;;; oni-eshell.el --- Eshell configuration           -*- lexical-binding: t; -*-

;; Copyright (C) 2019  Tom Willemse

;; Author: Tom Willemse <tom@ryuslash.org>
;; Keywords: local
;; Version: 2023.0414.233822
;; Package-Requires: (eshell-fringe-status esh-autosuggest xterm-color eshell-syntax-highlighting)

;; This program is free software; you can redistribute it and/or modify
;; it under the terms of the GNU General Public License as published by
;; the Free Software Foundation, either version 3 of the License, or
;; (at your option) any later version.

;; This program is distributed in the hope that it will be useful,
;; but WITHOUT ANY WARRANTY; without even the implied warranty of
;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
;; GNU General Public License for more details.

;; You should have received a copy of the GNU General Public License
;; along with this program.  If not, see <https://www.gnu.org/licenses/>.

;;; Commentary:

;; Eshell configuration.

;;; Code:

(require 'eshell)

(require 'em-dirs)
(require 'em-prompt)
(require 'esh-autosuggest)
(require 'xterm-color)

(defun oni-eshell--C-d ()
  "Call `delete-char' or close the buffer if it fails."
  (interactive)
  (condition-case err
      (call-interactively #'delete-char)
    (error (if (and (eq (car err) 'end-of-buffer)
                    (looking-back eshell-prompt-regexp nil))
               (kill-buffer)
             (signal (car err) (cdr err))))))

(defun oni-eshell--enable-truncating-buffers ()
  "Add `eshell-truncate-buffer' to `eshell-output-filter-functions'."
  (add-to-list 'eshell-output-filter-functions 'eshell-truncate-buffer))

(defun oni-eshell--enable-xterm-filter ()
  "Add ‘xterm-color-filter’ to ‘eshell-preoutput-filter-functions’."
  (add-to-list 'eshell-preoutput-filter-functions 'xterm-color-filter))

(defun oni-eshell--disable-ansi-color-handling ()
  "Remove ‘eshell-handle-ansi-color’ from ‘eshell-output-filter-functions’."
  (setq eshell-output-filter-functions
        (remove 'eshell-handle-ansi-color eshell-output-filter-functions)))

(defun oni-eshell--expand-keymap ()
  "Set `C-d' to quit eshell if used at end of prompt."
  (define-key eshell-mode-map (kbd "C-d") #'oni-eshell--C-d)
  (define-key eshell-mode-map (kbd "C-c b") #'oni-eshell-goto-buffer-directory))

(defun oni-eshell--set-xterm-variables ()
  "Set ‘xterm-color-preserve-properties’ to t."
  (setq xterm-color-preserve-properties t))

(defun oni-eshell-fix-esh-autosuggest-active-keymap ()
  "Set ‘company-posframe-active-map’ to ‘esh-autosuggest-active-map’."
  (setq-local company-posframe-active-map esh-autosuggest-active-map))

(defun oni-eshell-goto-buffer-directory (buffer-name)
  "Change the current directory to the given BUFFER-NAME’s directory."
  (interactive
   (list (read-buffer "Switch to buffer’s directory: "
                      nil t (lambda (buf)
                              (let ((b (if (consp buf)
                                           (cdr buf)
                                         (get-buffer buf))))
                                (buffer-file-name b))))))
  (eshell/cd (file-name-directory (buffer-file-name (get-buffer buffer-name))))
  (eshell-reset))

(defun oni-eshell-disable-beacon-on-scroll ()
  "Disable ‘beacon-blink-when-window-scrolls’ in the current buffer."
  (setq-local beacon-blink-when-window-scrolls nil))

(defun oni-eshell-change-font ()
  "Remap the default font to the one I use for terminals."
  (face-remap-add-relative 'default :family "Classic Console Neue"))

(defun oni-eshell-set-page-delimiter ()
  "Change the page delimiter so that it matches the prompt for easy navigation."
  (setq-local page-delimiter eshell-prompt-regexp))

(add-hook 'eshell-before-prompt-hook #'oni-eshell--set-xterm-variables)
(add-hook 'eshell-first-time-mode-hook #'oni-eshell--expand-keymap)
(add-hook 'eshell-load-hook #'oni-eshell--disable-ansi-color-handling)
(add-hook 'eshell-load-hook #'oni-eshell--enable-truncating-buffers)
(add-hook 'eshell-load-hook #'oni-eshell--enable-xterm-filter)
(add-hook 'eshell-mode-hook #'oni-eshell-change-font)
(add-hook 'eshell-mode-hook #'oni-eshell-disable-beacon-on-scroll)
(add-hook 'eshell-mode-hook #'oni-eshell-set-page-delimiter)
(add-hook 'eshell-mode-hook 'esh-autosuggest-mode)
(add-hook 'eshell-mode-hook 'eshell-syntax-highlighting-mode)
(add-hook 'eshell-mode-hook 'goto-address-mode)

(add-hook 'esh-autosuggest-mode-hook #'oni-eshell-fix-esh-autosuggest-active-keymap)

(when (display-graphic-p)
  (add-hook 'eshell-mode-hook 'eshell-fringe-status-mode))

(setenv "TERM" "xterm-256color")

(add-to-list 'display-buffer-alist
             '("\\`\\*eshell" display-buffer-at-bottom
               (side . bottom)
               (slot . 0)
               (window-height . 0.33)))

;;; Eshell prompt

(defun oni-eshell-shortest-unique-directory (current-path directory)
  "Find the shortest unique substring of DIRECTORY.
DIRECTORY should be a directory that exists within CURRENT-PATH."
  (catch 'result
    (dotimes (i (length directory))
      (let* ((current-directory (substring directory 0 (1+ i)))
             (dir-rx (rx string-start
                         (literal current-directory)
                         (zero-or-more any)))
             (matches (directory-files current-path nil dir-rx)))
        (when (= (length matches) 1)
          (throw 'result current-directory))))))

(defun oni-eshell-shorten-directory (directory)
  "Shorten DIRECTORY to the shortest unique names of each directory."
  (let ((current-path "/")
        (current-short-path "/")
        (home (concat (getenv "HOME") "/"))
        (components (string-split (expand-file-name directory) "/" t)))
    (dolist (dir components current-short-path)
      (let* ((shortened (propertize (oni-eshell-shortest-unique-directory current-path dir)
                                    'help-echo dir))
             (new-path (format "%s%s/" current-path dir))
             (new-short-path (if (string= new-path home)
                                 "~/"
                               (format "%s%s/" current-short-path shortened))))
        (setq current-path new-path
              current-short-path new-short-path)))))

(defun oni-eshell-show-perforce-info-p ()
  "Predicate to indicate whether or not powershell info should be shown."
  (locate-dominating-file "." ".p4config"))

(defun oni-eshell-perforce-workspace ()
  "Function returning the current Perforce workspace."
  (car (map-elt (mapcar (lambda (str) (split-string str ": "))
                    (split-string (shell-command-to-string "p4 info -s") "\n"))
            "Client name")))

(defun oni-eshell-perforce-root ()
  "Function returning the root directory of the current Perforce workspace."
  (string-replace
   "\\"
   "/"
   (car (map-elt (mapcar (lambda (str) (split-string str ": "))
                         (split-string (shell-command-to-string "p4 info") "\n"))
                 "Client root"))))

(defun oni-eshell-perforce-stream ()
  "Function returning the current Perforce stream."
  (string-trim-right (shell-command-to-string "p4 switch")))

(defun oni-eshell-prompt-function ()
  "Construct a prompt string for Eshell."
  (let* ((perforcep (oni-eshell-show-perforce-info-p))
         (pwd (eshell/pwd))
         (dir (if perforcep
                  (concat (propertize (oni-eshell-perforce-workspace)
                                      'face '((foreground-color . "#ca3cad90828e")))
                          ":"
                          (let ((relative-path (string-remove-prefix (oni-eshell-perforce-root) pwd)))
                            (if (string= relative-path "") "/" relative-path)))
                (oni-eshell-shorten-directory pwd)))
         (stream (if perforcep (concat " ("
                                       (propertize (oni-eshell-perforce-stream)
                                                   'face '((foreground-color . "#90e4ca3c828e")))
                                       ")")
                   "")))
    (concat dir
            stream
            (if (= (user-uid) 0) " # " " $ "))))

(setq eshell-prompt-function #'oni-eshell-prompt-function)

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