;;; my-eshell.el --- Configure eshell -*- lexical-binding: t -*-

;;; Commentary:

;;; Code:

(require 'cl-seq)
(require 'vc)
(require 'eshell)
(require 'esh-mode)
(require 'esh-module)

(setq eshell-modules-list
      '(eshell-alias
        eshell-basic
        eshell-cmpl
        eshell-dirs
        eshell-glob
        eshell-hist
        eshell-ls
        eshell-pred
        eshell-prompt
        eshell-script
        eshell-term
        eshell-tramp
        eshell-unix))

(require 'em-alias)
(require 'em-basic)
(require 'em-dirs)
(require 'em-glob)
(require 'em-hist)
(require 'em-term)
(require 'em-tramp)
(require 'em-prompt)

(defun my/eshell-mode-setup ()
  "Configures various aliases for eshell."
  (eshell/alias "e" "find-file $1")
  (eshell/alias "emacs" "find-file $1")
  (eshell/alias "ee" "find-file-other-window $1")
  (eshell/alias "ll" "ls -l")
  (eshell/alias "d" "dired $1")
  (eshell/alias "gs" "vc-diff")
  (eshell/alias "cal" "calendar")
  (eshell/alias "agenda" "org-agenda"))

(defvar-local my/eshell-output-buffer "*Exported eshell output*"
  "Name of buffer with the last output of Eshell command.")

(defvar-local my/eshell-output-delimiter "---"
  "Delimiter for successive `prot-eshell-export' outputs.")

(defun my/eshell--command-prompt-output ()
  "Capture last command prompt and its output."
  (let ((beg (save-excursion
               (goto-char (eshell-beginning-of-input))
               (goto-char (point-at-bol)))))
  (when (derived-mode-p 'eshell-mode)
    (buffer-substring-no-properties beg (eshell-end-of-output)))))

;; https://gitlab.com/protesilaos/dotfiles/-/blob/master/emacs/.emacs.d/prot-lisp/prot-eshell.el#L114
(defun my/eshell-export ()
  "Produce a buffer with output of the last Eshell command.
If `my/eshell-output-buffer' does not exist, create it.  Else
append to it, while separating multiple outputs with
`my/eshell-output-delimiter'."
  (interactive)
  (let ((eshell-output (my/eshell--command-prompt-output)))
    (with-current-buffer (get-buffer-create my/eshell-output-buffer)
      (goto-char (point-max))
      (unless (eq (point-min) (point-max))
        (insert (format "\n%s\n\n" my/eshell-output-delimiter)))
      (goto-char (point-at-bol))
      (insert eshell-output)
      (switch-to-buffer-other-window (current-buffer)))))

(defun my/short-pwd (path)
  "Turn a PATH of the form /foo/bar/baz into /f/b/baz, like fish shell."
  (let* ((home-path (replace-regexp-in-string (expand-file-name "~")
                                          "~"
                                          path))
         (current-dir (split-string home-path "/"))
         (cdir (last current-dir))
         (head (butlast current-dir)))
    (concat (mapconcat (lambda (s)
                         (if (string= "" s) nil
                           (substring s 0 1)))
                       head
                       "/")
            (if head "/" nil)
            (car cdir))))

(defmacro with-face (str &rest properties)
  "Set the PROPERTIES for the given STR."
  `(propertize ,str 'face (list ,@properties)))

(defun my/prompt ()
  "EShell prompt displaying VC info and such."
  (concat
   (with-face (concat (my/short-pwd (eshell/pwd)) " ") :foreground  "#070707")
   (if (= 0 (user-uid))
       (with-face "#" :foreground "#f43841")
     (with-face "λ" :foreground "#63c904"))
   (with-face " " :foreground "#000000")))

(define-key eshell-mode-map (kbd "C-c e e") 'my/eshell-export)

(customize-set-variable 'eshell-scroll-to-bottom-on-input 'all)
(customize-set-variable 'eshell-error-if-no-glob t)
(customize-set-variable 'eshell-hist-ignoredups t)
(customize-set-variable 'eshell-save-history-on-exit t)
(customize-set-variable 'eshell-cd-on-directory t)
(customize-set-variable 'eshell-prefer-lisp-functions nil)
(customize-set-variable 'eshell-prompt-function 'my/prompt)
(customize-set-variable 'eshell-highlight-prompt nil)
(customize-set-variable 'eshell-where-to-jump 'begin)
(customize-set-variable 'eshell-review-quick-commands nil)
(customize-set-variable 'tramp-shell-prompt-pattern "^[^$>\n]*[#$%>] *\\(customize-set-variable '\[[0-9;]*[a-zA-Z] *\\)*")
(customize-set-variable 'eshell-destroy-buffer-when-process-dies t)

(add-hook 'eshell-mode-hook 'my/eshell-mode-setup)

(provide 'my-eshell)

;;; my-eshell.el ends here