;;; -*- lexical-binding: t -*-
(require 'org)

;; Mapping of skews to tags active for that skew.
;; Pairs with symbol keys makes it a p-list.
(defconst recipe-skews '(normal (core) fluffy (core fluff)))

(defun recipe-get-skew ()
  "Get the current skew, error if invalid."
  (let* ((skew-str (or (getenv "SKEW") "normal"))
         (skew (car (read-from-string skew-str)))) ;; converts str "normal" to symbol 'normal
    (unless (plist-member recipe-skews skew)
      (error (format "Invalid skew: %s" skew)))
    skew))

(defun recipe-active (tag)
  "Return t if TAG active or nil if not."
  (let ((active-tags (plist-get recipe-skews recipe-skew)))
    (if (not active-tags)
        (error (format "No tags for skew: %s" recipe-skew))
      (member tag active-tags))))

(defun recipe-tangle-for (tag)
  "Return :tangle output for TAG, depending on whether it is active."
  (if (recipe-active tag) recipe-out-file "no"))

;; The current skew
(defvar recipe-skew (recipe-get-skew))
;; Define the out file based on the current skew
(defvar recipe-out-file (format "recipe-%s.tex" recipe-skew))

;; Turn off eval confirmation, since we're using in script mode.
(let ((org-confirm-babel-evaluate nil))
  (org-babel-tangle-file "recipe.org"))