;;; Eshell

;;; Eshell gets initialized differently.  When eshell.el first gets loaded, only
;;; the core is defined and `eshell-load-hook' is called. For every Eshell
;;; session, `eshell-mode' is run: it resets `eshell-mode-map', it loads
;;; modules, runs their hooks and concludes with `eshell-first-time-mode-hook'
;;; (for the first session only) and `eshell-mode-hook'.

(setq eshell-directory-name (concat emacs-cache-folder "eshell"))

;;; Use native 'sudo', system sudo asks for password every time.
(require 'em-tramp)

(with-eval-after-load "esh-module" ; Need a file name because `provide' is before the definition of `eshell-modules-list.
  ;; Don't print the banner.
  (delq 'eshell-banner eshell-modules-list)
  (push 'eshell-tramp eshell-modules-list))

(setq
 eshell-ls-use-colors t
 ;; ffap-shell-prompt-regexp changes the behaviour of `helm-find-files' when
 ;; point is on prompt. I find this disturbing.
 ffap-shell-prompt-regexp nil
 eshell-destroy-buffer-when-process-dies t)

;; TODO: Hour is printed twice. We don't need to set this?
;; (setq eshell-ls-date-format (replace-regexp-in-string "^\\+*" "" (getenv "TIME_STYLE")))

;;; Leave `eshell-highlight-prompt' to t as it sets the read-only property.
(setq eshell-prompt-function
      (lambda nil
        (let ((path (abbreviate-file-name (eshell/pwd))))
          (concat
           (format
            (propertize "(%s@%s)[%s]\n>" 'face '(:weight bold))
            (propertize (user-login-name) 'face '(:foreground "cyan"))
            (propertize (system-name) 'face '(:foreground "cyan"))
            (propertize path 'face `(:foreground ,(if (= (user-uid) 0) "red" "green") :weight bold)))
           " "))))
;;; If the prompt spans over multiple lines, the regexp should match
;;; last line only.
(setq-default eshell-prompt-regexp "^> ")

(with-eval-after-load 'em-term
  (nconc eshell-visual-commands
         '("abook" "alsamixer" "cmus" "fzf" "htop" "mpsyt" "mpv" "mutt" "ncdu" "newsbeuter" "pinentry-curses" "ranger" "watch"))
  (setq eshell-visual-subcommands
        '(("git" "log" "l" "lol" "diff" "d" "dc" "show")
          ("sudo" "vi"))))

;;; Support for Emacs' pinentry
(setq epa-pinentry-mode 'loopback)
(pinentry-start)

;;; Alias management possibilities:
;;; - Version eshell-alias and store it in user-emacs-directory. Simplest and
;;; fastest, but aliases cannot be included conditionnaly, e.g. depending on the
;;; existence of a program.
;;; - Store eshell-alias in cache and populate it dynamically on startup.
;; (setq eshell-aliases-file (concat user-emacs-directory "eshell-alias"))
;;;
;;; `eshell/alias' is too slow as it reads and write the file on each definition.
;;; Let's write manually instead.
(with-eval-after-load 'em-alias
  ;;; TODO: This conflicts with `evil-define-key' during the initialization of
  ;;; the first eshell session: the map in insert-mode will not take the changes
  ;;; into account. Going to normal mode and back to insert mode works.
  (eshell-read-aliases-list)
  (dolist
      (alias
       '(("l" "ls -1 $*")
         ("la" "ls -lAh $*")
         ("ll" "ls -lh $*")
         ;; ("ls" "ls -F $*")
         ;; ("emacs" "find-file $1")
         ;; ("em" "find-file $*")
         ("cp" "*cp -i $*")
         ("mv" "*mv -i $*")
         ("mkdir" "*mkdir -p $*")
         ("mkcd" "*mkdir -p $* && cd $1")))
    (add-to-list 'eshell-command-aliases-list alias))
  (eshell-write-aliases-list))

;;; Hooks
;;; `nobreak-char-display' makes some output look weird, e.g. with 'tree'.
(add-hook 'eshell-mode-hook 'turn-off-nobreak-char-display)
(add-hook 'eshell-mode-hook 'eshell-cmpl-initialize)

;;; REVIEW: Emacs' standard functions fail when output has empty lines.
;;; This implementation is more reliable.
;;; Reported at https://debbugs.gnu.org/cgi/bugreport.cgi?bug=27405.
(with-eval-after-load 'em-prompt
  (defun eshell-next-prompt (n)
    "Move to end of Nth next prompt in the buffer.
See `eshell-prompt-regexp'."
    (interactive "p")
    (re-search-forward eshell-prompt-regexp nil t n)
    (when eshell-highlight-prompt
      (while (not (get-text-property (line-beginning-position) 'read-only) )
        (re-search-forward eshell-prompt-regexp nil t n)))
    (eshell-skip-prompt))

  (defun eshell-previous-prompt (n)
    "Move to end of Nth previous prompt in the buffer.
See `eshell-prompt-regexp'."
    (interactive "p")
    (backward-char)
    (eshell-next-prompt (- n))))

(when (require 'bash-completion nil t)
  ;; REVIEW: `bash-completion-dynamic-complete-0' is almost what we want for eshell, it only needs a tiny modification.
  ;; Ask upstream to change the function arguments.
  ;; See https://github.com/szermatt/emacs-bash-completion/issues/13.
  (defun bash-completion-eshell-complete ()
    (cl-letf (((symbol-function 'comint-line-beginning-position)
               #'(lambda () (save-excursion (eshell-bol) (point)))))
      (bash-completion-dynamic-complete)))

  (defun eshell-set-default-completion ()
    (setq pcomplete-default-completion-function
          (lambda ()
            ;; TODO: Sometimes `eshell-default-completion-function' does better, e.g. "gcc <TAB>" shows .c files.
            ;; Does it matter since we have Helm at hand?
            ;; TODO: Lot's of things don't complete well, like "go". Use fish if available.
            (while (pcomplete-here (nth 2 (bash-completion-eshell-complete)))))))
  ;; `eshell-set-default-completion' must be run after `eshell-cmpl-initialize'.
  (add-hook 'eshell-mode-hook 'eshell-set-default-completion t))

(provide 'init-eshell)