;;; eshell-dat.el --- A better `cat' for Eshell -*- lexical-binding: t -*-

;;; Commentary:

;; An alternative to `eshell/cat'.  If you `dat' an image file it will be
;; displayed as a thumbnail in the terminal similar to Kitty's "icat" or the
;; "catimg" command.  If you Dat a file it will be shown with syntax
;; highlighting, sort of like how the "bat" command can be configured.

;; This is mostly lifted directly from
;; https://emacs.stackexchange.com/questions/3432/display-images-in-eshell-with-iimage-mode
;; and also a bit from https://github.com/manateelazycat/aweshell/blob/d246df619573ca3f46070cc0ac82d024271ed243/aweshell.el#L775
;; . However, I have gone ahead and cleaned up function names, et cetera.

;;; Code:

(defvar em-dat--old-eshell/cat (symbol-function 'eshell/cat))
(defvar em-dat--right-pad 50
  "Padding to use on the right of images displayed by `dat'.")

(defun em-dat--max-width (window)
  (- (window-width window t) em-dat--right-pad))

(defun em-dat--txtfile-print (filename)
  "Propertize the contents of FILENAME and output to terminal."
  (let ((existing-buffer (get-file-buffer filename))
	(buffer (find-file-noselect filename)))
    (eshell-print
     (with-current-buffer buffer
       (if (fboundp 'font-lock-ensure)
	   (font-lock-ensure)
	 (with-no-warnings
	   (font-lock-fontify-buffer)))
       (let ((contents (buffer-string)))
	 (remove-text-properties 0 (length contents) '(read-only nil) contents)
	 contents)))
    (unless existing-buffer
      (kill-buffer buffer)) nil))

(defun em-dat--imagep (filename)
  "Check if FILENAME is an image."
  (let ((extension (file-name-extension filename))
	(image-extensions '("png" "jpg" "bmp")))
    (member extension image-extensions)))
(defun em-dat--image-width (filename)
  "Get the width of the image FILENAME, using imagemagick."
  (string-to-number
   (shell-command-to-string
    (format "convert '%s' -ping -format \"%%w\" info:" filename))))
(defun em-dat--rescale-image (filename)
  "Rescale image FILENAME to a maximum width, or leave untouched if already
small.  Returns the new file path."
  (let ((file (make-temp-file "resized_emacs"))
	(max-width (em-dat--max-width (get-buffer-window (current-buffer)))))
    (if (> (em-dat--image-width filename) max-width)
	(progn
	  (shell-command-to-string
	   (format "convert -resize %dx '%s' '%s'" max-width filename file))
	  file)
      filename)))
(defun em-dat--image-print (file)
  "Print the single image FILE."
  (eshell/printnl (propertize " " 'display (create-image file))))

(defun em-dat--videop (filename)
  "Check if FILENAME is a video."
  (let ((extension (file-name-extension filename))
	(image-extensions '("mp4" "mov" "mkv")))
    (member extension image-extensions)))
(defun em-dat--vid2img (filename)
  "Given video FILENAME, return the path to a newly created thumbnail image."
  (let* ((width (em-dat--max-width (get-buffer-window (current-buffer))))
	 (new-fpath (make-temp-file "thumbnail_emacs")))
    (shell-command-to-string
     (format "ffmpegthumbnailer -i '%s' -f -s '%s' -o '%s'"
	     filename
	     width
	     new-fpath))
    new-fpath))
(defun eshell/dat (&rest args)
  "Wrapper around `em-dat--txtfile-print' for multiple ARGS.

Also, can cat images for some reason."
  (setq args (eshell-stringify-list (flatten-tree args)))
  (dolist (file args)
    (if (string= file "-")
	(apply 'em-dat--old-eshell/cat file)
      (cond ((em-dat--imagep file) (em-dat--image-print
				    (em-dat--rescale-image file)))
	    ((em-dat--videop file) (em-dat--image-print
				    (em-dat--vid2img file)))
	    (t (em-dat--txtfile-print file))))))

(put 'eshell/dat 'eshell-no-numeric-conversions t)
(put 'eshell/dat 'eshell-filename-arguments t)

(provide 'eshell-dat)
;;; eshell-dat.el ends here