	     (mapconcat 'identity
			(if (listp flags) flags (list flags)) " ")
	     (org-babel-process-file-name tmp-src-file)) "")
    (let ((results
           (org-trim
            (org-remove-indentation
	     (org-babel-eval
	      (concat tmp-bin-file (if cmdline (concat " " cmdline) "")) "")))))
      (org-babel-reassemble-table
       (org-babel-result-cond (cdr (assq :result-params params))
	 (org-babel-read results)
         (let ((tmp-file (org-babel-temp-file "f-")))
           (with-temp-file tmp-file (insert results))
           (org-babel-import-elisp-from-file tmp-file)))
       (org-babel-pick-name
        (cdr (assq :colname-names params)) (cdr (assq :colnames params)))
       (org-babel-pick-name
        (cdr (assq :rowname-names params)) (cdr (assq :rownames params)))))))

(defun org-babel-expand-body:fortran (body params)
  "Expand a block of fortran or fortran code with org-babel according to
its header arguments."
  (let ((vars (org-babel--get-vars params))
        (main-p (not (string= (cdr (assq :main params)) "no")))
        (includes (or (cdr (assq :includes params))
                      (org-babel-read (org-entry-get nil "includes" t))))
        (defines (org-babel-read
                  (or (cdr (assq :defines params))
                      (org-babel-read (org-entry-get nil "defines" t))))))
    (mapconcat 'identity
	       (list
		;; includes
		(mapconcat
		 (lambda (inc) (format "#include %s" inc))
		 (if (listp includes) includes (list includes)) "\n")
		;; defines
		(mapconcat
		 (lambda (inc) (format "#define %s" inc))
		 (if (listp defines) defines (list defines)) "\n")
		;; body
		(if main-p
		    (org-babel-fortran-ensure-main-wrap
		     (concat
		      ;; variables
		      (mapconcat 'org-babel-fortran-var-to-fortran vars "\n")
		      body)
		     params)
		  body) "\n") "\n")))

(defun org-babel-fortran-ensure-main-wrap (body params)
  "Wrap body in a \"program ... end program\" block if none exists."
  (if (string-match "^[ \t]*program\\>" (capitalize body))
      (let ((vars (org-babel--get-vars params)))
	(when vars (error "Cannot use :vars if `program' statement is present"))
	body)
    (format "program main\n%s\nend program main\n" body)))

(defun org-babel-prep-session:fortran (_session _params)
  "This function does nothing as fortran is a compiled language with no
support for sessions."
  (error "Fortran is a compiled languages -- no support for sessions"))

(defun org-babel-load-session:fortran (_session _body _params)
  "This function does nothing as fortran is a compiled language with no
support for sessions."
  (error "Fortran is a compiled languages -- no support for sessions"))

;; helper functions

(defun org-babel-fortran-var-to-fortran (pair)
  "Convert an elisp val into a string of fortran code specifying a var
of the same value."
  ;; TODO list support
  (let ((var (car pair))
        (val (cdr pair)))
    (when (symbolp val)
      (setq val (symbol-name val))
      (when (= (length val) 1)
        (setq val (string-to-char val))))
    (cond
     ((integerp val)
      (format "integer, parameter  ::  %S = %S\n" var val))
     ((floatp val)
      (format "real, parameter ::  %S = %S\n" var val))
     ((or (integerp val))
      (format "character, parameter :: %S = '%S'\n" var val))
     ((stringp val)
      (format "character(len=%d), parameter ::  %S = '%s'\n"
              (length val) var val))
     ;; val is a matrix
     ((and (listp val) (cl-every #'listp val))
      (format "real, parameter :: %S(%d,%d) = transpose( reshape( %s , (/ %d, %d /) ) )\n"
	      var (length val) (length (car val))
	      (org-babel-fortran-transform-list val)
	      (length (car val)) (length val)))
     ((listp val)
      (format "real, parameter :: %S(%d) = %s\n"
	      var (length val) (org-babel-fortran-transform-list val)))
     (t
      (error "The type of parameter %s is not supported by ob-fortran" var)))))

(defun org-babel-fortran-transform-list (val)
  "Return a fortran representation of enclose syntactic lists."
  (if (listp val)
      (concat "(/" (mapconcat #'org-babel-fortran-transform-list val ", ") "/)")
    (format "%S" val)))

(provide 'ob-fortran)

;;; ob-fortran.el ends here
