;;; colorscheme.el --- Syntax highlight and friends -*- lexical-binding: t -*-
;; Author: William Carroll <wpcarro@gmail.com>

;;; Commentary:
;;
;; TODO: Clarify this.
;; Since I have my own definition of "theme", which couples wallpaper, font,
;; with Emacs's traditional notion of the word "theme", I'm choosing to use
;; "colorscheme" to refer to *just* the notion of syntax highlight etc.

;;; Code:

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;; Dependencies
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(require 'cycle)

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;; Constants
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(defcustom colorscheme/install-kbds? t
  "If non-nil, enable the keybindings.")

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;; Library
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(defcustom colorscheme/whitelist
  (cycle/from-list
   (custom-available-themes))
  "The whitelist of colorschemes through which to cycle.")

(defun colorscheme/current ()
  "Return the currently enabled colorscheme."
  (cycle/current colorscheme/whitelist))

(defun colorscheme/disable-all ()
  "Disable all currently enabled colorschemes."
  (interactive)
  (->> custom-enabled-themes
       (list/map #'disable-theme)))

(defun colorscheme/set (theme)
    "Call `load-theme' with `THEME', ensuring that the line numbers are bright.
There is no hook that I'm aware of to handle this more elegantly."
    (load-theme theme)
    (prelude/set-line-number-color "#da5468"))

(defun colorscheme/whitelist-set (colorscheme)
  "Focus the COLORSCHEME in the `colorscheme/whitelist' cycle."
  (cycle/focus (lambda (x) (equal x colorscheme)) colorscheme/whitelist)
  (colorscheme/set (colorscheme/current)))

(defun colorscheme/ivy-select ()
  "Load a colorscheme using ivy."
  (interactive)
  (let ((theme (ivy-read "Theme: " (cycle/to-list colorscheme/whitelist))))
    (colorscheme/disable-all)
    (colorscheme/set (intern theme))))

(cl-defun colorscheme/cycle (&key forward?)
  "Cycle next if `FORWARD?' is non-nil.
Cycle prev otherwise."
  (disable-theme (cycle/current colorscheme/whitelist))
  (let ((theme (if forward?
                   (cycle/next colorscheme/whitelist)
                 (cycle/prev colorscheme/whitelist))))
    (colorscheme/load theme)
    (message (s-concat "Active theme: " (symbol/to-string theme)))))

(defun colorscheme/next ()
  "Disable the currently active theme and load the next theme."
  (interactive)
  (colorscheme/cycle :forward? t))

(defun colorscheme/prev ()
  "Disable the currently active theme and load the previous theme."
  (interactive)
  (colorscheme/cycle :forward? nil))

;; Keybindings
;; TODO: Prefer minor mode definition with a custom keymap.
(when colorscheme/install-kbds?
  (evil-leader/set-key
    "Ft" #'colorscheme/next
    "Pt" #'colorscheme/prev))

(provide 'colorscheme)
;;; colorscheme.el ends here