;; moe-theme-switcher.el
;; Author: kuanyui (azazabc123@gmail.com)
;; Date: 2013/05/11 11:39
;;
;; This file is not a part of GNU Emacs,
;; but this file is released under GPL v3.

(require 'moe-dark-theme)
(require 'moe-light-theme)
(require 'moe-theme)

(defvar moe-theme-switch-by-sunrise-and-sunset t
"Automatically switch between dark and light moe-theme.

If this value is nil, moe-theme will switch at fixed time (06:00 and 18:00).

If this value is t and both calendar-latitude and calendar-longitude are set
properly, the switching will be triggered at the sunrise and sunset time of the
local calendar.

Take Keelung, Taiwan(25N,121E) for example, you can set like this:

	(setq calendar-latitude +25)
	(setq calendar-longitude +121)"
)

(defvar moe-theme-which-enabled nil
  "Variable indicate which theme (moe-dark or light) is being used.")

(defun moe-load-theme (switch-to)
  "Avoid unnecessary load-theme and screen flashing in GUI version Emacs"
  (cond ((equal switch-to 'light)
         (if (not (equal moe-theme-which-enabled 'light))
           (progn (moe-light)
                  (setq moe-theme-which-enabled 'light)))) ;[FIXME] Maybe unnecessary
        ((equal switch-to 'dark)
         (if (not (equal moe-theme-which-enabled 'dark))
           (progn (moe-dark)
                  (setq moe-theme-which-enabled 'dark)))))) ;[FIXME] Maybe unnecessary

(defun switch-at-fixed-time ()
  (let ((now (string-to-number (format-time-string "%H"))))
    (if (and (>= now 06) (<= now 18))
        (moe-load-theme 'light)
      (moe-load-theme 'dark))
    nil))

;; (Thanks for letoh!)
;; Fix strange bahavior of sunrise-sunset when buffer's width is too narrow.
(defun get-sunrise-sunset-string ()
  "get the real result from `sunrise-sunset'"
  (save-window-excursion
    (let ((regex "[0-9]+:[0-9]+[ap]m")
          (s (sunrise-sunset))
          (buf (get-buffer "*temp*")))
      (unless (and (stringp s)
                   (string-match-p regex s))
        (when buf
          (with-current-buffer buf
            (let* ((s1 (buffer-string))
                   (s2 (if (string-match-p regex s1)
                           s1 nil)))
              (setq s s2)
              (kill-buffer buf)))))
      s)))

;; Convert am/pm to 24hr and save to 24h/sunrise & 24h/set
;; Excute every 24 hr
(defun convert-time-format-of-sunrise-and-sunset ()
  (let (rise_set a b c d e f)
    (setq rise_set (get-sunrise-sunset-string))
    (if (string-match "0:00 hours daylight" rise_set) ;If polar-night
        (progn
          (setq 24h/sunrise 'polar-night
                24h/sunset 'polar-night))
      (if (string-match "24:00 hours daylight" rise_set) ;If midnight-sun
          (progn
            (setq 24h/sunrise 'midnight-sun
                  24h/sunset 'midnight-sun))
        (progn                          ;Convert 12hr to 24hr
          (string-match "\\([0-9][0-9]?\\):\\([0-9][0-9]\\)\\([ap]m\\).+\\([0-9][0-9]?\\):\\([0-9][0-9]\\)\\([ap]m\\)" rise_set)
          (setq a (string-to-number (match-string 1 rise_set))
                b (string-to-number (match-string 2 rise_set))
               c (match-string 3 rise_set)
               d (string-to-number (match-string 4 rise_set))
               e (string-to-number (match-string 5 rise_set))
               f (match-string 6 rise_set))
         (if (equal c "pm")
             (setq 24h/sunrise (list (+ 12 a) b))
           (setq 24h/sunrise (list a b)))
         (if (equal f "pm")
             (setq 24h/sunset (list (+ 12 d) e))
           (setq 24h/sunset (list d e))))))))

;; Excute every minute.
(defun switch-by-locale ()
  (if (equal 24h/sunrise 'polar-night)  ;If polar-night...moe-dark!
      (moe-load-theme 'dark)
    (if (equal 24h/sunrise 'midnight-sun) ;If midnight-sun...moe-light!
        (moe-load-theme 'light)
      (progn
       (let ((now (list (string-to-number (format-time-string "%H"))
                        (string-to-number (format-time-string "%M")))))
         (if (and (or                        ;magic-logic [tm]
                   (> (car now) (car 24h/sunrise))
                   (and
                    (= (car now) (car 24h/sunrise))
                    (>= (second now) (second 24h/sunrise))))
                  (or
                   (< (car now) (car 24h/sunset))
                   (and
                    (= (car now) (car 24h/sunset))
                    (< (second now) (second 24h/sunset)))))
             (moe-load-theme 'light)
           (moe-load-theme 'dark)
           ))))))

(defun moe-theme-auto-switch ()
  "Automatically switch between dark and light moe-theme."
  (interactive)
  (if (boundp '24h/sunrise)
      (switch-by-locale)
    (switch-at-fixed-time))
  )

(if (and
     (boundp 'calendar-longitude)
     (boundp 'calendar-latitude)
     (eql moe-theme-switch-by-sunrise-and-sunset t))
    (progn
      (convert-time-format-of-sunrise-and-sunset)
      (run-with-timer 0 (* 60 60 24) 'convert-time-format-of-sunrise-and-sunset))
  ()
  )

(setq moe-timer (run-with-timer 0 (* 1 60) 'moe-theme-auto-switch))

;; [FIXME] A minor-mode to enable/disable moe-theme-switcher
(defun moe-theme-switcher-disable ()
  (interactive)
  (cancel-timer moe-timer))

(moe-theme-auto-switch)

(provide 'moe-theme-switcher)