;;; ob-picolisp.el --- Babel Functions for Picolisp  -*- lexical-binding: t; -*-

;; Copyright (C) 2010-2021 Free Software Foundation, Inc.

;; Authors: Thorsten Jolitz
;;	 Eric Schulte
;; Keywords: literate programming, reproducible research
;; 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:

;; This library enables the use of PicoLisp in the multi-language
;; programming framework Org-Babel.  PicoLisp is a minimal yet
;; fascinating Lisp dialect and a highly productive application
;; framework for web-based client-server applications on top of
;; object-oriented databases.  A good way to learn PicoLisp is to first
;; read Paul Grahams essay "The hundred year language"
;; (http://www.paulgraham.com/hundred.html) and then study the various
;; documents and essays published in the PicoLisp wiki
;; (https://picolisp.com/5000/-2.html).  PicoLisp is included in some
;; GNU/Linux Distributions, and can be downloaded here:
;; https://software-lab.de/down.html.  It ships with a picolisp-mode and
;; an inferior-picolisp-mode for Emacs (to be found in the /lib/el/
;; directory).

;; Although it might seem more natural to use Emacs Lisp for most
;; Lisp-based programming tasks inside Org, an Emacs library written
;; in Emacs Lisp, PicoLisp has at least two outstanding features that
;; make it a valuable addition to Org Babel:

;; PicoLisp _is_ an object-oriented database with a Prolog-based query
;; language implemented in PicoLisp (Pilog).  Database objects are
;; first-class members of the language.

;; PicoLisp is an extremely productive framework for the development
;; of interactive web-applications (on top of a database).

;;; Requirements:

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

(declare-function run-picolisp "ext:inferior-picolisp" (cmd))
(defvar org-babel-tangle-lang-exts) ;; Autoloaded

;; optionally define a file extension for this language
(add-to-list 'org-babel-tangle-lang-exts '("picolisp" . "l"))

;;; interferes with settings in org-babel buffer?
;; optionally declare default header arguments for this language
;; (defvar org-babel-default-header-args:picolisp
;;   '((:colnames . "no"))
;;   "Default arguments for evaluating a picolisp source block.")

(defvar org-babel-picolisp-eoe "org-babel-picolisp-eoe"
  "String to indicate that evaluation has completed.")

(defcustom org-babel-picolisp-cmd "pil"
  "Name of command used to evaluate picolisp blocks."
  :group 'org-babel
  :version "24.1"
  :type 'string)

(defun org-babel-expand-body:picolisp (body params)
  "Expand BODY according to PARAMS, return the expanded body."
  (let ((vars (org-babel--get-vars params))
        (print-level nil)
	(print-length nil))
    (if (> (length vars) 0)
        (concat "(prog (let ("
                (mapconcat
                 (lambda (var)
                   (format "%S '%S)"
                           (print (car var))
                           (print (cdr var))))
                 vars "\n      ")
                " \n" body ") )")
      body)))

(defun org-babel-execute:picolisp (body params)
  "Execute a block of Picolisp code with org-babel.
This function is called by `org-babel-execute-src-block'."
  (message "executing Picolisp source code block")
  (let* (
	 ;; Name of the session or "none".
	 (session-name (cdr (assq :session params)))
	 ;; Set the session if the session variable is non-nil.
	 (session (org-babel-picolisp-initiate-session session-name))
	 ;; Either OUTPUT or VALUE which should behave as described above.
	 (result-params (cdr (assq :result-params params)))
	 ;; Expand the body with `org-babel-expand-body:picolisp'.
	 (full-body (org-babel-expand-body:picolisp body params))
         ;; Wrap body appropriately for the type of evaluation and results.
         (wrapped-body
          (cond
           ((or (member "code" result-params)
                (member "pp" result-params))
            (format "(pretty (out \"%s\" %s))" null-device full-body))
           ((and (member "value" result-params) (not session))
            (format "(print (out \"%s\" %s))" null-device full-body))
           ((member "value" result-params)
            (format "(out \"%s\" %s)" null-device full-body))
           (t full-body)))
         (result
          (if (not (string= session-name "none"))
              ;; Session based evaluation.
              (mapconcat ;; <- joins the list back into a single string
               #'identity
               (butlast ;; <- remove the org-babel-picolisp-eoe line
                (delq nil
                      (mapcar
                       (lambda (line)
                         (org-babel-chomp      ;; Remove trailing newlines.
                          (when (> (length line) 0) ;; Remove empty lines.
                            (cond
                             ;; Remove leading "-> " from return values.
                             ((and (>= (length line) 3)
                                   (string= "-> " (substring line 0 3)))
                              (substring line 3))
                             ;; Remove trailing "-> <<return-value>>" on the
                             ;; last line of output.
                             ((and (member "output" result-params)
                                   (string-match-p "->" line))
                              (substring line 0 (string-match "->" line)))
                             (t line)
                             )
                            ;;(if (and (>= (length line) 3);Remove leading "<-"
                            ;;         (string= "-> " (substring line 0 3)))
                            ;;    (substring line 3)
                            ;;  line)
                            )))
                       ;; Returns a list of the output of each evaluated exp.
                       (org-babel-comint-with-output
                           (session org-babel-picolisp-eoe)
                         (insert wrapped-body) (comint-send-input)
                         (insert "'" org-babel-picolisp-eoe)
                         (comint-send-input)))))
               "\n")
            ;; external evaluation
            (let ((script-file (org-babel-temp-file "picolisp-script-")))
              (with-temp-file script-file
                (insert (concat wrapped-body "(bye)")))
              (org-babel-eval
               (format "%s %s"
                       org-babel-picolisp-cmd
                       (org-babel-process-file-name script-file))
               "")))))
    (org-babel-result-cond result-params
      result
      (read result))))

(defun org-babel-picolisp-initiate-session (&optional session-name)
  "If there is not a current inferior-process-buffer in SESSION then create.
Return the initialized session."
  (unless (string= session-name "none")
    (require 'inferior-picolisp)
    ;; provide a reasonable default session name
    (let ((session (or session-name "*inferior-picolisp*")))
      ;; check if we already have a live session by this name
      (if (org-babel-comint-buffer-livep session)
          (get-buffer session)
        (save-window-excursion
          (run-picolisp org-babel-picolisp-cmd)
          (rename-buffer session-name)
          (current-buffer))))))

(provide 'ob-picolisp)

;;; ob-picolisp.el ends here