;;;; Copyright © 2023, Jaidyn Ann <jadedctrl@posteo.at>
;;;;
;;;; 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/>.

;;;; FLORA-SEARCH-AURORA.UI
;;;; Generic menu-making, displaying, and management.
;;;; Let's get to it, we're on a deadline!

(in-package :flora-search-aurora.menu)


;;; ———————————————————————————————————
;;; Menu loops
;;; ——————————————————————————————————
(defun make-menu-state (menu-list)
  "Return a state-function for the game’s main menu, for use with STATE-LOOP."
  (lambda (matrix)
    (📋:menu-state matrix menu-list)))


(defun menu-state (matrix menu-plist)
  "Render a menu in menu-plist format to the given matrix, and process user-input.
A state-function for use with the #'state-loop."
  (sleep .02)
  (menu-state-draw matrix menu-plist)
  (menu-state-update menu-plist))


(defun menu-state-draw (matrix menu-plist)
  "Render a menu in menu-plist format to the given matrix.
A core part of #'menu-state."
  (render-menu-items matrix menu-plist 0 0))


(defun menu-state-update (menu-plist)
  "Update a menu — that is, take user input and modify the menu’s plist appropriately.
A core part of #'menu-state."
  (progress-menu-items menu-plist)
  (process-menu-input menu-plist))



;;; ———————————————————————————————————
;;; Menu display
;;; ———————————————————————————————————
(defun render-menu-item
    (matrix text x y &key (width (+ (length text) 2)) (height 3) (selection 0) (selected nil))
  "Render a “menu-item” — that is, text surrounded by a box with an optional
'selected' form. If selected is a non-zero number below 100, then that percent
of the box will be displayed as selected/highlighted. This percent is from
left-to-right, unless negative — in which case, right-to-left."
  (✎:render-string matrix text (list :x (+ x 1) :y (+ 1 y)) :width width)
  ;; Render the normal top and bottom bars.
  (dotimes (i width)
    (setf (aref matrix y (+ x i)) #\-)
    (setf (aref matrix (+ y (- height 1)) (+ x i)) #\-))

  ;; Render the weird “selected” top and bottom bars. A menu item might be
  ;; only partially-selected…
  (if (and selection
           (not (eq selection 0)))
      (let* ((bar-width
               (…:at-most width (ceiling (* width (* (abs selection)
                                                     .01)))))
             (bar-start (if (> 0 selection) (- width bar-width) 0)))
        (dotimes (i bar-width)
          (setf (aref matrix y (+ x bar-start i)) #\=)
          (setf (aref matrix (+ y (- height 1)) (+ x bar-start i)) #\=))))

  ;; Render the horizontal “earmuffs” for helping the selected item stand out.
  (when selected
    (dotimes (i (- height 2))
     (setf (aref matrix (+ y i 1) x) #\|)
     (setf (aref matrix (+ y i 1) (+ x width -1)) #\|))
   matrix))


(defun render-menu-items (matrix items x y &key (max-item-width 12) (height 3))
  "Render several menu items to the matrix, starting at the given x/y coordinates,
maximum width for any given item, and the height of all items.
The item list should be an plist of the following format:
   (((LABEL :en “BIRD” :eo “BIRDO”)(SELECTED . T)(SELECTION . 100))
    ((LABEL :en “BAR” :eo “BARO”)(SELECTION . -20)) ⋯)"
  (let ((row-x’es '()))
    (mapcar
     (lambda (item)
       (let* ((label (…:getf-lang item))
              (selection (or (getf item :selection)
                             0))
              (width (…:at-most max-item-width
                                (+ (length label) 2)))
              (row (or (getf item :row) 0))
              (item-x (or (getf row-x’es row) x))
              (item-y (+ y (* row height))))
         (render-menu-item matrix label
                           item-x item-y
                           :width width
                           :height height
                           :selection selection
                           :selected (getf item :selected))
         (setf (getf row-x’es row) (+ item-x width 1))))
     items))
  matrix)



;;; ———————————————————————————————————
;;; Menu logic
;;; ———————————————————————————————————
(defun progress-menu-items (menu-plist)
  "Given an property list of menu-items, decrement or increment each
item's “selected-percentage”, so that they converge at the right percent.
That is, 0 for non-selected items and 100 for selected items."
  (mapcar
   (lambda (item)
     (let* ((selection (or (getf item :selection) 0))
            (selectedp (getf item :selected)))
       (if selection
           (setf (getf item :selection)
                 (gravitate-toward
                  (cond ((and selectedp (< selection 0) 0)
                         -100)
                        (selectedp 100)
                        ('t 0))
                  selection 10)))))
   menu-plist)
  menu-plist)


(defun process-menu-input (menu-plist)
  "Get and process any keyboard input, modifying the menu plist as necessary."
  (if (listen)
      (let* ((input (⌨:read-gamefied-char-plist))
             (selected-item (nth (selected-menu-item-position menu-plist)
                                 menu-plist))
             (func (getf selected-item :function))
             (return-val-p (member :return selected-item))
             (return-val (getf selected-item :return)))
        (case (getf input :semantic)
          ('⌨:→ (progn (select-right-menu-item menu-plist)
                       't))
          ('⌨:← (progn (select-left-menu-item menu-plist)
                       't))
          ('⌨:↑ (progn (select-up-menu-item menu-plist)
                 't))
          ('⌨:↓ (progn (select-down-menu-item menu-plist)
                       't))
          ('⌨:↰ (progn (select-up-menu-item menu-plist)
                       (select-left-menu-item menu-plist)
                       't))
          ('⌨:↱ (progn (select-up-menu-item menu-plist)
                       (select-right-menu-item menu-plist)
                       't))
          ('⌨:↲ (progn (select-down-menu-item menu-plist)
                       (select-left-menu-item menu-plist)
                       't))
          ('⌨:↳ (progn (select-down-menu-item menu-plist)
                       (select-right-menu-item menu-plist)
                       't))
          ('⌨:❎
           nil)
          ('⌨:🆗
           (cond ((and func return-val-p)
                  (apply func '())
                  return-val)
                 (func
                  (apply func '()))
                 (return-val-p
                  return-val)
                 ('t
                  't)))
          (otherwise 't)))
      't))


(defun select-menu-item (menu-plist position)
  "Given a menu property list, select the menu-item at the given position."
  (let ((old-position (selected-menu-item-position menu-plist)))
    ;; The “polarity” (direction of selection) depends on the relative
    ;; direction of the previous selection.
    (setf (getf (nth position menu-plist) :selection)
      (if (< old-position position) 10 -10))
    (setf (getf (nth position menu-plist) :selected) 't)
    ;; Likewise for the previously-selected item.
    (setf (getf (nth old-position menu-plist) :selection)
          (if (< old-position position) -90 90))
    (setf (getf (nth old-position menu-plist) :selected) nil))
  menu-plist)


(defun select-next-item-of-row (menu-plist row)
  "Given a specific ROW, select the next item following the currently-selected
on that same ROW."
  (let* ((selected-n (selected-menu-item-position menu-plist)))
    (loop for i from (1+ selected-n) upto (length menu-plist)
         do (when (eq (or (getf (nth i menu-plist) :row) 0) row)
              (return (select-menu-item menu-plist i))))))


(defun select-previous-item-of-row (menu-plist row)
  "Given a specific ROW, select the next item preceding the currently-selected
on that same ROW."
  (when (>= row 0)
    (let* ((selected-n (selected-menu-item-position menu-plist)))
       (loop for i from (1- selected-n) downto 0
             do (when (eq (or (getf (nth i menu-plist) :row) 0) row)
                  (return (select-menu-item menu-plist i)))))))


(defun select-right-menu-item (menu-plist)
  "Select the item to the right of the currenty-selected item."
  (select-next-item-of-row
   menu-plist
   (or (getf (nth (selected-menu-item-position menu-plist) menu-plist) :row)
       0)))


(defun select-left-menu-item (menu-plist)
  "Select the item to the right of the currenty-selected item."
  (select-previous-item-of-row
   menu-plist
   (or (getf (nth (selected-menu-item-position menu-plist) menu-plist) :row)
       0)))


(defun select-up-menu-item (menu-plist)
  "Select the next item above the currently-selected item."
  (select-previous-item-of-row
   menu-plist
   (1- (or (getf (nth (selected-menu-item-position menu-plist) menu-plist) :row)
           1))))

(defun select-down-menu-item (menu-plist)
  "Select the next item to below the currently-selected item."
  (select-next-item-of-row
   menu-plist
   (1+ (or (getf (nth (selected-menu-item-position menu-plist) menu-plist) :row)
           0))))


(defun selected-menu-item-position (menu-plist)
  "Returns the index of the menu plist's selected item."
  (or (position
       't menu-plist
       :test (lambda (ignore list-item)
               (getf list-item :selected)))
      0))



;;; ———————————————————————————————————
;;; Misc. utils
;;; ———————————————————————————————————
(defun gravitate-toward (goal num delta)
  "Either add to a number, or subtract from it; whichever brings it closer to zero.
In addition, the resultant value shall not “pass” zero."
  (cond
    ((< num goal)
     (…:at-most goal (+ num delta)))
    ((> num goal)
     (…:at-least goal (- num delta)))
    ('t
     goal)))


;;"---{=============   -------------------"
;; | Kill your mom |    Give into despair
;; ---{=============   -------------------