ftw

(defcustom ftw-leader-key "C-a"
  "Customizable contol key for ftw navigation")

(defun left-edge (win)
  (let ((edges (window-edges win)))
    (nth 0 edges)))

(defun right-edge (win)
  (let ((edges (window-edges win)))
    (nth 2 edges)))

(defun top-edge (win)
  (let ((edges (window-edges win)))
    (nth 1 edges)))

(defun bottom-edge (win)
  (let ((edges (window-edges win)))
    (nth 3 edges)))

(defun win-width (win) 
  (- (right-edge win)
     (left-edge win)))

(defun win-height (win)
  (- (bottom-edge win)
     (top-edge win)))

(defun find-left (win)
  (let ((lwin))
    (walk-windows
     (lambda (wwin)
       (if (= (right-edge wwin)
	      (left-edge win))
	   (setq lwin wwin))))
    lwin))

(defun find-right (win)
  (let ((rwin))
    (walk-windows
     (lambda (wwin)
       (if (= (left-edge wwin)
	      (right-edge win))
	   (setq rwin wwin))))
    rwin))

(defun find-up (win)
  (let ((uwin))
    (walk-windows
     (lambda (wwin)
       (if (= (bottom-edge wwin)
	      (top-edge win))
	   (setq uwin wwin))))
    uwin))

(defun find-down (win)
  (let ((dwin))
    (walk-windows
     (lambda (wwin)
       (if (= (top-edge wwin)
	      (bottom-edge win))
	   (setq dwin wwin))))
    dwin))

(defun ftw-v () 
  (interactive)
  (split-window (selected-window) (/ (win-width (selected-window)) 2) t))

(defun ftw-h ()
  (interactive)
  (split-window (selected-window) (/ (win-height (selected-window)) 2)))

(defun ftw-del ()
  (interactive)
  (delete-window (selected-window)))

(defun ftw-right ()
  (interactive)
  (let ((rwin (find-right (selected-window))))
    (if rwin 
	(select-window rwin))))

(defun ftw-left ()
  (interactive)
  (let ((lwin (find-left (selected-window))))
    (if lwin 
	(select-window lwin))))

(defun ftw-up ()
  (interactive)
  (let ((uwin (find-up (selected-window))))
    (if uwin
	(select-window uwin))))

(defun ftw-down ()
  (interactive)
  (let ((dwin (find-down (selected-window))))
    (if dwin
	(select-window dwin))))


;;;###autoload
(define-minor-mode ftw-mode
  "For the window navigation"
  :global T
  :lighter " ftw"
  :keymap (let ((map (make-sparse-keymap)))
	    (define-key map (kbd (format "%s V" ftw-leader-key)) 'ftw-v)
	    (define-key map (kbd (format "%s H" ftw-leader-key)) 'ftw-h)
	    (define-key map (kbd (format "%s x" ftw-leader-key)) 'ftw-del)
	    (define-key map (kbd (format "%s h" ftw-leader-key)) 'ftw-left)
	    (define-key map (kbd (format "%s l" ftw-leader-key)) 'ftw-right)
	    (define-key map (kbd (format "%s k" ftw-leader-key)) 'ftw-up)
	    (define-key map (kbd (format "%s j" ftw-leader-key)) 'ftw-down)
	    map))

(provide 'ftw)