;;; -*- lexical-binding: t -*-
;;
;; --------------------------------------------------------------------------

(require 'cl-lib)
(cl-pushnew "." load-path :test #'string=)
(require 'luki-lisp)

;; --------------------------------------------------------------------------
;; civlized scrolling, one line at a time

(setq scroll-conservatively 10000)
(setq auto-window-vscroll nil)

;; --------------------------------------------------------------------------
;; vertical

(defun scroll-up-1 () (i)
  (scroll-down 1))

(defun scroll-down-1 () (i)
  (scroll-up 1))

;; --------------------------------------------------------------------------
;; automatic

(defun start-automatic-scroll-down () (i)
  (cl-loop
   for win = (window-end) do
   (scroll-down-1)
   (sleep-for 1) ; put speed here in seconds
   (redisplay)
   until (= win (window-end))))

;; (start-automatic-scroll-down)
;;                              ^ test here, stop with C-g

;; --------------------------------------------------------------------------
;; other window

(defun scroll-up-other-window () (i)
  (scroll-other-window-down 1))

(defun scroll-down-other-window () (i)
  (scroll-other-window 1))

;; --------------------------------------------------------------------------
;; panes

(defun get-window-lines ()
  (pcase-let* ((`(,_ ,top ,_ ,bottom)  (window-inside-edges))
               (lines (- bottom top)))
    (if (member major-mode '(Buffer-menu-mode package-menu-mode w3m-mode))
        (1- lines)
      lines)))

(defun scroll-up-pane () (i)
  (condition-case nil
      (or (scroll-down (get-window-lines)) t)
    (error nil)))

(defun scroll-down-pane () (i)
  (condition-case nil
      (or (scroll-up (get-window-lines)) t)
    (error nil)))

;; --------------------------------------------------------------------------
;; horizontal scroll

(put 'scroll-left  'disabled nil)
(put 'scroll-right 'disabled nil)

(setq hscroll-margin 1)
(setq hscroll-step   1)

(defun scroll-left-1 () (i)
  (scroll-right 1 0))

(defun scroll-right-1 () (i)
  (scroll-left 1 0))

;; --------------------------------------------------------------------------
;; keys

(defun set-pane-scroll-keys (kmap)
  "Set KMAP keys for vertical scrolling in panes."
  (keymap-set kmap "I" #'scroll-up-pane)
  (keymap-set kmap "K" #'scroll-down-pane))

(defun set-scroll-keys (kmap &optional hori)
  (when hori
    (keymap-set kmap "j" #'scroll-left-1)
    (keymap-set kmap "l" #'scroll-right-1))
  (keymap-set kmap "i"   #'scroll-up-1)
  (keymap-set kmap "M-i" #'scroll-up-1)
  (keymap-set kmap "k"   #'scroll-down-1)
  (keymap-set kmap "M-k" #'scroll-down-1)
  (set-pane-scroll-keys kmap))

(defun set-vertical-keys (kmap &optional button np tab funs)
  (pcase-let ((`(,up ,down) (or funs
                                (if button
                                    `(,#'backward-button ,#'forward-button)
                                  `(,#'previous-line ,#'forward-line)))))
    (keymap-set kmap "i" up)
    (keymap-set kmap "k" down)
    (when np
      (keymap-set kmap "p" up)
      (keymap-set kmap "n" down))
    (when tab
      (define-key kmap [backtab] up)
      (keymap-set kmap "TAB"     down))))

;; --------------------------------------------------------------------------

(<- 'll-scroll)