;;; conlanging-eittlandic.el --- Helper functions for the Eittlandic language -*- lexical-binding: t -*-

;; Author: Lucien Cartier-Tilet <lucien@phundrak.com>
;; Maintainer: Lucien Cartier-Tilet <lucien@phundrak.com>
;; Version: 0.1.0
;; Homepage: https://labs.phundrak.com/phundrak/conlanging.el
;; Keywords: convenience


;; 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.

;; This program 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 this program.  If not, see <https://www.gnu.org/licenses/>.

;;; Commentary:
;; This file includes functions to help write the documentation for
;; the Eittlandic language faster.

;;; Code:

(require 'dash)

(defconst conlanging-eittlandic--strong-common-noun-declension
  '((nil . "r") (nil . nil) (nil . nil) ("a" . "r")
    (nil . "r") (nil . nil) (nil . "um") ("a" . "r"))
  "Declensions of strong common nouns in Eittlandic.

The first element of a pair is the vowel to use if there is no
underlying vowel.  The second element is the declension suffix.

The order of the suffixes go like this:
- singular nominative
- singular accusative
- singular dative
- singular genitive
- plural nominative
- plural accusative
- plural dative
- plural genitive")

(defconst conlanging-eittlandic--strong-common-definite-noun-declension
  '(("i" . "nn") ("i" . "n") ("i" . "n") ("i" . "ns")
    ("i" . "nn") ("i" . "n") ("i" . "num") ("i" . "n"))
  "Declension of definite strong common nouns in Eittlandic.

See `conlanging-eittlandic--strong-common-noun-declension' for more info.")

(defconst conlanging-eittlandic--strong-neuter-noun-declension
  '((nil . nil) (nil . nil) (nil . nil) (nil . "s")
    (nil . nil) (nil . nil) (nil . "um") (nil . "s"))
  "Declensions of strong neuter nouns in Eittlandic.

See `conlanging-eittlandic--strong-common-noun-declension' for more info.")

(defconst conlanging-eittlandic--weak-noun-declension
  '((nil . nil) (nil . nil) (nil . nil) (nil . "s")
    (nil . "r") (nil . nil) (nil . "um") (nil . "s"))
  "Declensions of weak nouns in Eittlandic.

See `conlanging-eittlandic--strong-common-noun-declension' for more info.")

(defconst conlanging-eittlandic--other-definite-noun-declension
  '(("i" . "t") ("i" . "t") ("i" . "t") ("i" . "ts")
    ("i" . "tr") ("i" . "t") ("i" . "tum") ("i" . "t"))
  "Declensions of definite strong neutral and weak nouns in Eittlandic.

See `conlanging-eittlandic--strong-common-noun-declension' for more info.")

(defun conlanging-eittlandic--maybe-underlying-vowel (underlying-vowel default-vowel)
  "Return which underlying vowel should be used.

If DEFAULT-VOWEL is nil, it means there is no need to insert a
vowel.  However, if it is not, it should be used, unless
UNDERLYING-VOWEL is non-nil."
  (if default-vowel
      (if underlying-vowel underlying-vowel default-vowel)
    ""))

(defun conlanging-eittlandic--split-list (list)
  "Splits LIST int two halves and return both halves as a cons cell."
  (let* ((half (floor (length list) 2))
         (first-half (seq-subseq list 0 half))
         (second-half (seq-subseq list half)))
    (cons first-half second-half)))

(defun conlanging-eittlandic--make-noun-declension-from-table (root underlying-vowel table)
  "Decline a noun ROOT (with maybe an UNDERLYING-VOWEL) with TABLE."
  (seq-reverse
   (let (result)
     (dolist (declension table result)
       (push (concat root
                     (conlanging-eittlandic--maybe-underlying-vowel underlying-vowel (car declension))
                     (cdr declension))
             result)))))

(defun conlanging-eittlandic--make-noun-declension (root gender strength underlying-vowel &optional definite)
  "Create declensions of a word in Eittlandic.

Based on a word’s ROOT, GENDER, STRENGTH, UNDERLYING-VOWEL, and
whether it’s DEFINITE, create the declensions of a word as a
list, going in the following order:
- singular nominative
- singular accusative
- singular dative
- singular genitive
- plural nominative
- plural accusative
- plural dative
- plural genitive"
  (conlanging-eittlandic--make-noun-declension-from-table
   root underlying-vowel
   (if definite
       (if (and (eq 'strong strength) (eq 'common gender))
           conlanging-eittlandic--strong-common-definite-noun-declension
         conlanging-eittlandic--other-definite-noun-declension)
     (if (eq 'weak strength)
         conlanging-eittlandic--weak-noun-declension
       (if (eq 'common gender)
           conlanging-eittlandic--strong-common-noun-declension
         conlanging-eittlandic--strong-neuter-noun-declension)))))

(defmacro conlanging-eittlandic--build-noun-declension-org ()
  "Just to avoid typing all of this out."
  `(format "|      | Sg. | Def.Sg. | Pl. | Def.Pl. |
|------+-----+---------+-----+---------|
| Nom. | %s | %s | %s | %s |
| Acc. | %s | %s | %s | %s |
| Dat. | %s | %s | %s | %s |
| Gen. | %s | %s | %s | %s |"
           ,@(reverse (let (accessors i)
                        (dolist (case '(nominative accusative dative genitive) accessors)
                          (setq i 0)
                          (while (<= i 3)
                            (push `(nth ,i ,case) accessors)
                            (setq i (1+ i))))))))

;;;###autoload
(defun conlanging-eittlandic-insert-noun-declensions (root gender strength underlying-vowel)
  "Insert declensions of ROOT in org format at point.

The function will know how to create the declensions on ROOT
depending on its GENDER and its STRENGTH (whether it is a strong
or weak noun).  The UNDERLYING-VOWEL may or may not be nil and
can influence the word's declensions."
  (interactive
   (list
    (read-string "Word root: ")
    (pcase (completing-read "Gender: " '("masculine" "feminine" "common" "neuter") nil t)
      ("masculine" 'common)
      ("feminine" 'common)
      ("common" 'common)
      ("neuter" 'neuter)
      (other (error (format "Unknown gender: %S" other))))
    (pcase (completing-read "Strength: " '("strong" "weak") nil t)
      ("strong" 'strong)
      ("weak" 'weak)
      (other (error (format "Unknown strength: %S" other))))
    (let ((vowel (read-string "Underlying vowel (leave blank if none): ")))
      (if (string= "" vowel) nil vowel))))
  (let* ((indefinite (conlanging-eittlandic--make-noun-declension root gender strength underlying-vowel))
         (definite (conlanging-eittlandic--make-noun-declension root gender strength underlying-vowel t))
         (indefinite-split (conlanging-eittlandic--split-list indefinite))
         (definite-split (conlanging-eittlandic--split-list definite))
         (zipped (-zip (car indefinite-split) (car definite-split) (cdr indefinite-split) (cdr definite-split)))
         (nominative (nth 0 zipped))
         (accusative (nth 1 zipped))
         (dative     (nth 2 zipped))
         (genitive   (nth 3 zipped)))
    (insert (conlanging-eittlandic--build-noun-declension-org))))

(provide 'conlanging-eittlandic)

;;; conlanging-eittlandic.el ends here