spacemacs/core/core-spacemacs-buffer.el

;;; core-spacemacs-buffer.el --- Spacemacs Core File
;;
;; Copyright (c) 2012-2016 Sylvain Benner & Contributors
;;
;; Author: Sylvain Benner <sylvain.benner@gmail.com>
;; URL: https://github.com/syl20bnr/spacemacs
;;
;; This file is not part of GNU Emacs.
;;
;;; License: GPLv3
;;
;;; Commentary:
;;
;;; Code:

(defconst spacemacs-buffer-version-info "0.200"
  "Current version used to display addition release information.")

(defconst spacemacs-buffer-name "*spacemacs*"
  "The name of the spacemacs buffer.")

(defconst spacemacs-buffer-logo-title "[S P A C E M A C S]"
  "The title displayed beneath the logo.")

(defconst spacemacs-buffer-buttons-startup-lists-offset 25
  "Relative position between the home buffer buttons and startup lists.")

(defconst spacemacs-buffer--window-width 80
  "Current width of the home buffer if responsive, 80 otherwise.
See `dotspacemacs-startup-buffer-responsive'.")

(defconst spacemacs-buffer--cache-file
  (expand-file-name (concat spacemacs-cache-directory "spacemacs-buffer.el"))
  "Cache file for various persistent data for the spacemacs startup buffer.")

(defvar spacemacs-buffer-startup-lists-length 20
  "Length used for startup lists with otherwise unspecified bounds.
Set to nil for unbounded.")

(defvar spacemacs-buffer--release-note-version nil
  "If nil the release note is displayed.
If non nil it contains a version number, if the version number is lesser than
the current version the release note it displayed")

(defvar spacemacs-buffer--note-widgets nil
  "List of widgets used in currently inserted notes.
Allows to keep track of widgets to delete when removing them.")

(defvar spacemacs-buffer--current-note-type nil
  "Type of note currently displayed.")

(defvar spacemacs-buffer--fresh-install
  (not (file-exists-p dotspacemacs-filepath))
  "Non-nil if this Emacs instance if a fresh install.")

(defvar spacemacs-buffer--buttons-position nil
  "Horizontal position of the home buffer buttons.
Internal use, do not set this variable.")

(defvar spacemacs-buffer-mode-map
  (let ((map (make-sparse-keymap)))
    (define-key map [down-mouse-1] 'widget-button-click)
    (define-key map (kbd "RET") 'widget-button-press)

    (define-key map [tab] 'widget-forward)
    (define-key map (kbd "J") 'widget-forward)
    (define-key map (kbd "C-i") 'widget-forward)

    (define-key map [backtab] 'widget-backward)
    (define-key map (kbd "K") 'widget-backward)

    (define-key map (kbd "C-r") 'spacemacs-buffer/refresh)
    (define-key map "q" 'quit-window)
    map)
  "Keymap for spacemacs buffer mode.")

(with-eval-after-load 'evil
  (evil-make-overriding-map spacemacs-buffer-mode-map 'motion))

(define-derived-mode spacemacs-buffer-mode fundamental-mode "Spacemacs buffer"
  "Spacemacs major mode for startup screen.
\\<spacemacs-buffer-mode-map>
"
  :group 'spacemacs
  :syntax-table nil
  :abbrev-table nil
  (page-break-lines-mode)
  (setq buffer-read-only t
        truncate-lines t)
  ;; needed to make tab work correctly in terminal
  (evil-define-key 'motion spacemacs-buffer-mode-map
    (kbd "C-i") 'widget-forward)
  ;; motion state since this is a special mode
  (evil-set-initial-state 'spacemacs-buffer-mode 'motion))

(defun spacemacs-buffer//insert-ascii-banner-centered (file)
  "Insert the ascii banner contain in file and center it in the window.
FILE: the path to the file containing the banner."
  (insert
   (with-temp-buffer
     (insert-file-contents file)
     (let ((banner-width 0))
       (while (not (eobp))
         (let ((line-length (- (line-end-position) (line-beginning-position))))
           (if (< banner-width line-length)
               (setq banner-width line-length)))
         (forward-line 1))
       (goto-char 0)
       (let ((margin (max 0 (floor (/ (- spacemacs-buffer--window-width
                                         banner-width) 2)))))
         (while (not (eobp))
           (insert (make-string margin ?\ ))
           (forward-line 1))))
     (buffer-string))))

(defun spacemacs-buffer/insert-banner-and-buttons ()
  "Choose a banner according to `dotspacemacs-startup-banner'and insert it.
in spacemacs buffer along with quick buttons underneath.
Easter egg:
Doge special text banner can be reachable via `999', `doge' or `random*'.
Cate special text banner can de reachable via `998', `cat' or `random*'.
`random' ignore special banners whereas `random*' does not."
  (let ((banner (spacemacs-buffer//choose-banner))
        (buffer-read-only nil))
    (progn
      (when banner
        (spacemacs-buffer/message (format "Banner: %s" banner))
        (if (image-type-available-p (intern (file-name-extension banner)))
            (spacemacs-buffer//insert-image-banner banner)
          (spacemacs-buffer//insert-ascii-banner-centered banner))
        (spacemacs-buffer//inject-version))
      (spacemacs-buffer//insert-buttons)
      (spacemacs//redisplay))))

(defun spacemacs-buffer/display-startup-note ()
  "Decide of the startup note and display it if relevant."
  (when (file-exists-p spacemacs-buffer--cache-file)
    (load spacemacs-buffer--cache-file))
  (cond
   (spacemacs-buffer--fresh-install
    ;; we assume the user is  new to spacemacs and open the quickhelp
    (spacemacs-buffer/toggle-note 'quickhelp)
    (setq spacemacs-buffer--release-note-version spacemacs-version)
    (spacemacs/dump-vars-to-file '(spacemacs-buffer--release-note-version)
                                 spacemacs-buffer--cache-file))
   ((or (not spacemacs-buffer--release-note-version)
        (version< spacemacs-buffer--release-note-version
                  spacemacs-version))
    ;; check the variable ;; spacemacs-buffer--release-note-version
    ;; to decide whether ;; we show the release note
    (spacemacs-buffer/toggle-note 'release-note)))
  (spacemacs//redisplay))

(defun spacemacs-buffer//choose-banner ()
  "Return the full path of a banner based on the dotfile value."
  (when dotspacemacs-startup-banner
    (cond ((eq 'official dotspacemacs-startup-banner)
           (if (and (display-graphic-p) (image-type-available-p 'png))
               spacemacs-banner-official-png
             (spacemacs-buffer//get-banner-path 1)))
          ((eq 'random dotspacemacs-startup-banner)
           (spacemacs-buffer//choose-random-text-banner))
          ((eq 'random* dotspacemacs-startup-banner)
           (spacemacs-buffer//choose-random-text-banner t))
          ((eq 'doge dotspacemacs-startup-banner)
           (spacemacs-buffer//get-banner-path 999))
          ((eq 'cat dotspacemacs-startup-banner)
           (spacemacs-buffer//get-banner-path 998))
          ((integerp dotspacemacs-startup-banner)
           (spacemacs-buffer//get-banner-path dotspacemacs-startup-banner))
          ((and dotspacemacs-startup-banner
                (image-type-available-p (intern (file-name-extension
                                                 dotspacemacs-startup-banner)))
                (display-graphic-p))
           (if (file-exists-p dotspacemacs-startup-banner)
               dotspacemacs-startup-banner
             (spacemacs-buffer/warning (format "could not find banner %s"
                                               dotspacemacs-startup-banner))
             (spacemacs-buffer//get-banner-path 1)))
          (t (spacemacs-buffer//get-banner-path 1)))))

(defvar spacemacs-buffer--random-banner nil
  "The random banner chosen.")

(defun spacemacs-buffer//choose-random-text-banner (&optional all)
  "Return the full path of a banner chosen randomly.
If ALL is non-nil then truly all banners can be selected."
  (setq spacemacs-buffer--random-banner
        (or spacemacs-buffer--random-banner
            (let* ((files (directory-files spacemacs-banner-directory t ".*\.txt"))
                   (count (length files))
                   ;; -2 to remove the two last ones (easter eggs)
                   (choice (random (- count (if all 0 2)))))
              (nth choice files)))))

(defun spacemacs-buffer//get-banner-path (index)
  "Return the full path to banner with index INDEX."
  (concat spacemacs-banner-directory (format "%03d-banner.txt" index)))

(defun spacemacs-buffer//insert-image-banner (banner)
  "Display an image banner.
BANNER: the path to an ascii banner file."
  (when (file-exists-p banner)
    (let* ((title spacemacs-buffer-logo-title)
           (spec (create-image banner))
           (size (image-size spec))
           (width (car size))
           (left-margin (max 0 (floor (- spacemacs-buffer--window-width width) 2))))
      (goto-char (point-min))
      (insert "\n")
      (insert (make-string left-margin ?\ ))
      (insert-image spec)
      (insert "\n\n")
      (insert (make-string (max 0 (floor (/ (- spacemacs-buffer--window-width
                                               (+ (length title) 1)) 2))) ?\ ))
      (insert (format "%s\n\n" title)))))

(defun spacemacs-buffer//inject-version ()
  "Inject the current version of spacemacs.
Insert it in the first line of the buffer, right justified."
  (with-current-buffer (get-buffer-create spacemacs-buffer-name)
    (save-excursion
      (let ((maxcol spacemacs-buffer--window-width)
            (version (format "%s@%s (%s)"
                             spacemacs-version
                             emacs-version
                             dotspacemacs-distribution))
            (buffer-read-only nil))
        (goto-char (point-min))
        (delete-region (point) (progn (end-of-line) (point)))
        (insert (format (format "%%%ds" maxcol) version))))))

(defun spacemacs-buffer//insert-footer ()
  "Insert the footer of the home buffer."
  (save-excursion
    (let* ((maxcol spacemacs-buffer--window-width)
           (badge-path spacemacs-badge-official-png)
           (badge (when (and (display-graphic-p)
                             (image-type-available-p
                              (intern (file-name-extension badge-path))))
                    (create-image badge-path)))
           (badge-size (when badge (car (image-size badge))))
           (heart-path spacemacs-purple-heart-png)
           (heart (when (and (display-graphic-p)
                             (image-type-available-p
                              (intern (file-name-extension badge-path))))
                    (create-image heart-path)))
           (heart-size (when heart (car (image-size heart))))
           (build-lhs "Made with ")
           (build-rhs " by the community")
           (buffer-read-only nil))
      (when (or badge heart)
        (goto-char (point-max))
        (spacemacs-buffer/insert-page-break)
        (insert "\n")
        (when badge
          (insert (make-string (floor (/ (- maxcol badge-size) 2)) ?\ ))
          (insert-image badge))
        (when heart
          (when badge (insert "\n\n"))
          (insert (make-string (floor (/ (- maxcol
                                            (length build-lhs)
                                            heart-size
                                            (length build-rhs)) 2)) ?\ ))
          (insert build-lhs)
          (insert-image heart)
          (insert build-rhs)
          (insert "\n"))))))

(defun spacemacs-buffer//notes-render-framed-text
    (content &optional topcaption botcaption hpadding max-width min-width)
  "Return a formated string framed with plained lines.
The width of the created frame is the width of the content, unless it does not
satisfy max-width or min-width.  Note that max-width can be limited by the
window's width.
CONTENT can be a text or a filepath.
TOPCAPTION is a text to be encrusted at the top of the frame.
BOTCAPTION is a text to be encrusted at the bottom of the frame.
HPADDING is the horizontal spacing between the text and the frame.  The vertical
         spacing is always one line.
MAX-WIDTH is the maximum width of the frame,  frame included.  When
          `dotspacemacs-startup-buffer-responsive' is t, MAX-WIDTH will be
          limited to the window's width.  MAX-WIDTH takes precedence over
          MIN-WIDTH.
MIN-WIDTH is the minimal width of the frame, frame included.  The frame will not
          shrink any thinner than MIN-WIDTH characters unless MAX-WIDTH says
          otherwise."
  (with-temp-buffer
    (if (not (file-exists-p content))
        (insert content)
      (insert-file-contents content)
      (goto-char (point-max))
      (when (eq ?\n (char-before))    ;; remove additional newline at eof
        (delete-char -1)))
    (let* ((hpadding (if hpadding hpadding 1))
           (text-width (spacemacs-buffer//get-buffer-width))
           (width (+ 2 (* 2 hpadding) text-width))
           (fill-column text-width)
           (sentence-end-double-space nil)    ; needed by fill-region
           (paragraph-start "\f\\|[ \t]*$\\|[ \t]*[-+*] \\|[ \t]*[0-9]+[.)] ")
           (topcaption-length (if topcaption (length topcaption) 0))
           (botcaption-length (if botcaption (length botcaption) 0)))
      (setq max-width (or max-width width)
            min-width (or min-width 1)
            max-width (if (< max-width min-width) min-width max-width)
            max-width (if (> max-width spacemacs-buffer--window-width)
                              spacemacs-buffer--window-width
                            max-width))
      (when (< width min-width)
        (setq width min-width
              fill-column (max 0 (- min-width 2 (* hpadding 2)))))
      (when (> width max-width)
        (setq width max-width
              fill-column (max 0 (- max-width 2 (* hpadding 2)))))
      (spacemacs-buffer||notes-adapt-caption-to-width topcaption
                                                      topcaption-length
                                                      width)
      (spacemacs-buffer||notes-adapt-caption-to-width botcaption
                                                      botcaption-length
                                                      width)
      (fill-region (point-min) (point-max) nil nil)
      (concat
       "╭─" (when topcaption (propertize (concat " " topcaption " ")
                                         'face
                                         '(:weight bold)))
       (make-string (max 0 (- width (if topcaption 6 4) topcaption-length)) ?─) "─╮\n"
       (spacemacs-buffer//notes-render-framed-line "" width hpadding)
       (mapconcat (lambda (line)
                    (spacemacs-buffer//notes-render-framed-line line width hpadding))
                  (split-string (buffer-string) "\n" nil) "")
       (spacemacs-buffer//notes-render-framed-line "" width hpadding)
       "╰─" (when botcaption (propertize (concat " " botcaption " ")
                                         'face '(:weight bold)))
       (make-string (max 0 (- width (if botcaption 6 4) botcaption-length)) ?─)
       "─╯" (when botcaption "\n")))))

(defmacro spacemacs-buffer||notes-adapt-caption-to-width (caption
                                                          caption-length
                                                          width)
  "Adapt caption string's length to the note's frame current width.
For internal use in `spacemacs-buffer//notes-render-framed-text'.
CAPTION: string to be encrusted onto the note's frame
CAPTION-LENGTH: length of the caption
WIDTH: current external width of the note's frame."
  `(when (> ,caption-length (- ,width 6)) ; minimum frame width is 6
     (if (> ,width 8)
         (setq ,caption (concat (substring ,caption
                                           0
                                           (min -3 (- (- ,width 6 3)
                                                      ,caption-length)))
                                "..."))
       (setq ,caption nil
             ,caption-length 0))))

(defun spacemacs-buffer//notes-render-framed-line (line width hpadding)
  "Return a formated LINE with borders of a frame on each side.
WIDTH: external width of the frame.  LINE should be shorter than WIDTH.
HPADDING: horizontal padding on both sides of the framed string."
  (let ((fill (max 0 (- width 2 hpadding (length line)))))
    (concat "│" (make-string hpadding ?\s) line (make-string fill ?\s)
            "│\n")))

(defun spacemacs-buffer//notes-insert-note
    (file topcaption botcaption &optional additional-widgets)
  "Insert the release note just under the banner.
FILE: the file that contains the content to show.
TOPCAPTION: the title of the note.
BOTCAPTION: a text to be encrusted at the bottom of the frame.
ADDITIONAL-WIDGETS: a function for inserting a widget under the frame."
  (save-excursion
    (goto-char (point-min))
    (search-forward "Search in Spacemacs\]") ; TODO: this is dirty
    (forward-line)
    (let* ((buffer-read-only nil)
           (note (concat "\n"
                         (spacemacs-buffer//notes-render-framed-text file
                                                                     topcaption
                                                                     botcaption
                                                                     2
                                                                     nil
                                                                     80))))
      (save-restriction
        (narrow-to-region (point) (point))
        (add-to-list 'spacemacs-buffer--note-widgets (widget-create 'text note))
        (let* ((width (spacemacs-buffer//get-buffer-width))
               (padding (max 0 (floor (/ (- spacemacs-buffer--window-width
                                            width) 2)))))
          (goto-char (point-min))
          (while (not (eobp))
            (beginning-of-line)
            (insert (make-string padding ?\s))
            (forward-line))))
     (save-excursion
        (while (re-search-backward "\\[\\[\\(.*\\)\\]\\]" nil t)
          (make-text-button (match-beginning 1)
                            (match-end 1)
                            'type 'help-url
                            'help-args (list (match-string 1)))))
      (funcall additional-widgets)
      (spacemacs-buffer//center-line)
      (delete-trailing-whitespace (line-beginning-position)
                                  (line-end-position)))))

(defun spacemacs-buffer//notes-insert-quickhelp ()
  "Insert quickhelp."
  (let ((widget-func
         (lambda ()
           (add-to-list
            'spacemacs-buffer--note-widgets
            (widget-create 'push-button
                           :tag (propertize "Evil Tutorial"
                                            'face 'font-lock-keyword-face)
                           :help-echo
                           "Teach you how to use Vim basics."
                           :action (lambda (&rest ignore)
                                     (call-interactively #'evil-tutor-start))
                           :mouse-face 'highlight
                           :follow-link "\C-m"))
           (widget-insert " ")
           (add-to-list
            'spacemacs-buffer--note-widgets
            (widget-create 'push-button
                           :tag (propertize "Emacs Tutorial"
                                            'face 'font-lock-keyword-face)
                           :help-echo "Teach you how to use Emacs basics."
                           :action (lambda (&rest ignore)
                                     (call-interactively #'help-with-tutorial))
                           :mouse-face 'highlight
                           :follow-link "\C-m"))
           (widget-insert " ")
           (add-to-list
            'spacemacs-buffer--note-widgets
            (widget-create 'push-button
                           :tag (propertize "Vim Migration Guide"
                                            'face 'font-lock-keyword-face)
                           :help-echo "Documentation for former vim users."
                           :action (lambda (&rest ignore)
                                     (spacemacs/view-org-file
                                      (concat spacemacs-docs-directory
                                              "VIMUSERS.org") "^" 'all))
                           :mouse-face 'highlight
                           :follow-link "\C-m")))))
    (spacemacs-buffer//notes-insert-note (concat spacemacs-info-directory
                                                 "quickhelp.txt")
                                         "Quick Help"
                                         nil
                                         widget-func)))

(defun spacemacs-buffer//notes-insert-release-note ()
  "Insert release note."
  (let ((widget-func
         (lambda ()
           (add-to-list
            'spacemacs-buffer--note-widgets
            (widget-create 'push-button
                           :tag (propertize "Click here for full change log"
                                            'face 'font-lock-warning-face)
                           :help-echo "Open the full change log."
                           :action
                           (lambda (&rest ignore)
                             (funcall 'spacemacs/view-org-file
                                      (concat spacemacs-start-directory
                                              "CHANGELOG.org")
                                      (format "Release %s.x"
                                              spacemacs-buffer-version-info)
                                      'subtree))
                           :mouse-face 'highlight
                           :follow-link "\C-m")))))
    (spacemacs-buffer//notes-insert-note (concat spacemacs-release-notes-directory
                                                 spacemacs-buffer-version-info
                                                 ".txt")
                                         (format "Important Notes (Release %s.x)"
                                                 spacemacs-buffer-version-info)
                                         "Update your dotfile (SPC f e D) and\
 packages after every update"
                                         widget-func))
  (setq spacemacs-buffer--release-note-version nil)
  (spacemacs/dump-vars-to-file '(spacemacs-buffer--release-note-version)
                               spacemacs-buffer--cache-file))

(defun spacemacs-buffer//notes-clear-notes-and-widgets ()
  "Remove existing note widgets if exists."
  (when spacemacs-buffer--note-widgets
    (mapc 'widget-delete spacemacs-buffer--note-widgets)
    (setq spacemacs-buffer--note-widgets nil)
    (setq spacemacs-buffer--release-note-version spacemacs-version)
    (spacemacs/dump-vars-to-file
     '(spacemacs-buffer--release-note-version) spacemacs-buffer--cache-file)))

(defun spacemacs-buffer//notes-redisplay-current-note ()
  "Delete and rediplay the currently displayed note."
  (spacemacs-buffer//notes-clear-notes-and-widgets)
  (let ((type spacemacs-buffer--current-note-type))
    (cond
     ((eq type 'quickhelp) (spacemacs-buffer//notes-insert-quickhelp))
     ((eq type 'release-note) (spacemacs-buffer//notes-insert-release-note))
     (t))))

(defun spacemacs-buffer/toggle-note (type)
  "Toggle the displayed note based on TYPE.
If TYPE is nil or unknown, just remove the currently displayed note.  Currently
allowed types are `quickhelp' and `release-note'"
  (spacemacs-buffer//notes-clear-notes-and-widgets)
  (if (or (eq spacemacs-buffer--current-note-type nil)
          (not (eq spacemacs-buffer--current-note-type type)))
      (progn
        (setq spacemacs-buffer--current-note-type type)
        (cond
         ((eq type 'quickhelp) (spacemacs-buffer//notes-insert-quickhelp))
         ((eq type 'release-note) (spacemacs-buffer//notes-insert-release-note))
         (t (setq spacemacs-buffer--current-note-type nil)
            (message "Unknown note type: %s" 'type))))
    (setq spacemacs-buffer--current-note-type nil)))

(defun spacemacs-buffer/set-mode-line (format)
  "Set mode-line format for spacemacs buffer.
FORMAT: the `mode-line-format' variable Emacs will use to build the mode-line."
  (with-current-buffer (get-buffer-create spacemacs-buffer-name)
    (setq mode-line-format format)))

(defun spacemacs-buffer/message (msg &rest args)
  "Display MSG in *Messages* prepended with '(Spacemacs)'.
The message is displayed only if `init-file-debug' is non nil.
ARGS: format string arguments."
  (when init-file-debug
    (message "(Spacemacs) %s" (apply 'format msg args))))

(defvar spacemacs-buffer--warnings nil
  "List of warnings during startup.")

(defun spacemacs-buffer/warning (msg &rest args)
  "Display MSG as a warning message but in buffer `*Messages*'.
ARGS: format string arguments."
  (let ((msg (apply 'format msg args)))
    (message "(Spacemacs) Warning: %s" msg)
    (when message-log-max
      (add-to-list 'spacemacs-buffer--warnings msg 'append))))

(defun spacemacs-buffer/insert-page-break ()
  "Insert a page break line in spacemacs buffer."
  (spacemacs-buffer/append "\n\n"))

(defun spacemacs-buffer/append (msg &optional messagebuf)
  "Append MSG to spacemacs buffer.
If MESSAGEBUF is not nil then MSG is also written in message buffer."
  (with-current-buffer (get-buffer-create spacemacs-buffer-name)
    (goto-char (point-max))
    (let ((buffer-read-only nil))
      (insert msg)
      (if messagebuf (message "(Spacemacs) %s" msg)))
    (spacemacs-buffer/set-mode-line "")))

(defun spacemacs-buffer/replace-last-line (msg &optional messagebuf)
  "Replace the last line of the spacemacs buffer with MSG.
If MESSAGEBUF is not nil then MSG is also written in message buffer."
  (with-current-buffer (get-buffer-create spacemacs-buffer-name)
    (goto-char (point-max))
    (let ((buffer-read-only nil))
      (delete-region (line-beginning-position) (point-max))
      (insert msg)
      (if messagebuf (message "(Spacemacs) %s" msg)))
    (spacemacs-buffer/set-mode-line "")))

(defun spacemacs-buffer/loading-animation ()
  "Display the progress bar by chunks of size `spacemacs--loading-dots-chunk-threshold'."
  (when (and (not noninteractive)
             dotspacemacs-loading-progress-bar)
    (setq spacemacs-loading-counter (1+ spacemacs-loading-counter))
    (setq spacemacs-loading-value (1+ spacemacs-loading-value))
    (when (>= spacemacs-loading-counter spacemacs-loading-dots-chunk-threshold)
      (let ((suffix (format "> %s/%s" spacemacs-loading-value
                            (length configuration-layer--used-packages))))
        (setq spacemacs-loading-counter 0)
        (setq spacemacs-loading-string
              (make-string
               (max 0
                    (- (* spacemacs-loading-dots-chunk-size
                          (floor (/ spacemacs-loading-value
                                    spacemacs-loading-dots-chunk-threshold)))
                       (length suffix)))
               spacemacs-loading-char))
        (spacemacs-buffer/set-mode-line (concat spacemacs-loading-string
                                                suffix)))
      (spacemacs//redisplay))))

(defmacro spacemacs-buffer||add-shortcut
    (shortcut-char search-label &optional no-next-line)
  "Add a single-key keybinding for quick navigation in the home buffer.
Navigation is done by searching for a specific word in the buffer.
SHORTCUT-CHAR: the key that the user will have to press.
SEARCH-LABEL: the word the cursor will be brought under (or on).
NO-NEXT-LINE: if nil the cursor is brought under the searched word."
  `(define-key spacemacs-buffer-mode-map
     ,shortcut-char (lambda ()
                      (interactive)
                      (unless (search-forward ,search-label (point-max) t)
                        (search-backward ,search-label (point-min) t))
                      ,@(unless no-next-line
                          '((forward-line 1)))
                      (back-to-indentation))))

(defun spacemacs-buffer//center-line ()
  "When point is at the end of a line, center it."
  (let* ((width (current-column))
         (margin (max 0 (floor (/ (- spacemacs-buffer--window-width width)
                                  2)))))
    (beginning-of-line)
    (insert (make-string margin ?\ ))
    (end-of-line)))

(defun spacemacs-buffer//insert-buttons ()
  "Create and insert the interactive buttons under Spacemacs banner."
  (goto-char (point-max))
  (spacemacs-buffer||add-shortcut "m" "[?]" t)
  (widget-create 'url-link
                 :tag (propertize "?" 'face 'font-lock-doc-face)
                 :help-echo "Open the quickhelp."
                 :action (lambda (&rest ignore)
                           (spacemacs-buffer/toggle-note 'quickhelp))
                 :mouse-face 'highlight
                 :follow-link "\C-m")
  (insert " ")
  (widget-create 'url-link
                 :tag (propertize "Homepage" 'face 'font-lock-keyword-face)
                 :help-echo "Open the Spacemacs Github page in your browser."
                 :mouse-face 'highlight
                 :follow-link "\C-m"
                 "http://spacemacs.org")
  (insert " ")
  (widget-create 'url-link
                 :tag (propertize "Documentation" 'face 'font-lock-keyword-face)
                 :help-echo "Open the Spacemacs documentation in your browser."
                 :mouse-face 'highlight
                 :follow-link "\C-m"
                 "http://spacemacs.org/doc/DOCUMENTATION.html")
  (insert " ")
  (widget-create 'url-link
                 :tag (propertize "Gitter Chat" 'face 'font-lock-keyword-face)
                 :help-echo
                 "Ask questions and chat with fellow users in our chat room."
                 :mouse-face 'highlight
                 :follow-link "\C-m"
                 "https://gitter.im/syl20bnr/spacemacs")
  (insert " ")
  (widget-create 'push-button
                 :help-echo "Update Spacemacs core and layers."
                 :action (lambda (&rest ignore) (spacemacs/switch-to-version))
                 :mouse-face 'highlight
                 :follow-link "\C-m"
                 (propertize "Update Spacemacs" 'face 'font-lock-keyword-face))
  (let ((len (- (line-end-position)
                (line-beginning-position))))
    (spacemacs-buffer//center-line)
    (setq spacemacs-buffer--buttons-position (- (line-end-position)
                                                (line-beginning-position)
                                                len)))
  (insert "\n")
  (widget-create 'push-button
                 :help-echo "Update all ELPA packages to the latest versions."
                 :action (lambda (&rest ignore)
                           (configuration-layer/update-packages))
                 :mouse-face 'highlight
                 :follow-link "\C-m"
                 (propertize "Update Packages" 'face 'font-lock-keyword-face))
  (insert " ")
  (widget-create 'push-button
                 :help-echo
                 "Rollback ELPA package updates if something got borked."
                 :action (lambda (&rest ignore)
                           (call-interactively 'configuration-layer/rollback))
                 :mouse-face 'highlight
                 :follow-link "\C-m"
                 (propertize "Rollback Package Update"
                             'face 'font-lock-keyword-face))
  (spacemacs-buffer//center-line)
  (insert "\n")
  (widget-create 'push-button
                 :tag (propertize "Release Notes"
                                  'face 'font-lock-preprocessor-face)
                 :help-echo "Hide or show the Changelog"
                 :action (lambda (&rest ignore)
                           (spacemacs-buffer/toggle-note 'release-note))
                 :mouse-face 'highlight
                 :follow-link "\C-m")
  (insert " ")
  (widget-create 'url-link
                 :tag (propertize "Search in Spacemacs"
                                  'face 'font-lock-function-name-face)
                 :help-echo "Search Spacemacs contents."
                 :action
                 (lambda (&rest ignore)
                   (let ((comp-frontend
                          (cond
                           ((configuration-layer/layer-usedp 'helm)
                            'helm-spacemacs-help)
                           ((configuration-layer/layer-usedp 'ivy)
                            'ivy-spacemacs-help))))
                     (call-interactively comp-frontend)))
                 :mouse-face 'highlight
                 :follow-link "\C-m")
  (spacemacs-buffer//center-line)
  (insert "\n\n"))

(defun spacemacs-buffer//insert-string-list (list-display-name list)
  "Insert a non-interactive startup list in the home buffer.
LIST-DISPLAY-NAME: the displayed title of the list.
LIST: a list of strings displayed as entries."
  (when (car list)
    (insert list-display-name)
    (mapc (lambda (el)
            (insert
             "\n"
             (with-temp-buffer
               (insert el)
               (fill-paragraph)
               (goto-char (point-min))
               (insert "    - ")
               (while (= 0 (forward-line))
                 (insert "      "))
               (buffer-string))))
          list)))

(defun spacemacs-buffer//insert-file-list (list-display-name list)
  "Insert an interactive list of files in the home buffer.
LIST-DISPLAY-NAME: the displayed title of the list.
LIST: a list of string pathnames made interactive in this function."
  (when (car list)
    (insert list-display-name)
    (mapc (lambda (el)
            (insert "\n    ")
            (widget-create 'push-button
                           :action `(lambda (&rest ignore)
                                      (find-file-existing ,el))
                           :mouse-face 'highlight
                           :follow-link "\C-m"
                           :button-prefix ""
                           :button-suffix ""
                           :format "%[%t%]"
                           (abbreviate-file-name el)))
          list)))

(defun spacemacs-buffer//insert-bookmark-list (list-display-name list)
  "Insert an interactive list of bookmarks entries (if any) in the home buffer.
LIST-DISPLAY-NAME: the displayed title of the list.
LIST: a list of string bookmark names made interactive in this function."
  (when (car list)
    (insert list-display-name)
    (mapc (lambda (el)
            (insert "\n    ")
            (let ((filename (bookmark-get-filename el)))
              (widget-create 'push-button
                             :action `(lambda (&rest ignore) (bookmark-jump ,el))
                             :mouse-face 'highlight
                             :follow-link "\C-m"
                             :button-prefix ""
                             :button-suffix ""
                             :format "%[%t%]"
                             (if filename
                                 (format "%s - %s"
                                         el (abbreviate-file-name filename))
                               (format "%s" el)))))
          list)))

(defun spacemacs-buffer//get-org-items (types)
  "Make a list of agenda file items for today of kind types.
TYPES: list of `org-mode' types to fetch."
  (require 'org-agenda)
  (let ((date (calendar-gregorian-from-absolute (org-today))))
    (apply #'append
           (loop for file in (org-agenda-files nil 'ifmode)
                 collect
                 (spacemacs-buffer//make-org-items
                  file
                  (apply 'org-agenda-get-day-entries file date
                         types))))))

(defun spacemacs-buffer//agenda-list ()
  "Return today's agenda."
  (require 'org-agenda)
  (spacemacs-buffer//get-org-items org-agenda-entry-types))

(defun spacemacs-buffer//todo-list ()
  "Return current todos."
  (require 'org-agenda)
  (spacemacs-buffer//get-org-items '(:todo)))

(defun spacemacs-buffer//make-org-items (file items)
  "Make a spacemacs-buffer org item list.
FILE: file name.
ITEMS:"
  (loop
   for item in items
   collect
   (spacemacs-buffer//make-org-item file item)))

(defun spacemacs-buffer//make-org-item (file item)
  "Make a spacemacs-buffer version of an org item.
FILE: file name.
ITEM:"
  (list (cons "text"
              (get-text-property 0 'txt item))
        (cons "file" file)
        (cons "pos"
              (marker-position
               (get-text-property 0 'org-marker item)))
        (cons "time"
              (get-text-property 0 'time item))))

(defun spacemacs-buffer//org-jump (el)
  "Action executed when using an item in the home buffer's todo list.
EL: `org-agenda' element to jump to."
  (require 'org-agenda)
  (find-file-other-window (cdr (assoc "file" el)))
  (widen)
  (goto-char (cdr (assoc "pos" el)))
  (when (derived-mode-p 'org-mode)
    (org-show-context 'agenda)
    (save-excursion
      (and (outline-next-heading)
           (org-flag-heading nil)))    ; show the next heading
    (when (outline-invisible-p)
      (outline-show-entry))            ; display invisible text
    (recenter (/ (window-height) 2))
    (org-back-to-heading t)
    (if (re-search-forward org-complex-heading-regexp nil t)
        (goto-char (match-beginning 4))))
  (run-hooks 'org-agenda-after-show-hook))

(defun spacemacs-buffer//insert-todo-list (list-display-name list)
  "Insert an interactive todo list of `org-agenda' entries in the home buffer.
LIST-DISPLAY-NAME: the displayed title of the list.
LIST: list of `org-agenda' entries in the todo list."
  (when (car list)
    (insert list-display-name)
    (setq list (sort list
                     (lambda (a b)
                       (cond
                        ((eq "" (cdr (assoc "time" b)))
                         t)
                        ((eq "" (cdr (assoc "time" a)))
                         nil)
                        (t
                         (string< (cdr (assoc "time" a))
                                  (cdr (assoc "time" b))))))))
    (mapc (lambda (el)
            (insert "\n    ")
            (widget-create 'push-button
                           :action `(lambda (&rest ignore)
                                      (spacemacs-buffer//org-jump ',el))
                           :mouse-face 'highlight
                           :follow-link "\C-m"
                           :button-prefix ""
                           :button-suffix ""
                           :format "%[%t%]"
                           (format "%s %s %s"
                                   (abbreviate-file-name
                                    (cdr (assoc "file" el)))
                                   (if (not (eq "" (cdr (assoc "time" el))))
                                       (format "- %s -"
                                               (cdr (assoc "time" el)))
                                     "-")
                                   (cdr (assoc "text" el)))))
          list)))

(defun spacemacs//subseq (seq start end)
  "Adapted version of `cl-subseq'.
Use `cl-subseq', but accounting for end points greater than the size of the
list.  Return entire list if end is omitted.
SEQ, START and END are the same arguments as for `cl-subseq'"
  (let ((len (length seq)))
    (cl-subseq seq start (and (number-or-marker-p end)
                              (min len end)))))

(defun spacemacs-buffer//do-insert-startupify-lists ()
  "Insert the startup lists in the current buffer."
  (let ((list-separator "\n\n"))
    (mapc (lambda (els)
            (let ((el (or (car-safe els) els))
                  (list-size
                   (or (cdr-safe els)
                       spacemacs-buffer-startup-lists-length)))
              (cond
               ((eq el 'warnings)
                (when (spacemacs-buffer//insert-string-list
                       "Warnings:"
                       spacemacs-buffer--warnings)
                  (spacemacs-buffer||add-shortcut "w" "Warnings:")
                  (insert list-separator)))
               ((eq el 'recents)
                (recentf-mode)
                (when (spacemacs-buffer//insert-file-list
                       "Recent Files:"
                       (spacemacs//subseq recentf-list 0 list-size))
                  (spacemacs-buffer||add-shortcut "r" "Recent Files:")
                  (insert list-separator)))
               ((eq el 'todos)
                (when (spacemacs-buffer//insert-todo-list
                       "ToDo:"
                       (spacemacs//subseq (spacemacs-buffer//todo-list)
                                          0 list-size))
                  (spacemacs-buffer||add-shortcut "d" "ToDo:")
                  (insert list-separator)))
               ((eq el 'agenda)
                (when (spacemacs-buffer//insert-todo-list
                       "Agenda:"
                       (spacemacs//subseq (spacemacs-buffer//agenda-list)
                                          0 list-size))
                  (spacemacs-buffer||add-shortcut "c" "Agenda:")
                  (insert list-separator)))
               ((eq el 'bookmarks)
                (when (configuration-layer/layer-usedp 'spacemacs-helm)
                  (helm-mode))
                (require 'bookmark)
                (when (spacemacs-buffer//insert-bookmark-list
                       "Bookmarks:"
                       (spacemacs//subseq (bookmark-all-names)
                                          0 list-size))
                  (spacemacs-buffer||add-shortcut "b" "Bookmarks:")
                  (insert list-separator)))
               ((and (eq el 'projects)
                     (fboundp 'projectile-mode))
                (projectile-mode)
                (when (spacemacs-buffer//insert-file-list
                       "Projects:"
                       (spacemacs//subseq (projectile-relevant-known-projects)
                                          0 list-size))
                  (spacemacs-buffer||add-shortcut "p" "Projects:")
                  (insert list-separator))))))
          (append
           '(warnings)
           dotspacemacs-startup-lists))))

(defun spacemacs-buffer//get-buffer-width ()
  "Return the length of longest line in the current buffer."
  (save-excursion
    (goto-char 0)
    (let ((current-max 0))
      (while (not (eobp))
        (let ((line-length (- (line-end-position) (line-beginning-position))))
          (if (< current-max line-length)
              (setq current-max line-length)))
        (forward-line 1))
      current-max)))

(defun spacemacs-buffer//center-startup-lists ()
  "Center startup lists after they were inserted."
  (let* ((lists-width (spacemacs-buffer//get-buffer-width))
         (margin (max 0 (- spacemacs-buffer--buttons-position
                           spacemacs-buffer-buttons-startup-lists-offset)))
         (final-padding (if (< spacemacs-buffer--window-width
                               (+ margin lists-width))
                            (max 0 (floor (/ (- spacemacs-buffer--window-width
                                                lists-width)
                                             2)))
                          margin)))
    (goto-char (point-min))
    (while (not (eobp))
      (beginning-of-line)
      (insert (make-string final-padding ?\s))
      (forward-line))))

(defun spacemacs-buffer/insert-startup-lists ()
  "Insert startup lists in home buffer."
  (interactive)
  (with-current-buffer (get-buffer spacemacs-buffer-name)
    (let ((buffer-read-only nil))
      (goto-char (point-max))
      (spacemacs-buffer/insert-page-break)
      (insert "\n")
      (save-restriction
        (narrow-to-region (point) (point))
        (spacemacs-buffer//do-insert-startupify-lists)
        (spacemacs-buffer//center-startup-lists)))))

(defun spacemacs-buffer/goto-link-line ()
  "Set point to the beginning of the link line."
  (interactive)
  (with-current-buffer spacemacs-buffer-name
    (goto-char (point-min))
    (with-demoted-errors "spacemacs buffer error: %s"
      (widget-forward 1))))

(defun spacemacs-buffer//startup-hook ()
  "Code executed when Emacs has finished loading."
  (with-current-buffer (get-buffer spacemacs-buffer-name)
    (when dotspacemacs-startup-lists
      (spacemacs-buffer/insert-startup-lists))
    (spacemacs-buffer//insert-footer)
    (if configuration-layer-error-count
        (progn
          (spacemacs-buffer-mode)
          (spacemacs-buffer/set-mode-line
           (format
            (concat "%s error(s) at startup! "
                    "Spacemacs may not be able to operate properly.")
            configuration-layer-error-count))
          (face-remap-add-relative 'mode-line
                                   '((:background "red") mode-line)))
      (spacemacs-buffer/set-mode-line spacemacs--default-mode-line)
      (spacemacs-buffer-mode))
    (force-mode-line-update)
    (spacemacs-buffer/goto-link-line)))

(defvar spacemacs-buffer--last-width nil
  "Previous width of spacemacs-buffer.")

(defun spacemacs-buffer/goto-buffer (&optional refresh)
  "Create the special buffer for `spacemacs-buffer-mode' and switch to it.
REFRESH if the buffer should be redrawn."
  (interactive)
  (let ((buffer-exists (buffer-live-p (get-buffer spacemacs-buffer-name)))
        (save-line nil))
    (when (not buffer-exists)
      (setq spacemacs-buffer--note-widgets nil))
    (when (or (not (eq spacemacs-buffer--last-width (window-width)))
              (not buffer-exists)
              refresh)
      (setq spacemacs-buffer--window-width
            (if (bound-and-true-p dotspacemacs-startup-buffer-responsive)
		(window-width)
              80)
            spacemacs-buffer--last-width spacemacs-buffer--window-width)
      (with-current-buffer (get-buffer-create spacemacs-buffer-name)
        (page-break-lines-mode)
        (save-excursion
          (when (> (buffer-size) 0)
            (set 'save-line (line-number-at-pos))
            (let ((inhibit-read-only t))
              (erase-buffer)))
          (spacemacs-buffer/set-mode-line "")
          (spacemacs-buffer/insert-banner-and-buttons)
          (if (bound-and-true-p spacemacs-initialized)
              (progn
                (spacemacs-buffer//notes-redisplay-current-note)
                (configuration-layer/display-summary emacs-start-time)
                (when dotspacemacs-startup-lists
                  (spacemacs-buffer/insert-startup-lists))
                (spacemacs-buffer//insert-footer)
                (spacemacs-buffer/set-mode-line spacemacs--default-mode-line)
                (force-mode-line-update)
                (spacemacs-buffer-mode))
            (add-hook 'emacs-startup-hook 'spacemacs-buffer//startup-hook t))))
      (if save-line
          (progn (goto-char (point-min))
                 (forward-line (1- save-line))
                 (forward-to-indentation 0))
        (spacemacs-buffer/goto-link-line))
      (switch-to-buffer spacemacs-buffer-name)
      (spacemacs//redisplay))))

(add-hook 'window-setup-hook
          (lambda ()
            (add-hook 'window-configuration-change-hook
                      'spacemacs-buffer//resize-on-hook)
            (spacemacs-buffer//resize-on-hook)))

(defun spacemacs-buffer//resize-on-hook ()
  "Hook run on window resize events to redisplay the home buffer."
  (let ((home-buffer (get-buffer-window spacemacs-buffer-name))
        (frame-win (frame-selected-window)))
    (when (and dotspacemacs-startup-buffer-responsive
               home-buffer
               (not (window-minibuffer-p frame-win)))
      (with-selected-window home-buffer
        (spacemacs-buffer/goto-buffer)))))

(defun spacemacs-buffer/refresh ()
  "Force recreation of the spacemacs buffer."
  (interactive)
  (setq spacemacs-buffer--last-width nil)
  (spacemacs-buffer/goto-buffer t))

(defalias 'spacemacs/home 'spacemacs-buffer/refresh
  "Go to home Spacemacs buffer")

(defun spacemacs/home-delete-other-windows ()
  "Open home Spacemacs buffer and delete other windows.
Useful for making the home buffer the only visible buffer in the frame."
  (interactive)
  (spacemacs/home)
  (delete-other-windows))

(provide 'core-spacemacs-buffer)

;;; core-spacemacs-buffer ends here