;;; ob-elixir.el --- Org Babel functions for Elixir -*- lexical-binding: t; -*-

;; Copyright (C) 2024 Your Name

;; Author: Your Name <your.email@example.com>
;; URL: https://github.com/username/ob-elixir
;; Keywords: literate programming, reproducible research, elixir
;; Version: 0.1.0
;; Package-Requires: ((emacs "27.1") (org "9.4"))

;; This file is not part of GNU Emacs.

;; 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.

;;; Commentary:

;; Org Babel support for evaluating Elixir code blocks.
;;
;; Features:
;; - Execute Elixir code in org-mode source blocks
;; - Support for :results value and :results output
;; - Variable passing with :var header argument
;; - Mix project context support
;;
;; Usage:
;; Add (elixir . t) to `org-babel-load-languages':
;;
;;   (org-babel-do-load-languages
;;    'org-babel-load-languages
;;    '((elixir . t)))

;;; Code:

(require 'ob)
(require 'ob-eval)

;;; Customization

(defgroup ob-elixir nil
  "Org Babel support for Elixir."
  :group 'org-babel
  :prefix "ob-elixir-")

(defcustom ob-elixir-command "elixir"
  "Command to execute Elixir code.
Can be a full path or command name if in PATH."
  :type 'string
  :group 'ob-elixir
  :safe #'stringp)

;;; Header Arguments

(defvar org-babel-default-header-args:elixir
  '((:results . "value")
    (:session . "none"))
  "Default header arguments for Elixir code blocks.")

;;; Language Registration

;; File extension for tangling
(add-to-list 'org-babel-tangle-lang-exts '("elixir" . "ex"))

;; Associate with elixir-mode for syntax highlighting (if available)
(with-eval-after-load 'org-src
  (add-to-list 'org-src-lang-modes '("elixir" . elixir)))

;;; Execution

(defconst ob-elixir--value-wrapper
  "result = (
%s
)
IO.puts(inspect(result, limit: :infinity, printable_limit: :infinity, charlists: :as_lists))
"
  "Wrapper template for capturing Elixir expression value.
%s is replaced with the user's code.")

(defun ob-elixir--wrap-for-value (body)
  "Wrap BODY to capture its return value.

The wrapper evaluates BODY, then prints the result using
`inspect/2` with infinite limits to avoid truncation."
  (format ob-elixir--value-wrapper body))

(defun ob-elixir--execute (body result-type)
  "Execute BODY as Elixir code.

RESULT-TYPE is either `value' or `output'.
For `value', wraps code to capture return value.
For `output', captures stdout directly.

Returns the result as a string."
  (let* ((tmp-file (org-babel-temp-file "ob-elixir-" ".exs"))
         (code (if (eq result-type 'value)
                   (ob-elixir--wrap-for-value body)
                 body)))
    (with-temp-file tmp-file
      (insert code))
    (let ((result (org-babel-eval
                   (format "%s %s"
                           ob-elixir-command
                           (org-babel-process-file-name tmp-file))
                   "")))
      (string-trim result))))

(defun org-babel-execute:elixir (body params)
  "Execute a block of Elixir code with org-babel.

BODY is the Elixir code to execute.
PARAMS is an alist of header arguments.

This function is called by `org-babel-execute-src-block'."
  (let* ((result-type (cdr (assq :result-type params)))
         (result-params (cdr (assq :result-params params)))
         (result (ob-elixir--execute body result-type)))
    (org-babel-reassemble-table
     (org-babel-result-cond result-params
       result
       (org-babel-script-escape result))
     (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))))))

(provide 'ob-elixir)
;;; ob-elixir.el ends here